In-situ formation of Si3N4-nano SiC composite

The purpose of the present work is to fabricate Si3N4 with SiC nano-particles by a cost effective method. The SiC nano-particles are formed by in-situ reaction between an oxide phase on the surface of Si3N4 powder and carbon which is coated on Si3N4 powder by thermal decomposition of methane (CH4) gas. The advantages of the present process are 1) easy to process 2) low cost 3) fine SiC particles less than 50 nm in diameter are obtained, and 4) direct bonding between SiC particle and Si3N4 grain at grain boundary without glassy phase. Another advantage of this method is applicability of surface oxidized Si3N4 powders which are generally regarded as deteriorated powders. An oxidized powder is used to produce high duality Si3N4 ceramics by using the present carbon coating method. (C) 1997 Acta Metallurgica Inc.