Chemical Vapor Deposition of Silicon Carbide and Silicon Nitride—Chemistry's 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 CH 3 SiCl 3 , and Si 3 N 4 by reaction of SiCl 4 with NH 3 . This technique can also be used for pore filling in objects made of SiC and Si 3 N 4 (gas phase impregnation) and for producing extremely fine SiC and Si 3 N 4 (gas phase impregnation) and for producing extremely fine SiC and Si 3 N 4 powder and SiC monofilaments suitable as components for SiC composites. Moreover, gas phase impregnation can also give fiber composites.