ウィスカー/粒子複合セラミック多孔体の細孔構造制御

抄録

Porous ceramic composites consisting of SiC whiskers (W) and mullite particles (M) were fabricated by a combined procedure of homogeneous dispersion in aqueous media, forced sedimentation and high temperature heating. Green bodies of the W-M composites with W:M = 3:1, 1:1 and 1:3 in volume ratio were formed by filtration of aqueous W-M mixed suspensions under reduced pressure. Heating the green bodies at 1250℃ in air caused the reaction bonding between mullite particles and SiO₂ produced by the oxidation of SiC whiskers. Porosities of the W-M composites could be controlled by changing the mixing ratio of W and M, ranging from 68% to 82% for the W:M=1:3 to 3:1 composites, respectively. The examination on the stability at higher temperatures (1450° ～1550℃) was also conducted for the composites thus fabricated. The weight loss of the composites was observed after heat-treatment in Ar atmosphere, which might be due to the reaction SiC(s)+2SiO₂(s) → 3SiO(g)+ CO(g). This reaction could be inhibited by HfO₂-coating on the surface of SiC whiskers, which would lead to the fabrication of the porous W-M composites with improved high-temperature performance.