WU Qide , LIU Kaisong ,Tu Long Li Na

(Key Laboratory for Silicate Materials Science and Engineering of Education, Wuhan University of Technology,

Wuhan Hubei 430070, China)

Abstract: In this paper, the effects of pressure forming and gel-casting on the microstructure and bending strength of RBSC have been presented. SEM analysis indicated that the green-compact acquired by pressure forming revealed an uneven distribution of micro-pore structure，while the green body formed by gel-casting showed a uniform microstructure: SiC and C surrounded by each other and dispersed homogeneously. Microstructure analysis showed that the combination of metallographic observation and mercury penetration analysis could reflect the structure of the green body more accurately. Compared with pressure forming, RBSC obtained by gel-casting showed a more uniform distribution of free silicon, which was an important factor for the improvement of RBSC's bending strength. The RBSC with a uniform microstructure and fewer internal defects was obtained by Gel-casting using the modified SiC powder (0.8μm) and the highest bending strength came up to 690MPa.

Key words: RBSC; gel-casting; free silicon; microstructure; strength