Opportunities in Protection Materials Science and Technology for Future Army Applications (2011) / Chapter Skim
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Appendix E: Processing Techniques and Available Classes of Armor Ceramics
Appendix E: Processing Techniques and Available Classes of Armor Ceramics
Pages 125-135
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From page 125... ...
The low-cost alumina armor plates manufac- and Al2O3–Y2O3, have been tested as sintering aids for SiC tured by means of uniaxial pressing, slip casting, and sinter- powder to enhance the sintering rate and to reduce grain ing are used in vehicle armor applications in large volumes. The typical cost of these plates runs about $2.50/lb to $10/ lb for the finished tile.
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From page 126... ...
Methods used to produce $85/lb. The pressureless sintering processes of B4C and densification of B4C by solid state sintering techniques10 pressureless sintered B4C have been developed at the Geor gia Institute of Technology and commercialized at Verco are slow, and it is difficult to reach high density due to low Materials,13 as well as by larger armor producers such as self-diffusion.
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From page 127... ...
Significant advantages exist for using current-assisted sintering over that of hot-pressing, ing aids (boron and carbon, for example) ; additional carbon hot isostatic pressing, or pressureless sintering; the most imis added to remove the silica passivation layers from the portant advantage is lower sintering temperature and reduced SiC particles.
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From page 128... ...
5-22 in Advances in Ceramic Armor VI: Ceramic Engineering and Sciof silicon carbide and boron carbide ceramics processed by spark plasma ence Proceedings 31(5)
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2009. The effect of thixotropic casting.44,45,46 particle size distribution on the microstructure and the mechanical properties of boron carbide-based reaction-bonded composites.
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The remarkable mechanical perfor- wood and cellulose-fiber paper and cardboard have also been of interest for their potential use as armor materials.55 In mance of certain natural materials stems from their complex ordered microstructure, organized over several length scales, particular, wood-based biomorphic SiC (bioSiC) is a promiseven though the materials are often made of relatively weak ing material for armor.
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From page 131... ...
Although manufacturing defects and excesporosity and microstructure of the C-preform and can be sive residual silicon in bioSiC reduce ballistic performance, varied widely by using tailored green bodies. Because practi- especially in multi-hit situations, appropriate armor system cally no change in geometry occurs during siliconization or design -- that is, with the right selection of ceramic thickness in reproducible contraction rates during pyrolysis, even large and type and backing thickness -- allows the materials to and complicated shaped parts can be manufactured using a withstand even armor-piercing rounds.
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2001. Aluminum foam integral armor: A new dimension in armor Transparent armor ceramics must provide good transdesign.
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2008. Crack detection in armor plates using ultrathe European Ceramics Society 24(9)
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From page 134... ...
However, in Shortly after research on photonic band gaps began to show promise of controlling the flow of photons, the idea was extended to mechanical waves in periodic elastic struc- 86Mie theory, also called Lorenz-Mie theory, Lorenz-Mie-Debye theory, tures. Referred to as phononic crystals, such structures can and Mie scattering, is an analytical solution of Maxwell's equations for the create what are called phononic, or acoustic, band gaps.
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From page 135... ...
The use of fluids (which support only the allowed modes and their wave speeds inside the material, longitudinal waves) makes it difficult to form gaps because such that the frequencies of various material loss regimes of the conversion of shear modes into longitudinal modes at may be matched with the density of states and frequencies the solid-fluid interface.
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