LAO Xinbin 1, LI Yage 2, JIANG Weihui 1,2, LIU Jianmin 1, LIANG Jian 1, LIU Xuefeng 2, TANG Zijuan 2
(1. National Engineering Research Center for Domestic and Building Ceramics, Jingdezhen 333001, Jiangxi, China; 2. School of Materials Science and Engineering, Jingdezhen Ceramic Institute, Jingdezhen 333403, Jiangxi, China)
Abstract: Reaction-bonded silicon carbide ceramics were prepared by using a carbon-buried sintering method, with α-SiC powders of different sizes as the aggregates and silicon and graphite powders as the matrix-phases for in-situ formation of β-SiC. The effect of molding pressure on phase composition, microstructure and properties of the reaction-bonded SiC ceramics was studied. The samples were characterized by using XRD and SEM. It is found that β-SiC whiskers were formed through the gas-solid reaction mechanism, while the reaction suppressed the densification process. The content of β-SiC whiskers was decreased and the density was increased with increasing molding pressure. When the molding pressure was 12 MPa, the sample showed optimum properties, with water absorption rate of 8.37%, porosity of 21.08%, bulk density of 2.37 g/m3, flexural strength of 40.7 MPa for and fracture toughness of 0.42 MPa·m1/2.
Key words: reaction-bonded SiC; molding pressure; β-SiC whiskers; morphology of whiskers; flexural strength