Influence of sintering atmosphere on the fabrication of SiC ceramics with a powder mixture of sialon composition

Silicon carbide ceramics with a powder mixture of sialon composition as a densification aid were prepared by hot pressing through a transient liquid phase, and the effects of sintering atmosphere and starting phases on the microstructural characteristics were investigated. The sintered SiC with the additive of a Y–α-sialon composition in argon showed high sintered density and grains with large aspect ratio. But sintered specimens in nitrogen yielded grains with low aspect ratio and small grain size, because of the retardation of phase transformation and grain growth. The SiC specimen prepared from the starting β–SiC powder with Y–α-sialon composition showed the highest fracture toughness of approximately 6.0 MPa m1/2.