Formation and transportation of intergranular and nodular fine-grained. beta. -SiC in reaction-sintered SiC

Abstract

Quantitative characterization of the microstructure of reaction-sintered SiC bodies prepared under various conditions was performed experimentally to observe the formation and transportation of both intergranular fine-grained and nodular fine-grained {beta}-SiC. The results showed that, by lowering the sintering temperature (min. {approx} 1,420{degree}C), the quantity of {beta}-SiC increased progressively from the outside of the specimen toward its center. However, the {beta}-SiC was almost completely transported onto the larger grain through liquid Si at 1,600{degree}C under vacuum. It was concluded that the formation of the fine-grained {beta}-SiC was due to the higher degree of supersaturation in the lower temperature outer region of the specimen.