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AssigneeStemcor Corporation
InventorsWolfgang D. G. Boecker, Stephen Chwastiak, Tadeusz M. Korzekwa, Sai-Kwing Lau
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Crystalline silicon carbide wherein at least 90 weight percent of the silicon carbide is formed from a plurality of hexagonal crystal lattices wherein at least 80 weight percent of the crystals formed from the lattices contain at least a portion of opposing parallel base faces separated by a distance of from 0.5 to 20 microns. The crystals may be in the form of separate particles, e.g. separate platelets, or may comprise an intergrown structure. The crystalline silicon carbide of the invention is produced by heating a porous alpha silicon carbide precursor composition comprising silicon and carbon in intimate contact to a temperature of from 2100.degree. C. to 2500.degree. C. in a non-reactive atmosphere. The materials are high performance materials finding use in reinforcing, high temperature thermal insulating, improvement of thermal shock resistance, and modification of electrical properties.
A method of producing a silicon carbide product which is at least 95% pure alpha silicon carbide which product comprises at least 1000 alpha silicon carbide crystals, at least 90 weight percent of the crystals being formed from hexagonal crystal lattices wherein at least 80 weight percent of the crystals formed from the lattices contain at least a portion of opposing parallel base faces separated by a distance of from 0.5 to 20 microns and wherein those crystals having at least two adjacent 120.degree. C. corners, have a distance of from 2.5 to 150 microns between said corners, said method comprising heating a porous silicon carbide precursor composition comprising silicon and carbon in intimate contact to a temperature of from 2100.degree. C. to 2500.degree. C. in the presence of a hexagonal crystal growth control additive and in a non-reactive atmosphere, for a time sufficient to cause formation of said crystals.
Dependencies are inferred from the claim text.