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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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CHAPTER 3

MATERIALS SCIENCE AND ENGINEERING AS A MULTI DISC IP LINE*

*  

This chapter draws heavily on the work of COSMAT Panel II, and of its chairman, Richard S.Claassen in particular, and also on the work of Daniel C.Drucker and N.Bruce Hannay of Panel V.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

CHAPTER 3
MATERIALS SCIENCE AND ENGINEERING AS A MULTIDISCIPLINE

MATERIALS, THE MATERIALS CYCLE, AND THE ROLE OF MATERIALS SCIENCE AND ENGINEERING

Materials are ubiquitous, so pervasive we often take them for granted. Yet they play a central role in much of our daily lives, in practically all manufacturing industries, and in much research and development in the physical and engineering sciences. Materials have a generality comparable to that of energy and information, and the three together comprise nearly all technology. For COSMAT purposes, we define materials as substances having properties which make them useful in machines, structures, devices, and products.

It is useful to depict a global materials cycle, shown in the Frontispiece. The earth is the source of all materials as well as the ultimate repository. Minerals and oils are taken from the earth, and trees and vegetable materials are harvested. Through beneficiation, purification, refining, pulping, and other processes these raw materials are converted into useful industrial materials—metals, chemicals, paper, for example. In subsequent processing, these bulk materials are modified to become engineering materials aimed at meeting performance requirements. The engineering materials are then fashioned by manufacturing processes into shapes and parts which are assembled to make a useful end-product. The product, once its useful life has finished, is eventually returned as waste to the earth, or it undergoes dismantling and material recovery to provide basic materials to feed into the materials cycle again.

The materials cycle thus divides naturally into two sections: the left-hand (materials supply) side is primarily concerned with obtaining industrial materials, whether from the earth or by reclamation, and from a knowledge viewpoint is generally within the province of the mineral, earth, and forestry technologies; the right-hand (materials consumption) side is primarily concerned with the uses of industrial materials in the manufacture of structures, devices, and machines, and their subsequent performance. Again, from the knowledge viewpoint, this side of the cycle is the main arena for materials science and engineering, the subject of this report. However, as the diagram clearly brings out, there is intimate interdependence among all stages of the overall materials cycle. The diagram also portrays the role of recycling—any way which enables materials to keep circulating in the right-hand side of the diagram reduces the demand for new raw materials from the earth in the left-

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

hand side.

Any step taken in any part of the materials cycle may have repercussions elsewhere in the cycle. New paths around the cycle are continually being opened up through researches which lead to new materials, new applications, and thereby new demand and consumption patterns for materials. Furthermore, the materials cycle is not an isolated entity: every stage of the cycle consumes energy and can affect the environment. Increasingly, therefore, it is necessary for the specialist in MSE to consider the effects of technological changes on the complete system of the total materials cycle, including energy consumption and environmental quality.

INNOVATION IN MATERIALS SCIENCE AND ENGINEERING

MSE has become a basic instrument in bringing about technological changes. Discoveries of new materials and improvements to old ones—all undergirded by deeper understanding of the intimate relations between the processing, composition, and structure of materials on the one hand, together with their properties and function on the other—lead repeatedly to higher performance and efficiency in existing technologies (e.g. improved process for extracting titanium) and to the creation of new ones (e.g. silicon and the solid-state electronic industry). By the same token, a breakthrough in understanding the physics and chemistry of biocompatibility of synthetic materials could have a dramatic effect on the prosthetics industry.

MSE is both creative and responsive. New insights gained, often unexpectedly, through research on the properties and phenomena exhibited by materials can lead through development and engineering stages to new products and applications of benefit to mankind. But often it is the perception of some potential market or societal need for a product that stimulates the appropriate engineering and development and, in turn, the support of considerable applied and even basic research.

Whether MSE is operating in a creative or a responsive mode, it is having a technological and social impact at a very basic level. Materials as such are usually not very visible to the public that is primarily concerned with end-products and tends to take materials for granted. Yet materials are the working substance of all hardware used in all technologies and are crucial to successful product performance. Between the introduction of materials and the final product, there are often numerous manufacturing stages where extra value is added. Thus, an improved or new material may be decisive in determining the success, usefulness, or social value of a product, even though the cost of the material or the improvement might be very modest compared with the total product or social value. In this sense, materials can frequently be said to exert high economic leverage. Color TV has been made possible by the development of special phosphors; synthetic fibers, such as nylon and dacron, have made drip-dry apparel possible. There are also instances of low leverage in which materials improvements, while useful, do not exert such an enormous change in the end-product or in social patterns; such an example might be the change in steel used for making cans. Materials, and industries devoted completely to them, may represent about one-fifth of the Gross National Product, but without them there would be no Gross National Product.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

Materials are often looked upon as relatively unspecific media which may find their way into a great variety of end-products. New materials or improved ones may lead to a whole variety of end-products involving widely different industries. For example, fiberglass lends itself for use in pleasure boats, as housing construction material, and as automobile bodies. Hence, materials can be said to have a relatively high degree of proprietary neutrality. One consequence of this situation is that materials research often forms a more neutral, yet broadly applicable, base for governmental support and cooperative ventures among companies than does research in various end-product technologies.

Besides the direct application of MSE to technology, innovation in the field can have important consequences for materials demand and consumption patterns, the consumption of energy, and the quality of the environment. MSE can play a vital role in meeting man’s needs for better transportation equipment, prosthetic devices, and the generation, transmission, and storage of energy. But by wreaking such technological changes, it can often change drastically the need or consumption patterns for materials and energy. New materials made from more abundant raw materials can often be developed as substitutes for old ones made from scarcer or ecologically less desirable raw materials; new ways can often be found for performing needed technological functions, e.g. transistors have replaced vacuum-tube triodes as basic amplifying elements in electronic circuits, and in more recent years integrated circuits replaced boxes of complex electronic equipment made up of many components. Looking ahead with another example, present work in certain forms of levitated ground transport, if successful, could lead to greatly increased demands for new magnetic or superconducting alloys. Or again, development of suitable catalysts based on relatively abundant materials could significantly reduce demand for platinum catalysts for treating automobile exhaust gases and for use in chemical processes.

As regards energy-consumption patterns, MSE has much to contribute in all phases—making new forms of generation possible, e.g. by finding solutions to the problem of fuel swelling under radiation damage in nuclear reactors; enabling new forms of electrical power distribution, e.g. through superconducting or cryogenic transmission lines; finding more efficient ways to store energy, e.g. through solid electrolytic batteries or fuel cells; and through finding more efficient ways of using and conserving energy, e.g. in more efficient materials-processing and manufacturing operations, and in the development of better thermal insulation materials.

Concerning environmental quality, MSE has much to contribute in finding, for example, cleaner materials processes, effective uses for waste materials, materials and designs more acceptable from the consumer viewpoint, and in developing instrumentation to monitor and control pollution.

Thus, innovation in MSE can play a significant role in the economy, in raising the standard of living, in minimizing demands for energy, in improving environmental quality, and in reducing demands for imported materials with a consequent favorable impact on the U.S. international trade balance. In the remainder of this chapter, therefore, a detailed examination will be made of the nature and scope of MSE and the factors that influence its potency as a multidiscipline.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

CHANGING CHARACTER OF MATERIALS TECHNOLOGY

Science-Intensive and Experience-Based Technologies

Historically man has made use of materials more-or-less readily available from nature. In this century, however, he has repeatedly demonstrated an ability to synthesize radically new materials to meet increasingly complex and demanding requirements, an ability which so often depends on the latest in scientific knowledge. In fact, so successful has MSE been in recent years that designers and engineers have increasingly come to feel that somehow new materials can be devised, or old ones modified, to meet all manner of unusual requirements.

In the past, remarkable progress has been made in utilizing materials based on empirical knowledge of their properties and behavior related to their source and subsequent treatment. Many of the important alloys and ceramics were initially developed in this way. This approach is still invaluable and widely practiced. Graphite is a recent example of a material which has solved important problems in missiles where it forms rocket nozzles and as structural components in nuclear-power reactors. Yet, the necessary development was achieved by an enlightened empirical approach in a company which was very much material-source oriented. Graphite is a most complex material whose physical properties depend on the nature and processing of raw materials, on the quality of the initial carbon-containing material, on binder pyrolysis, and on a variety of processing variables. The most practical approach to development of a special graphite to withstand high temperature and pressure was a systematic study, therefore, of the dependence of properties on processing parameters. The starting point was an initial observation that hot pressing of normal-density carbon yielded a body of high density and high strength. Science was able to provide only a very general framework for the planning and execution of this program.

This important graphite development also illustrates a governing feature of the historical mode in materials development. Without a complete science framework and lacking a few broad unifying concepts, the practitioner in graphite development necessarily needed to know a very large collection of facts based on past experience in graphite. For that reason, he was material-source oriented and tended to be more affiliated with the material supplier than with the material consumer.

In recent decades, the interest in materials properties has been broadened from that of the supplier to include that of the consumer. In some programs, such as space and the solid-state electronics industry, the material user cannot meet all his objectives with presently existing materials. This, in turn, has often caused the user to become interested in the discovery and development of completely new materials. It has also caused a closer working relationship to be established between the material developer and the material user. Further, the programs which have run into materials limitations of the kind that determine success or failure are, in general, those which are straining for the utmost out of sophisticated science and technology generally. It has, therefore, been natural for the people involved to expect materials development likewise to utilize scientific contributions when available.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

At the same time that the material users have been entering into materials development, the underlying knowledge and understanding in solid-state physics and chemistry has advanced tremendously. These two sciences have evolved several unifying concepts which reach across many materials and now provide common guidance to what seemed previously like disconnected problems in materials development.

Advances of fundamental understanding and the ability to design materials properties to exacting specifications have been most marked in the case of electronic materials. In other areas, our level of fundamental understanding is a long way from enabling us to design materials to withstand new uses and environmental conditions without considerable trial and error. Far from nearing saturation, fundamental understanding of the properties of the vast majority of materials and the consequent ability to develop new materials to specifications has barely begun.

The term science-intensive technology is used to designate those activities in which specific performance is at a premium and in which the generation of new fundamental understanding of materials is necessary before the desired performance can be achieved. Thus the descriptor, science-intensive technology or high technology, usually denotes an emerging area where knowledge and practice are changing rapidly and where there has not yet built up a widely based fund of experience and practical knowledge.

A familiar example to illustrate high technology is the space program where it is mandatory that a component must function in the desired manner at the proper time. Because the entire success of an expensive mission may depend upon the proper functioning of this component it is natural to expend whatever R & D is required to assure success. The actual cost of the materials making up the component becomes a secondary consideration. Another example is found in nuclear-power reactors. Fuel cladding must be of sufficient integrity to guarantee against hazardous release of radioactive byproducts. In the design and fabrication of the fuel cladding, considerable effort at a sophisticated scientific and engineering level is justified to achieve safety goals. In the solid-state electronics industry, we find an example where highly sophisticated and costly effort on materials is justified in terms of the overall product value—both the processing of semiconductor material and the assembly into discrete devices or integrated circuits requires a degree of control which would be unbelievable in most industrial situations.

The term experience-based technology, or low technology, is used to refer to programs which are not science intensive—in other words, which rely on more empirical approaches or which may be highly forgiving of manufacturing and processing variations. Typically, large material quantities are involved so that unit material costs are important. Examples are the manufacturing of dishes and structural steels; many tires are assembled in traditional ways involving much hard work; conventional approaches prevail in the construction of roads and highways where unit cost is of great importance; and the paper industry continues to use long-standing, empirically-derived processes.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

Relative Pace of Innovation

There is a familiar pattern in the growth, development, and diffusion of a technology. At the birth and in the early stages of a new technology, such as solid-state electronics or nuclear-power reactors, the pace of invention is high and the innovating company or nation may well achieve a commanding position in the market for its new technology. In this premarketing stage, cost is of secondary importance, or rather it is an administrative decision related to some perception of the eventual pay-off. Later, the inventive pace begins to slacken while, at the same time, other companies or nations with the necessary educational level and technical competence are acquiring the knowledge and skills to catch up. The formerly commanding position of the original innovator is gradually eroded as the relevant technological capability diffuses nationally and internationally. In this stage, where the technology is termed as becoming mature, commercial advantage is kept by, or passes to, that company or nation that can most effectively minimize production and marketing costs while safeguarding the integrity of the product. Process innovation can then assume more importance than further product innovation.

The early stages of a technology, when the inventive pace is high, are often science-intensive, and are commonly referred to as “high technology.” It seems that high technologies in which the U.S. has been in the forefront, such as aerospace, computers, and nuclear reactors, have also been generally associated with international trade surpluses for the U.S. In the more mature stages, the science content of further developments in the technology can then be referred to as experience-intensive or “low technology.” Such technologies may be assimilated by developing countries, and are more likely to be associated with shifts in trade balance since the latter countries usually enjoy lower costs, primarily through lower labor rates. When a technology reaches this phase, the U.S. runs the risk of becoming quite dependent for further developments in that technology on foreign enterprise. This may be acceptable for some technologies but not for others critical to national economic and military security. The primary metals industries are prime examples of such experience-intensive technologies facing very severe foreign competition. Other industries in which technological leadership may have been lost by the U.S. are tires and various consumer goods such as shoes and bicycles. Still other technologies, some of which are regarded as high technologies, are moving in the same direction, e.g., automobiles, consumer electronics, and certain aircraft products.

The implications for materials technology in the U.S. in order to meet foreign competition and maintain viable domestic industries are that high inventive pace must be created or maintained in certain fields so as to create new high technologies and safeguard existing ones, and that the technological level must be raised and production costs lowered in selected, critical, mature industries. This must be done within the structure of U.S. industry which can be roughly classified, for our purposes, into the materials-producing and the materials-consuming industries. The former tend to be experience-intensive, while high-technology industries tend to fall in the latter category. The high-technology industries, if their commercial bases are sufficiently large, are more accustomed to maintaining a balanced, although product-oriented, R & D effort than are the low-technology industries.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

Disciplinarity, Interdisciplinarity, and Multidisciplinarity

In the materials field, universities have evolved in the past along disciplinary lines—physics, chemistry, metallurgy, ceramics, and so on. Similar segmentation is apparent in the industrial sphere, some industries specializing in metals, others in ceramics, in glass, in chemicals, or in crystalline materials for electronics. In addition, there has tended to be segregation in another direction, between materials science on the one hand, embracing the traditional scientific disciplines, and materials engineering on the other, embracing those parts of the engineering disciplines concerned with developing processes and applications for materials.

Such separations are practical only when the technical objectives, scientific or engineering, are relatively simple or straightforward. For example, metallurgists may have the requisite knowledge to cope with the problem of developing improved alloys for use as electrical conductors. In such cases, the traditional, disciplinary approach can be adequate for pursuing a problem from the research phase to the production phase. But nowadays the trend in technology is towards ever more complex performance requirements, product and device designs, and dependence on more sophisticated knowledge of the physical phenomena that characterize an increasing diversity of materials. The areas of knowledge required to develop, say, an integrated circuit or a biomedical material are not at all coincident with the traditional disciplinary boundaries. It is obvious that many complex technologies call for knowledge and skills that may cut across several disciplines, including science and engineering. Thus, we see an increasing need for interdisciplinary approaches in order to achieve technical objectives.

But the interdisciplinary mode is by no means limited to applied research and development programs. This is also happening in basic materials research. The very core of materials science, the relation of properties to structure and composition, implies a need for the combined efforts of physicists, metallurgists and chemists, etc. In the past the physicist has too often made unrealistic assumptions about the composition, purity, and quality of the materials of his researches; the metallurgist has too often not understood sufficiently how the physical phenomena exhibited by a solid relate to its structure and composition.

We believe that materials research provides a natural meeting-ground for specialists from the various scientific and engineering disciplines, from basic research to applied research, development and engineering, and that the pressure for such interdisciplinary collaboration will grow in the future. It is vital, therefore, to establish the factors that are conducive to effective interdisciplinary materials research.

The field of MSE, broadly speaking, constitutes a multidisciplinary matrix of those disciplines which are related through the structure/property/processes/function/performance linkage of materials. At times, these disciplines are only loosely coupled and interact mainly through the diffusion of knowledge. But frequently, these disciplines are purposefully coupled together in various combinations in order to meet an objective; such groupings are defined as interdisciplinary. It will be shown that the multidiscipline of MSE has proved eminently effective as a medium for many clusters of interdisciplinary activity.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

DEFINITION OF MATERIALS SCIENCE AND ENGINEERING

Many forces have served to shape the multidisciplinary field which has become known as materials science and engineering.

In the first place, MSE has come to be regarded as central to the industrial materials used for machines, devices, and structures.

Second, there is growing awareness of the integral role played by materials in the general fabric of society and of the increasingly sophisticated demands made on materials by complex technologies.

Third, this increasing recognition of the importance of materials is coupled with a growing appreciation of the ways in which the societal demands for materials often have an adverse effect on environmental quality.

Fourth, there is new concern that the rate at which the earth is being mined will lead to severe shortages for certain key materials in the near future, and that industrial processes for minerals and materials are significant consumers of energy.

Fifth, in addition to these external pressures, there are important forces working within the field itself. There is growing realization that basic concepts and questions pervade throughout various classes of materials. These intellectual stimuli serve to draw together individuals from many different disciplines to achieve, by combining their knowledge and skills, that which none could achieve alone.

Thus, through this combination of external and internal pressures, we see the multidisciplinary field of MSE evolving, forwarding the quest for deeper understanding of materials on the one hand and, on the other, bringing this scientific endeavor closer to the needs of technology and society generally. We are led, therefore, to propose the following definition:

Materials science and engineering is concerned with the generation and application of knowledge relating the composition, structure, and processing of materials to their properties and uses.

SOME ASPECTS OF MATERIALS SCIENCE AND ENGINEERING

Materials

What is meant by “materials” in MSE is clear to anyone until he is asked to define it. Are foods materials? Fuels? Drugs? Bones and muscle? In the broader sense, the answer is “Yes.”

However, a tradition has built up in MSE which focuses on industrial or engineering materials. Thus food, fuels used in their natural state, and some other categories are usually excluded. Exclusion is often based on lack of modification of the original properties of the material prior to usage; little processing; substantial tolerance of the product to quality variations; or little durability in use. These boundaries have, of course, been changing with time. But for the purposes of this report, the principal classes of materials falling within the field of MSE are broadly covered by the typical labels: ceramics and glass, metals and alloys, plastics, single crystals,

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

and certain natural materials such as wood, stone, and sand.

But new ways of categorizing materials are evolving. Because of the spill-over of knowledge and applications from one class of materials into another, the traditional boundaries between classes of materials are becoming increasingly blurred. Instead, it is becoming common and useful to consider and classify materials according to their function or application—for example, structural, electronic, biomedical, energy, etc.

Disciplines

The principal disciplines and subdisciplines involved in the multidisciplinary field of MSE are solid-state physics and chemistry, polymer physics and chemistry, ceramics, and metallurgy, and portions of most engineering disciplines. The field embraces parts of synthetic, structural, dynamic, and theoretical chemistry; and chemical, mechanical, electrical, electronic, civil, environmental, aeronautical, nuclear, and biomedical engineering. Many other disciplines and subdisciplines, such as economics and management, interface with these central activities. It is to be emphasized that the disciplinary or subdisciplinary boundaries to the field are indistinct and continually evolving.

Activities and Style

MSE. encompasses the entire spectrum of R & D relevant to materials, from basic or curiosity-motivated research done without much thought of its immediate application, to the engineering and design of devices, machines, and structures on the basis of available materials data. It can include such fundamental topics as the structure and properties of solidified gases at very low temperatures or the optimization of materials design for high-temperature gas turbines, the developing of an ability to predict the physical properties of plastics from a knowledge of their molecular configurations, or the exploration for suitable catalysts for treating automobile exhausts. MSE also interacts strongly with related activities: education and teaching, commerce and industrial economics, national security, and environmental quality. The multidisciplinary nature of the field undoubtedly aids its involvement in a wide range of human concerns and interests.

MSE includes both the scientific, rigorous approach to acquiring and applying knowledge and the long-standing empirical method. Often the two go hand-in-hand, building on each other—empirical observations of the behavior of materials suggest phenomenological models for their explanation which, in turn, often get refined into predictive, analytical models. Both the phenomenological and more rigorous approaches suggest new ways to proceed, say, in endeavoring to optimize desired material properties. Examples of this mixture of the scientific method and empiricism are the continuing searches for superconductors with higher transition temperatures, for cheaper and more efficient catalysts, and for textured alloys with superior strength-to-weight ratios.

But always, in its most ambitious reaches, MSE relates a fundamental understanding of the behavior of molecules, atoms, and electrons to the real

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

world of the performance of devices, structures, machines, and products. MSE offers opportunities to combine the deep intellectual challenges and excitement of basic research with the satisfactions of solving real and socially significant problems.

Relevance

Even though the field includes vital activities in basic research not immediately related to applications, MSE as a whole is directly relevant to all man’s activities that involve machines, devices, or structures. It is involved with the improvement of communications, computers, consumer goods, national defense, energy supply, health services, housing, transportantion, and so on. Either directly or through the intermediary of these technologies, the field is also very relevant to several other key concerns of mankind, particularly environmental quality and the conservation of natural material and energy resources. In sum, the field plays an essential role in raising mankind’s standard of living and in enhancing economic, social, and national security. MSE is, then, a necessary, though by no means sufficient, component for the progress and even survival of mankind. While we cannot always be certain beforehand where MSE will lead us, we do know that without it, technological advance would slow down and society would have to live with, or do without, the present state of technology.

ILLUSTRATIVE EXAMPLES OF MATERIALS SCIENCE AND ENGINEERING

Some Past Achievements

One way of describing MSE is to give some examples of earlier achievements. The listing in Table 3.1 is arranged under three column headings—Basic Research, Material or Process, and Examples of Applications. The table illustrates the interdependence of these three categories; but by no means should it imply that the initiative for a new development always comes from basic research. The opposite is more typically the case. Occasionally, basic research in materials turns up discoveries which may be of momentous importance, such as the discovery of superconductivity, the theory of transistor action, and the discovery of masers and lasers, but more often than not basic research is stimulated by, and supported because of, its ultimate relevance to practical applications as foreseen by the sponsor if not always the actual performer.

In addition to the examples in Table 3.1, a number of past achievements have been chosen for broader study aimed at elucidating the characteristics of MSE and the way it operates. More complete case studies are given in Appendix A of this Chapter, but here we offer some comments on particular features of each example.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

TABLE 3.1 Some Achievements in Materials Science and Engineering

BASIC RESEARCH

MATERIAL OR PROCESS

EXAMPLES OF APPLICATIONS

1.

Elemental semiconductors, effects of impurities on conduction properties, impurity chemistry (segregation, alloy systems), crystal-growth studies, dislocations, surface chemistry, etc.

Zone refining, float-zone crystal growth, controlled doping in Czochralski growth, epitaxial growth, controlled alloying, diffusion, oxide masking, photo- and electron-beam lithography.

Transistor, integrated circuits, tunnel diodes, impatt diodes, charge-coupled devices.

2.

Binary compound semiconductors, plus special emphasis on optical properties—luminescence, electroluminescence. Band structure theory.

Increased control over epitaxial growth—liquid-phase epitaxy. Gallium arsenide, gallium phosphide, silicon carbide. Group II-Group VI compounds.

Light-emitting diodes, injection lasers, bulk negative-resistance devices.

3.

Ternary-compound semiconductors . Phase-diagram explorations. Properties vs. composition.

New semiconductor materials for optical and nonlinear optical applications.

 

4.

Ferroelectrics. Dielectric properties of polar and non-polar crystal lattices. Pyroelectric properties.

Nonlinear optical materials Electro-optic materials. (e.g. LiNb03, LiTa03, BaxSr1–xNb03, BaxNa1–xNb03, etc.) Lead zirconate titanate.

Optical modulators, deflectors, harmonic generators. Parametric oscillators and amplifiers. Infrared pyroelectric detectors. Microphones. Transducers. Piezoelectric filters.

5.

Phase-equilibria studies under extremes of pressure and temperature.

Synthesis of diamond. Boron nitride.

Abrasives

6.

Superconductivity. Electrical magnetic and thermodynamic properties of metals at extremely low temperatures. Many-body theory. Lattice modes.

New superconductors—high transition temperature, high critical current, e.g. ß—tungstens . Superconducting switches. New phenomena—Josephson effect—in thin superconducting films.

Superconducting solenoids, for high magnetic fields. Ultra-low electromagnetic signal detectors. Cryogenic logic.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

BASIC RESEARCH

MATERIAL OR PROCESS

EXAMPLES OF APPLICATIONS

7.

Magnetic properties of insulating crystals—relating magnetic properties to crystal structure and composition.

Ferrite crystals. Garnet crystals.

Microwave devices-circulators isolators. Bubble-domain memory and logic devices.

8.

Magnetic alloys—relation of magnetic properties to composition, micros tructure, and deformation process.

Grain-oriented silicon-iron . Permalloy. Remendur. Cobalt rare-earth alloys.

Transformer cores. Nonlinear magnetic devices-pulse transformers, amplifiers, memories, Controlled coercive-force alloys. High coercive-force alloys.

9.

Physical chemistry of hydrothermal growth process.

Synthetic quartz.

Frequency standards and filters.

10.

Theory of sintering. Basic annealing studies.

Powder metallurgy. Lucalox-high-density, transparent ceramics.

Lamp envelopes. Light-weight armor.

11.

Magnetic properties of polycrystalline ferrites.

Hard and soft magnetic ferrites.

Computer core memories (soft).

Magnetic door latches (hard).

Deflection cores for TV tubes.

High-voltage transformer cores.

12.

Electron-beam optics.

Scanning and transmission electron microscope. Electron beam lithography.

Materials characterization. Integrated circuit technology.

13.

Wetability of surfaces.

Float-glass process.

Cheaper plate glass.

14.

Surface chemistry. Oxidation-reduction reactions. Electro-chemistry—electrode kinetics.

Fuel cells.

Power supplies. Hydrogen-oxygen fuel cells.

15.

Rheology. Physical chemistry of surfaces. Synthesis of compounds.

Structural adhesives. Pressure-sensitive adhesives. Anerobic adhesives.

Joining techniques. Scotch tape, Band-aids, Epoxy cements.

16.

Solidification studies.

Metal fiber spinning, cheocasting.

Steel wire. Aluminum die castings.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

BASIC RESEARCH

MATERIAL OR PROCESS

EXAMPLES OF APPLICATIONS

16a.

Solidification studies, transparent analogues.

Directional solidification, better continuous casting. Amorphous materials.

Turbine blades, Magnetoresistance devices, Anisotropic magnets. Premium castings.

17.

High-temperature phase equilibria.

Chemistry of steelmaking. Basic oxygen process.

Cheaper steelmaking. Longer—life furnace linings.

17a

Nonstoichiometry and phase equilibria.

Composition control in crystals.

Improved light-emitting diodes—GaP.

18.

Radiation damage in crystals.

Ion implantation.

Integrated-circuit technology .

18a.

Radiation damage in polymers.

Polymer cross-linking.

Heat-shrinkable polyethylene and polyvinylchloride.

19.

Thermal expansion of ceramics. Nucleation and phase precipitation.

Pyroceramics.

Ovenware.

20.

Nucleation theory.

Ductile iron.

Engine blocks.

21.

Thermodynamics of phase diagrams, chemical processes. Particle strengthening.

Dispersion alloys—internally oxidized particles to strengthen materials; thoria-dispersed nickel; dispersion-hardened A1, Cu, Ag. Spinodal decomposition.

Aerospace alloys. Aluminum conductor cables. Copper conductors, electrical contacts. High-strength and magnetic alloys.

22.

Structural stability in high-radiation flux.

Fuel elements. Stable cladding.

Nuclear power.

23.

Fracture studies. Fatigue; dislocation theory,

Nondestructive-testing techniques. Computer-aided metals design. High fracture-toughness materials.

Wide range of structure high-performance applications.

24.

Deformation theory for polycrystalline solids. Annealing behavior. Precipitation hardening. Recrystallization. Super plasticity.

Hydrostatic extrusion and forming. Textured materials. Superplastic forming. Tableware. Shape and memory effect.

Shapes and parts. Transformer steel. Alnico magnet. Spring metals. Heat-shrinkable metals.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

BASIC RESEARCH

MATERIAL OR PROCESS

EXAMPLES OF APPLICATIONS

25.

As above.

New alloys. Al-based and Ni-based precipitation hardening. Precipitation hardened stainless steel.

Aerospace applications. Turbine blades. Razor blades. Quality cutlery.

26.

Spectroscopy of impurities in crystalline hosts.

Optically pumped lasers.

Optical communications. Ranging for ordnance and surveying. Machining.

27.

High-temperature erosion studies. Pyrolysis.

Firebricks. Weather resistance. Ablation. Carbon-fiber processing from polymer precursor.

Reinforced plastic nosecones and ablation shields. Furnace linings. Constructional materials.

28.

Spectroscopy of impurities in glasses.

Photochromic glasses.

Sunglasses. Windshields.

29.

Ion exchange and diffusion in glasses.

Surface-strengthened glass.

Strong fibers. Optical fibers.

30.

Photochromic effects in crystals. Optical radiation damage.

Holography.

Optical memories.

31.

Crystal growth.

Vapor-liquid-solid growth processes.

Cold cathodes.

32.

Heterogeneous catalysis.

Electroless deposition.

Electroless coatings of Au, Co, Cu, Ni, Sn, Al, Mg, Ti.

33.

Orientation of macromolecular chains.

Spinning of fibers from melts and solutions: rayon, nylon, acrylins, polyesters.

Synthetic textiles.

34.

Role of molecular networks in determining the properties of rubber.

Vulcanization.

Tires.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

Heatshield Design Problems

(See Appendix 3A; p. 3–60)

This example particularly illustrates the systems approach. The materials development is embedded in a broader design problem, but the overall design is strongly influenced, in fact almost completely determined, by materials capabilities. The development of an adequate heatshield for manned re-entry of space vehicles required the contribution of a wide range of disciplines and utilized contributions from several organizations and many locations. In our language, this program is science-intensive. The program had a clearly defined overall objective and is an example of responsive materials R & D.

Transistors

(See Appendix 3B; p. 3–67)

The transistor story emphasizes the changing nature of a materials R & D program with time. In its early phases, only fundamental understanding of the nature of electrical conduction in semiconductors was involved. The motivation or “application” was stated only in a most general way, but there was a perceived need to replace vacuum tubes in communications circuitry. Although this program substantially increased understanding of the solid state, it necessarily built on much basic work in physics and chemistry which had been completed in earlier decades. As the program succeeded in providing device capabilities, the emphasis naturally shifted from research on phenomena to the engineering aspects of design and manufacture. Movement of personnel from research to development played an important role. This program provides a particularly strong example of close coupling between basic research and engineering. The solid-state industry which has grown out of the original transistor work is the arch-type of a science-intensive industry and creative materials R & D. The transistor story also illustrates the cardinal importance of proper intellectual and working environment for innovative materials R & D. A sense of direction was provided by the management in a sufficiently general way so that individual creativity and insight were encouraged, and yet was sufficiently definite to arouse the enthusiasm and dedication of the experts involved. Leadership in the research and development programs fell naturally on those able to span intellectually and motivationally the full scope of such programs.

Razor Blades

(See Appendix 3C; p. 3–72)

In an industry which might be thought of as experience-based, the internal objective to achieve substantial improvement in shaving performance led to a materials R & D program requiring considerable science and sophisticated techniques. The program was quite interdisciplinary, involving experts in biophysics, physical chemistry, physical metallurgy, and contributions from the life sciences. The use of a new scientific diagnostic instrument, the

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

scanning electron microscope, for the first time provided a way of measuring the performance difference of various razor-blade materials. A key point in the program was the somewhat accidental observation of deposition of thin films of polymers on steel surfaces. The major feature, however, was the organizational climate and the ability of the investigators to recognize the importance of this observation and to properly exploit it for their overall objective. Materials R & D seldom runs a neatly planned course; it requires perception, training, and freedom to capitalize on an unexpected event or observation. The result was a new, hard-alloy coating of the blade covered, in turn, by a thin, tough plastic layer.

Synthetic Fibers

(See Appendix 3D; p. 3–74)

The field of synthetic fibers, spanning several decades in time, is very large in terms of the number of investigators and organizations involved in R & D as well as in terms of market volume. As in the case of the transistor, the early effort was on basic understanding, but there was also a perceived need to improve on natural fibers. In time, engineering emphasis was added but not at the expense of further scientific investigation so that we now find the general problem of synthetic fibers being attacked across the entire spectrum from basic science to engineering. The major contributions to this important development have been made by chemistry, but inputs were required from other disciplines such as the metallurgical development appropriate containers for the hot-liquid corrosive melt. To reach the ultimate customer, this materials advance also required innovations in spinning and weaving machinery for the new fibers.

Textured Materials

(See Appendix 3E; p. 3–79)

Textured materials is a description used in this report to refer to polycrystalline microstructures in which a degree of control is exercised on the alignment of neighboring crystals. Examples are permanent magnet alloys, and high-strength phosphor bronze alloys for use as springs in relays and connectors.

The cental theme of materials science in the relation between composition, structure, and properties is beautifully illustrated by this program. Here the emphasis is on structure, more particularly control of structure, and its influence on properties. Basic work by a physicist, followed many years later by metallurgists in the laboratory and supported by extensive computation techniques from the mathematicians, has led to a capability for predicting the structure and related physical properties of materials in terms of the processing steps used in its preparation. This program has set a high standard for the direct contributions which science can make to practical programs.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

Integrated Circuits

(See Appendix 3F; p. 3–81)

Although this is a logical follow-on to the transistor story, it is included as a separate piece because different aspects of materials R & D are illustrated. In the rapid development of integrated circuits, effective coupling has been achieved principally through cross-licensing of patents, among industrial organizations which are highly competitive. Whereas the transistor required important new scientific understanding, the creation of the sophisticated integrated circuits resulted principally from inventiveness and engineering ingenuity, particularly in processing technology. At the same time, the small dimensions and extreme material purity needed for integrated circuits could not be achieved without a wide array of diagnostic tools and instrumentation provided by earlier unrelated scientific programs.

Aluminum Conductors

(See Appendix 3G; p. 3–86)

Copper conductors for electricity come from an experience-based industry, but recent problems in copper availability as reflected in price have injected new science and engineering into the industry. Although aluminum as it existed a few years ago was unsatisfactory for many copper-wire applications, materials R & D has demonstrated that it is possible to modify and control aluminum alloys to meet the necessary properties, such as electrical conductivity, ductility, and corrosion resistance. The objectives of the program were clear, the time scale was relatively short, and the contributions were more of an engineering nature than scientific. This is a clear example of the user in a sciences-intensive industry demanding new material capabilities and providing leadership to attain that end. It illustrates the ability to develop, through materials R & D, a substitute material to satisfy a specified function.

Polymer-Modified Concrete

(See Appendix 3H; p. 3–88)

Concrete and cement is an experience-based industry with long traditions, very high volume, and intense pressure on unit cost. An expansion of the polymer field has now touched this long-standing material and is providing new capabilities through polymer latex-modified Portland cement. At the same time, new understanding is being generated concerning the fundamental mechanisms of cementitious attachment. Closer coupling has been accomplished between academic and industrial investigators in this area.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

TV Phosphors

(See Appendix 3I; p. 3–91)

The discovery of an important red phosphor illustrates the wide span of scientific knowledge which is sometimes required in materials R & D and the very close linkage which can be obtained between new scientific understanding and very practical application. Scientific studies in support of laser host materials led to the discovery of a commercially significant red phosphor. A central element of this program was the ability of the investigators to pursue and exploit unpredicted observations.

Ceramic Oxides

(See Appendix 3J; p. 3–96)

Major new materials may result from the application of new understanding in one field applied to a different class of problems. Such was the case in the development of new high-density and, therefore, pore-free ceramics. Insight and stimulation for this work resulted from the earlier contributions of metallurgy and physics.

Problems and Failures

The conclusion should not be drawn that all programs in materials R & D are successful. Large-scale programs where criticism is most likely to strike are usually embedded in such complex situations that it becomes very difficult, after the fact, to identify the circumstances which blocked success. In some cases, substantial materials development is done in support of a given application; cancellation of the application then calls the materials development into question. A well-known example of this sequence was the major investment in titanium in the 1950’s which had been criticized by some as being unjustified or overly expensive. The titanium development program was conceived and conducted in direct response to projected needs of the Air Force for supersonic aircraft which could not be built with the then-existing materials. By the time a substantial titanium industry had been established in this country, the successful development of intercontinental ballistic missiles superseded the Air Force plans for constructing a new supersonic fleet of aircraft. The titanium development was left without its largest potential customer. The titanium program itself, nevertheless, appears to have been successful in evolving a new engineering material together with the necessary processing techniques to meet stated performance requirements.

Examples of more recent attention in the materials community, such as Corfam or the Rolls-Royce composite carbon-fiber-reinforced compressor blade, are equally complex to the extent that it is not clear whether the materials R & D was or was not adequate.

A famous and tragic example of material failure was the metal fatigue experienced in the early commercial jet aircraft. The aluminum alloy used in the fuselage had been analyzed and tested in many ways, but apparently insufficient attention had been given to the precise design details in the ultimate

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

aircraft structure, particularly the influence of the window cutouts on crack propagation under the alternate loading and unloading caused by a hunting pressure system.

A similar type of failure was experienced in the selection of a stainless steel for a high-pressure bottle in a space application. An alloy was chosen on the basis of its high modulus, but its strength suffered from the welding process. A better and stronger overall product could have been obtained by the choice of a stainless steel with less strength but superior welding characteristics.

Engineers were surprised when they developed nickel-brass alloy springs for telephone switching equipment. Although these components had received exhaustive environmental testing before they were released to production, the springs installed with new equipment in Los Angeles began to fail after a relatively short time in service. Careful “technical detective” work showed that stress-corrosion cracking occurred in the presence of airborne ammonium nitrate in periods of high humidity.

Trouble has been experienced in the space program with solder joints on printed circuit boards. Experience has now shown that cycling between the extreme temperatures in service can cause failure of the solder and loss of electrical continuity.

Tinted glasses which are used for absorption of solar radiation have cracked because the stresses created by uneven solar absorption—for example, at a shadow line—have exceeded the tensile strength of the glass.

Polyacetyl plastics have desirable properties, but failures in service have brought out the fact that in the presence of oxides of nitrogen a chemical reaction is catalyzed which completely degrades the material.

In the consumer area, there have been a number of materials developments which have been less than successful. Plastic components of some appliances, particularly refrigerators and vacuum cleaners have lacked adequate durability. In refrigerators, plastic parts such as doors, shelves, chiller trays, and the like have failed in service. In vacuum cleaners, the floor or rug nozzles sometimes break when the tools are made of plastic. The sealed-rod type of heating element used in most cooking appliances does not always stay sealed. The filler material which is supposed to prevent contact between the heating wire and the outer cover has proved to be hygroscopic, and when the seal fails an electrical leakage path to the outside of the element creates a shock hazard. A more complete analysis of the complex requirements imposed on this filler material in service might have corrected this problem during development.

Finally, there are the failures of omission. The public or the customer often does not know what to ask for because they are unaware of what materials technology may be able to provide. This is in an area in which the materials community might provide more leadership.

Project SAPPHO1 in Great Britain has addressed the question of success or failure in industrial innovation in the chemical and scientific instrument industries. Although Project SAPPHO is more general in scope than materials

1  

A Study of Success and Failure in Innovation; carried out at the Science Policy Research Unit, University of Sussex.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

R & D, it seems likely that some of its conclusions are applicable to our interests. One principal conclusion is that the successful innovators have a much better understanding of user needs. In our consideration of materials R & D, this means that the materials developer should establish a thorough understanding of the way in which his materials are to be applied. Too often, inadequacies in materials R & D appear to result from insufficient knowledge of the entire system in which the materials work is embedded.

Another significant conclusion of the SAPPHO study is that success is not so much correlated with institutional size as with the size of the group that worked on the project.

CHARACTERISTICS OF MATERIALS SCIENCE AND ENGINEERING

General

MSE is an arena in which traditional scientific disciplines interact, as appropriate, with engineering disciplines. These interactions are enhanced by common interests in achieving particular technological goals. And increasingly, these technological goals are being selected from the point of view of overall societal value. Thus, from an overall perspective, MSE has the following prime characteristics: (a) It is a multidisciplinary field embracing an enormous diversity of disciplinary and interdisciplinary activities and programs, and (b) it is science in action to meet man’s needs even though, at any given time, a number of the activities in the field will be more curiosity-motivated than application-oriented.

This multidisciplinary field embraces activities in the traditional single disciplines, including the work of individuals, as well as interdisciplinary activities which, by definition, require the collaboration of two or more individuals. COSMAT believes that the need for interdisciplinary projects and programs can only grow in the future if many of the technological problems facing society are to be met.

There are two main modes for MSE: it is responsive to specific needs, and it is creative.

Viewed as a whole, MSE is science and engineering aimed at satisfying specific needs. In the responsive mode, these needs supply motivations and establish a climate for close interaction between the materials specialists and the design engineers. This, in turn, facilitates feedback of changed requirements to the materials specialist as his work becomes steadily more refined. The formulation of new materials for medical implants has involved close interplay between clinical experience and material characterization. The development of continuous hot-strip rolling of sheet steel was motivated by the need for lower-cost manufacturing processes. Fundamental studies on electrode reactions allowed the discovery of an anodic-protection process which makes it possible to employ carbon steels or stainless steels in handling corrosive media such as hot sulfuric acid.

MSE is also creative. This field of endeavor has its share of individuals with gifted foresight and insight. Knowledge of new advances in scientific understanding, coupled in one individual’s mind with knowledge of potential

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

applications, occasionally leads to the evolution of a material with new properties which is then recognized to have wide application utility. The early work of Bain and Davenport on the decomposition of austenite led directly to the concept of the hardenability of steel. In another example, Boesch and Slaney were familiar with the original work of Pauling relating the bond between atoms of sigma-forming elements to the average number of electron vacancies in the bonding orbitals of certain elements. They also knew of a formula which Rideout and Beck had derived from this relationship to predict the composition of sigma-forming alloys in certain ternary systems. Starting with this scientific knowledge, Boesch and Slaney were able to produce nickel-based superalloys without the sigma phase and therefore not subject to the entrée of time-temperature induced brittleness.

Yet another illustration is the detailed understanding of the exchange-coupling in magnetic systems and the critical influence of minor impurities which has led to the development of superior garnets for utilization as isolators in electronic circuits.

Nature of Materials Research

Our definition of MSE includes both the generation and the application of knowledge about materials. Materials science is usually concerned with the generation part, materials engineering with the application part.

Two of the vital ingredients for viable, healthy MSE are the ever-present needs and areas of application on the one hand, and the generation of new materials and knowledge concerning materials on the other. Continuing societal needs and desires will always provide areas of application for new materials developments. But the flow of new materials developments would dry up if basic, nonprogrammatic research in the field of MSE were to be suddenly removed. There might be no noticeable effect on the rate of introduction of new technology for several years, but thereafter, the technological capability of the U.S. relative to other countries would decline steadily. The decline would be precipitous in some (not all) of the fast-developing high-technology sectors, slower in the low-technology sections. But since the typical time-span between the performance of basic research in materials and its eventual usefulness to society is 10 to 20 years, the U.S. could be led to a seriously inferior position on this time scale. Such a delay-time for the fruits of basic research seems to be intolerable for many industrial managements, politicians, and even for the general public, but it is relatively short compared with the waiting period for the fruits of research in other fields such as astrophysics and elementary-particle physics.

Consider a scale which extends from the more basic research on properties of certain materials to the routine application of these materials. At the left-hand of the scale are the investigations aimed at understanding and describing the observed materials phenomena. Such programs are typically motivated by the curiosity of the investigator, his creative insight, and by unanswered questions in the field itself. This approach to research has provided an incredible and invaluable foundation throughout the field of MSE. It is the basis for better understanding of the properties of many engineering

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

materials and for the more systematic and efficient solutions of materials problems. Not only is basic research the key to improvement across the whole field, but it is most often the source of dramatic innovations in the field. The laser could never have been developed by applied-science or engineering improvements to incandescent or fluorescent light sources. Basic research may be closely coupled to engineering and development as was true in the early days of the transistor, or it may be very loosely coupled as is the case in some surface research where a considerable buildup of knowledge is required before practical problems in catalysis or surface deterioration can be treated in a systematic way.

At the right-hand end of the aforementioned scale is routine application of engineering materials; for example, those well described in the handbooks and those with a long history of usage. It is also important to recognize that there remain many practical materials problems which will be most efficiently resolved by empirical approaches based on existing knowledge and past experience, It would be a disservice to denigrate this type of activity or to imply that it will no longer make an important contribution to society. Good engineering has the responsibility to reach objectives in a cost-effective way.

Between these two extremes on the scale is a continuum where science blends into engineering and there is often strong coupling between the two. Figure 3.1 is a simple representation of the change which is taking place on the science-engineering dimension with time. The pertinence of this simple diagram is not always apparent because a scientist may from time to time become interested in an application and may, himself, move into engineering. Similarly, an engineer may find that the most direct route to his application is, first, the acquisition of new scientific knowledge or understanding, and so he may sometimes perform as a scientist. Although this blending may be somewhat distracting to one who is seeking a simple picture of MSE, it is in fact one of the very important ways in which coupling is effected between science and engineering in the field. In general, such interaction is very efficiently carried by personnel moving from one area to another, within the same organization. The most valuable individuals in a R & D organization are usually those who can straddle, both intellectually and in practice, the interface between science and engineering,

The time scale (program duration) often has a strong influence on the science-engineering dimension. For the most part, very short-term applications are handled by engineering methods, for there is not time available to acquire additional scientific insight; however, exceptions may occur if the applications are exploiting recent discoveries. The early days of the transistor and the laser were examples where close interplay between science and engineering was achieved even though the time for development was short. Well organized materials-development programs with longer than a few years’ duration may start with an emphasis on scientific understanding. As such long-term programs progress, the emphasis tends to shift to engineering, and in the final phase, further scientific research may be only very loosely coupled to the engineering work.

In addition to the above operational forces which are serving to shape the role of materials research, there are also significant internal, intellectual forces. It is now recognized that interests in basic phenomena and

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

FIGURE 3.1 CHANGE WITH TIME OF COUPLING BETWEEN SCIENCE AND ENGINEERING IN THE MATERIALS FIELD.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

materials properties transcend the traditional classifications of materials, such as metals, ceramics, plastics, etc. The unifying theme throughout MSE, which brings together a broad span of activities and a multitude of materials, is the relation between the working properties of a material, or the phenomena that it can exhibit, and its structure and composition—the so-called structure-property-function relationship. The properties are diverse (e.g. structural, mechanical, electrical, magnetic, optical, chemical, biological, etc.) and the material types are many, but increasingly those engaged in materials research are acquiring the ability to maneuver in these many dimensions in whatever way seems most effective for achieving the desired scientific or technological goal.

Nature of Materials Development, Design, and Engineering

Society wants things or services which require materials, but there must be the intermediary of a design or application specialist to transform material into a product or service.

Design is used here in the broadest sense of “the process of selecting the means and contriving the elements, steps, and procedures for producing what will adequately satisfy some need,”2 or in an engineering context, “the drawing up of specifications as to structure, forms, positions, materials, texture, accessories, decorations in the form of a layout for setting up, building, or fabrication,”3 The design engineer has broad responsibilities for understanding the nature of the materials utilized. In addition, he has responsibility for quality control and product evaluation.

The contribution of materials development to the public consumer is almost inevitably made through a design or application. There are exceptions such as synthetic sapphire which is marketed directly as a material, but these are comparatively rare. Much of the work in the materials development is naturally supportive or responsive in that new and demanding designs are frequently limited by available materials or material properties. As a case in point, the designer of a turbine blade for a jet engine would like a very high temperature of operation for thermodynamic efficiency. The lack of a high-temperature, high-strength material for this service was met by the materials community through the development of special alloys with controlled microstructure. The search for higher-intensity, more-efficient lighting was supported by the development of pore-free aluminum oxide which is highly translucent and yet can contain the high-pressure sodium discharge. In the creative mode, materials development often is the key to entirely new designs. Such new capabilities pervade all technology, but two familiar examples will illustrate the point. The one-piece molded fiberglass sailboat which is leak tight and requires little maintenance is a direct consequence of the development of fiberglass. Pyroceram cooking-ware resulted from a

2  

Webster’s Third New International Dictionary, 1966.

3  

Ibid.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

program to develop high-performance ceramics for missile nose cones.

In either mode, whether responsive or creative, the materials development must work through a designer or applications engineer to reach the consumer and connect its contribution to society. Therefore, the interface between the materials developer and the designer is of paramount importance. A methodology or philosophy which has been successful in smoothing this interface is the systems approach. The interdependence of the designer and materials developer is so strong that it is frequently impossible to apportion credit or blame when a program has succeeded or failed. Thus, the materials development specialist has a responsibility to establish close liaison with the design or applications engineer.

A considerable portion of the COSMAT inquiry has been devoted to the relationship between materials development and national goals. In some programs, materials development does play an important and even central role, but only in conjunction with other factors. Examples of both past and possible future programs stress the design or application aspect even though we are primarily concerned with the materials problems. The reason for this is that the device or product is the common ground for understanding between the materials community and the general public. We recognize that attention to materials problems alone will not normally solve any of the concerns faced by society, nor will exclusive attention to design without adequate materials development. Therefore, this report emphasizes the inseparable connection between materials development, design, and application.

Systems Approach to Materials Development

Methods of systems planning and systems engineering, in which the repercussions throughout the system of a change introduced at any point in the system are recognized and taken into account have been highly developed, for example, in defense and communications systems. The systems approach is sometimes shrugged off as “just trying to think of everything,” but this is essentially what it is. There are various needs and opportunities for extending this approach in the materials field.

Technological Systems of Materials

As a technology advances, each material tends to become more highly adapted to its specific role in the end-product. These products are composed of systems of materials, each chosen to fit a particular profile of functional properties and environmental requirements. Modern technological products—nuclear reactors, jet engines, integrated circuits, etc. —consist of intricate, highly interdependent assemblies of materials, each carefully adapted to its specific role in the total structure. Changes made in any one part of the system can have a very significant effect on the performance of the whole system (for example, the materials problem that Rolls-Royce faced when it introduced carbon-fiber-reinforced composites for compressor blades) and can often necessitate complete redesigns.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×
Materials Cycle

The materials cycle is also a system in which steps taken at any part of the cycle can have repercussions (often surprising ones) at other parts of the cycle as well as having concomitant effects on energy supplies and the environment. For example, a successful demonstration of a magnetically levitated transport system could lead to a dramatic increase in demand for liquid helium and/or rare earths useful in magnetic alloys. The successful demonstration of power generation by thermonuclear fusion or direct conversion of solar energy could cause great changes in the demand and consumption patterns for fossil fuels. In a different dimension, environmental legislation may reduce use of certain materials currently in high demand (e.g. mercury in paper processing and batteries), accelerate use of others (e.g. platinum for automobile emission catalysts), and offer increased availability of some (e.g. sulfur from stack recovery). One of the most important emerging forces in the materials cycle is the limited availability of certain raw materials. These growing shortages on various time-scales have important repercussions throughout the cycle, but particularly spotlight a vital role for MSE—to develop substitute materials made from abundant or renewable natural resources and to engineer ways of making do with considerably less of the scarce materials. Thus, the need for concerted approaches wherever possible rather than just haphazard or separate approaches in the materials cycle is becoming more critical.

Methodology

The phrase “systems approach” describes a methodology which has been developed to deal with complex systems constructed of many closely interacting parts. The systems approach provides an effective framework for a program in which many different groups or individuals must make specialized contributions. It is particularly effective in highlighting those critical parts of the program which require particular attention and extra effort. The systems approach has been utilized to deal with a wide variety of problems in technology, business, politics, and national security.

In MSE, the systems approach is needed to provide the best match between the materials development and its ultimate application. Rather than start immediately upon a materials development, the MSE practitioner must first ask how the material is to be employed and for what purposes. This is not a casual question but rather a deep and searching one. The actual function required of the material must be delineated, together with an understanding of the technical and economic tradeoffs between materials properties, processing methods, and performance difficulties. This prior understanding of the many factors at play can also lend to the possibility of alternate solutions, so that the result may be creative as well as responsive. During the life of the program, new information will become available as to the practicalities of achieving certain materials properties. This information can be fed back in a meaningful way to the applications designer so that the overall engineering solution can be modified. A flow sheet of the overall process is illustrated in Figure 3.2.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

FIGURE 3.2 EXAMPLE OF SYSTEMS ENGINEERING APPLIED TO MSE TAKEN FROM OECD REPORT ON “PROBLEMS AND PROSPECTS OF FUNDAMENTAL RESEARCH IN SELECTED SCIENTIFIC FIELDS—MATERIALS.”

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Contemporary Expansions of the Systems Approach

While the systems engineering helps MSE make its contribution to society more effective, it also seems to be the area where there has been the most difficulty. When we reviewed a number of projects in which MSE failed to live up to expectations, we most frequently found that some aspect of the systems approach was missing.

It is noteworthy that, in the past, most contributions in MSE have neglected one key element of the total system, namely, the environmental impact. In selecting or developing materials for a particular application, the material cycle must be kept in mind. To move towards the contemporary national goal of environmental quality, materials recycling and disposal must be an important element in materials decisions. With the striking control over materials properties which MSE can provide, there are many tradeoffs which can be considered between raw-material costs, fabrication, product performance, and ease of recycling or disposal. The latter two have assumed increasing relevance and must be fully accounted for in future systems considerations by MSE practitioners.

Another growing force in the materials cycle is the supply/demand pattern for energy. This impinges not only on the energy consumption entailed by a new product in its manufacture or service but on all stages of the materials cycle. No major development at one part of the materials cycle can be dealt with in isolation; the consequent impact on energy resources and distribution at other stages of the materials cycle must also be considered.

In summary, there will be growing need in the future to pursue the systems approach both internally and externally in major MSE programs. The complexity of modern technological hardware requires the systems approach on internal materials systems; the mounting problems of resource availability, fuel supplies, and environmental quality require the systems approach to be applied to MSE engineering in an external context as well.

Multidisciplinary and Interdisciplinary Activities

We have already noted that the field of MSE is multidisciplinary in that it embraces activities in a wide range of the traditional disciplinary areas, activities which are very often undertaken by individuals. But while much basic research and creative invention may be carried out in the disciplinary mode, within the multidiscipline of MSE there are growing opportunities for various interdisciplinary endeavors in which a variety of specialists, many of whom are also in the forefront of their respective disciplines, interact in achieving progress towards scientific or technological objectives. Without such interaction many well-known achievements, such as the transistor, color phosphors for TV, reactor fuel elements, and titanium aircraft skins would not have been possible.

Even in basic research, with new knowledge as the prime objective, there is increasing awareness of the fact that very often significant progress cannot be made within one discipline alone. It is frequently necessary, instead, for individuals from two or more disciplines to combine their skills, their knowledge and approaches to attain something which none of them could achieve

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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on his own. The bodies of knowledge needed for progress in the materials field are often not congruent with the traditional scientific disciplines. They call more-and-more for creative cooperation among disciplines—including the physical and life sciences, engineering, and the social sciences—in order to carry ideas, discoveries, or inventions through to successful application. Interaction, even friction, among specialists from different disciplines is a prime source for the vitality of MSE.

Interdisciplinarity is a practice. Interdisciplinarity cannot readily be measured or quantified; it is an attitude, a way of working, but its mastery is not a self-contained goal as it is in many disciplines. It is an intellectual and adventurous path and those who travel it sense an experience which may have lessons for other spheres of human endeavor. Interdisciplinarity, related mainly to research and development, is a new stage in the evolution of scientific knowledge but it is not necessarily the only way by which science and engineering can advance. Historically, as science broadened, it fragmented into separate disciplines; now interdisciplinarity based on close cooperation brings new combinations together. These interdisciplinary combinations may also be transient, fragmenting in turn, and so the social organization of technology evolves and adapts to changing interests, needs, and priorities, and sometimes coalesces into new disciplines. Much of the strength of MSE lies in its flexibility and adaptability which arise from the diversity of talents, viewpoints, and knowledge bases.

Interdisciplinarity does not imply any submergence of an individual’s personal satisfactions and professional recognition; rather, these may well be enhanced by making his contributions more evident and more widely known. Unlike group efforts in some other fields, MSE projects have the advantage of offering many such opportunities for personal satisfactions within group endeavors. The synergistic interaction and mutual recognition of the value of each individual’s contributions can well lead to achievements and an esprit de corps which surpass those which any person could reach himself.

We see MSE as becoming increasingly more adaptable to interdisciplinary clusters. At first thought, this would seem to conflict with the role of outstanding individuals such as Kroll in the making of ductile titanium; Matthias in the creation of many new superconductors; Land in the conception of the synthetic light polarizer; and Baekeland in the invention of Bakelite plastic. Closer examination shows that the creative efforts of these individuals were followed by interdisciplinary team activities in order to bring their inventions to practical fruition. This pattern will continue. We will always need creative individuals, but in the future they will more likely flourish in a multidisciplinary environment, and they will require the efforts of complementary disciplines in the interdisciplinary modes to complete the innovation.

COUPLING WITHIN THE FIELD OF MATERIALS SCIENCE AND ENGINEERING

As noted, the technological needs of society are generally not congruent with the traditional scientific and engineering disciplines. Nor can they usually be met by engineering alone, but require a balanced range of activities extending from basic research to marketing. Further, there is

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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frequently good reason for coupling the activities of different institutions, academic, governmental, and industrial, in order to achieve technological advances. In this section, some aspects of coupling between disciplines, between activities, and between institutions will be examined together with factors that influence the effectiveness of such arrangements with MSE.

Coupling, as we usually regard it, applies to mechanisms for promoting cooperation, collaboration, and knowledge transfer among individuals, among different parts of an organization, and among institutions. In trying to arrive at a description of this multiply-connected system, it is helpful to note some important dimensions of MSE:

  1. The time scale for a program may vary from a few months to years.

  2. Geographic coupling may be as close as the same laboratory or cooperation may extend over continents.

  3. The size of the project may involve one investigator or many.

  4. One project may find extremely tight coupling between science and engineering necessary, while another may involve only one or the other. Some developments in MSE have required contributions from many disciplines; others have been pursued within just one of the classical disciplines,

  5. In some programs involving several people, the coupling has occurred on a person-to-person basis; in other cases, the coordination is effected through organizations so the individual investigator need not be personally involved in the transfer of his specialized knowledge and findings to other disciplines.

  6. The material of concern may be as simple as a nearly perfect single crystal of one element, or it may be as complex as a composite containing many elements, phases, and impurities.

Loosely-Coupled Multidisciplinary Activities, Tightly-Coupled Interdisciplinary Activities

MSE is a multidisciplinary (MD) field within which there are increasing opportunities for interdisciplinary (ID) programs and projects. Generally we picture the MD activities as “loosely coupled,” whereas the ID activities are more “tightly coupled.”

In the loosely-coupled, MD mode, organizations may be guided by an overall purpose or theme (see below) which serves as a natural stimulus, a common interest, for bringing about collaboration between professionals in different disciplines (D) in a more or less spontaneous way. But it is by no means necessary, or even desirable, for every individual to work in collaboration with others. Some will do so much of the time, others only part of the time, and yet others not at all, each according to their interests and effectiveness. However, the contributions of all are important to the overall purpose of the

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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organization.

An individual working on his own is generating knowledge which others will want to draw on, but he himself may do nothing beyond using the traditional vehicles of talks and publications to see that his knowledge is made available to others. To see that this knowledge gets effectively coupled into other projects is then much more the responsibility of the management or sponsors who are presumably aware of what everyone in the organization is doing and why it is being supported. So in this framework, an individual’s mode of operation may very from time to time between D and ID, as he sees fit. In the larger context, the MD mode preserves many more of the traditional academic freedoms for the individual than does the ID mode. It is particularly suited to the longer-term R & D programs (5 to 15 years or more) and is likely to be more acceptable, say, to the academic solid-state science communities than is the ID mode. But the MD mode is probably also a good description of the inclinations of academic metallurgists and ceramists; for example, the metallurgist studying the principles of spinodal decomposition is probably no more tightly coupled into an overall purpose than the solid-state physicist who is developing a fundamental understanding of the nonlinear optics of a crystal. Both will spend most of their time pursuing their own ideas and researches, but both may eventually recognize the practical implications of their work and sense when it is likely to be useful to establish contact, and perhaps even short-term collaboration, with professionals who are more application-oriented. To help further illustrate the nature of the MD mode—essentially all of solid-state physics is vital for MSE, but by no means does this imply that all solid-state physicists are tightly coupled into MSE all the time.

The more tightly-coupled ID mode of collaboration may involve a group of professionals, drawn together from various disciplines to tackle a specific mission or reach a stated goal. It implies a commitment on the part of the individual to choose his own direction and the corresponding time scale in support of the ID group objective. The freedom of the individual has to take second place to the overriding importance of reaching the group’s overall objective on time. The individual is constrained to spend a major part, if not all, of his time working on the group project. Obviously, this ID mode is more acceptable to those persons who find satisfaction in the cooperative achievements of a group, and is less so to those who value an individual sense of achievement more highly. This ID picture is synonymous with the way in which much of industry tackles its development and engineering work. It also is more typical of short-term (e.g. up to 5 years) research than of the longer term.

Factors Aiding Interdisciplinary Coupling in Materials Science and Engineering

Individuals from different disciplines can work most effectively with each other if they have a common language. The materials field provides several such common languages which transcend disciplinary boundaries. These languages provide an intellectual catalyst for ID efforts.

The common languages include basic theories and concepts about solids, materials-processing methods, experimental techniques and instrumentation, and

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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computer applications. Such languages emphasize the features that are common to metals, ceramics, plastics, electronic materials, and natural products. Some examples of these common languages are described below.

Basic Theme and Concepts

There are some basic physical models of solids which have been shown to apply to many materials. One of the most important of these is the recognition of the defect nature of solids. At one time it was thought that single crystals were nearly perfect geometric arrays of atoms or molecules in the particular structure revealed by x-ray diffraction. Through experiments on single-crystal filaments, on semiconductors, and other work, it has been shown that practically all solid samples contain important defects. Many of the properties in turn, particularly electronic, optical and mechanical, are dominated by the defect structure. The concept of defects in solids is a fundamental building block in understanding the behavior of any solid material. Chemical impurities are a special type of defect. The importance of an impurity to both the chemical and physical properties of solids has been revealed particularly through the extensive studies of semiconductors and metals, and is now being applied to other materials.

The idea of a band structure is another unifying concept which has been proven in studying many types of materials. Phase relations and thermodynamic equilibrium have also played key roles in greater understanding of conductors and insulators of crystals and amorphous materials. The concepts of nucleation and growth, of diffusion and segregation are applied to many classes of materials. Studies on the deformation of metals have provided essential inputs to understanding the deformation of ceramics and glasses. The idea of a domain has played a major role in magnetic and ferroelectric materials which, in turn. may be metallic or ceramic. Another example of a prevailing physical entity is the grain boundary. On its simplest level, the grain boundary is an array of dislocations caused by the intersection of two single-crystal regions oriented at an angle with respect to each other, but they are usually much more complex. Grain boundaries are of dominant importance in any polycrystalline solid regardless of its material or classification.

Materials Preparation

The methods of materials preparation have also been a factor in minimizing the differences between the old materials classifications. The development of solid-state devices requiring highly purified materials was built upon the knowledge gained of segregation at a solidification front as studied earlier in metals. Techniques for growth of crystals of one particular type are often shown to have much more general application. The advent of complex materials-preparation schemes such as the combination of high temperature and high pressure leads the investigator to search for opportunities to exploit his technical investment in other types of material.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Experimental Techniques and Instrumentation

Basic science couples very closely with MSE in the area of diagnostic tools for direct measurements of phenomena occurring at the microscopic and atomic levels. In the past it has been basic research, particularly in all branches of physics, which has given rise to the new and powerful measurement techniques, and it is to be expected that this will continue in the future. Many of the newer diagnostic techniques are sufficiently difficult to master that individuals specialize in the technique itself. The unifying influence then results from the natural desire of the investigator to apply his instrumentation to as many different materials as possible.

A related factor bringing together an unifying approach to all materials is that of evaluation and nondestructive testing. Again we see detection methods developed over the past few years which are applicable to many types of materials. Examples are gamma ray and neutron inspection, helium-leak detection, infrared imaging, holography, ultrasonics, and acoustic emission.

Computers

Another development having a strong influence on the unification of MSE is the high-speed digital computer. Most materials problems are complex, and particularly so if they are involved in engineering application. Only rarely does one encounter a materials problem in which the important phenomena can be treated in a mathematically simple way. As a result, until recently, it was necessary to make grossly simplifying assumptions in order to yield a mathematically tractable problem. More often than not, these simplifications were strongly material dependent and, therefore, highly restrictive. With the aid of high-speed computation, it is now possible in some cases to start with fundamental principles and to keep track of many of the complexities of a real material in analyzing its properties in terms of structure and composition. Not only does this elucidate the relation between the scientific knowledge and the external behavior of a materials, but also revealed is the common dependence of diverse materials on the same scientific models or concepts.

Importance of Purpose

A hallmark of a continuingly successful R & D organization is a clear recognition by all concerned of the overall long-term purpose, mission, or theme of the organization. Success of inhouse governmental laboratories and industrial laboratories in MSE has reflected especially the degree to which the overall mission of the laboratory has been defined, understood, and accepted, so as to provide a central interest that draws professionals from different disciplines together and provides continuity in basic studies beyond the span of individual development projects.

In striving to follow the overall purpose of an organization, there are usually tempting opportunities into byways which often have to be resisted. Otherwise, the greater goals would become fragmented and the main capability to focus a diversity of knowledge from many fields of science and engineering

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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into a joint effort toward an ultimate goal would be badly obscured.

As Dr. Alvin Weinberg of Oak Ridge National Laboratory has stated, “a research institution must have a purpose that transcends the individual purposes and aspirations of its scientists; that it can fulfill its purpose only insofar as the separate disciplines and techniques interact with one another to produce more than they could achieve working in monastic isolation.”

The notion of a combination of gifted people from various disciplines of science and engineering, working together intimately but independently, is an institutional approach which has arisen almost entirely in the past few decades. A clear understanding of the institutional objective on the part of the assembled community is vital, but the objective must be very carefully chosen and stated—it must be sufficiently important, suitably broad, and technically meaningful that talented individuals will be inspired by it, challenged to help achieve it, and rewarded by a sense of worthwhile accomplishment as progress is made toward the goal. The continuing overall purpose of an organization may well be in the areas of human needs. Themes such as energy, transportation, defense, health services, communications, are broad enough to draw on many disciplines, yet specific enough to give all a sense of mission.

Such themes serve in a variety of ways; they can foster cohesiveness in an organization and help create an esprit de corps; they can facilitate decision-making as to which course to follow in research, personnel and program planning, etc.; and they can add even further zest to the most basic of the research activities. The latter point is especially noteworthy in that basic research often flourishes, and even the scientists themselves become specially intrigued, when a connection can be traced between the basic research and important new applications—for example, trying through basic research to determine what limits the superconducting transition temperature of a material is spiced by the realization that a breakthrough in the theory might have tremendous consequences for energy technology.

Interdisciplinary themes such as those just mentioned, while common in industrial and governmental organizations, are still relatively rare on the unviersity campus. Yet they would appear to offer challenging and timely opportunities for academic evolvement. COSMAT believes that there is an urgent need for university science and engineering departments to devote at least part of their resources to advancing the frontiers of interdisciplinary research and education in areas of technology that relate to societal requirements. There is a need to develop a better balance between the interdisciplinary and the disciplinary activities in academia.

COSMAT also sees no reason why the selection of appropriate themes for foster effective interdisciplinary activities should compromise the traditional academic standards of quality and freedom. Interdisciplinary research need not be of inferior quality to the traditional research by an individual—often the converse will be true.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Institutional Aspects of Coupling

Departmental Composition

The effectiveness of interdisciplinary MSE is influenced by the climate in which it operates. The climate is set by the organization. The special approach of MSE originated at, and has been most effective in, large R & D organizations in both industry and mission-oriented governmental laboratories. In those establishments, materials developmental problems have been relatively clearly identified and have been closely coupled with functions, designs, and applications. The management of such organizations has had the flexibility to involve appropriate individuals of various disciplines as required to solve the particular problem. Such goal—or program-oriented institutions do not accept the constraint of organizing by disciplines, but rather are guided by the talent requirements to accomplish the mission. Thus, strictly disciplinary groupings in departments are avoided. Functional groups covering a broad range of MSE areas are established which, in turn, couple with project groups aimed at specific objectives.

Geographical Barriers

Geographical separation between individuals and groups engaged in MSE programs should be minimized. Wherever there has to be a geographical separation, other ways have to be found for maintaining close communication. Common management is a frequent mechanism. Organizational and functional arrangements to be avoided are those which simultaneously create geographical separations and separations by discipline, or by research versus development versus engineering.

Size of Organization

Small organizations, industrial or governmental, may be able to support only small programs in MSE if the usual commercial factors are operating. These small programs then have to be very directly related to the product-objectives of the organization if they are to be regarded as cost-effective—the outcome of, and time scales involved in, more basic research programs are generally too uncertain. But in large establishments engaged in complex technologies, there is a much greater chance that results from various MSE projects will find applicability somewhere in the range of technological activities that the organization is concerned with. Size is, therefore, an important parameter, particularly as it affords flexibility to form new groups and mixes of personnel as new requirements arise.

However, sheer size of the organization is not a guarantee of success in its various projects. In its study of successes and failures in innovation in the chemical and instrumentation industries, Project Sappho revealed that perhaps the most important factor for success was the size of the project group rather than the size of the organization. A large organization spread over

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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many subcritical size projects could fail; in other words, selectivity and concentration seem desirable. Clearly, in a small organization, it is critical that the right project be selected, and therein lies the principal risk, whereas in a large organization care must be exercised to see that programs are adequately manned.

A corollary to this discussion is that, generally, small organizations are not justified to engage in basic materials research but have to concentrate on development, engineering, and marketing—entrepreneurship. However, to do this still requires individuals who are able to interpret and exploit the results of basic research performed elsewhere.

Member-of-the Club Principle

For effective communication of knowledge and information between institutions, the receiving institution must be “tuned” to the transmitting institution; it must be staffed with some individuals and support some materials programs rather similar in quality and content to those in the transmitting institution. Otherwise, the receiving institution would be less able to interpret, understand, or exploit any of the information it received.

By maintaining individuals and programs at the institutional interface, an organization is able to respond quickly to new developments wherever they occur?

By the same token, an institution must generally expect to generate and transmit new information itself if it is to receive information in kind from other sources. Thus, for example, an institution that performs and publishes the results of basic research is, in effect, paying its “subscription” to the national and even international basic research “club.” By so doing, the institution puts itself in a position where it can more rapidly assimilate and exploit new research results the moment they appear. By not paying its “subscription,” an organization will tend to trail behind those that do, often having to rely on patent-right and royalty negotiations rather than on original invention for its economic health.

While the above remarks are couched to apply to institutions, they apply equally to the country as a whole. National competence in all aspects of MSE is vital if the U.S. is to maintain its position vis-a-vis other countries with such competence.

The principle also applies particularly to the industry-university interface. If industry is to make best use of the fruits of basic research in the universities, it must undertake some comparable programs itself. Failure to do so can lead only towards two non-communicating cultures.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Some Human Aspects of Coupling

Key Individual

A study made in 1966 and reported in Principles of Research-Engineering Interaction,4 identified the importance of a “key individual.” In a detailed study of a number of case histories, the Tanenbaum Committee found that one of the most common elements in programs of successful innovation and transfer of technology to practical application was a key individual. This individual played the role of champion for a particular idea or cause and appeared to be a necessary, if not a sufficient, factor for overall success in the program.

In reviewing successful examples of materials R & D, we also find that the key individual is important. To achieve coupling between science and engineering or between different disciplines, some one champion has to have the interest, understanding, and ability to span the entire program with some minimum level of competence in all sectors. The technical contributions in materials R & D are normally made by professionals who have highly specialized in a particular discipline. The additional element in materials R & D is that the same individual, although highly specialized, must also develop some appreciation and perhaps understanding for the contributions needed from other disciplines to solve the common problem. If a given program is large, requiring several individuals in the materials and applications groups, or if the problem is of such a nature as to require a wide spectrum of disciplines, then the key individual or champion must have an unusually wide span of interests and knowledge. Thus, at least one individual in the group must have an intimate understanding of the overall program and how the various elements will combine for the ultimate solution. It is tempting to assume that here is the proper place for a generalist. In practice, we find that the key individual is usually himself competent in some specialized field, but in addition, he has made an effort to understand in some depth the nature of the problem and the character of the solution for each of the disciplines involved. At the same time, the key individual, if a scientist, should also appreciate the engineering constraints, or if an engineer, be conversant with the scientific aspects of the problem.

Throughout this report, we emphasize the coupled nature of materials R & D and the crucial importance of contributions from various disciplines. While recognizing the advantages of such a group effort, we must at the same time note the irreplaceable value of a collection of knowledge and understanding in one mind. The one mind identifies the key individual in materials R & D.

Personal Satisfaction

The practical problems of the materials world are complex and normally require the insight provided by more than one specialty or discipline.

4  

Report of the Ad Hoc Committee on Principles of Research-Engineering Interaction, MAB-222-M (1966), NAS-NRC, Washington, D.C.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Furthermore, the interaction between two or more disciplines can establish a synergistic climate for creativity. As already pointed out, success of the interdisciplinary group depends very much on a clear definition or a well-defined common goal and the acceptance by the group members. But in addition, it is also desirable to manage the effort in such a way that each professional member is in a position to make an individual and identifiable contribution in his own specialty.

All members of the group should have some breadth of view and appreciation for the importance of contributions being made by other specialists. Yet, to the extent that any member prefers to maintain his disciplinary identity, he is likely to be better motivated if he sees the possibility of receiving recognition for his personal contribution.

Nature of Groupings

There is danger of confusing the team approach which is characteristic of any large development or engineering program with the interdisciplinary approach characteristic of materials R & D. For a large project which must be completed in a limited time, it is necessary to organize a team of individuals in order that the job can be accomplished. The requirement may simply be one of assigning sufficient manpower to complete the total work in the given time. An example might be the development of a new computer software system. This might be accomplished by appointing a lead system programmer and assigning a number of other programmers to support him by carring various parts of the overall project. Similarly, in preparing the plans for a large building, the job could be broken down so that one architect might be responsible for one part of the project, another architect for another part and so on. One can readily think of other examples where development requires a team approach in which all the personnel are of essentially the same discipline.

Materials R & D is normally carried out in a group approach, too. It is often associated with development programs whose magnitude and time scales require a number of individuals to complete the job within the allocated time. What is special about materials R & D, however, is that different disciplines must usually be focused on the same problem in order to achieve a solution. The difference between the team approach and materials R & D becomes most apparent in the extreme of small groups. In the small group limit, namely, two persons, the team approach often has two individuals of the same discipline and training; for example, two aerodynamicists or two chemists. Materials R & D on the other hand, tends to converge on two individuals with different disciplines and training. Examples of such pairs are a physicist and a metallurgist; an aerodynamicist and a thermochemist; an electrical engineer and an inorganic chemist; and a metallurgist and a structural engineer. Thus, it is the interdisciplinary element which is important, not just the combination of two or more individuals.

Supervision of Group

The question of leadership or supervision of an interdisciplinary group

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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deserves much emphasis, but at the same time is hard to describe precisely. Supervision of an R & D activity is difficult, but that of materials R & D has an added dimension of challenge.

In a typical development program, the project is organized under a project leader and consists of several professionals to accomplish the objectives in the time allotted. The supervisor must himself be technically competent, must be sensitive to the originality and judgment of the members of his group, and should have that undefinable quality which provides leadership rather than just direction. Nevertheless, in such a group there is a clear understanding of a supervisory-subordinate relationship. In the case of interdisciplinary materials R & D, the added complexity derives from the need for a group to act as an individual. No longer is there the neat arrangement of a project leader, but rather a way must be found so that the inputs from several members can have even weight. This requirement for a true group effort results from the very nature of the interdisciplinary problem which demands significant inputs from two or more disciplines. The very quality most needed can be destroyed by an insensitive attempt to “direct” the work for more “efficiency.”

Coupling Through Mobility of Personnel

Coupling between organizations or between separate locations within the organization is a critical problem in materials R & D. Without question, the most effective coupling between separate groups has been accomplished by the movement of knowledgeable and involved individuals. Although the documentation and publication record is good in materials R & D, there is no way to transmit on paper the many subtleties and sensitivities connected with the processes for producing new materials with special properties. Experience has repeatedly shown that a complex new materials process developed at one site can more easily be transferred to a different manufacturing location if some of the key individuals are also transferred. If that is not possible, then special attention must be taken to assure adequate transfer of technology from one site to another. Industrial organizations and governmental agencies solve this problem by, first, defining clearly the required objectives, second, by supporting extensive travel between the two sites, and third, by applying special management effort. The experience of the ARPA university-industrial coupling programs illustrates the difficulty of achieving effective interaction when compelling objectives common to the two locations are missing and where there is little or no personnel movement. The problems experienced in this ARPA program do not in any way reduce the need for more effective cooperation between university and industry. It does emphasize, however, that coupling is something more than just good technical work. Attention must also be paid to perceptive management, to acceptance of common goals, and to the time required for person-to-person contacts and intergroup working arrangements to mature. Further experiments on university-industry coupling are urgently needed.

There are good examples of close coupling between materials R & D and the design or application engineers in industry and government. On campus, however, this coupling tends to be weak. The traditional academic structure, with departments matching disciplines, militates against this type of coupling,

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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and there is normally no funding to support joint efforts by the materials and design sectors of the faculty. Ways should be found to try block-funding for two or three faculty members in a joint effort to couple materials development with design for a specific product or service.

Consulting arrangements have been helpful in coupling university-generated knowledge to industry and governmental agencies. Joint appointments, where the same individual works both on and off campus, may be even more effective. The industrial community in materials R & D appears only weakly coupled to academia, partly because of the relatively small numbers of experienced materials development people who participate in regular faculty activities. The shifting of individuals from one location to another is an important element of coupling within an industry. This was particularly true during the rapid development of the new solid-state industry when many Bell Laboratory solid-state specialists moved into newly emerging commercial firms and also to a number of campuses. A dynamic, two-way flow could further enhance information transfer in MSE.

Roadblocks to Effective Coupling

Many of the obstacles to effective coupling can be inferred from the preceding sections but a few additional comments are in order.

In the early stages of an interdisciplinary materials program, the group may be composed mainly of basic research scientists with a relatively small number of engineers. As the project progresses towards application, more engineers may join the group while the basic research scientists may drop off and move on to other programs that are starting up. Such an evolutionary sequence in the R & D spectrum provides a very effective way for surmounting the “not-invented-here” syndrome so often characteristic of programs in which the research, development, and engineering are done in sequential stages by different groups or departments.

The literature on interdisciplinary research contains discussions of other roadblocks, too, as well as the strengths and weaknesses of interdisciplinarity. A particularly useful summary of the pros and cons appears in “Interdisciplinary Research—An Exploration of Public Policy Issues.”5 Though the study is primarily concerned with the problems of interdisciplinary research involving both the physical and the social sciences, many of the conclusions are directly applicable to MSE. Some extracts from that study are given in Appendix 3K; p. 3–97.

IMPLICATIONS OF MATERIALS SCIENCE AND ENGINEERING FOR UNIVERSITIES

Education in Materials Science and Engineering

5  

Report prepared for the Subcommittee on Science, Research, and Development of the Committee on Science and Astronautics, U.S. House of Representatives, by the Science Policy Research Division; Legislative Reference Service, Library of Congress, October 30, 1970.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

Every professional field requires individuals of high caliber with regard to intelligence, insight, creativity, and motivation. MSE is no different. Actually, however, it must operate successfully with its fair share of the distribution of the available talents among professional people. The more meaningful question then becomes: What training and experience can be expected to supply effective contributors in the field of MSE?

Materials development is complex. In spite of the success of science in unifying the field, there still remains an amount of empirical knowledge which must be known by the practitioner. Furthermore, an individual knowledgeable in one aspect of the field must have a good working appreciation for the contributions which can be made by other disciplines and specialties.

We have repeatedly emphasized the multidisciplinary and interdisciplinary nature of MSE and the requirement for individual contributors to be highly specialized in particular areas. Metallurgy, ceramics, and polymerics appear to be merging toward a common discipline; but the range of materials problems faced by MSE is so vast that other disciplines such as electrical engineering, structural mechanics, physics, chemistry, medicine, and biology will continue to contribute in many important ways.

To illustrate the varied concepts and viewpoints which different disciplines bring to a problem, Table 3.2 lists a number of characteristics or attributes which are commonly associated with three disciplinary fields. From this listing, it is obviously unreasonable to expect one individual to fully absorb all of these different viewpoints and concepts to the degree that he can compete with specialists in any one field. Moreover, these are not the only disciplines which contribute to MSE; Table 3.2 is not meant to be restrictive or exclusive but only tries to illustrate the differences among disciplines.

It is helpful to distinguish between those individuals who generate new knowledge in MSE and those who apply such knowledge. There is a basic difference between these two activities and that difference must be reflected in the training which is appropriate.

The creation of new knowledge implies that the investigator is fully informed of preceding work which has been done in his specialty. In addition, he must have mastery of analytical and experimental techniques peculiarly suited to his line of investigation and, above all, the time for careful measurements followed by detailed analysis and intellectual scrutiny. Therefore, the logical preparation for a substantial number of contributors in the future will be at the doctoral level. The heavy content of science in MSE makes the higher-level degree a natural training route for those who will attack the most basic problems in the field. During the past dozen years, academia has been remarkably effective in preparing individuals for careers in materials science by training at the masters, doctoral, and postdoctoral levels. The establishment and support of the interdisciplinary materials research laboratories played a central role in this response of the universities to emerging needs of technology. The high level of accomplishment in materials science needs to be maintained, but it is also time to recognize that the broad spectrum of MSE should be fully reflected in the academic educational program. In particular, materials engineering now requires similar upgrading, emphasis on interdisciplinarity, and major facility investment which materials science has enjoyed through the interdisciplinary

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

TABLE 3.2 Comparative Characteristic and Attributes of Some Disciplines Involved in MSE

Those trained in physics tend to:

Those trained in chemistry tend to:

Those trained in materials, metals, ceramics, polymers, tend to:

Isolate the problem until it is susceptible to quantitative treatment.

Use some theoretical models, but depend more on correlations, classifications, and comparisons to deal with chemical problems.

Accept complex problems associated with practical needs.

Seek rigorous treatment of relatively simple systems.

Accept a relaxation of rigor necessary to allow treatment of complex systems.

Adapt theory from physics and chemistry but add empirical approach to achieve results.

Propose theoretical hypotheses to be followed by experiment.

Place emphasis on experiment; theories often phenomenological.

Make extensive observations followed by empirical relationships, rules, and theories.

Know a few basic concepts applicable to many phenomena and relationships.

Use basic concepts plus laws on composition, thermodynamics, and kinetics (statistical wiping-out of detail).

Use elemental concepts plus general guiding principles or rules plus experience and knowledge of material classes

Have confidence to attack any physical science problem.

Have knowledge and experience to solve chemical-related problems in most efficient way.

Have the interest, knowledge, and experience to solve practical problems within time and budget limitations.

Center interest on how or why something happens.

Emphasize the material.

Be interested in how of why, but oriented to application more than basic understanding.

Place emphasis on the material, including practical matters of manufacturing.

Be interested in utility; desire to deal with real-world problems.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

Those trained in physics tend to:

Those trained in chemistry tend to:

Those trained in materials, metals, ceramics, polymers, tend to:

Use zero-order approximations or idealized representations to identify important factors.

Use models plus intuitive reasoning based on experience.

Deal with multiphases, partial crystallinity, grain size, texture, defects, and thermomechanical history.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

laboratory programs.

An individual whose principal function is the application of knowledge relating structure, properties, and processing to materials function and performance can contribute with a broader and less specialized training. His aim is to understand existing knowledge in MSE and to determine how it can be applied to new products or designs. In such an objective, he will naturally be more oriented toward processing and product across the entire field of materials. The larger share of practitioners in MSE are found in this category because new knowledge in the field can be appropriately applied in many different situations. The generalist is particularly suitable for the smaller companies which do not have the resources to develop new materials properties as a normal part of product development. Because of the breadth and complexity of MSE, the masters level has become appropriate for those who will be mainly concerned with applications in the field, but even here, there is increasing attention to doctoral programs.

Because MSE, in the main, is a purposeful endeavor, it is desirable that students slated for advanced degrees should acquire some working contact with practical materials problems during the course of their education. One method which has worked well is the cooperative program in which a student alternates between an industrial job and a period on campus. This scheme has been used primarily at the undergraduate level where the candidate may be limited in the skills which he can apply to a technical assignment. Nevertheless, most graduates of such programs feel strongly that they were benefitted in understanding how their academic training could be put to use.

Another excellent way for a student to gain some firsthand understanding of practical problems is summer employment in an industrial or governmental laboratory. This can be accomplished when the student is further along in his academic training and can, therefore, contribute more effectively. The completion of the B.S. or the first summer in graduate work may be convenient break points. It is hampered to some extent by both students and faculty who regard the summer away from campus as an interruption in the graduate program. A broader view might suggest that such experience is an integral part of the educational process in MSE and should be balanced with the academic courses and research training on the campus.

Unfortunately, programs for student work experience in governmental and industrial laboratories suffer severe cutbacks during economic recessions. However, this in no way reduces the importance of this educational component. Substantial effort should be devoted to creating opportunities for MSE students to gain practical experience before completion of their academic training.

University Research in Materials Science and Engineering

The materials research performance of the universities in this country has been mixed. The output of fundamental materials science in academia has in aggregate been excellent. However, materials research in the interdisciplinary mode has not faired quite so well when compared with the better industrial and governmental laboratories. The universities have two cardinal principles which interfere with interdisciplinary materials research on campus. Each principle is securely based on centuries of experience in

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

education. The first is the organization of the university by branches of learning, in other words, by disciplines. Once the disciplines such as physics, chemistry, or metallurgy have been established, the very nature of organizations and human beings is such that close cooperation within a discipline is more easily accomplished than across disciplines. In addition, the main peer groups off-campus are the professional societies which tend to be discipline-oriented. Thus, both peer evaluation and rewards are structured along disciplinary lines.

The second cardinal principle on campus is the pre-eminence of individual contribution. Scholarship and creativity are most easily identified and evaluated when they can be attributed to a single individual. On the other hand, for some problems originating in nature and in society, such as many of those in MSE, a joint effort may be required for effective solution and the campus has not been a ready setting for such an arrangement. If materials research is to be adequately performed at the universities, then some modifications in the funding, traditions, and reward system are required. However, if the universities are to serve mainly as training grounds for professionals in MSE, then simply a change in emphasis and motivation may be required. After all, the universities do not feel obliged to run businesses on campus in order to properly train future business leaders.

Materials research is generally interdisciplinary in nature when conducted in industrial or governmental laboratories. Materials research laboratories on the campus, therefore, are ideally situated for bridging between the traditional discipline-oriented activities of universities and the interdisciplinary activities outside the campus. But too frequently these laboratories have failed to take advantage of their opportunities along these lines. Instead, they have often served to provide additional support on campus to the traditional activities organized by discipline. For example, central facilities such as electron microscopes and crystal-growing laboratories are not being used in an interdisciplinary way if physicists, chemists, metallurgists, and so on, simply take turns at using them rather than apply them to truly collaborative researches. In general, a major aim of materials research laboratories should be to provide opportunities for members from the vatious disciplines to undertake, when appropriate, interdisciplinary, collaborative programs, but by no means should every individual be required to be engaged in interdisciplinary work all the time.

Materials research laboratories can offer an effective meeting ground for professionals of different disciplines where joint programs can be initiated and research results obtained which none alone could achieve. A good stimulus for such collaborative efforts is for the center, or a section of it, to have a broad technological focus which serves to promote a common interest among individuals from different scientific and engineering disciplines. Some centers may choose to focus on electronic materials and relate to the electrical engineering departments, others on biomaterials and relate to medical departments. Still others may elect broad themes such as energy or communications. When astutely chosen, such themes can embrace a wide range of scientific and engineering activities; they are not unduly restrictive but rather stimulate further intellectual interactions, and for those who desire it (possibly a growing proportion), they provide a connecting thread between pure scientific endeavor on the one hand and usefulness to society on the other. COSMAT feels

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

that universities possess, with their materials research laboratories, vehicles that offer exciting opportunities for interplay between traditional academic pursuits and societal needs. It is important to insure that these laboratories make the most of their opportunities.

Funding and Reward Mechanisms

In the traditional academic departments, it is usual for individual faculty members to seek their own research grants and contracts. Such practice is less useful in interdisciplinary research projects which are more subject to changing external requirements. An effective support mechanism for such programs is forward block-funding administered by local laboratory management and subject to outside review. Block-funding provides flexibility for adapting to the varying needs of different interdisciplinary programs and also provides a source of seed money for new ventures.

It is important to the success of interdisciplinary programs that there be recognition and reward schemes which compare with those accorded the traditional disciplinary areas. Universities appear to have much to learn in this respect, and are generally behind their industrial counterparts.

OUTPUTS OF MATERIALS SCIENCE AND ENGINEERING

What are the outputs of MSE? First, and most obviously, the answer is new materials, new processes, new materials systems, and improvement in the existing technology of materials. In either its creative or responsive mode, MSE has as an overall major objective the development of a material which meets particular application requirements or opens up new application opportunities.

Secondly, MSE has an output which is additional understanding in the field itself. When the scientific approach is used, the new understanding and findings from a given project can be generalized and applied to a wider class of problems. As an example, the early studies on segregation at the solid-liquid interface in metals were later applied to the purification of semiconductor materials for electronic applications. Zone refining as it was then labeled has since been applied to the purification and compositional control of many other materials.

A third output of MSE is the identification or stimulation of an area for expanded fundamental research. Sometimes the work being done to meet particular materials goals uncovers a phenomenon which had not been previously reported and which cannot be readily understood. Such unanswered questions are the livelihood of fundamental research. In other cases, materials development for a specific need may arouse new interest in a particular area of basic science.

Yet another way in which MSE can stimulate fundamental research is in the creation of new techniques, instruments, or machines for the production of certain materials. One example is the making of synthetic diamonds by high-pressure, high-temperature conversion of graphite to the diamond form. Successful synthesis of diamonds required the development of new high-pressure

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

apparatus whose capacity extended far beyond that of the classic work of Bridgman. The announcement of commercial quantities of man-made diamonds dramatized the practical importance of high-pressure technology. Moreover, the new high-pressure techniques also became available to the entire technical community. As a result, there was a sudden increase in studies on the effect of high pressure on material properties and on the synthesis of new materials at high temperature and pressure. Similarly, the discoveries of the bistable nature of the conductivity of certain amorphous materials led to a flurry of fundamental investigations attempting to understand the exact nature of conductivity through amorphous materials and the influence of high local currents.

In a very general way, the broad field of metallurgy has identified the problem of oxidation and corrosion. A large volume of research is now addressed to the basic chemical and physical phenomena involved in oxidation and corrosion.

The success of medical implants, such as plastic tubes to repair arteries, has kindled a new field of fundamental study. Although successful in many cases, such plastic implants suffer two major problems, namely abrasive degradation of blood cells and undesirable clotting. As a result, investigators are now examining the basic physical, chemical, and biological reactions of such surfaces.

Most glasses are permeable to helium even at room temperature, a property which gives rise to problems in glass vacuum envelopes. This knowledge was turned to advantage when the U.S. faced a severe helium shortage. Suitably designed glass tubes at elevated temperature were used as helium-permeable membranes to extract the noble gas from the discharge of certain natural gas wells. This dramatic solution of a problem of central interest throughout the scientific community served to direct new attention to the fundamental question of precisely how gas is transported through amorphous solids such as glass.

MSE also has a widespread output in the more efficient design or improved performance of many existing products. This transfer of a capability designed for one program to another application is a form of spin-off. There are few sports or leisure activities which have not felt the impact of materials developments during the past two decades. Snow skis and water skis use fiberglass construction; sailboats fly dacron sails; tennis rackets are made of high-strength aluminum alloy and the stringing is nylon; football fields are covered with turf woven from artificial fibers.

MSE has even generated entire consumer industries. One of the most dramatic is the artificial fiber industry which now outproduces the combined output of cotton and wool in this country. Of equal importance is the synthetic plastics industry to which MSE has contributed heavily. Another large and growing sector is the solid-state electronics industry, whose origin rests squarely on MSE. Still another relatively new and rapidly expanding industry which touches on the daily lives of most Americans is the office copying machine. The development of the electrostatic photocopying surface fully meets all of our criteria for the definition of MSE. The tape-recording industry is another example of the creation of new commercial activity which rests upon the development of new material capabilities. This has benefitted the music world, both in radio transmission and in home

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

reproduction systems. MSE has also played a vital role in large-scale computer systems and in the television industry.

NEW OPPORTUNITIES FOR MATERIALS SCIENCE AND ENGINEERING

Changing Nature of Materials Science and Engineering

Like all science, engineering, and technology, MSE is changing rapidly with time. It is necessary that we identify the trends in the materials field in order that we can project these into the coming years. Our study has revealed the growing incidence of interdisciplinary projects in MSE. A few decades ago there were isolated instances of such work; in recent years, examples have been more frequent. We believe that an important trend has been established, a trend which should be accelerated.

Review of a number of case histories has shown that science-intensive programs have been the most likely candidates for the practice of this interdisciplinary mode. Such programs had two characteristics in common: (a) The project had established overall objectives which could not be met with existing materials. This statement has categorical success-or-failure signifance and is contrasted with many development programs in which materials development might make only an incremental contribution to better performance or lower cost. Examples which come immediately to mind are nuclear-reactor fuel elements in which materials and methods had to be devised to contain radioactive products, or the oft-cited transistor program which required an entirely new level of semiconductor chemical purity and single-crystal perfection, (b) A second feature of the science-intensive programs was that the entire effort had moved out beyond the traditional engineering achievements. New approaches were required. This created a climate of more-open consideration of new ideas, concepts, developments, and changes. Within this open framework, the materials specialists were in a better position to interact strongly with the applications engineers and to make the kinds of trade-offs which have been described here earlier under the systems approach.

This interdisciplinary mode, however, has not existed solely in the glamour projects. In some instances, we find individual companies or sectors of the economy where a challenging new goal has been internally generated, and where these internal goals have been sufficiently demanding to require a science-intensive approach for their solution. Some examples are the development of polymers-coated razor blades, the creation of the synthetic fiber industry, and the integrated-circuit business.

In reviewing the trends of MSE, one must conclude that the contributions to society have been considerable but uneven; that is, some have been served more satisfactorily than others. One of the themes which has emerged in the COSMAT study is that MSE is motivated by and is responsive to societal needs. In some cases, specific needs have led to increased scientific investigation and understanding as, for example, in the problem of oxidation and corrosion of steel. But scientists usually prefer to work on problems which yield good opportunities for scientific advances, and societal requirements have often been too complex to offer much promise of scientific reward. In such instances,

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

the trial-and-error approach or merely dependence upon past experience has had to suffice.

If we now try to project the future of MSE, it is clear that several factors combine to continue and possibly accelerate the trend toward the interdisciplinary approach which has already been established. First of all, we are rapidly obtaining greater scientific knowledge and capability, especially in the fields that apply to materials. Since science feeds on its own previously acquired knowledge, this buildup in understanding is an autocatalytic phenomenon and provides a common language which links the various parts of the materials field. The eventual result will be a science and engineering of materials which is capable of handling a much broader range of problems, even those of societal complexity.

At the same time that the capabilities of MSE are rising, the manufacturer of any product is under pressure from many quarters to squeeze more performance out of his materials. He is asked to hold prices in the face of rising labor costs, to process materials without hazards and pollution, to satisfy increasing customer demands for product quality and reliability, and to relieve pressure on dwindling sources of raw materials. In more and more cases, these conflicting demands will result in a requirement for new material or process capabilities. As time goes on, it is likely that some of the industries which are now clearly experience-based will be forced to rebuild on a science-base. Historically, knowledge has diffused to new fields. If there are experience-based industries in which the old ways are too firmly entrenched, the science-based approach will enter by some other industrial segment taking over.

Increased labor costs will undoubtedly exert a strong influence on the activities in MSE. The role of materials resources and processes which are labor-intensive will inevitably decline. The ever-increasing cost of individual repair work will lead to emphasis on material properties not only for first manufacture but also subsequent repairability. Similarly, it may be expected that designs will be modified to facilitate easy repair by the user.

Thus, all indicators seem to point to increasing emphasis on materials development which makes maximum usage of scientific understanding closely integrated with design and application in the broad sense, and which is fully balanced with regard to the overall materials cycle.

Changing Industrial Scene for Materials Science and Engineering

Many of the outstanding advances in MSE have been achieved by industrial organizations making it a practice to support comprehensive, suitably balanced, and coupled R & D programs. Such industrial accomplishments include the discovery and subsequent development of nylon, the transistor, the high-field superconductor, the laser, color phosphors for TV, high-strength magnetic alloys, magnetic ferrites (Netherlands), polyethylene (U.K.), and so on. What is noticeable about these breakthroughs is that they took place in companies that supplemented the traditional, experience-based approach to materials and product development with science-intensive research programs aimed at building the body of knowledge on which the technology was ultimately based. These companies established leadership, both for themselves and for the nation,

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

by not leaving this vital longer-range activity to other industries or laboratores, either domestic or foreign.

With the broadening emphasis on national goals, from aerospace, defense, and atomic energy to more civilian-oriented technologies, the practical objectives of industry are changing, but there is no evidence whatsoever that the importance and value of research will be diminished. Enough basis is presented elsewhere in this report to indicate the many fresh technical challenges facing industry in addition to those which arise directly from the growing problems of materials availability and concern over environmental quality. Many of the newer challenges can be met only with the help of a sustained, science-intensive approach; reliance cannot be placed solely on the experience-intensive approach, inasmuch as often there is no such experience. And the evidence of the past quarter of a century is that science-intensive or high-technology industry is a much more positive factor in the U.S. international trade balance than low-technology industry.

Yet, despite the proven long-term values of comprehensive in-house R & D programs, faced with the pressures of competition from other companies and other countries, the recent trend has been to reduce costs by cutting back on relatively long-range R & D, even in the science-intensive industries. The cut-back has been even more severe in the experience-based industries; what relatively basic research they did has been eliminated in many cases. Cutting back on R & D may improve a company’s profit position in the short run, but it leads the company and the entire industry into a less dynamic and less innovative position in the long run. Furthermore, the company that continues to perform R & D may even see itself priced out of an eventual market by those companies who simply avoided R & D costs and instead went immediately into production using the results of the R & D performing company. Because this can happen in many instances, there is the growing attitude that the penalties for failure in an R & D program are too great, while the rewards for success are too easily appropriated by others, and hence too uncertain. For the company not in a position of leadership, it often makes most sense to obtain its new technology from other companies through cross-licensing or royalty agreements, for example; but for the company that is striving for leadership, investment in a balanced R & D program is vital. The same pattern has been developing on an international scale; while it was in the catching-up phase, Japan imported most of its new technological ideas. Now that it has caught up in many areas and is aiming at leadership, Japan is investing rather more heavily in R & D.

All programs in technology are influenced, of course, by the magnitude and arrangement of financial support. One such aspect of MSE needs special emphasis. The most critical stage in the development of any new material is in its transfer from the R & D laboratory to full-scale production. Successful transfer to production is a prerequisite for the contribution of any new material to society. At the same time, this is normally the most expensive phase of the program. Moreover, the depressed industries are often those which are in greatest need of innovation in materials and manufacturing processes. Foreign producers using new steelmaking processes developed abroad have impinged on the expansion of steel-plant capacity in this country. Already faced with unsatisfactory profits, it is difficult for the individual steel company to commit to major new plant investment as would be required

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

for longer-term economic advantages. New ways must be found to promote the implementation of new manufacturing processes which can yield significant economic or environmental advantages. Added incentives are needed which, on the one hand, reflect the broader perspective of the nation, and on the other hand, retain the insight of the profit-oriented company. Plant investments for new materials and processes are normally major expenditures and the decision to commit resources for these purposes requires a climate which is attractive to significant risk-taking.

Changing Societal Goals and Support-Base for Materials Science and Engineering

At any given time, a society has a number of goals which receive priority. The method for establishing the goals is ofen not precise; but, nevertheless, a general consensus is somehow reached. Societal goals are a way of drawing attention to programs which require adequate allocation of resources and contributions from many segments of the society. Frequently, achievement of the goals depends on a strong technological input. In the period following World War II, the development of weapons, both nuclear and conventional, received high priority. Following Sputnik, the demonstration of technological excellence through the man-in-space project was a goal of our society. More recently, emphasis has shifted toward goals which more directly affect the daily lives of the general population such as energy, health care, transportation, environmental quality, housing and urban renewal. Dramatic progress in meeting these goals can only be achieved through considerable innovation, and much of that innovation will be in materials technology.

Economic strength of the nation is the foundation for attaining cultural improvements no less than for the elimination of poverty, the maintenance of world peace, or the capability, to aid developing nations. Innovation is one factor which has traditionally provided the U.S. with economic leadership in the world markets and with a rising standard of living at home. Innovation has spawned a number of science-intensive industries such as television, the airframe industry, computers, plastics, and many others. Innovation has also augmented economic strength by advances within established industries such as: communication by microwave links, wrinkle-resistant fabrics, self-developing photography, prestressed concrete, and many more. In most cases, innovation includes the development or modification of a material.

More and more frequently, interdisciplinary research, development, and engineering is proving to be the most successful, often necessary, approach to innovation. Opportunities for the lone inventor are relatively limited as evidenced by the percentage of patents granted to individuals not affiliated with a large company.6 The sophistication of modern technology increasingly requires a group effort in which participants—each with specialized training and knowledge—jointly achieve innovation of significant impact. Therefore, successful practice of the interdisciplinary approach deserves special attention.

6  

In 1901, independent investigators obtained 82% of all patents; in 1967, their share was only 23.4%. SSLA: Ekonomike, Politika, Ideolgiga, April 1971.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

MSE will continue to play an important role in meeting our societal goals. It will often be a cardinal element in innovation, particularly in matters bearing upon energy resources, environmental control, and economic strength. In many examples, MSE has demonstrated the power of an interdisciplinary approach to solve difficult problems. Most of these examples are found in science-intensive technology programs. That is where the performance requirements on materials have been sufficient to demand the science-intensive approach for the adequate solution. Moreover, in many of these activities, the customer has been the government rather than the public market, and cost considerations have played a different role. It is interesting to note that the science-intensive technologies are relatively new; typically, there is no long established body of knowledge and well-identified group of practitioners. Rather, the nature of the problem causes a new cohesion to be formed. It is in this situation that the highest reception prevails for new ideas, new approaches, and the maximum utilization of science to reach engineering objectives.

Conversely, the long established activities are the ones where we find the greatest communication problem between the MSE practitioner and the traditional applications man. If MSE is to make significant contributions in experience-intensive areas which are of prime importance to the economy, ways must be found to support technical advances with mechanisms for adequate transfer of new technologies across a broad front of applications.

Until recently much of the federal support for materials R & D was by the Department of Defense, NASA and the AEC. These three agencies have accounted for some 90% of support for R & D in (metallurgy and) materials engineering in FY 66 and 81% in FY 717 (See Table 3.3). With regard to MSE, the three agencies had in common the pursuit of programs which were materials-limited. For example, in the DoD, the development of infrared surveillance devices required semiconducting materials with higher quantum efficiency and lower noise. In the AEC, the development of more efficient reactors required fuel elements for fast-neutron breeder reactors. In NASA, adequate rocket performance demanded control-vane materials with high-temperature strength and corrosion resistance never before attained. This list of three examples could be expanded almost indefinitely. In that technological environment, materials development was recognized as of central importance. Consequently, MSE has been supported extensively in the agencies’ own laboratories, at universities, and in relevant industries, both directly and indirectly. Reduction of the total R & D effort in these three agencies can be expected to be reflected in a proportionate reduction of support in MSE. It is now appropriate to ask whether the capacity of MSE in the country, so released, should be turned to the new programs in response to societal needs.

On first look, it appears that the new governmental agencies such as HUD and DOT will not require the same proportion of MSE as have the defense, atomic energy, and space agencies. The new agencies will first need to go

7  

This trend is consistent with the overall reduction of R & D support by defense-related and space-related agencies, 51.7% in FY66 to 39% in FY71 (NSF–70–46, Funds and Manpower in the United States 1953–1971.)

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

TABLE 3.3 Federal Funds for Total Research in Metallurgy and Materials Engineering in FY 1966 through 1971 (Est.)*

 

Millions of Dollars

Agency

1966

1967

1968

1969

Total

 

153.434

 

120.588

 

118.206

 

140.703

Commerce (NBS)

 

1.523

 

1.563

 

1.367

 

2.185

DoD

 

98.198

 

60.405

 

54.317

 

63.220

Army

16.990

 

13.748

 

12.522

 

13.472

 

Navy

20.562

 

14.010

 

16.574

 

17.948

 

Air Force

31.458

 

22.525

 

18.608

 

24.398

 

Other Agencies

29.188

 

10.122

 

6.613

 

7.402

 

HEW

 

1.558

 

1.782

 

1.910

 

0.362

HUD

 

 

0.050

 

0.050

 

0.005

Interior

 

5.725

 

7.750

 

11.108

 

11.374

BuMines

5.725

 

7.750

 

10.977

 

11.344

 

Other

 

 

0.127 (Genl. Surv.)

 

0.030 (Water Res.

 

DOT

 

 

 

1.017

 

7.080

Aviation (FAA)

 

 

 

 

Highway (FHB)

 

 

1.017

 

7.080

 

Railway (FRA)

 

 

 

 

AEC

 

24.537

 

25.515

 

25.216

 

24.427

NASA

 

17.487

 

19.533

 

20.591

 

25.790

NSF

 

2.287

 

4.181

 

2.577

 

3.202

* From NSF Federal Funds for Research, Development, and Other Scientific Activities, Volumes XVI–XX, 1967–1971.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

 

Millions of Dollars

Agency

1970

1971 Est.

1972 Est.

Total

 

151.549

 

154.734

 

159.750

Commerce (NBS)

 

1.928

 

2.013

 

2.012

DoD

 

71.359

 

73.916

 

82.124

Army

15.360

 

14.923

 

15.661

 

Navy

19.030

 

19.973

 

24.848

 

Air Force

27.139

 

28.053

 

29.215

 

Other Agencies

9.830

 

10.967

 

12.400

 

HEW

 

0.031

 

0.036

 

0.041

HUD

 

0.284

 

0.474

 

0.510

Interior

 

14.464

 

17.746

 

16.647

BuMines

14.448

 

16.827

 

15.297

 

Other

0.020 (Water Res.)

 

0.950 (OCR)

 

1.150 (OCR)

 

DOT

 

6.914

 

6.324

 

7.341

Aviation (FAA)

 

 

 

Highway (FHB)

6.374

 

6.134

 

7.181

 

Railway (FRA)

0.500

 

0.150

 

0.120

 

AEC

 

30.986

 

30.950

 

30.320

NASA

 

22.458

 

21.178

 

17.633

NSF

 

3.020

 

1.987

 

3.060

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

through a phase of utilizing and applying exising knowledge. An example is BART in the San Francisco Bay Area, the first underground transportation system designed since 1907. BART required little, if any, new materials development. Similarly, there is no one major materials impediment to the construction of wide-scale, low-cost urban housing. In the health area, the largest problems of the present time center about the provision and distribution of medical services rather than the limitations of any one surgical procedure or treatment technique.

On second look, the situation is not that simple. As mentioned, the first phase of the new programs can make significant contributions by utilizing existing technology, including materials. As time goes on, however, needs will become evident for further materials development and refinement. Indeed, we already see examples in the area of environmental quality and pollution. Internal combustion engines emit among other things undesirable oxides of nitrogen. A suitable catalyst could provide for elimination of such a compound, but no satisfactory catalyst is now available. It would appear that new approaches are required. A quite different way to avoid the emissions from internal combustion engines is the use of the electric batteries for vehicle power. There is some indication that batteries with solid electrolytes might overcome the classical difficulties of battery-operated automobiles. At the present time, materials are clearly the limitation to this approach. The dangers of mercury pollution of water have been publicized in only the past few years. One possible solution toward the management of this low-level but toxic contaminant is through surface adsorption on solid particles; but the development of any practical, economic system awaits further understanding of surface states and the interaction of adsorbed particles with the substrate. These are but a few examples to make the point that the newly emphasized societal programs will definitely depend on contributions from MSE.

It is difficult to estimate the time which will elapse during the first phase of technology application via the new federal agencies. It is likely, however, to be of the order of five to ten years. This is just about the time scale required by the university community to respond in the training of students through undergraduate and graduate programs. There is some danger, however, that because of the recent technological and economic recession, the country will overcorrect on the rate of supply of new professionals for a given field and thereby undershoot the longer-range requirements.

The changing agency-base for governmental support in MSE has another important implication. The changing goals and programs forecast a shift in emphasis within MSE from science to engineering and application.

In the industrial segment the situation has also changed rapidly during the past few years. The technological trickle-down theory from scientific research has met with skepticism. It is now felt that considerable engineering and applications-oriented effort must be expended directly on the problem in hand to produce significant results. Some companies consider that they have created a backlog of scientific knowledge relevant to their business and must now spend proportionately more of their resources in applying this knowledge. The economic recession of 1971 has accelerated the realization that an individual company needs more engineering effort on its specific problems at the expense of science. At the same time many companies, particularly

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

in the experience-based industries, could benefit from more science involvement in their development and production programs.

In the societal goals such as transportation, housing, and environmental quality, there are materials problems to be solved, but there are also many other impediments. Substantial gains can be obtained through a systematic engineering application of knowledge which is already available in some form. Therefore, the MSE contribution in these new areas will, for the first few years, be more engineering than scientific in character.

We are discussing here only a change in emphasis between science and engineering and by no means an elimination of the scientific portion of MSE. The big three agencies continue to support materials research a a high level. The nature of their objectives requires the continued expansion of materials science knowledge. Even for the newer societal goals, the demand for additional scientific understanding will rise as the existing relevant knowledge is applied in the early engineering accomplishments.

The more recent federal agencies such as DoT, HUD, and EPA do not have a long tradition of working with materials professionals. Program managers in the agencies may not be aware of the potential contributions of MSE. The MSE community should take the initiative in closing this gap.

Opportunities for Materials Science and Engineering in Some Areas of Concern to Society

We have already shown how MSE has been responsive to societal needs when these have been clearly expressed and adequately funded. The country’s desires for new military technology, for exploitation of nuclear energy, and for the conquests of space have all been answered by important contributions in the interdisciplinary mode of MSE. Major industrial advances and creation of new industries, also related elsewhere in this report, have resulted directly from contributions in MSE. When viewed in today’s perspective, the materials community might be criticized for giving inadequate attention to certain elements of the materials cycle such as pollution and recycling, but every evidence indicates that MSE will respond as new goals are defined and requirements spelled out. In the following chapter, the relations between MSE and several newly evolved national goals is described in sufficient detail to portray the kinds of contributions which MSE can be expected to make. At this point, however, it is appropriate to comment briefly on such areas.

Resources, Substitutes, and Synthesis

Resources, substitutes, and synthesis set a perspective for material availability over the next several decades. This is not a detailed projection for planning purposes. Rather, the point with respect to MSE is that with sufficient planning and effort we can have adequate resources for the foreseeable future. In order to accomplish this, substitution at several levels will be required. This is precisely where MSE will play a central role. First, one material can be directly substituted for another. The example of substituting aluminum for copper is discussed in Appendix 3G of this chapter.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

Secondly, one can substitute a different function for one which is limited by scarce materials. An example is the use of microwave links to avoid long runs of copper-containing cable. At the third level, substitution may take the form of an entire new technology such as generation of electrical power by nuclear reactors to supersede oil-and coal-fired generators. In many cases, the development of adequate substitutes will require synthesis of new materials, which is precisely the arena where MSE plays a central role.

Materials for Housing and Urban Renewal

In the section on “materials for housing and urban renewal” in the next chapter, the point is made that while materials development can make important contributions to this national goal, the principal roadblocks lie in the nature of the industry, the inertia of building codes, and the requirements for long-life performance. Perhaps, MSE can have the greatest leverage on material development for housing construction through the creation of a material review board of truly national scope and prestige which could provide a critical and impartial evaluation of new materials sufficient to establish confidence in the minds of the architect, the builder, and the customer. Without doubt, science and engineering must couple closely to develop a knowledge-base on which to predict material performance for periods as long as 50 years. MSE can also make a significant contribution by helping to provide scientifically-based fire standards and fire-testing procedures for materials of construction.

Environmental Quality

Environmental quality is a goal toward which MSE should play a pivotal role. Although much can be accomplished by better exploitations of known engineering practices, ultimately a much larger science-base will be required for the optimal control of environmental quality. Purposeful coupling of science and engineering in MSE can effectively aid in the solution of a number of major problems such as pollution, recycling, manufacturing-process efficiency, and instrumentation to measure environmental degradation.

Materials Science and Engineering in Medicine and Biology

With a few important exceptions, the medical profession has done what it could on implanted prostheses using materials which had been evolved for other purposes. Recent development of new materials accomplished by close cooperation between materials specialists and medical practitioners has dramatized the progress which can be made in this field. Such instances afford excellent illustrations of the interdisciplinary nature of this activity, the need for additional scientific understanding, and the opportunities for new modes of interaction between the materials community and medical science.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×
Energy

Energy is one of the foundations of society. Attention has been focussed recently on the production of electrical energy, highlighting the conflict between rapidly expanding demand on the one hand, and on the other, growing concern about the undesirable by-products of electrical generation. Resolution of this conflict can be achieved by several routes. Nuclear-breeder reactors can eliminate the undesirable air pollution of fossil fuels, and produce more nuclear fuel. Significant improvement in turbine materials leading to higher operating temperatures can significantly shift the desirable-undesirable ratio in a central power plant. Magnetohydrodynamics (MHD) offers the possibility of converting heat directly to electricity at high efficiency. Solid-state electrolyte batteries may provide a virtually pollution-free energy source for some mobile applications. New superconducting materials can raise the efficiency in power generation and reduce losses in distribution. Each of these desired improvements in the generation of electrical power depend critically on materials development of the type which has been successfully handled by the interdisciplinary MSE approach.

This brief list of societal goals is in no sense complete, but it is sufficient to demonstrate that major national goals can be readily identified for which MSE must respond in vital ways.

Diffusion of Materials Science and Engineering into Low-Technology Indus tries

Coupling from an established field to an emerging activity is an important facet of MSE. Wood products serve as a good example. Until recently, structural wood was kiln-dried, inspected by visual criteria, and utilized with large safety factors to offset the wide variation from board to board. The concepts of solid-state science and engineering are now being reviewed for application to the problem. One of the newest developments to improve the engineering properties of wood is a special application of nondestructive testing (NDT). Whereas NDT is usually applied to other materials in order to detect unwanted inclusions or discontinuities, in wood it is being adopted to measure physical properties. For this purpose, various mechanical and electronic devices are employed to measure deflections and loads, or to monitor vibrations, in order to determine the modulus of elasticity. From such testing, other strength properties such as modulus of rupture are estimated through correlative procedures. Thus, the stronger pieces can be identified, and although the properties have not been modified in any way, the engineer can now select a superior material to design more efficient load-carrying structures. Overtones of effective conservation are evident in the practice of NDT methods.

However, it has been found that correlative procedures for estimated strength properties from modulus of elasticity are not sufficiently precise for some critical engineering applications, such as for the chord members of trusses, or the bottom members of laminated beams. Hence, there is continuing effort to improve NDT techniques. One possibility in this direction is based on the theory that energy dissipation or internal friction may be related

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

to the same mechanism that controls strength properties. Wood is a mass of discontinuities at all levels of observation, and so it seems reasonable to assume that the theory has validity as well as feasibility in relation to wood. Studies thusfar in various wood research laboratories have led to conflicting conclusions regarding the possible utility of this approach.

At the moment, this research on internal friction deals primarily with electronic instrumentation in an effort to improve the precision of measurement of vibrational decay parameters. However, it will also be necessary to determine the relationships between these parameters and specific discontinuities as they further relate to strength properties. Fundamental studies in this field involve fracture mechanics, stress-wave theory, mathematical modelling, physics, and basic wood structure.

MATERIALS SCIENCE AND ENGINEERING AND THE BROADER SCENE

In the final analysis, MSE may fail even though it is properly organized as an interdisciplinary team and staffed with individuals of proper training and experience. Difficulty may well arise in the acceptance of new materials. Such obstacles may be due to human qualities, such as habit or inertia, or to organizational barriers which impede change and progress. In emerging programs, where there is generally high enthusiasm to develop something new, the requirement for materials development is more often recognized, and materials contributions are accepted because the success of the program is seen to demand their acceptance.

In mature industries, however, the situation may be quite different. Long-known materials and processes are familiar and comfortable; new materials may seem threatening and introduce unknown technical risks. In industries where the material itself is directly observable by the customer, there is also much reluctance to accept different materials. The shoddy ersatz materials necessitated by World War II shortages sensitized the public adversely to material substitutes. Fortunately, the outstanding successes of a wide variety of plastic materials with superior characteristics have offset this suspicion to the extent that many products are now quickly accepted, industry-wide self-discipline with regard to releasing new materials should also help eliminate this long-standing public prejudice against substitute materials.

Until now, MSE has contributed to national welfare mainly by technical proficiency. It is time to recognize that the role of MSE in new national goals will require more than elegant solutions of technical problems. Also important are related factors in the realm of social science due to problems arising from long-held customs, threat of change, building confidence in something new, and communication of semitechnical information to the public. Thus, MSE must learn how to join forces with social research in order to meet its larger objectives. Some effort along these lines has been started in governmental laboratories and industrial concerns, but the university would appear to be an ideal location for this type of broad interdisciplinary activity.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

CASE STUDIES OF MATERIALS SCIENCE AND ENGINEERING

APPENDIX 3A

Heatshield Design Problems

Introduction

The primary purpose of the heatshield in any reentry system is to provide thermal protection from the reentry environment and thereby allow successful completion of the intended mission. From the first definition of heatshield requirements to synthesis of a system to meet these requirements, support in the areas of orbital mechanics, aerodynamics, trajectory analysis, heat transfer, physics, chemistry, material science, experimental testing, and manufacturing techniques is essential. The hostile environments generated as a result of reentry are dependent upon the mission, vehicles design, and payload. These three considerations form the basis for trajectory selection, vehicle performance (ballistic coefficient) and payload tolerance level, and, therefore, to a large extent define the range of expected reentry environmental parameters. Obviously, the applications can be widespread—from the safe return of man from planetary or earth orbital missions to severe reentry of Intercontinental Ballistic Missiles. The range of resultant reentry parameters is so extreme that design of one vehicle to be optimum for all applications is not feasible. In fact, vehicle design, depending upon the mission, could be predicated on deceleration level, temperature, material response, thermal stress, or combinations of these. The design problem is relieved somewhat by the availability of materials, design concepts, and calculational procedures which have evolved most noticeably over the past 10 to 15 years, We describe briefly the environments and resultant heatshield or thermal-protection system design problems related to manned earth orbital or lunar return reentry (APOLLO) and unmanned planetary return (SNAP-RADIOISOTOPIC HEAT SOURCE).

Reentry Environments

Perhaps the single most important parameter which determines the reentry environment is the vehicle ballistic coefficient or weight-to-drag area ratio (W/CDA). Examination of simplified equations of motion shows functional relationships between the ballistic coefficient and velocity, altitude of maximum deceleration, altitude of maximum heating rate, and maximum heating rate. For a fixed reentry velocity and angle, an increase in ballistic coefficient produces higher heating rates and increased total integrated heat. The value of maximum deceleration is not strongly dependent on ballistic coefficient, but rather depends on reentry velocity and angle, with increases in velocity and angle yielding an increase in deceleration loads. It is apparent that selection of a low ballistic-coefficient vehicle leads to a reduction in the overall thermal environment to be experienced. The magnitude

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

of vehicle “local” thermal environments is further influenced by vehicle size and configurations and will be discussed later. The major reentry environmental parameters for vehicles entering the earth’s atmosphere are the convective heating rate, total heat-load or integrated convective heating rate, total pressure, and vehicle deceleration. Representative values of these parameters for several systems are shown in Table 3.4. It is these parameters which set the heatshield design and material property requirements.

Early Development

Early in 1960, studies for a manned lunar mission were initiated by the Space Task Group of NASA; Space Nuclear Auxiliary Power (SNAP) devices then envisioned employed the burn-up concept so that intact reentry was not a requirement. Most aspects of the thermal environment were reasonably well established by the techniques available at that time. It was recognized in the Apollo program that a relatively blunt vehicle would be required to minimize convective heating, but some concern was expressed over the magnitude of nonequilibrium radiation from the shock layer to the body. Estimates made in this time period indicated that nonequilibrium radiation might be orders of magnitude higher than equilibrium radiation and might be a dominant factor in entry heating. Further theoretical studies and experimental work conducted in shock tubes and light gas guns dispelled this concern and showed that for the Apollo application the command module configuration should be designed to provide minimum convective heating. However, lunar ballistic reentry allowed entry in a narrow corridor seven miles wide. In order to widen the corridor, a moderately lifting vehicle (L/D=0.3 to 0.5) was suggested, and undershoot trajectories limited to 20 g’s for crew survival and overshoot trajectories (5000 nm range) for maximum heat load were studied. Therefore, the manned lunar mission, entry corridor, convective heating and deceleration limits defined the major design requirements for reentry of the Apollo command module.

By the mid 1960’s, studies had shown that the previously used burn-up philosophy during reentry of SNAP devices was unsafe in that a potential existed for dispersing radioactive material in the earth’s atmosphere. It was decided at this time to convert the fuel capsule in the Nimbus-B/SNAP–19 generator system from a metallic burn-up capsule to a graphite-heatshield protected system to provide intact reentry. The concept of the omnidirectional vehicle with graphite external heat shield was adopted and applied to heat sources in the Apollo (SNAP–27) Transit (Navy satellite), and Pioneer (Jupiter Fly-By) programs. The design requirements for these systems were extremely broad since manned reentry was no longer a consideration and mission applications ranged from earth orbital decay to extreme planetary return reentries. In addition to very large total heat loads (42,000 BTU/ft2), high heating rates and severe thermal-stress problems arose from high-velocity, high-angle planetary returns. These problems were further complicated by the fact that internal heat generation by radioisotopic fuel decay was inherent in the vehicle. This led to a heatshield design requirement to provide adequate ablation performance, thermal-stress resistance, protection of internal components for entry and impact, and to provide the necessarily fine

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

TABLE 3.4 Typical Reentry Environment Parameters for Reentry Vehicles Entering the Earth’s Atmosphere

Mission

Reference Heating Rate,

Total Integrated Heat,

Vehicle Maximum

Vehicle Maximum Deceleration (g)

SNAP 27 Preorbital

300

8,500

1.4

25.0

SNAP 27 Earth Orbital

100

42,000

0.17

7.0

SNAP 27 Lunar Return (6.25°)

500

25,000

0.37

14.0

SNAP 27 Lunar Return (38°)

1,600

9,000

5.4

200.0

Pioneer Jupiter Return (9°)

1,500

40,500

2.0

45.0

Apollo (Entry Design Limits)

700

42,000

1.5

20.0

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

thermal balance for acceptable steady-state operational temperatures for internal components. These problems were moderately relieved by the fact that generally blunt, low ballistic-coefficient vehicles were allowed in the weight and space specifications for the devices.

Heatshield-Material Selection and Design Concepts

Early wind tunnel data in the Apollo program on the command-module heating distribution showed that a reradiative protection approach was theoretically possible on a large area of the conical region. Uncertainties in the level of heating in flow attachment regions and the indeterminate problems of an ablator-radiator juncture, however, led to the choice of an all-ablative system. Many thermal protection materials were undergoing tests during the preliminary design phase in 1960 and 1961. The Mercury heatshield material, a high density (110 1b/ft3) glass phenolic, was considered but dismissed because its high conductivity was ill-suited to a long entry. Nylon-reinforced phenolic (75 1b/ft3) was studied by the NASA Langley Research Center. When described in terms of “effective heat of ablation,” the material looked promising but would result in a thermal-protection system weight of 2900 1bs. During the winter and spring of 1960–61, several materials were considered by aerospace contractors for the lunar return mission. These included phenolic nylon, epoxy ablators, and Avcoat 5026–22 epoxy-novalac, a silica fiber reinforced material. Phenolic nylon tiles over a supporting honeycomb-sandwich structure of stainless steel was the approach finally selected. The main design requirements for the ablator were that it limit the temperature at the ablator-steel interface to 600° F during entry, that it be compatible with the steel substructure, and that it survive thermal cycling from -250° F to +250° F prior to entry. In addition, it was required to provide boost thermal protection and to withstand micrometeoroid, vacuum, and ultraviolet exposure.

By contrast, the materials chosen for the isotopic heat source were required to have high steady-state surface temperature capabilities (900° F), resistance to high heating rates, and the capability to limit the thermal input to the vehicle during entry. These properties were exhibited by the POCO and ATJ-S bulk graphites. In addition, the bulk graphites displayed acceptable ablation rates (thermochemical) and thermal stress resistance over the range of pressure, temperature, and enthalpy experienced.

Supporting Analytical Program

Early methods used to predict the required ablator thickness at each point on the body of the CM used a recession correlation based on effective heat of ablation coupled to a solid-state conduction analysis. Attempts to study special regions, such as protuberances, suggested that wholly rational treatment of singular regions was not possible. The requirement for a safe design coupled with available analytical techniques led to conservatism, undefined margins of safety, and in some cases undesirable weight penalties. While the heat of ablation approach, expressed as a function of environmental

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

energy, surface temperature, and heating rate, was considered fast and convenient for design, a more complex analysis was required to verify final heat shield designs. More elaborate approaches have now been developed which involve a complete energy balance at the surface and an accurate treatment of the characteristics in systems employing charring ablators.

Supporting Materials Program

It is evident from the previous description of the reentry environment and heatshield design problems that synthesis of materials tailored to meet the design requirements was essential. This role was fulfilled by MSE. The specific contribution of the materials professional within the ablation heat-shield development team might be exemplified by a brief description of the general process of materials selection and the tools which are used. In general, the materials specialist is involved in the physical phenomena and chemical interactions between the reentry environment and an ablative material. Current ablation theory states that an ablation material can reject heat in the following ways:

  1. by warming from some temperature to the decomposition point and above (high Cp);

  2. by decomposing into small fragments (high decomposition energy);

  3. by tailoring the fragments to have high specific heats in order to carry off a large amount of heat; and

  4. by forming an outside layer of porous char which reradiates some of the heat energy away and which adds additional heat to the gaseous fragments which perculate through it.

In addition to these heat-rejection mechanisms, the ablator performs the function of insulating the interior of the vehicle from the high-temperature surface. Depending upon the reentry environment and proposed application, the materials engineer, whose role is to assess the practicality of tailoring a material to fit a set of desired attributes, will select one or more of the four ablation mechanisms to be the predominant method of heat removal.

In order to make the first cut choice of an ablator, the materials man uses expertise from several disciplines: organic and physical chemistry, physics, mechanics, and polymer chemistry. An example will illustrate the process more fully.

Assume that the guidance from the other part of the team indicated that the material must, as one of several requirements, have a high decomposition energy. The materials expert would then begin to optimize materials for each part of the requirement, after which he would run a series of parametric studies to obtain an ablator.

To address the requirement of high decomposition energy, chemical theory would first direct him to the most thermally stable organic molecules, as follows: Chemical-bond thermodynamics shows that in organics p bonds are

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

stronger than s bonds (142 versus 80 kcal/mole). In addition, the theory of quantum—mechanical resonance of conjugated p bonds indicates that additional stability can be obtained by delocalization of as many p bonding electrons as possible. This results in the selection of aromatic hydrocarbons as near to the structure of graphite as possible.

The next step is to incorporate this molecular structure in a usable material. Since graphite is not a workable material, other smaller aromatic molecules are considered (benzene, toluene, biphenyl, phenol, etc.). These molecules alone are of no value; therefore, they must be made into a usable solid, a polymer. Chemical-bond thermodynamics and resonance theory again provide the direction for the kind of joining required, all p bonds. However, polymer structure-property relationships indicate that an aromatic polymer will not be usable when the aromatic rings are joined by p bonds. Trade-off studies have shown that the best system would be to use a carbon-to-carboh bonds with as few as possible in the joining link and hace as many joining links as possible.

At this point, a decision must be made as to the kind of polymer desired, a thermoplastic, a rubber, or a thermoset material. Polymer thermal-decomposition studies show that, in general, the higher the crosslinking, the more thermally stable. Also, from mechanical considerations of heatshield strength a crosslinked material is required. When these considerations are combined with a knowledge of organic reactions, a reaction is selected which will allow a first-cut material to be made. This reaction is a condensation reaction of formaldehyde with phenol (phenolic polymer) to yield an aromatic structure joined together by two a carbon-carbon bonds in each link. In addition, since phenol has a possibility of three reaction sites, two ortho and one para to the hydroxyl, the degree of crosslinking can be varied to suit the requirements.

Condensation reactions usually yield by-products, small molecules which are removed in gaseous form. When large test samples are required, the diffusion times for these gases to be swept from the system become prohibitively long. If heat and pressure are used to speed the diffusion and condensation reaction, large material defects, bubbles and voids, will always occur. A compromise which allows the preparation of good samples in spite of the offgassing is obtained from the knowledge that, first, some polymerization reactions can be carried part way to completion, stopped, and then restarted. This allows the removal of an appreciable amount of the gas before sample synthesis is attempted. Parametric studies are done to optimize the amount of prereaction. Second, diffusion studies have shown that gaseous diffusion is several orders of magnitude larger along polymer interfaces than through a bulk polymer. Thus, any filler which would give a continuous interface would enhance the removal of the gas. With this expertise, blocks of material can be made for testing.

In the manner just described, also addressed in the MSE mode are: fiber technology, char technology, layup technology, ablation-reaction chemistry, adhesion, physics of transpiration cooling, all to optimize each desired attribute. Then parametric studies are used to distill the mixture of best attributes into one best ablator for a given application.

Thermal properties, including calorimetry for specific heat and enthalpy, are needed to determine the amount of energy required to warm the material to

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

the decomposition point. Thermal conductivity of the virgin material and the char is needed to indicate the velocity of the heating front. Thermal expansion and thermal shock resistance are required to determine compatibility with the substructure as well as the structural integrity of the virgin ablator and the char during the service conditions.

Mechanical properties include static and dynamic loading at elevated temperatures on both the virgin material and the char. These data allow stress analysis in order to make predictions of the performance of the heat-shield during flight and other loadings. In addition, early in the study, certain of the mechanical tests would be used as screening methods to determine which of several fibers (e.g., carbon, quartz, or nylon), available through previous research, would be the best choice in this application. Several generations of material are required to optimize and trade-off the requirements of all members of the design team.

Both preliminary ablation testing to help screen candidate composite formulations by visual postmortem, material loss and energy absorbed/unit material, and final proof testing with conditions as near those of the flight as possible must be made. The final shield or test article should be instrumented with heat, material removal, char depth, etc., sensors to show final acceptance (usually in concert with a heat [energy] transport team member).

The synthesis of prototypes and actual heatshields would be the next requirement of the materials man. He must include in his considerations such things as, how should any reinforcing fibers or cloth matrix be used to produce the correct mechanical properties? How should the material be configured? How should the ablation shield be attached to the substructure? Has the weight allotment been met? Can better physical geometries be found through parametric computer studies? Can the shield be made more reliable by computer control of the fabrication equipment?

To consummate the discussion, one must remember that as the solutions to most problems are never black or white, neither is the choice of ablator without its trade-offs. To obtain a very necessary property, such as low back-surface temperature, other properties, such as char formation, will degrade. These trade-off studies, along with testing, theories of ablation, decomposition, polymer synthesis, composite synthesis (mechanical properties), are also functions of MSE.

Material characterization is carried out with laboratory samples sufficiently large to measure chemical and physical properties, bearing in mind that, as an example, the mechanical characteristics of a reinforced polymeric system can be significantly affected by its geometry. Thermogravimetric and differential thermal analyses, as well as gas chromatography and mass spectrometry, are used to determine the decomposition energy, the amount of char and the gaseous species formed during ablation. These tests will also show the compatibility between the organic and the fiber and substructure. At this point, additional molecular tailoring may be done to further enhance a property. An aid is the use of microscopy and x-ray diffraction to identify structure and structural changes of both the virgin material and the subsequent char.

The importance of MSE in the heatshield design area is further exemplified when one considers the serious problem of variability of material properties in materials supplied by commercial vendors. Vehicle design

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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considerations and safety factors based on minimum material properties lead to conservative design, a luxury which may not be tolerated in extreme reentry environments. As reentry environments become more severe, it is through the work of MSE under controlled labroatory conditions that new materials will be created to satisfy the demand for ever-increasing performance of ablative heat shield materials.

APPENDIX 3B
Discovery of the Transistor

One of the best-known examples of multidisciplinary and interdisciplinary R & D is that which led to the discovery of the transistor and the subsequent creation of a whole new technology.

The transistor was discovered in the Bell Telephone Laboratories. As expressed in its corporate goal, the Bell Telephone System has the obligation of meeting one of the major needs of society, namely, “To provide the best communications service at the lowest possible cost consistent with financial health.” This goal must be met in ways which enable the Bell System to compete with other industries for the necessary capital and other financing. Thus, Bell Telephone Laboratories is an R & D organization coupled to an industry required to meet a social need in a financially (competitive) efficient manner. From the management point-of-view, this immediately translates into having continually to find ways of improving the technology of communications. In this way the Bell System can meet the external pressures of social demands for better (i.e., more diverse and reliable, cheaper, quicker, etc.) communications and the internal corporate pressures for competing in the market (i.e. , lowering costs, installing equipment more quickly, higher reliability, etc.)

So, in the mid 1930’s, Mervin Kelly, then Executive Vice President of BTL, found himself wondering about the limitations of relay and electron-tube technologies. It was his job to look ahead 10 to 15 years. He reasoned that if one had to rely only on tube or relay improvements, the Bell System would not be able to afford the larger, more complex, and more capable communications systems that would be needed in the future. There were simply too many intrinsic physical limitations in both electron-tube and relay technologies. Relays were low in cost and reliable, but far too slow to perform the more challenging functions of the new switching systems needed. They could work for digital functions, such as low-speed logic and memory, but could not be applied to the many other analogue and high-speed digital functions that a complete future communications system would require. On the other hand, electron tubes were very fast. All they had to do was move electrons in vacuum in response to information signals. They could perform both high-speed digital and analogue functions. But electron tubes extracted a large economic penalty. The hot cathode consumed power in wasteful quantities and the failure rates of tubes were too high to allow the use of large numbers of tubes per system. Thus, operating costs and maintenance expense would prohibit the applications of electron tubes to the much larger, more complex switching and multichannel transmission systems that were needed. And, of course, tubes were absolutely ruled out of telephone apparatus by their short

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

comings on power and reliability as well as size. So Kelly concluded that a new component technology was needed. It must be fast and versatile like the tube, but it must be efficient in its use of power. Above all, it must be many orders of magnitude more reliable than tubes it it were to be applied to the much larger, more complex systems of the future.

The outbreak of World War II made it necessary to shelve plans to follow this train of thought with action; but after the war, Kelly returned to the problem. When he told his research people what concerned him, they told him of the current state of understanding in many relevant areas of physical electronics such as cold-cathode gas-discharge phenomena, magnetics, electroluminescence, and conduction of electricity in such solids as metals, insulators, and semiconductors. One by one, most of the possibilities were eliminated because of one limitation or another; insufficient speed, too many restrictions in functions, or the judgment that sufficient understanding to achieve application could not be developed soon enough. The search narrowed down to solids, such as insulators, metals, or semiconductors. In a conductor there are many electrons, but not enough of the basic science was known to control them. In an insulator, there are very few electrons and not much to be done about it without altering the basic material structure. But in a semiconductor, there can be many electrons or not, depending upon what one does to the semiconductor with impurities, heat, light, or electric stimuli. For many years, empirically-discovered semiconductor devices had been used in electrical technology, such as copper oxide and silicon rectifiers, and resistors whose characteristics could be controlled in response to thermal, light, and electric signals. Researchers were trying to understand why a semiconductor behaves as it does. How does it differ from metals and insulators? Why is its resistance so sensitive to impurities, imperfections, and various forms of energy? Wilson and Mott had studied these problems in England; Davidoff and Joffe in Russia; Schottky in Germany; Lark-Horowitz at Purdue University; just as people had done at Bell Laboratories. There was indeed a large and impressive body of theoretical and experimental work at hand. Shockley and Fisk concluded that the most promising and relevant area in which one might look for new electronic phenomena for amplification lay in semiconductors—if one could understand the basic physical and material science.

The best theory in those early days did not explain the relation between structure and function in any quantitative way for copper oxide or germanium rectifiers. In fact, it would not even predict accurately the direction of rectification. But certain promising things and aims were known: It was known that the need was to produce and control the flow of electrons such that the basic atomic structure of matter would not be altered; otherwise the same kind of wear-out problem would result as with hot cathodes. It was known there could be many electrons in semiconductors at room temperature, and that they could be moved very fast without altering the basic material structure. For example, silicon and germanium rectifiers would behave as very fast electronic switches, and other similar devices would also respond to heat- and light-signal energy. So the real question became: Can we understand, and thereby learn how to economically generate and control, the electrons in semiconductors? The decision to do research on semiconductors was finally made; it was signaled by Kelly, but only Fisk, Shockley, and their fellow

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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researchers knew the scientific potential. Together, managers and scientists formed a synapse between a broad long-term system need and a possible answer in a relevant area of science. They had no concrete ideas on what form any new electronic device might take, but they had faith that basic understanding of semiconductors could lead to the snythesis of a new electronic device.

Nobody could put a quantitative value on the probability of success or on how long it would take to succeed. All that could be said was that there was an excellent chance of achieving understanding because the quantum physics of solids was mature and powerful; at least, understanding of the simplest elemental semiconductor, such as germanium, should result. This was why work started with germanium and later turned to silicon, despite the fact that more complex semiconductors, such as copper oxide and silicon carbide, were in much larger commercial use as empirically developed devices. The simplest material was picked because basic understanding was being sought which, it was hoped, would in turn lead to control and use based on such understanding.

The Research that Led to the Transistor

The decision to intensify research into semiconductors, which were originally discovered by Faraday in 1833, reflected awareness of the intriguing variety of properties of these materials that had been discovered in the preceding hundred years as well as their use already in a number of rudimentary devices. These basic discoveries and the development of a formal understanding of them were very much the inspired work of individuals whom we would nowadays call solid-state physicists—for example;

1839–

Becquerel discovers photovoltage between semiconductor and electrolyte. 1873–Smith discovers photoconductivity in selenium.

1874–

Braun discovers non-ohmic behavior at metal-sulfide contacts.

Schuster discovers non-ohmic behavior at copper-tarnished copper contacts.

1876–

Adams and Day make barrier-layer photoelement with selenium.

1879–

Hall effect discovered, indicating some metals have positive carriers.

1883–

Fritts makes first large-area dry rectifier with selenium.

1904–

Various discoveries that point contacts on galena, silicon carbide, tellurium, and silicon make good detectors of radio waves. (Silicon was found to be the most stable and though the rectification mechanism was not known, it was shown not to be thermal.)

We see from the above list that some basic properties of semiconductors and particularly the rectifying properties of contacts were established as far back as 1883. By 1904 it had been shown that such contacts could be used for

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

detecting radio waves but the suitability of vacuum tubes at that time for such applications lessened or delayed interest in semiconductor effects.

However, in the 1920’s, various commercial semiconductor devices started making their appearance including the copper oxide and selenium rectifiers and selenium photocells. These commercial devices created a demand for a better understanding of how they worked, so that through the 1920’s and 30’s much experimental research went into the properties of semiconductors. Some of the best controlled studies were made in Germany by Gudden and Pohl on the related materials, (generally more insulators than semiconductors) alkali halides; their progress, it was clear, was considerably aided by the fact that such materials could be prepared fairly readily in single-crystal form. As a result of such researches, it was established that rectification and photovoltages were contact or surface properties; conductivity and photoconductivity were body properties. In the meantime, theoretical physicists were beginning to invoke conceptual models for the energy states and electronic properties of solids. In 1928 Sommerfeld developed a better understanding of conduction in metals, and in 1931 Wilson published his famous work which established the energy band model and the role of valence, conduction and forbidden energy bands. These advances, of course, were very much based on the new concepts of quantum theory, statistical mechanics, and the Schrödinger equation which had been introduced in the 1920’s and were now finding a wide range of applications in the physical world.

Based on the Wilson model of semiconductors, a number of their body properties became more readily understood, such as the temperature dependence of conductivity, conduction and photoconduction, and in the later 30’s the roles of donor and acceptor impurities electrons and positive holes, and the chemical picture (based on bonding) of electrons being ionized from bands into the freely conducting state. A conceptual blind-spot that persisted for some years was a realization of the important role of minority carriers. Progress was less rapid with the surface properties. Good rectifiers seemed more an art than a science. Experimentally, correlation was established between the direction and rectification and the sign of the majority carrier of the semiconductor but early theories (by Mott, Schottky, Davydov) predicted the wrong direction of rectification. It turned out later this was because the role of minority carriers was overlooked.

As research into the properties of semiconductors progressed, it was realized more and more how vital was the ability to control the composition and structure of the materials. Chemists and metallurgists were appealed to for help in getting purer silicon and later (after recognizing how n- or p-type, rectification direction, and accidental p-n junctions correlated with impurity segregation) controlled amounts of identified impurities which led to control over the n- or p-type nature of a semiconductor. Such was the state-of-the-art when World War II struck. Based on this art, nevertheless, many important semiconductor devices were produced, notably for microwave detectors in radar. When the War ended, following Kelly’s urging outlined earlier, researchers at Bell Laboratories resumed the attack on semiconductors. They had the intuitive feeling that if only they understood semiconductors better and had more control over the material, important new electronic devices, particularly amplifiers, would be forthcoming. Specifically, Shockley believed that it should be possible to modulate the resistance of a thin layer

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

of semiconductor by imposing a strong electric field gradient across the layer and quickly controllably changing the number of available carriers of current. It was obvious that electronic amplification could be based on this effect if it existed. Thus, several physicists, chemists, metallurgists, and electrical engineers started working together in the interdisciplinary MSE mode. The years 1945–1948 saw much experimentation, the posing of phenomenological models, the failure to confirm the model with experiment, the devising of new models, predictions of certain effects which experiment failed to confirm, and so on—a familiar scenario to researchers striving towards a deep understanding of nature. New concepts had to be proposed to replace the old ones that had failed. An important one was Bardeen’s theory of surface states, which was introduced in order to explain the failure to observe the large field effects in solid-state triode structures that Shockley had expected. This idea led to a realization of the importance of minority carriers in the behavior of contacts. And in 1948, the point contact transistor was discovered by Bardeen and Brattain. It is clear that these unanticipated, important, and radically new results emerged from the steady pursuit of exact science with a purposeful goal, and not simply from the elaboration of known technology.

Once the role of minority carriers had been understood, Shockley quickly followed with the prediction of the junction transistor, both p-n-p and n-p-n. The potential performance of such junction devices appeared more promising than that of the point-contact transistor, particularly for its stability and its power handling capacity. But to realize such a structure, called for even better control over material preparation. From this point on, it is perhaps fair to say that, though physicists and electrical engineers continued to have many of the device ideas, the pace of progress in semiconductor R & D was determined very much by the progress of the chemists and metallurgists. Absolutely vital steps were the discovery of zone refining by Pfann and the development of ways to grow high-quality single crystals of germanium and silicon. As a result, the grown junction transistor was demonstrated in 1951.

New methods of preparing junctions and transistors with improved performance followed quickly, first alloying, then diffusion processes. New devices and applications were not far behind, including silicon power rectifiers and solar “batteries.” The family of useful semiconductors was extended in 1953 by Welker working at Siemens in Germany, who showed that a range of binary compounds based on the group 3 and group 5 columns of the periodic table were analogs of the group 4 elements, silicon and germanium. These new compounds were eventually to lead to whole new classes of important semiconductor devices.

The materials work, directed towards improving the technology of semiconductor devices, proved a rich source of new fundamental understanding of materials. Important spin-offs were better control over doping, the identification of impurities, new techniques for growing crystals, deeper understanding of solid-state solution theory and crystal-growth kinetics, thermodynamic theory, and by no means least, the nature and consequences of dislocations. The last topic, for which solid-state research laid much of the groundwork, was to have far-reaching influences in other areas of MSE.

And so solid-state electronics was born.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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APPENDIX 3C
The Development of Coated Stainless Razor Blades

In the decade beginning with the year 1945, an interdisciplinary group of scientists and engineers at the Gillette Company began a long-range study of the properties and uses of razors and razor blades. This group comprised chemists (polymer, organic, and physical), metallurgists, physicists as well as mechanical and electronic engineers. The work of this MSE group set the stage for a series of discoveries for improving shaving, which is continuing to this day. Fundamental studies of razor-blade edge geometry and metallurgy were undertaken using electron microscopy which was a new tool at that time.

After considerable difficulty, techniques were devised to study razor blade edges with the electron microscope. This new tool showed that the heretofore unresolved edge dimension was a few hundred angstrom units on mass-produced razor blades. For the first time, it was possible to demonstrate that the mechanism of failure in service was different for high-carbon steel blades than for stainless steel blades. These studies also showed that the carbon steel blades were being chemically eroded during shaving. This led to a program to reduce the deterioration of carbon steel edges during shaving. One of the means explored to accomplish this end was to coat the carbon-steel edges with metal coatings. Most of these were applied by vacuum evaporation of the metal onto the edges. Because of the very small ultimate edge dimension of the blade, these coatings were kept very thin, no more than a few hundred angstroms at the most. Improved shaving life of carbon steel blades resulted with some sacrifice in initial shaving quality.

While this work was proceeding, one of those side experiments, so common in research, was performed. This experiment was to test whether a high molecular—weight polymer could be transferred across a vacuum onto a metal surface to form a continuous coating. PTFE was chosen as the polymer for the test because of its extremely high heat stability. The transfer was conducted onto razor blade edges (rather than on the articles then of primary interest) solely because razor blades were the most convenient objects available to be used in the particular apparatus employed. The PTFE was heated in an incandescent tungsten coil until an increase in pressure in the vacuum chamber was observed. The razor blade edges were examined after deposition by light microscopy. Wetting tests showed that some PTFE had, indeed, transferred across the vacuum chamger. Further tests showed that contrary to expectations, the cutting ability of razor blades had been improved by the PTFE coating. Subsequent shaving with these blades showed an improvement, beyond that normally obtainable with uncoated blades.

This was the first time a razor blade had been obtained with a shaving quality above and beyond that obtainable by normal sharpening practice and despite the fact that a rather thick coating had been bonded to the ultimate edge of the sharpened blade.

This discovery led, in due course, to an exhaustive study of fluorocarbons for coating razor blade edges. It was clear from the initial experiment that degradation of the high molecular-weight PTFE had taken place and that a lower molecular-weight material had actually been deposited onto the blade edges. Studies of the “evaporated” PTFE showed it to have a lower melting point and higher crystallinity than the starting material.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Attempts were made by the group to synthesize fluorocarbons of carefully controlled molecular weights. Great difficulty was encountered in this work and soon help was sought outside the company from a large chemical manufacturer expert in this field. A major problem with commercially available high molecular-weight PTFE was the particle size combined with the very high melt viscosity. These polymer particles, when heated well above their melting point, failed to flow and coalesce into a pore-free film. Although the particles did sinter to form an adherent bonded film on the blade edge, adequate surface coverage required several layers of particles in the film. Since virtually no flow of the particles took place during sintering, the resulting PTFE film thickness was in the order of a micron or more. This film thickness was detrimental to initial shaving quality and as a result, a “break-in” period of several shaves was required as the film wore thinner before optimum shaving quality was realized.

To avoid this loss of initial shaving quality, a PTFE-type polymer with a melt viscosity in which the melted particles would flow freely and coalesce during sintering was sought. PTFE-type polymers and telomers with molecular weights ranging from as low as a thousand to as high as several million were made. The very low-molecular weight PTFE, while flowing freely, failed with respect to shaving life of the film on blades. Intermediate molecular-weight material from about 30,000 to 200,000 exhibited the desired melt-flow properties for film formation and, surprisingly, produced blades of shaving life exceeding that of the very high molecular-weight commercial PTFE polymers. PTFE-type polymers in this molecular-weight range could produce much thinner pore-free films (of the order of one-to two-tenths of a micron) which showed excellent shaving quality from the very first shave.

The result of the better flow properties of these polymers was easier film-thickness control in mass production.

Concurrently with the work on synthesizing new fluorocarbon polymers, studies were made of high molecular-weight PTFE and its behavior when heated on different metallic surfaces in a variety of gases. This work showed that there was an interaction between the PTFE, the metal, and the gas to produce a variety of different PTFE coatings under the same heating conditions.

Studies of PTFE-coated blades were made after various stages of shaving. It was possible to show that the PTFE coating persisted around the ultimate edge of the blade for several shaves. The PTFE coatings were removed from the blade edge after shaving by dissolving the steel and floating off the coating, which could be shown to remain intact across the ultimate edge in many places.

More recent work on razor blades, where electron microscopy and physical metallurgy have played a predominant role, has been the development of edge-strengthening metallic alloy coatings. Studies of evaporated and sputtered metallic coatings for razor blade edges has led to the use of an ordered alloy of platinum and chromium. This alloy, with a superlattice of the intermetallic compound Cr3Pt, when coated on razor blade edges and then overcoated with PTFE, provides blade edges of excellent shaving life. While it is easy to demonstrate the presence of the ordered superlattice structure of the Cr3Pt alloy in bulk melted samples by conventional x-ray diffraction techniques, it is extremely difficult to show this in thin films on razor blade edges. However, a careful electron microscopic and electron diffraction

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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analysis of alloy coatings, 300 to 500 Å thin, reveals that intermetallic compound with the characteristic A15 cubic ordered crystal structure does form in these vapor-deposited thin films. The grain size was shown to be extremely small, and the presence of some lattice defects was found within the fine grains. It was not possible to analyze the structure by any other technique. Under some circumstances, the line broadening due to small grain size and lattice defects was so great that the characteristic lines effectively overlapped, giving rise to a broad diffuse ring in the electron diffraction pattern.

The Cr3Pt alloy exhibits a DPHN hardness in excess of 1400. This is far in excess of the normal hardness of PTFE-coated razor blades which range in hardness from 550 to 650 DPHN. X-ray diffraction techniques have made it possible to characterize the structure of the Cr3Pt alloy in bulk, while the electron microscope has made that possible in thin films useful for razor blade edges.

APPENDIX 3D
Synthetic Fibers

Introduction

Textile materials have been developed over many hundreds of years and the most suitable natural fibers have provided the basis for today’s textile industry. These natural (as opposed to synthetic) textile fibers are cotton, wool, flax, and silk, with silk giving the highest strength properties. Except that silk is spun by the silkworm, methods for the spinning and weaving of natural fibers have been accepted routines since before the Industrial Revolution.

Although still of great importance, natural fibers have given way to the science and engineering developments of regenerated (natural) fibers and more significantly to the developments of synthetic fibers. Synthetic fibers are those in which man has chemically synthesized the fiber-forming polymer-base material and engineered the operation of fiber production through the use of machines, in contrast to relying on either plant or animal life to do either of these jobs.

The development of the synthetic fiber industry as we know it today required intense interfacing of various MSE disciplines. An excellent example of this is the story of “nylon,” a duPont polyamide fiber. Nylon emerged as a very important lightweight, high-strength fiber during WWII for making parachutes, rope, tire cord, etc., and subsequently for producing hosiery and other important textile materials. As is the case for all synthetic fibers, the fiber is spun from a polymer-base material synthesized from basic chemicals derived from coal, oil, etc. (materials science). Nylon fiber is obtained from the polymer-base material by melting it and squeezing it through tiny holes (spinning) into thin strands which are stretched like taffy into the filaments desired (materials engineering).

The way for the convergence of MSE to produce nylon was paved by the starting of a “pure research” program in 1928 aimed to obtain fundamental knowledge. DuPont history tells us that the initial purpose of the program

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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was for future company diversification, but not oriented toward a specific product. It should be recognized, however, that the selection of Dr. Wallace H.Carothers (1896–1937) from the Harvard faculty, who was known to have intense interests in the field of polymer chemistry, to head up this research program is indication that the future importance of synthetic polymer science and engineering was foreseen.

The advancing materials science provided the capabilities for synthesizing the new high molecular-weight polymers required, and engineering disciplines provided the know-how for causing the macromolecular chains of these materials to align under the shear of extrusion through spinnerets. It was also learned that after extrusion the spun fiber could be further stretched to improve the molecular alignment of chains for improved strength and performance characteristics.

It is of interest to examine in more detail the MSE responsible for putting synthetic fibers into today’s economy.

The Materials Science

Born in the twentieth century, polymer science is one of today’s most important materials sciences. A polymer molecule is a giant molecule made up of many thousands or millions of simple molecules linked together into long chain-like structures (macromolecules). All natural fibers are made up of macromolecules, and the important mechanical properties of fibers are the result of interactions between the long chains. Long-chain molecules are lined up parallel to each other in fiber formation. The better this alignment is, the stronger are the interactions between polymer chains, and the higher is the tensile strength of the fiber.

In the late 1920’s, there was an awareness of the importance of polymeric materials. Natural materials were known to be made of giant molecules or polymers and in particular the value of polymer materials such as wool, cotton, and man-made rayon were known. Also, early ground work in the field of polymer synthesis was being laid in a few laboratories, but no work had been successful at that time in synthesizing a polymer which could be made into a synthetic fiber with useful properties. When Dr. Carothers was brought in by duPont, he was encouraged to carry on fundamental research in organic chemistry of his own choosing. His interests were concerned with the synthesis of high polymers such as those found in nature, and in his new research position he chose to investigate polymerization by condensation as well as the structure of high molecular-weight substances. He commenced his research in the midst of other research groups in the laboratory and soon he had a group of chemists numbering about a dozen working under his personal supervision. These consisted principally of organic and physical chemists, the former to synthesize polymers and the latter to determine their properties.

The role of the research chemists and their discoveries cannot be overemphasized in discussing the origins of synthetic fibers. By synthesizing new polymeric materials unknown in nature, by recognizing their importance, and by synthesizing them in high enough molecular weights to be useful (in this case, for being converted to fibers with strengths to compete with silk), the organic chemists achieved great successes.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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The chemical research led to synthetic procedures for polyamides, polyesters, polyanhydrides, and neoprene rubber—all synthetic polymers. The early research on polyesters opened the way to many important scientific observations. It was found that molten polymer could be drawn out into threads using a glass rod. It was further found that these threads could be pulled (cold-drawn) to several times the original length of the thread and that the resulting drawn filament would exhibit much higher tensile strength than the undrawn filament. Moreover, the drawn fiber still had the ability to undergo elongation under stress, an important fiber property.

Another important discovery of the research team was the fact that the drawn fiber polyester appeared to be nearly as strong when wet as it was when dry. This was very definitely an improvement over natural man-made cellulosic fibers or yarn. When investigated by x-ray diffraction the polyester fiber showed orientation of crystalline phases similar to that of silk and rayon fiber. It was later observed that polyester could be dry spun from chloroform like acetate rayon, and it could also be cold-drawn.

The research group of synthetic chemists was able to prepare linear polyesters having molecular weights above 10,000 (“superpolymers”) which were fiber forming. However, because of their low melting points, their lack of stabilities, and their solubilities in a number of solvents, the polyesters did not show promise as textile fibers at that time. The useful properties of polyesters for fibers were not recognized until additional important concepts and properties associated with aromatic polyesters were discovered by J.R.Whinfield and J.T.Dickson at the end of the 1930’s.

Without the benefit of future knowledge about aromatic polyesters, the Carothers group concentrated its research on the polyamides synthesized in the early 30’s. The synthetic polymer which was chosen for fiber development was that synthesized from hexamethylenediamine and adipic acid in the mid 30’s. Each one of these monomers contains a small six-carbon chain and so the polyamide synthesized from these monomers was referred to as a 66 polymer, later called “Nylon 66.” This was the synthetic polymer that engineers with fifteen or so years experience in the rayon textile field devoted their attention to as development of nylon was commenced. The basic principles of the synthesis and the needs for high molecular weights and fiber orientation were established.

The Engineering

Looking back, one of the first attempts to market an unnatural fiber came in the last half of the 19th century when collodion was extruded into fine thread and woven into fabric as an artificial silk. The high flammability of this material contributed most to its failure, but weakness was also a very significant shortcoming. The widespread use of silk in clothes, household furnishings, parachutes, fish line, etc., now attests to the demand for strong fibrous materials. However, much had to be learned in the basic physical sciences before the structural aspects of materials which contribute to strength properties could be explained and exploited for producing synthetic fibers.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Thus, driven by this recognition of inadequacy in MSE in addition to the 20th century need to replace or supplement the supply of silk with a high-strength synthetic fibrous material, observations of the silkworm making its cocoon must have been taken more seriously. The silkworm had long afforded clues for the development of engineering processes for producing synthetic fibers since it was known to extrude a liquid substance through its glands, solidifying into a continuous filament on emerging into cool air. The engineer could simulate this by forcing a substance (either in solution or melted) through a spinneret with small orifices and achieve much the same results, provided that the substance being spun would hang together and subsequently withstand strong stresses or pulling. Only polymeric substances (long-chain molecules) would be capable of this.

Spinning polymeric materials from solution was being investigated before the 1920’s in developing the basic art for producing rayon fibers. Chemically degrading high polymeric natural cellulose by either acid (acetate process) or alkali (viscose process) to a somewhat lower molecular weight derivative, and then subsequently regenerating the cellulosic material from solution in the form of fibers had been accomplished. The lowered molecular weight of the regenerated cellulose fibers rendered them weaker than silk fibers which possessed their high natural molecular weight, so that the high strength problem for synthetic fibers had not been solved.

Thus, a large body of knowledge had been amassed and engineering aspects on the spinning and the packaging of rayon for market had been worked out by the time Carothers’ group became productive in the preparation of new synthetic polymers. The possible impact of synthetic fibers on the textile industry and society was realized to some extent. The knowledge that linear synthetic polymers of very high molecular weight (“superpolymers”) could give rise to high-strength fibers to replace silk for many important applications was already in the minds of astute engineers and scientists. About 1935 the decision to commercialize nylon was made and development problems were handed to the engineers producing rayon (man-made fiber from natural polymercellulose).

Although the research in chemistry did not cease, it was now the time for the engineers (and engineering science) to be drawn upon. Much experience and technical skill had been acquired in the production of rayon and these people had valuable experience in spinning, weaving, and knitting of rayon. Despite the depth of experience in the engineering science of textiles, new innovations and discoveries were required to solve the problems specifically associated with the spinning and weaving of this purely synthetic fiber. Problems in processing and equipment design were immense.

Before a satisfactory solution to the problems of spinning nylon was arrived at, an entirely new concept of melt spinning at temperatures approaching 300°. C was derived. Instead of extruding a solution of polymer into a coagulation bath where fibers are hardened by precipitation (wet spinning) or into a hot gas chamber where fibers are hardened by evaporation of the solvent (dry spinning), the nylon polymer was heated above its melting point of 263° C and the molten polymer extruded into a cool gas chamber for hardening the fiber (melt spinning).

Developing a pumping system for the hot molten polymer requiring small clearances and the use of the polymer itself as a lubricant was an engineering

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

accomplishment in itself. Special non-softening, non-warping, abrasion-resistant steels had to be utilized. Problems involved with properties of polymers could not be handled by classical fluid mechanics based on small-molecule behavior. The engineers were required to confront new design problems to produce new textile equipment since the rayon and acetate equipment was not adaptable to this new synthetic polymer. Nevertheless, they were successful in commencing pilot production of nylon in 1938.

Additional Disciplines

In addition to the contributions of the organic and physical chemists, one might further distinguish a contributing discipline by reference to analytical chemistry. For example, the chemists synthesizing the new polymers were aided greatly by the wet chemical analysis performed by analytical chemists to determine the number of chain ends which were still present in a polymerization mixture. By detecting the number of chain ends in a sample, the analytical chemist could calculate the number of molecules which had linked together to tell him the molecular weight which had been achieved. Analysis and determination of molecular weights of giant molecules was in its infancy around 1930. The development of this analytical capability for polymers gave the organic chemist necessary information from which he could develop reaction conditions to increase and control the molecular weights obtained from the polymerization reactions. As indicated above, high-molecular weight “superpolymers” were required in order to obtain fibers with tensile strengths comparable to that obtained from silk.

During the early days of research on the polyesters and polyamides, another materials science played an important role in the development of synthetic fibers. That materials science was physics. Physicists had previously investigated natural and regenerated natural fibers by x-ray diffraction methods. Diffraction patterns indicating orientation of the long polymer-chain molecules in silk were to a large extent understood and the effects of drawing to orient polymer chains and improve strength in rayon fibers were known. The physicist then developed structure-property relationships of great fundamental importance and contributed greatly to the understanding of the high tensile strength obtained from cold drawing the early filaments produced by the organic chemists. The knowledge of polymer orientation from x-ray diffraction was directly applied to the synthetic fiber research.

Prior developments in the field of metallurgy, as a part of MSE, had to be relied upon by the engineers who dealt with the problems of spinning nylon. When it came time to scale-up the polymerization reactions of nylon, the engineers used copper vessels in initial runs. However, when molten polymer was extruded from the copper vessels it was found to be dark in color indicating the chemical reaction had taken place between the metal vessels and the molten polymer at temperatures approaching 300° C. A search had to be made for different types of materials which were more corrosion resistant in the large-scale environment. Glass vessels were known to be acceptable because these had been used previously in the laboratory. But of all the other materials tested in an extensive search, only silver and stainless steel were

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

found to resist corrosion when in contact with the molten nylon polymerization mixture. Although the technology of stainless steel was still in relatively early stages of development, it was fortunate that significant developments had been made in this area of MSE to be able to furnish a quality of stainless steel which could be utilized under the high temperature conditions imposed by the new melt-spinning method.

APPENDIX 3E
Textured Materials

Textured polycrystalline materials, with physical properties related to those of single crystals, are finding an increasing number of applications in devices where strong mechanical, magnetic, and other physical properties are desired. The feature that distinguishes textured materials from others is the preferential directional alignment of the individual crystalline grains making up the material.

Most materials in use today are polycrystalline aggregates of a large number of microscopic crystals, or grains. The directional alignment among neighboring crystals ranges from random to nearly perfect. We call a material textured when a reasonably good alignment occurs. Thus, a textured material resembles somewhat a giant crystal. Because a crystal may be mechanically stronger or more magnetic in one direction than another, properties of polycrystalline materials can be enhanced by texturing.

Recently-developed textured materials are being used for permanent magnet alloys in electronic and electrical equipment, for magnetic memory devices called twistors, and for high-strength phosphor bronze and other copper alloys as springs in relays, connectors, and many other devices.

Texture is developed in several ways. One method starts with cast ingots. When an ingot is deformed, such as by rolling or wire drawing, textural changes take place. Interestingly enough, the crystals often do not assume random orientations when the deformed material is subsequently annealed. A new set of crystals forms by recrystallization, and the new crystals often take on a new texture with a different orientation from the old texture.

Recent researches have led to advances in understanding how texture is developed—an essential first step in the control and exploitation of this phenomenon in materials.

In one study, undertaken by two research metallurgists, the formation of texture in castings was simulated and followed by observing the steps by which freezing occurs in certain transparent, nonmetallic materials that possess thermodynamic properties similar to those of metals. The study of castings of these transparent materials has led to better understanding and control of texture in castings. An impressive application of texture control by casting is in the use of directional solidification for turbine blades for jet engines. Other metallurgists concerned with finding improved magnetic alloys have, quite recently, also employed directional solidification to enhance the magnetic properties of powerful permanent magnet alloys made of cobalt, copper, and samarium (or cerium). Commercial Alnico permanent magnets have likewise been improved by texture control via directional solidification. This type of texture control is most suitable for brittle

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

materials which cannot be mechanically deformed.

If the material is ductile, deformation processes such as wire drawing and rolling can also produce texture. During deformation, certain crystal planes glide over each other, forcing the individual crystals to assume a common directional alignment. These crystal planes can vary from one material to another, thereby producing different textures.

The basic mathematics of analyzing the development of texture during deformation was worked out by the mathematical physicist, Sir Goeffrey I.Taylor, in Cambridge in 1937. The treatment is essentially one of optimization, calling for the selection of a set of slip planes and directions that would accomplish the deformation with a minimum expenditure of mechanical work. Widespread application of the analysis, however, was delayed because of the extremely laborious calculations involved at the time. With the development of linear programming in the 1940’s and with the advent of electronic computers, successful application of Taylor’s treatment became assured. This was done in collaborative effort between a research metallurgist and a mathematician who have been able to trace the texture development by modeling the deformation on a computer. Graphic computer plots are generated which not only reveal the final texture of the crystals within the polycrystalline material, but how it is arrived at as well. Thus, a considerable degree of textural control can be exercised.

The degree of control over the crystal texture is primarily a function of how the material is deformed. By adjusting die sizes, or the roll spacing through which the metal is passed, the metal is reduced in successive stages. Depending on the sequence and extent of reduction, different textures can be obtained and, therefore, different physical and mechanical properties from the metal. Within the Bell System, such control has led to improved soft magnetic alloys in wire and tape form for use in certain magnetic memory devices, and also to alloys with enhanced mechanical properties for springs and electrical connectors. In the latter, after final heat treatment, yield strengths of such materials as phosphor bronze, nickel silver, cupronickel, and copper beryllium have been, on the average, almost doubled without loss of ductility.

Elsewhere, texture strengthening has been responsible for increased strength in spherical pressure vessels of titanium alloys. In one example, a pressure vessel made of textured Ti-5 Al-2.5 Sn alloy sheet exhibited a yield strength level 40 percent higher than that predicted for randomly oriented material, and the burst strength was about 75 percent higher than that available without texture control. Improved mechanical properties in magnesium and beryllium have also been attained through texture control.

Texture control has been and continues to be a major activity aiming to upgrade the quality of deep-drawing sheet steels. These steels are consumed in huge quantitites as automobile body fenders and appliance housings, to name two of their numerous uses. How deep a cup can be drawn from a blank depends heavily on the strength of the cup wall and on the ease of deformation in the flange region. It has been theoretically predicted, and experimentally proven, that improved drawability can be achieved with the proper texture. In addition, “ears,” or undulations of the rim, which must be trimmed away, are directly related to the texture and can be suppressed through texture control. Textured deep-drawing steels are now offered on

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

a limited commercial basis.

These studies emphasize the positive aspects of textured materials. Occasions do arise, however, when texture may be undesirable. For example, some recent work has indicated that thin-film capacitors made from textured aluminum or hafnium film perform poorly as compared to those made from randomly oriented materials. Hence, texture control implies suppression as well as accentuation of texture.

Much work into textured materials remains to be done, but the above examples demonstrate the number and variety of potential applications for these materials. Since certain crystal orientations tend to have better physical properties than others, texture control affords the opportunity to utilize a material’s capability more fully.

APPENDIX 3F
Integrated Circuits

The development of the transistor led to a number of basic techniques required for integrated circuits, such as semiconductor purification, crystal growth, alloying, diffusion, oxide masking, and epitaxial growth. The semiconductor industry had reached the point in 1958, when the integrated circuit was born, where it worked daily with crystals of chemical, physical, and structural perfection many orders of magnitude higher than in any other industry, and produced novel, discrete, electronic devices, often with superior performance to that of vacuum tubes.

Silicon was beginning to become important, though germanium was the predominant semiconductor material. Silicon looked particularly promising in military applications where its superior high-temperature performance was necessary. Transistors were being designed into circuits where small size and weight and low power drain were critical, though the cost was still not competitive with vacuum tubes. The first commercial products to use significant quantities of transistors were miniature hearing-aids and portable radios. Computers and communications were obvious candidates in the industrial area, and IBM and BTL had large semiconductor programs. Another was the development of military equipment such as the Polaris and Minuteman missile programs. All of these large-system applications of semiconductor devices spurred the push to miniaturization. This, then, was the status of semiconductors in 1958 when Kilby at Texas Instruments first conceived of and constructed an integrated circuit. Though the practical use of transistors was relatively new, the needs for even further reduction in size, weight, and power were already in sight.

Kilby, an electrical engineer, joined Texas Instruments from Centralab where he had been working on miniaturization of electronic circuits by the silk screening of conductive inks on a ceramic substrate to form resistance and capacitance. Hence, he had experience and a strong interest in miniaturization. In 1958, he conceived of processing the elements of a complete circuit, such as resistors, capacitors, transistors, and diodes in a monolithic bar of semiconductor. The technology for accomplishing this already existed, having been developed for fabricating discrete devices. Diffusion and alloying were used for introducing controlled amounts of desired

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

impurities to create localized p- and n-regions. Metal evaporation and thermocompression bonding were available for making electrical contacts to and between such regions. Kilby’s first working semiconductor circuit was a simple phase-shift oscillator with components connected either through the bulk semiconductor when resistance was desired, or by bonding wires between them. This technology permitted fabrication of only simple circuits involving a few tens of devices, and several subsequent advances were necessary before the complex, reliable, and inexpensive integrated circuits of today became a reality. Some of the more important of these advances were made in the continuing effort to improve discrete transistors as mentioned earlier; however, their application to integrated circuits was rapidly recognized and exploited.

The key developments were the application of photoresist and oxide etches to determine the regions into which impurities were to be diffused; the planar process using the above techniques for diffusion but leaving the silicon oxide layer on the surface to protect the ambient sensitive p-n junctions; the use of evaporated and photoresist-patterned metal films on the oxide to interconnect the devices; and the application of chemical vapor deposition for growing thin epitaxial layers of silicon on silicon substrates containing different impurity doping. Each of these developments, and their application to integrated circuit improvement, will be briefly described.

The ability of an SiO2 layer to mask against the diffusion of many of the group III and V doping impurities was described by Frosch, a chemist at Bell Laboratories in 1957. A wax pattern was applied to the oxide, the unprotected regions chemically etched away to expose the silicon, the wax removed, and impurities diffused into the exposed regions to form p- and n-doped material. Though this technique was useful, it was limited to formation of relatively large regions, several hundred microns in size. Photosensitive materials, known as photoresists, had been developed at Eastman Kodak for the patterned etching of metal on printing plates and on printed circuit boards. These were solutions containing organic compounds which polymerized upon exposure to ultraviolet light. The unexposed resist could be dissolved by appropriate solvents leaving an etch-resistant mask on the metal. Lathrop, a physicist, and Nall, a chemist, working on miniaturization of components at Diamond Ordnance Fuse Laboratory realized, in 1957, that photoresist might be applicable to patterning the SiO2 for silicons-diffused transistors. This allowed windows of the order of 200 µm in size to be etched. Continued improvements in photoresists, with emphasis on their use with semiconductors, increased their definition capabilities to about 25 µm by 1960 and to less than 1 µm today. A major advantage in these photoresist techniques is the ability to pattern all of the areas on a two-inch diameter silicon slice simultaneously, with consequent reduction in processing cost.

The next major technological advance was the planar process, developed by Hoerni, a physicist at Fairchild. This process applies the oxide-masking and photoresist technologies already described; however, SiO2 is regrown into the windows during the diffusion steps and the oxide is left over all of the device or circuit surface except the contact areas. This has two major advantages, The oxide, as had been shown by Atalla, eliminates slow surface states and protects the sensitive regions (where p-n junctions intercept the silicon surface) from the effect of ambients, thereby leading to improved device characteristics and greater reliability. Also the oxide is a good

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

insulator and allows evaporated metallization patterns connecting the devices to be formed directly on the oxide surface. Again, photoresist techniques are used to define these metal interconnection patterns. It is also possible, by depositing another SiO2 layer over the first metallization, to then form a second set of interconnections allowing even more complex circuits to be fabricated.

Still another significant development necessary for the success of integrated circuits was the application of chemical vapor deposition to grow epitaxial silicon layers. Circuits made with planar technology, but on bulk silicon slices, had severe limitations. Many circuits required significantly better electrical isolation between individual regions or devices than was afforded by the bulk silicon resistance alone. Hence, such circuits could not be integrated. Epitaxial growth, as will be described, allowed suitable isolation to be achieved.

Chemical vapor deposition for growing single crystals of silicon and germanium was demonstrated in the early 1950’s by Sangster, a chemist at Hughes, and by Teal and Christensen, chemists at Bell Laboratories, The conductivity type and resistivity of the deposited semiconductors could be controlled by introducing appropriate impurity gases during the deposition. Several investigators attempted to use this technique for growing successive multiple n- and p-type layers to form diodes and transistors directly, rather than by starting with uniform material and altering regions by impurity diffusion, However, these attempts gave poor results. The characteristics of the resulting p-n junctions were poor, probably due to imperfections or contamination at the interfaces between the layers. And whereas diffusion could be patterned into localized areas, there was no comparable way of patterning the epitaxial regions. However, a interdisciplinary team at Bell Laboratories, Loar (physicist), Christensen (chemist), Kleimack (physicist), and Theurer (metallurgist), realized and demonstrated that a more limited use of epitaxial deposition could significantly improve planar transistor performance.

The diffused base and emitter regions in planar transistors are quite shallow, extending only a few, or at most a few tens, of microns in from the silicon surface. Yet, in order to be handled during processing without excessive breakage, the silicon slices must be several times that thick. Since the resistivity in the collector region adjacent to the base needs to be of the order of 1 ohm-cm, the extra thickness adds additional collector series resistance which is detrimental to transistor performance. By starting with a heavily doped, hence low resistivity, silicon slice of sufficient thickness to provide the necessary mechanical strength, and growing a lightly doped epitaxial layer only thick enough to contain the active regions of the transistor, a significant reduction was obtained in collector series resistance.

This same technique was subsequently applied to silicon integrated circuits to achieve electrical isolation between components. A thin n-type epitaxial layer suitable for fabrication of the desired devices was grown on a p-type silicon substrate. During processing, a group III impurity was diffused through the thin n-layer to the p-type substrate in a pattern that surrounded those devices requiring isolation with p-type material. The high resistance of the reversed bias p-n junction provided the isolation.

Based on the technologies which have been described, integrated circuits containing bipolar transistors as the active devices were developed to perform

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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a variety of electronic functions, and a major commercial business resulted. Meanwhile, back in the laboratories, a new active semiconductor device was being studied, the metal oxide semiconductor transistor. It is interesting to note that the MOS transistor is in essence, the field-effect device that Shockley had originally sought, but only more recently made possible through advances in materials technology. This device had significant advantages over bipolar transistors for some applications. The electrical power requirements were lower. High packing densities on integrated circuits were possible. And fewer processing operations were required during manufacturing, resulting in higher yields and lower costs. However, the device also brought new technical problems which had to be solved before its usefulness could be realized.

Inasmuch as the critical, active region of the MOS transistor lies very close to the silicon-SiO2 interface, the instabilities in the SiO2 and near the interface strongly influence the transistor properties. Such instabilities can be caused by many things, a common one being the presence of sodiumion contamination in the SiO2. The high electronic field present across the oxide during operation of the device causes the sodium to migrate, and transistor characteristics shift accordingly. Many man-years of effort in several laboratories by chemists, physicists, and electrical engineers were required before the causes of, and cures for, these instabilities reached a point where reliable MOS integrated circuits became practical. This area is now growing rapidly in importance, with integrated circuits containing as many as 10,000 individual components being manufactured in high volume and incorporated into equipment such as electronic desk and hand calculators.

So the integrated circuit has evolved, in a little over a decade, from Kilby’s first phaseshift oscillator with a few components to the large-scale manufacturing of circuits with over 10,000 components; and these at much lower cost and higher reliability than the sum of the individual components.

The critical steps in the integrated-circuit story are shown in Figure 3.3.

The Role of Materials Science and Engineering In Integrated Circuits

The overall effort was both multidisciplinary and interdisciplinary. Chemists and metallurgists developed epitaxial growth techniques with the scope of the studies ranging from basic investigations of the kinetics and thermodynamics of the vapor-solid reactions to the design of production reactors capable of handling several slices at a time. A chemist discovered the diffusions-masking ability of SiO2. A physicist, who had previously spent several years in a university chemistry department, conceived of the planar process. A physicist and chemist first applied photoresist methods to semiconductors. Metallurgists perfected the metal systems evaporated onto the surface for interconnecting the components. Electrical engineers designed the devices and circuits, and laid out the diffusion-masking and interconnection patterns such that circuits would perform the desired functions. Today, because of the extreme complexity of circuits containing in excess of 10,000 components, layout and interconnection patterns are performed on computers, requiring programmers and software specialists, and they must interact

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

Figure 3.3 Key Integrated-Circuit Developments, 1958–1971

SOME PRE-INTEGRATED CIRCUIT DEVELOPMENTS INVENTION OF:

Point-Contact Transistor–1948

Junction Transistor–1949

WORK BY:

Chemists & Metallurgists on growing, purifying and doping crystals. Grown junction, alloying and diffusion processes.

Physicists on recombination mechanisms, carrier transport, band structure, surface states.

Electrical Engineers on transistor design, power and frequency improvement, circuit design.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

closely with the chemists, physicists, and process engineers to assure compatibility between the design and the process capabilities. Finally, metallurgists and ceramic engineers developed the hermetically sealed packages to protect the silicon circuits.

Interaction between science and engineering certainly existed to a high degree. While investigators were busy writing up their work for publication in scientific journals, they were simultaneously phasing their developments into the production lines. The time between scientific advance and production was extremely short.

The technological advances described here borrowed very heavily from developments in other areas. Nearly all were motivated by attempts to improve the performance of discrete transistors rather than integrated circuits. Diffusion of impurities had been studied for years in other materials, such as metals. Photoresist was developed for the printing and circuit-board industries. But those concerned with the perfection of the integrated circuit quickly recognized the applicability of such techniques.

There were certainly many individuals and institutions involved, both in the initial discoveries and even more in the subsequent development into useful processes. Few of the significant contributions to process technology involved basic research. Most grew out of applied research and engineering, with the latter predominating.

The development of integrated circuits, in fact the entire development of modern electronic devices, was not only a case where the MSE approach was followed, but one where this approach was essential for success to be achieved so effectively.

APPENDIX 3G
Aluminum Conductor Telephone Cables

Introduction

In 1965 the Bell System undertook an extensive development project with the specific aim of establishing an aluminum-conductor telephones-cable technology as a commercially viable alternative to copper conductor cable. This goal was accomplished, and the problems overcome in reaching it are outlined in the following section. The major impetus for this development, as with most other substitutions of aluminum for copper in electrical applications, stemmed from periodic instabilities in both the price and availability of copper and the growing cost differential between these two metals. As the largest single consumer of copper in the U.S. (approximately 270,000 tons or 14 percent of all the copper processed in the U.S. in 1971), the Bell System is particularly vulnerable to these factors.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×
Problems in Substituting Aluminum for Copper In Telephone Cables

The problems divided themselves into design and manufacturing categories. The former focussed on providing a cable and connector technology of equivalent electrical, mechanical, and reliability performance to that achieved with copper. The latter focussed on developing a manufacturing process as fully compatible as possible with the high-speed tandem operations of wire drawing, annealing, and insulating, now used for copper. The hallmarks then were equivalent reliability and maximum compatibility.

The problems posed by aluminum itself include:

  1. Its lower electrical conductivity (= 65 percent copper standard).

  2. Its highly resistive and quick-forming oxide.

  3. Its high electropositive potential.

  4. Its normally poor combination of strength, ductility, and creep resistance when high (>60 percent) electrical conductivity is sought.

These problems are not serious for electric-power transmission lines nor for motor and transformer windings when properly designed. Communication cables and building wire do present serious problems arising particularly from (b), (c), and (d).

These difficulties were dealt with in the aluminum-conductor telephone cable as follows:

  1. To meet current cable transmission requirements and provide equivalent copper conductivity, the electrical conductivity of aluminum was specified as 60 percent copper standard and a 2-gage size larger cross-section was used. (The cable size penalty incurred in adopting aluminum alloys with less than 60 percent arises not only from larger conductor cross-sections but also from thicker insulation needed to maintain cable capacitance requirements.)

  2. Oxide characteristics required a pressure-type connector capable of providing a gas-tight joint under thermal cycling and conductor creep. This was accomplished with an indium-plated, phosphor bronze, knife-type connector shown to maintain satisfactory contact resistance,

  3. The electrolytic and galvanic corrosion properties of aluminum necessitate exclusion of moisture from the conductor and from connectors where dissimilar metals are in contact. The extruded polyethylene wire insulation is the primary conductor moisture barrier; the new cable sheath with a continuous aluminum foil barrier is the second; pressurized gas or petroleum jelly filling in the cable is

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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the third.* The connector housing was also filled with an organic gel.

  1. Although the desired strength and ductility of electrical-grade aluminum was satisfactory for wire sizes of 17 and 20 gage, a new alloy was required for 24-gage wire. An Al-0.8Fe-0.12Mg was developed for this and subsequently found to have creep properties comparable to toughs-pitch copper and far superior to electrical-grade aluminum.

In the area of processing, the aluminum-alloy producers were convinced of the need to use liquid-metal filtering to achieve low wire breakage on drawing. A new cleaning and inductions-annealing procedure was adopted and an H-11 temper (20 percent reduction in area) was found to give the best combination of strength and ductility.

Observations

The aluminum industry was initially reluctant to participate strongly in this program, questioning both the size of the market and the need for further alloy and processing development in this area. When convinced, however, they participated actively, and provided the new Al-Fe-Mg alloy which they are now promoting for this and other electrical applications. The Bell System worked with the major U.S. aluminum producers in this development and the functional interactions were with the working-level plant metallurgists in these organizations. On the producers’ side, marketing and sales people provided a strong stimulus when made aware of the market potential and research people became involved at the later stages to “fine tune” pragmatic solutions already reached.

There is no unique example of technology-transfer either into or out of this case but several associated technologies, e.g., connectors, were affected by the substitution, and parallel programs were needed to solve these problems. This lengthened the program’s duration (approximately 5 years) and emphasized critical-path considerations and the desirability of a systems approach. Having solved the basic problems in an all-aluminum conductor system, the expedient nature of a copper-clad aluminum substitution becomes more apparent.

APPENDIX 3H
Polymer Latex-Modified Portland Cement

A “polymer latex-modified portland cement” is obtained when a part of

*  

Historical note: In the early 1950’s, the Bell System experimented with an aluminum conductor telephone cable employing paper-pulp-insulated wire. These cables failed catastrophically in the field due to electrolytic corrosion in the presence of the applied voltage and ingressed moisture from cable-sheath damage. This failure posed a psychological barrier to acceptance of the new cable which was only slowly overcome with successful field performance.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

the water quantity that would be required in mixing a conventional (i.e., non-polymer containing) composition is replaced by colloidal polymer-latex particles. This modification, with appropriate latexes, is sometimes accompanied by significant alteration of properties in the resultant material as, for example, enhancement of compressive, tensile, and shear strength values, altered elastic moduli, improved resistance to chemical attack, and increased adhesion to various substrates.

In many instances, the increases in tensile strength and bonding characertistics have been so dramatic (as with brick mortars) that new structural cesigns and fabrication methods become feasible. In other situations, upgraded chemical resistance, or bonding properties, has allowed introduction of portland-cement-base compositions into applications earlier considered impractical. Methods of installation or of repair (as with surfacing compositions or precase concrete wall-panel patching) have been enabled or simplified.

Many individuals and many organizations have contributed to the development of polymer latex-modified portland cement. One group’s efforts are described here to provide an explicit example; the description is intended as representation of the contributions made by MSE in this field.

The People

The three principal investigators have been:

Herman B.Wagner, Professor of Chemistry at the Drexell University, a physical chemist experienced in organic polymers and hydraulic cements.

Dallas G.Grenley, a polymer chemist at the Dow Chemical Company, experienced in polymer latex synthesis.

Jerry Isenburg, a physicist at the Dow Chemical Company, specializing in portland cement rheology and scanning electron microscopy.

Each of the above individuals has been intimately acquainted with polymer modified-portland cement compositions for a number of years, from the chemical, engineering, and commercial aspects.

The Program

When this program was started in 1961, there was a considerable amount of empirical data relating to such gross variables as identity of the polymer modifier, the level of polymer content, and environmental conditions surrounding the cement hydration (hardening) reactions. No mechanism had been established for the observed reinforcements of cement by certain polymers although numerous suggestions had been put forward. This interdisciplinary team set out to establish a more basic understanding of such systems in terms

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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of the physical and chemical interactions between the polymer and cement. Earlier research in physics and chemistry, entirely unrelated to cement technology, provided the necessary experimental tools.

Some Preliminary Considerations

The results obtained up to this time are best presented with reference first to an unmodified cement composition. With a typical portland cement powder, tricalcium silicate and betadicalcium silicate constitute about three-quarters of its weight. Under ordinary temperature conditions, and with only water available, the hydration of these two major constituents is essentially complete within 7 days. Hydration of other constituents requires considerably longer for completion. In any case, the “cement gel” that is progressively developed as the product of these hydration reactions comprises chemical species of high specific surface. The new surface area that can ultimately develop may be 500 to 1000 times larger than that of the initial cement grains, and the strength properties of the hardened cement are importantly linked to this increased surface area, and to the structure and packing density of the colloidal hydration products.

A polymer latex may be visualized as relatively uniform-diameter (e.g., 2000 Å) spherical polymer particles colloidally dispersed in water. Here, typically, one-fourth of the volume of the latex would be an organic polymer, such as polystyrene, and three-fourths of the volume water. Additionally, small concentrations of surfactants, soaps, polymerization initiators, and other minor constituents required for manufacture or stabilization of the dispersion are also present. When such a latex is mixed with the cement powder, a fluid suspension of the cement grains is initially obtained. This fluidity is imparted not only by the water but also by the polymer particles which are considerably smaller than the cement grains.

Following this mixing, one might expect or visualize a number of events and effects, including (a) progressive hydration of the cement grains, as with conventional cement, (b) coalescence of the latex particles with one another, as the dispersant water phase is consumed by the cement-hydration reaction, (c) modification of the rate and/or course of the hydration reactions caused by the presence of the polymer latex particles or other constituents of the latex, (d) physical attachment or chemisorption of the latex particles at the surface of the cement grains and/or cement gel, (e) chemical reaction of the polymer latex in this environment, altering the character of the polymer surface presented, etc.

Experimental Methods

Among the experimental techniques employed in this investigation were transmission and scanning electron microscopy, electron probe, infrared spectroscopy, electrophoresis, BET absorption, and radio-isotope tracing. Special techniques and apparatus have been developed by the various investigators to obtain data on coalescence, adhesion, surface adsorption, mortar rheology, and engineering properties. As one example, the tremendous

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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depth-of-field of the scanning electron microscope has been exploited in studying the cement structure in convenient steps of magnification from 20 to 100,000X. The morphology of the cement grains is thus found to be altered by the hydration reactions, and the various crystalline forms can be observed. The very small latex particles are perfect spheres in the mortar mixes, but upon drying they coalesce to form a continuous film in which the individual particles lose their identity.

Conclusions

The development of polymer coalescence was found to occur gradually, over a period of hours to days, and the structure of the coalesced polymer within these compositions was detailed microscopically and related to the inorganic components. The rate of generation of specific surface area of the cement gel was retarded by some latexes and accelerated by others; ultimately the surface area developed is not affected by the latex type, and the chemical structure of the cement gel is comparable.

The enhanced compressive strength observed is primarily the result of densification of the cement gel structure. Tensile and adhesive strength increases, on the other hand, are determined by levels of bonding that are affected between cement and aggregate interfaces and within the hardened cement paste; these are specific to the chemical latex employed.

Moduli of elasticity and rupture were found to be related to extent of cement hydration achieved and to specific effects of the polymer or interfacial adhesion.

A detailed picture of the structural and chemical events occurring as such compositions harden is being assembled, and it is expected that a systematic procedure for developing effective latexes and polymer-modified materials is emerging.

APPENDIX 3I
Phosphors for TV

The story of phosphors is a rich one, extending back many decades in fundamental studies of the interaction of light and matter. Throughout the same period, phosphors have played an important technical role, for example, in creating luminescence on cathode-ray screens. In even such as limited a field as red phosphors for color TV screens, there has been a wealth of contributions from several major laboratories. A team of workers at the Philips Laboratory independently discovered the potential for color TV applications of europium-doped yttrium oxide phosphors and the related material, gadolinium oxide. Others had independently explored oxy-sulfide systems and had developed the yttrium compound Y2O2S: Eu. The following is a description of the development work of three individuals at the General Telephone and Electronic Laboratory in Palo Alto, which led to the development of the new red phosphor of commercial importance. While singling out one group has the effect of neglecting the important contributions of others, the intent here is to portray as specifically as possible one material development

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

characteristic of MSE and to identify precisely the various elements of the situation. For present purposes, the details of one specific development, which were readily available to us, seem to outweigh the advantage of the usual scientific custom of giving due credit and reference to all significant contributions

Early color TV screens were limited in brightness by the characteristics of the red phosphor. The blue and green phosphors were operated at reduced electron current to balance with the red phosphor which exhibited current saturation and a color short of bright red. In 1961, an interdisciplinary team at General Telephone and Electronics developed a new red phosphor material with a redder color and a capability of operation at higher energies. All TV tubes manufactured in the U.S. now use this phosphor, or rare-earth compounds subsequently developed by other organizations. The host material is yttrium oxide, which is durable and has good optical properties. The activator which fluoresces and emits the desired (red) light is europium, a rare earth. This material has a high efficiency for cathode-ray excitation. A similar oxide, yttrium vanadate (YVO4), which was recognized as a good phosphor through the yttrium oxide work, has been shown to give an even redder emission color (desirable for TV) although somewhat less efficiently.

The People

As is true in every MSE effort, the people are of central importance. The three principal investigators were:

Robert White, trained in physics, with experience and emphasis on magnetic materials and resonance phenomena.

Kenneth Wickersheim, trained in physics and specialized in optical spectroscopy.

Robert Lefever, trained as an inorganic chemist with considerable experience in materials preparation and crystal growth.

These three individuals, with different backgrounds and different areas of specialization, maintained a high level of interaction on a daily basis. Each of them had an interest in and a detailed knowledge of the other’s current programs. Each understood how his work could influence and could be influenced by that of the other two.

The Program

It is important to note that the program pursued by these three researchers had as its original objective not the development of new phosphors, but rather the development of suitable host materials for lasers. The rare earths were identified as promising candidates for laser materials because of the sharp line spectra which are characteristic of rare-earth ions. The

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

sharp lines result from emissions in the 4f shell which is shielded from the local environment by the completed 5p shell. It is this same shielding which leads to the close chemical similarity between the rare earths and yet provides a selection of strong optical lines by choosing different rare earths. There had been some previous experience with rare-earth activators for phosphorescence but much of that had been discouraging. With the insight gained by the work now being described, it is clear that rare-earth impurities had caused line quenching in some cases and that the host material had not been suitably chosen. It now appeared that the rare-earth oxides in cubic form would be desirable hosts in that the material is refractory, has the proper crystal symmetry, and is chemically stable. These physical and chemical properties plus extensive knowledge of material-growth techniques, optical absorption and emission, as well as interaction of dopant atoms with the host lattice, made the rare-earth oxide approach seem promising.

Knowledge Required

Fortunately all the fundamental science necessary for this development had been completed, and these investigators were familiar with the considerable span of knowledge required for proper pursuit of this materials development program. In addition, close interplay was achieved between a knowledge of growth of refractory oxides and a knowledge of line-broadening mechanisms which are the principal road block in the achievement of good phosphors.

Lefever had previous experience with the use of flame fusion (Verneuil) techniques for the production of single crystals of refractory oxides through growth of refractory oxides for his studies on ferromagnets. The standard Verneuil apparatus is a concentric-tube oxy-hydrogen burner in which the center tube is used to supply the raw material for crystal growth and oxygen. From this work and related studies on flux growth of crystals, he gained a detailed understanding of the importance of crystal imperfections and impurities on radiation line widths (in this case, radiating in the RF frequency range). A particular example, discussed later, is the presence of silicon in yttrium-iron garnet which leads to line broadening by an intermediate process. This experience emphasized that specific impurities can be important in an almost unique way when one is considering a particular physical process. It is impossible to eliminate all foreign impurities from a single crystal, but it may be possible to reduce to an extremely low level one or two foreign species which are particularly troublesome.

Phosphorescence is a material phenomenon in which energy introduced into the material by electron bombardment or ultraviolet radiation is partially re-emitted over a period of time in the visible spectrum. Normally the light is emitted from impurity atoms which serve as activators. Mechanisms which reduce the efficiency of phosphorescence include poor transfer of the absorbed energy to the activator, nonradiating energy loss from the excited activator, and line broadening of the spectrum of the activator atoms.

Line-broadening mechanisms are attributed to many physical processes, all of which need to be understood in a detailed analysis of the behavior of a particular phosphorescent material. In a solid, the optical emission lines are usually very broad and often indistinguishable because there are so many

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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ways in which the energy levels can be varied by influences from neighboring atoms. This variation is found for well-defined positions in single crystals. The electron bond to an individual atom can have its energy level changed by a large variety of physical mechanisms, some of which are discussed briefly. The sum of these interactions leads to a statistical distribution of energy for the large number of atoms involved in any real sample, and the result is a broadening of the emission line.

Crystalline field splitting is the term used to describe variation in energy level due to the interaction between the electric fields in the crystal and a specific electron state or orbit. If the electron state is not spherically symmetrical and if the crystalline field varies along major directions of the lattice, the energy level will depend on the relative orientation between the electron orbit and the crystal.

A low-symmetry atomic site can be beneficial when the desired line is forbidden as is the case in the europium 4f shell. Y2O3 has two rare-earth acceptor sites, one of moderately high symmetry and one of very low symmetry. This was an important reason for choosing Y2O3.

Lattice vibrations are a frequent source of line broadening. The lattice is not rigid but rather is in a continual state of vibration due to thermally-induced stationary mechanical waves. Solid-state physics has developed an elegant way of treating these vibrations in terms of phonons which can be much more readily manipulated theoretically. Phonons are a mechanical analogy to electromagnetic quanta. They represent a discrete energy of activation and may be thought of as particles in their interaction with other entities such as the electron bound to an atom or an electron in the conduction band of a solid. Phonons are created or destroyed depending on whether energy is added to or taken from the mechanical system. If a phonon interacts with an electron at the time of emission, the line may be of longer of shorter wavelength depending on whether a phonon is created or destroyed. Y2O3 was known from infrared spectroscopy to have a phonon spectrum which coupled weakly with photons in the visible region and therefore contributed little line broadening.

Exchange forces which lead to exchange splitting are a purely quantum-mechanical effect which has no classical analog. Fundamental particles, such as the electron, are identical to the extent that there is no observation which can be made to distinguish whether the particles have exchanged places. If two electron orbits share some common space (wave functions overlap), it is possible for them to exchange positions. The effect on the energy level of each orbit will depend on the relative alignment of the electron spins. This phenomenon is called exchange coupling and is most important in solids when magnetic ions are involved.

Magnetic fields can also change the energy of the electron state. Every electron has an intrinsic spin with which is associated a magnetic moment. The magnetic moment can interact with a magnetic field. In addition, some states of the electron can be thought of as having an associated electric current which interacts with the magnetic field. Magnetic interactions are of course particularly large in materials containing the transition metals such as iron and nickel with their large magnetic moments.

Resonance broadening is an important concept to understand in studying line radiation from solids. If an electron state is weakly coupled to another of identical frequency, resonance will occur between the two and the electron

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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energy will be perturbed, leading to a broadened line. The GT&E group had done a considerable amount of work on ferrites and garnets where resonance is an important phenomena in line broadening in the radio-frequency spectrum. The work on garnets illustrates the close coupling between material preparation and its use; it set the stage for the phosphor development. Wickersheim and Lefever had earlier identified the presence of a silicon impurity in the yttrium-iron garnet at the tetrahedral oxygen site. The silicate ion is incorporated in a tetravalent state in contrast to the trivalent cations in the normal host material. The quadrivalent silicon provides a mechanism for incorporation of a compensating divalent ion to maintain charge neutrality. It has been hypothesized that ferrous iron is introduced from the melt to provide the divalent ion. White had recently provided some confirmation of a theory by Kittel, Portis, and de Genes on line broadening of the magnetic resonance which occurs at a few gigahertz. Fe++ is strongly coupled to the magnetic lattice and in turn is coupled to the rare earth ion by resonance. The result is an easy path for draining energy from the activated atom to the lattice. From this experience, these three investigators were well sensitized to the degree to which the nature of the host and impurities might need to be controlled to obtain narrow-line radiation from a rare-earth activator and consequently high efficiency.

Research Environment

The research environment was an important element in this example of MSE. This work was carried out in an industrial laboratory where there was considerable latitude available to the investigators to pursue directions which they believed to be most promising. At the same time, the program was being carried on for an applied purpose. Because of the close relationship between GT&E Laboratory and Sylvania, an operating Company, it was well known in the Laboratory that the TV industry had need for improved colored phosphors for the cathode ray tubes and the nature of the required improvements. As a result, a span of knowledge was achieved which extended from scientific investigation to commercial application.

There was an extremely close working interaction between the three individuals of different background and training. In particular, there was a thorough understanding of just what material characteristics were desired and how they should be reflected in the physical properties of the material. This knowledge was not something which was established a priori and left fixed through the life of the project. Rather, the close interaction modified and refined the material characteristics and requirements as the project developed. With respect to the phosphor development, most of the close interaction required had already been accomplished in the garnet work.

Yttrium oxide was chosen as a laser-host candidate for several reasons. First, the symmetry of the crystal sites for europium were known to be of low symmetry, that is, the local crystal fields vary with direction. Low symmetry is desirable because it removes the forbiddenness of some important 4f transitions in the rare earths. Second, Y2O3 has a phohon spectrum which couples weakly with the excited levels of the excited europium activator. The weak coupling increases the probability that excitation energy will be emitted

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

optically rather than by transfer to the crystal without optical radiation. Third, Y2O3 had already been grown by Lefever; its optical transmission had been measured by Lefever and Wickersheim and was known to be appropriate. Fourth, Y2O3 accepts trivalent europium at a trivalent site. In previous laser material, the rare earth had replaced a divalent ion giving rise to charge compensation and therefore a crystal defect for every activator resulting in line broadening. Y2O3: Eu was the only material chosen for initial studies. The extensive and detailed knowledge in hand precluded the need for a systematic empirical search through many materials.

Results

Lefever was able to grow yttrium-oxide single crystals with europium doping. In order to do so, he had to develop a modification of the flame fusion burner, and then in order to prevent cracking of the crystals he devised a technique for protecting the growing crystal with a coating of powder which reduced thermal gradients in the crystal. Both improvements were patentable.

When the first sample of europium-activated yttrium-oxide laser crystal was examined in the spectrograph under ultraviolet excitation, it was immediately evident to the eye that this was a superior red phosphor. Few scientists in any field are privileged to make a discovery in such a dramatic and instantaneous way. Because of the commercial interest in cathode luminescence, apparatus was built to measure the light emitted due to electron bombardment. The europium-doped yttrium oxide was found to emit a red line of brightness comparable to the green phosphor (willemite) under identical excitation conditions. The color was redder than the red TV phosphor in use at that time, accepted high beam currents without saturating, and emitted efficiently even at elevated temperatures.

It is important to remember that the objective of the program was development of a hardy, sharp-line laser material, a goal that was achieved. However, as a result of understanding the properties of the material and an awareness of technical requirements for improved phosphors, the potential value of Y2O3: Eu was immediately recognized and, because of program flexibility, efforts were channeled into further work on the phosphor aspect of the material.

Much work has been done subsequently by others on rare-earth phosphors for TV applications. Such work was stimulated in large part by the Palo Alto GT&E group and later studies at Sylvania and the GT&E Bayside Laboratories.

APPENDIX 3J
Sintering of Ceramic Oxides, e.g. Lucalox

Better understanding of the driving forces, material-transport mechanisms, and kinetics involved in the sintering of ceramic oxides, has been evolving over the past 30 years. The understanding is not yet complete, but knowledge already grained has led to better control of manufacturing processes and improved properties in many ceramic products.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Early theoretical work that contributed to this progress was that of the Russian theoretical physicist, J.Frenkel, who published a paper in 1945 on “Viscous Flow of Crystalline Bodies Under the Action of Surface Tension.” In 1950, a theoretical physicist at Bell Laboratories, C.Herring, published two papers entitled “Effect of Changes of Scale on Sintering Phenomena” and “Diffusional Viscosity of a Polycrystalline Solid.” At approximately the same time, a third theoretical physicist, F.Nabarro at Bristol University in England, made similar studies and today there are frequent references in the ceramic literature to the “Nabarro-Herring diffusion creep model.”

Another major contributor at about this time and continuing to this day was the metallurgist, G.C.Kuczynsky at the University of Notre Dame, who developed quantitative models for sintering rates and checked them experimentally with metal and glass macroscopic spheres as well as with fine powders. He was the first to demonstrate experimentally in metallic systems that mass flow can occur by volume diffusion during sintering. The ceramists, W.D.Kingery and M.Berg in 1955, were the first to do so in oxide systems. However, the person who is responsible for the first commercial product to be developed based on fundamental studies of sintering is the ceramist, R.L. Coble. This occurred around 1958 and the product became General Electric’s Lucalox. This is a transparent polycrystalline aluminum oxide of nearly theoretical density containing 0.1 to 0.25 percent of magnesium oxide concentrated at the grain boundaries which acts as a grain-growth inhibitor. Competitive products are now also available from Coors (“Vistal”), Philips, Sudplastik, and Keramik, etc. The principal application is as envelopes for high intensity, sodium vapor lamps.

Related development of useful products has been extended to ceramics whose major components are yttrium oxide (G.E.’s Yttralox for infrared-transmitting windows), magnesium aluminate (possibly a superior material for high-intensity lamp envelopes), and magnesium oxide (for potential applications as transparent armor). It should be noted that all of these compositions are relatively simple. The first extension to more complex materials is the development of the lanthanaum-doped lead zirconate titanate systems (first at Sandia) for purely optical applications such as optical switching, optical memories, and image-display devices.

APPENDIX 3K

Interdisciplinary Research—An Exploration of Public Policy Issues*

Roadblocks to Interdisciplinary Research

Professionals trained in a given discipline speak a special language, use their own methodologies and scientific tools, and may consider one part of

*  

Library of Congress, Science Policy Research Division, Prepared for Committee on Science and Astronautics, U.S. House of Representatives, 30 October 1970.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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a research problem significantly different in importance from another disciplinary professional.

Disciplinary orthodoxy and differences between disciplines are items which have varying import for the concept and conduct of interdisciplinary research in various institutional settings. Possible issues are outlined and described below:

1. Disciplinary Orthodoxy May Produce Strains in Doing Interdisciplinary Research:

The most important and obvious difference is the fact that interdisciplinary research brings together persons with different foci of interest as well as different conceptual systems. These systems have potentialities for integration, but they also have strong tendencies toward competition. A second factor is the differential status of the disciplines. This has a bearing on both the formal and the informal structure of the research team and its administration and plays an important part in determining the handling of the decision-making process. Closely related to this are the expectations, stereotypes, and images, overt and covert, that members of one discipline hold regarding persons trained in other fields. These may have an important bearing on interpersonal relationships. Fourth are the differences in methodology among the disciplines, together with subtle and often unrecognized differences in philosophic orientation and ideology, which tend to have some relationship to disciplinary affiliation and to bring members of some disciplines more closely together than those of others.

2. Disciplinary Differences May Produce a Power Hierarchy, Inhibiting the Conduct of Effective Interdisciplinary Research:

When interdisciplinary research takes place within complex research organizations, participants are unlikely to have equal formal or informal status, which would produce strains in the relationships…The differences in background, status, skills, and values that participants bring to the group could lead to a struggle for power. This is a serious problem…

There are many difficulties in getting these groups to operate smoothly. When there are struggles for power, research activities probably suffer. Relations of power become involved in making decisions about the selection of problems and techniques and the necessary tests for the validity of results. Each kind of specialist approaches the problem area from his own perspective and is often incapable of understanding the approaches of others; he may interpret the arguments of others as devices to win power, and they may be precisely that. Perhaps a “least common denominator” approach comes to be used in the selection of problems and concepts. When this happens, significant theoretical findings are unlikely to be obtained.

3. Uneven Levels of Development of the Disciplines Involving Interdisciplinary Research Make Collaboration Difficult:

The readiness of the particular disciplines to cooperate in a specific problem is an important criterion. To be ready for interdisci

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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plinary research, the disciplines involved must have arrived at a stage of sophistication. This cannot be forced. Even within the same discipline there are great differences in the degree of preparedness to collaborate with areas of neighboring disciplines. Interdisciplinary research cannot be undertaken until and unless there is a feeling of need for help from outside one’s own discipline.

4. Interdisciplinary Research Requires Collaboration in Use of Concepts; and Sharing of Work Tasks With Each Disciplinary Researcher Using the Appropriate Research Techniques:

An interdisciplinary team is a group of persons who are trained in the use of different tools and concepts, among whom there is an organized division of labor around a common problem, with each member using his own tools, with continuous intercommunication and re-examination of postulates in terms of the limitations provided by the work of the other members, and often with group responsibility for the final product.

…For research to be considered interdisciplinary there must be integration of concepts. Without some integration, the situation is similar to having occasional meetings with people in other disciplines, or even to just reading about what they are doing. One is influenced to some extent by this kind of interdisciplinary exposure, but more than this is needed for a project to be considered interdisciplinary.

Difficulties due to disciplinary orthodoxy appear to be most severe in academia as brought out clearly by the following discussion related to interdisciplinary research on environmental quality:*

It will not be easy to begin new problem-focused programs at universities, despite the need for trained professionals and the seriousness of the problems, Dr. J.Kenneth Hare, Professor of Geography at the University of Toronto and former President of the University of British Columbia, commented on these difficulties in an open letter:

“Let me start, then, with the question of environmental studies in a modern University. We all know the conservative quality of such places, where nothing can easily be done for either the first or the last time. The status quo is defended in depth by the vested interest of a large number of able people. Among these interests are those of the traditional departments and the largely analytical disciplines they profess. Also strong are the numerous special institutes and centers that have got started in spite of the resistance of the departments. When we propose to start up a broad spectrum, synthesizing effort like environmental studies we run fulltilt into all these vested interests.

*  

John S.Steinhart and Stacie Cherniack— “The Universities and Environmental Quality—Commitment to Problem Focussed Education.” A Report to the President’s Environmental Quality Council, Office of Science and Technology, September 1969.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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“We also bang ourselves against the clan-spirit of the traditional faculty groupings. Humanists, social scientists, natural scientists, and professionals like lawyers and engineers may fight like cats within the clan, but they close ranks and hitch up their kilts when someone questions their loyalties. Environmental studies have to involve many of these clans, which are not used to combining in the way required. If we suggest, as I do, that some of them—notably the humanists—may be utterly transformed by such combinations we alarm the timid and anger the Tories among them.

“But the greatest hazard in our path is inherent in Lyndon Johnson’s acid query “Therefore, what?” which he threw at a group of professors who had just briefed him on the Middle Eastern situation. The political interest in the environment demands proposals for action—on all time scales, from the immediate assault on pollution problems and other festering sores of today, to the long-term reconstruction of society in a better relation with environment. At present we are not equipped to make such proposals. We are not action-oriented and on every campus there is a dead-weight of opinion that regards action-oriented programs as hostile to the academic life…

“I must also stress the incompetence of the established disciplines to tackle society’s real problem. What we mean by a discipline is an agreed tested body of method—usually analytical—that we bring to bear on problems of our own choosing. The essence of our thinking is that we cannot tackle problems that don’t fit the competence of our own discipline. It’s true that we constantly try to enlarge that competence. Confronted with a new problem, we spare no effort to improve our methods. But if we don’t succeed, we don’t tackle the problem, and we tend to condemn colleagues who try.”

Lessons for Interdisciplinary Research

As discussed earlier the coupling between disciplines can range from loose to tight, i.e.,

  1. Research workers in different disciplines make a parallel study of various aspects of a single problem and submit separate reports; thanks to this juxtaposition, it is hoped that further light will be shed on the problem under consideration. —Multidisciplinary, loosely-coupled mode.

  2. Research workers in different disciplines tackle the same problem simultaneously and synchronize their efforts, exchange findings, and draft separate reports, which will be prefaced by a joint report attempting to integrate all these findings; in this instance what is sought is some degree of convergence, if not through the investigation, then at least in the comparison of findings.

  3. Research workers tackle a single problem together, compare their working hypotheses, make a critical assessment of each other’s methods and draft a final joint report. —Interdisciplinary, tightly-coupled mode.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×

There appear to be certain characteristics of close collaboration:

  1. From the standpoint of the research problem

    1. Focus on a single clearly defined problem.

    2. Problem definition determined by demands of problem rather than by disciplinary or individual interests.

    3. Formulation of the research problem in such a way that all participants can contribute to its solution.

    4. Existence of collaborative potential as a result of previous work on the problem by more than one discipline.

  1. From the standpoint of theory

    1. Acceptance of a unified over-all theory.

    2. Acceptance of a common set of hypotheses and assumptions.

    3. Agreement on definition of common concepts.

    4. Agreement on operational definitions.

  1. From the standpoint of methodology

    1. Utilization of resources of all relevant disciplines in exploring possible methodologies.

    2. Team agreement on most appropriate methodology, including research procedures, relevant variables to be measured or controlled, and methods to be used.

  1. From the standpoint of group functioning

    1. Team members selected on basis of their ability to contribute to research objectives.

    2. Approximate equality of influence exerted by the representatives of one discipline on another.

    3. Acceptance of leadership regardless of disciplines from which leader and researchers come.

    4. Flexibility of roles.

    5. Development and use of a common language.

    6. Free communication among all team members.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
×
  1. Free interchange of information about the research, with mechanics for facilitating such interchange when necessary.

  2. Sharing of suggestions, ideas, and data among members from different disciplines.

  3. Participation of all team members in joint planning of each step of the research.

  4. Reciprocal teaching and learning among team members—a continuous learning process.

  5. Problem-centered rather than discipline- or individual-centered team activity.

  6. Minimum influence on research plans and operations exerted from outside the research team.

  7. Willingness of participants to subordinate own methods and interests to achieve project aims.

  8. Publication of research reports by the group as a whole, rather than by individual members.

Some of these manifestations of close collaboration will be found to some degree in any project. A few projects where the collaboration is very close appear to contain most of them.

Strengths and Weaknesses in Interdisciplinary Research

The interdisciplinary mode is not a universal panacea. While it is essential for many achievements in complex technology, it has its weaknesses as well as its strengths. Some of these are listed:

Weaknesses and dangers;

  1. As teams become larger, originality is apt to be stifled.

  2. Individual freedom is restricted through the coordination and organization necessary in group research.

  3. Interpersonal difficulties are more likely on larger teams.

  4. Interdisciplinary team research can be expensive.

  5. When an interdisciplinary team is utilized unnecessarily, resources are spent that could be used more effectively.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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  1. Closely related to the large investment of money and personnel often required in interdisciplinary research are the pressures for demonstrable results.

  2. Interdisciplinary research requires more time in communication, time which might be spent more profitably on the research itself.

  3. As teams become larger, more time is needed for administration.

  4. The circumstances under which interdisciplinary research is conducted may be distracting.

On the positive side:

  1. A team of investigators can tackle larger problems than they can individually.

  2. Interdisciplinary research generally gives a broader outlook, opens new horizons, and stimulates more people than individual research.

  3. The collaborative experience of interdisciplinary research is more than an additive process, the end result more than the sum total of what each of the disciplines could have achieved independently.

  4. One of the most important aspects of interdisciplinary work is the fruitfulness of the challenges from one part of the group in stimulating others to mobilize their resources.

  5. Interdisciplinary research broadens understanding through having to translate concepts and approaches between disciplines.

  6. Interdisciplinary research illuminates borderline areas and enables one to examine problems lying between disciplines that had previously been ignored by the single disciplines.

  7. Interdisciplinary work is advocated enthusiastically by some because of the hope and belief that, by requiring reformulation in translatable terms, it will result in an integrated set of constructs and may even produce a new theoretical framework and a new discipline.

  8. Interdisciplinary research facilitates the creation of situations that may result in new and productive combinations.

  9. An interdisciplinary approach is valuable in contributing specific techniques and skills from various disciplines to each other.

  10. The use of specialists in different fields provides a short cut to information.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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  1. Interdisciplinary research can be a valuable learning experience that can be utilized effectively for training purposes.

Many of the pitfalls and problems of interdisciplinary team research can be minimized or avoided by recognizing them in advance and guarding against them. Interdisciplinary research should never be conducted for the sake of being interdisciplinary. But many of the complex problems facing the investigator require the concerted attack of several disciplines. When used appropriately, the values of interdisciplinary research far outweigh its disadvantages and it should make increasing contributions toward understanding and solving some of the important problems of today.

Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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Suggested Citation:"3. Materials Science and Engineering as a Multidiscipline." National Research Council. 1975. Materials and Man's Needs: Materials Science and Engineering -- Volume I, The History, Scope, and Nature of Materials Science and Engineering. Washington, DC: The National Academies Press. doi: 10.17226/10436.
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