Abstract
We investigated the Si3N4-SiC ceramics prepared from Si-SiO-C mixed powder compacts. Si3N4 matrix and SiC particles were formed during the sintering process in the ceramics. During heat treatment at 1350°C in Ar, SiC particles were formed first and, after nitridation at 1400°C, self-composed Si3N4-SiC ceramics were obtained. In these ceramics, SiC particles about 100nm in diameter were dispersed in Si3N4 matrix particles. Yttrium which originate from sintered aide (Y2O3) was detected at the grain boundary between Si3N4 matrix and SiC particles intragranularly dispersed in the matrix. It is suggested that the SiC particles were dispersed in the Si3N4 during the α→β transformation or the grain growth of Si3N4 grains. Thermogravimetry (TG) and differential thermal analysis (DTA) results suggested that SiO and CO gases were concerned in the formation of the SiC particles.
