Research Opportunities in Corrosion Science and Engineering (2011) / Chapter Skim
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1 Corrosion - Its Influence and Control
1 Corrosion - Its Influence and Control
Pages 11-38
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From page 11... ...
Today, the impact of corrosion on society and the associated degradation of materials are far reaching owing in part to the increased complexity and diversity of materials systems, which include not only metallic materials but also ceramics, polymers, and composites, which are subject as well to environmental extremes. While legacy corrosion concerns remain, advancing technology and the need for global sustainability bring with them new and emerging corrosion issues whose negative impacts must be minimized through appropriate materials selection, mitigation and monitoring, and new materials development.
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From page 12... ...
Several studies, including a recent National Research Council (NRC) report on corrosion education,2 have described both the economic impacts of corrosion and the less measurable impacts such as loss of readiness -- that is, the nation's ability to respond militarily or otherwise to emergencies or other situations involving national security.
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From page 13... ...
Corrosion can affect public health, the environment, and global sustainability in ways that cannot be quantified simply in terms of GDP loss. The deterioration of an early generation of medical devices and implants resulting from interactions with human body fluids, the leaching of corrosion products into the environment, and the weakening of the nation's energy and transportation infrastructures all have impacts that greatly exceed those that are purely financial.
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From page 14... ...
Rarely does a single mechanism or event drive corrosion; rather, a number of events combine to produce severe effects. Thus, we must keep in mind that corrosion processes usually occur in the context of other factors (loads, wear, crevices, temporally and spatially varying environments, etc.)
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From page 15... ...
It is the biological inflammatory response to these processes that generates aggressive oxidative environments in vivo (generation of reactive oxygen species, etc.) that combine to lead to severe attacks on medical alloys.
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From page 16... ...
Usually alloys such as stainless steel or nickel chromium can be used unprotected in innocuous environments and in a certain range of aggressive environments such as seawater or mild acids, depending on the content of alloying elements. Superpassive metals -- such as tantalum, which resists strong hydrochloric acid -- also exist but are considerably more expensive.
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From page 17... ...
, may not be correct, however, given that some invented materials, like stainless steel, will also endure for thousands of years because their surface is protected by passivating oxide films. 1 Alan Weisman, The World Without Us, Thomas Dunne Books, New York, 2007.
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From page 18... ...
Examples of active mitigation techniques include inhibitors, external cathodic protection, with or without coatings, and sacrificial anodes. Passive techniques include material selection, organic and inorganic coatings, and metallic coatings (including both barrier and sacrificial coatings)
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From page 19... ...
, and development of active systems. The responses are given in more detail in Appendix B, "Results of the Commitee's Corrosion Mitigation Questionnaire." SuCCESS STORIES FROM CORROSION RESEARCH The success stories that follow are not exhaustive.
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From page 20... ...
The first useful stainless steels were developed in the beginning of the twentieth century by Monnartz in Germany and Brearley in England,5 but it was not until the 1912-1914 period that the commercial success of these austenitic steels -- primarily based on the addition of 18 percent chromium and 8 percent nickel -- was first recognized.6 In the 1970s -- when strength considerations became an issue for stainless steels -- duplex versions were developed, which also increased resistance to chloride stress corrosion cracking. In the 1980s stainless steels with higher molybdenum were formulated to solve problems with localized corrosion encountered in ag gressive environments.
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From page 21... ...
The emergence of the metallic glasses and alumina-forming stainless steels as potentially highly corrosion-resistant materials is only one example of the progress that is continuing to be made. Both show ways in which lessons learned, new materials developments, the incorporation of modern tools into research activities, and growing understanding of the relationships between structure, materials behavior, and component design can speed the development of such alloys.
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From page 22... ...
Similarly, exhaust systems are made from relatively inexpensive but long-lasting stainless steel, while chrome trim has either been eliminated or galvanically isolated. Polymeric materials have replaced metals in car bumpers and fenders for both corrosion resistance and weight reduction.
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From page 23... ...
There is also intense work on aluminum/magnesium engine blocks. Corrosion mitigation for these materials will certainly need the attention of the corrosion community.
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From page 24... ...
Conclusion (Aging Aircraft Airframes) Understanding of aluminum alloy corrosion and mitigation was advanced by large multi-institutional efforts funded by government agencies and a need to address specific technological problems.
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From page 25... ...
have been used along with better inspection programs. For high-pressure natural gas transmission lines, the most feared hazards are two forms of external stress corrosion cracking: One is associated with failure of cathodic protection to penetrate to the base of a coating defect, and the other is associated with near-neutral water that has equilibrated with the soil.
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From page 26... ...
The experience gained by the corrosion community in nuclear waste container life prediction could be utilized in CO2 containment, but unique challenges remain for mitigating corrosion in high-pressure CO2-water systems. Conclusion (Pipelines)
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From page 27... ...
Other implantable devices such as stents, orthopedic joints, and spinal appliances were originally made of stainless steels. Sometimes corrosion was observed in such implants, especially if the materials were not processed optimally.
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From page 28... ...
As advances in the understanding of medicine and technology allow for inno vative devices and therapies, new and better materials will have to be developed for use in the human body. Up to now most of the materials used in implantable medical devices were developed for other applications and later applied for medi cal uses because they had some of the desired requirements (strength, flexibility, fatigue resistance, electrical conductance, corrosion resistance)
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From page 29... ...
In boiling water reactor systems, the dominant problem had been intergranular stress corrosion cracking (SCC) in 304 austenitic stainless steel sensitized by welding, which was causing crippling levels of plant outage.
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From page 30... ...
in the design of components and control systems to avoid operational problems from 14 International Atomic Energy Agency, High Temperature On-Line Monitoring of Water Chemis try and Corrosion Control in Water Cooled Power Reactors: Report of a Coordinated Research Project, -, IAEA-TECDOC-1303, July 2002; Nuclear Energy Education Research, Electrochemistry of Water-Cooled Nuclear Reactors, Nuclear Energy Education Research (NEER) Final Technical Progress Report, Grant No.
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From page 31... ...
Supercritical water poses extreme risks of stress corrosion failure, especially in pressure vessel designs (as opposed to the CANDU-like design) , and water radiolysis in such conditions is not well enough understood to provide a baseline for definition of the environment.
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From page 32... ...
While translation to practice awaits policy and political decisions, this research has led to a vast improvement in corrosion science and to technological confidence that an engineered waste barrier can be perfected to contain nuclear waste. Protective Coatings for High-Temperature Combustion Turbines Coatings are used in a variety of applications to protect alloys that exhibit at tractive properties at high temperatures but would be too reactive in the service environment.
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From page 33... ...
Fox, and N.S. Jacobson, SiC recession caused by SiO2 scale volatility under combustion conditions: II, Thermodynamics and gaseousdiffusion model, Journal of the American Ceramic Society 82:1826-1834, 1999; P.F.
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From page 34... ...
Through government and industry collaborations, a fundamental understand ing of the degradation mechanisms associated with high-temperature volatiliza tion of SiC matrix composites, combined with the development of highly reliable coating processes, has paved the way for use of the high-temperature SiC matrix composites in aero propulsion and land-based combustion turbine applications. The ability to use SiC matrix composites in oxidizing environments containing water vapor and other impurities has pushed by 200°C the envelope for the tem perature at which this structural material can be used, making it one of the most robust commercial materials for very high temperature applications.
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From page 35... ...
Corrosion in our infrastructure systems results in reduced structural capacities, which can lead to structural failures. Figure 1.3.1 shows the underside of a steel bridge member exhibiting significant corrosion -- in this case, good inspection practices revealed the damage, thereby preventing failure.
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From page 36... ...
repair costs. The Pipeline and Hazardous Materials Safety Administration (PHMSA)
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From page 37... ...
Recent advances in data analysis and engineering practice are aimed at predicting and managing lifetime using advanced techniques of informatics, which can be of great value to knowledge discovery regarding corrosion processes and development of mitigation strategies but has, for the most part, been lacking in corrosion efforts. Hence, corrosion is not one of the properties generally considered in this new prognosis strategy.
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