CHEMICAL VAPOR-DEPOSITION OF SILICON-CARBIDE AND SILICON-NITRIDE - CHEMISTRYS CONTRIBUTION TO MODERN SILICON CERAMICS

Pure silicon carbide and silicon nitride have valuable properties in bulk pore‐free form; however, their industrial exploitation has hardly been possible so far. Neither compound can be melted or sintered in pure form; hot pressing or sintering at normal pressure requires the presence of additives; and the reaction‐sintering process in which only Si and C or Si and N are employed as additives affords porous materials.–The novel process of chemical vapor deposition has partly overcome the drawbacks of the previous methods. In the new process SiC is produced, e.g., by pyrolysis of CH3SiCl3, and Si3N4 by reaction of SiCl4 with NH3. This technique can also be used for pore filling in objects made of SiC and Si3N4 (gas phase impregnation) and for producing extremely fine SiC and Si3N4 (gas phase impregnation) and for producing extremely fine SiC and Si3N4 powder and SiC monofilaments suitable as components for SiC composites. Moreover, gas phase impregnation can also give fiber composites. Copyright © 1979 by Verlag Chemie, GmbH, Germany