China's Refractories

Abstract: In order to fabricate porous ceramics with good properties and proper production cost, SiC-Al2O3 porous ceramics were prepared at 1 450 ℃ for 2 h from the powders of commercial silicon carbide and white fused corundum via a polymeric replication method. Effects of the mass ratio of SiC powder to white fused corundum powder (1∶3, 1∶1 and 3∶1) on the appearance, phase composition, sintering properties and thermal shock resistance were investigated. The research results indicate that the as-prepared SiC-Al2O3 porous ceramics have uniform pores, and their linear shrinkage ratio, apparent porosity and bulk density reach 4.70%, 67.17% and 0.83 g·cm^-3, respectively. The thermal shock cycles from 1 400 ℃ to room temperature reach 23 including 15 cycles in air cooling condition and then 8 cycles in water cooling condition. Their main phases are α-Al2O3 and Al6Si2O13 as well as a small amount of SiC and free SiO2. The as-prepared porous ceramic with the ratio of m(SiC)∶m(Al2O3)=1∶1 possesses prior comprehensive properties.

Key words: porous ceramics, polymeric replication method, silicon carbide, white fused corundum, sintering properties, thermal shock resistance