Mechanical Properties of SiC/.BETA.-sialon Composites at High Temperature

The relation between the high-temperature mechanical properties and the microstructure of SiC/ beta -sialon composites was investigated. Addition of SiC increased the flexural strength and the creep resistance of beta -sialon at high temperatures. Average grain size of beta -sialon in SiC/ beta -sialon composites was smaller than that of beta -sialon ceramics. A part of sintering aid (Cb sub 2 O sub 3 ) existed at the inside of beta -sialon grains in SiC/ beta -sialon composites. The better mechanical properties of SiC/ beta -sialon composites may be attributed to the decrease of the amount of liquid phase, the thickness of intergranular phase, and the size of triple grain junctions. SiC particles existed both at the intergranular phase and within the matrix grains. The creep resistance was also improved probably due to inhibition of the grain boundary sliding.