Study on Synthesis and Properties of Porous SiC Composite Ceramics

Mullite bonded SiC porous ceramics were fabricated through an in-situ reaction technology by using bauxite, SiC and graphite as raw materials. The green bodies were molded by pressing and sintered in air. The phase composition, microstructure, flexural strength, open porosity and pore size distribution were investigated. According to the results, the pores were produced by the stacking of SiC particles and burning out of graphite. Under high temperature, Si O2 obtained by the oxide of SiC could reaction with bauxite to form mullite. Graphite content has great impact on the flexural strength, open porosity and pore size distribution of the porous ceramics. The samples with 10wt% graphite content sintered at 1400 ℃ for 3 h have an open porosity 44.9% and flexural strength 41.0 MPa.