Fabrication and Mechanical Properties of Silicon Carbide‐Silicon Nitride Composites with Oxynitride Glass

Abstract

A microstructure that consisted of uniformly distributed, elongated β‐Si3N4 grains, equiaxed β‐SiC grains, and an amorphous grain‐boundary phase was developed by using β‐SiC and alpha‐Si3N4 powders. By hot pressing, elongated β‐Si3N4 grains were grown via alpha right arrow β phase transformation and equiaxed β‐SiC grains were formed because of inhibited grain growth. The strength and fracture toughness of SiC have been improved by adding Si3N4 particles, because of the reduced defect size and the enhanced bridging and crack deflection by the elongated β‐Si3N4 grains. Typical flexural‐strength and fracture‐toughness values of SiC‐35‐wt%‐Si3N4 composites were 1020 MPa and 5.1 MPam1/2, respectively.