Silicon nitride-silicon carbide composite material and process for production thereof.

摘要

The present sintered composite material is substantially formed of silicon nitride predominantly in beta -phase and about 5 to 35% by weight of silicon carbide predominantly in beta -phase, which is characterized by the microstructure such that the silicon nitride is in the form of fine grains comprising:-elongated grains 0.2 to 1.0 mu m in length of minor axis and 1 to 10 mu m in length of major axis, and equiaxed grains 1 mu m or below in average size; and the silicon carbide is in the form of equiaxed grains 1 mu m or below in average size, said silicon carbide grains being uniformly dispersed. Having a three-point flexural strength of at least 95 kc/mm<2> and a fracture toughness (KIC) of at least 54 MN/m<3/2>, the present sintered material is excellent in toughness and strength. The process for producing such a material is disclosed in detail.