关键词: 多孔碳化硅陶瓷, ρ-Al₂O₃-CAC, 玻璃-莫来石复相结合, 抗热震性, 透气度

Abstract: In order to improve the performance of porous SiC ceramics,green silicon carbide was used as the main raw material,graphite as the pore forming agent,and ρ-Al₂O₃-CAC as a composite sintering aid which is prepared from calcium aluminate cement (CAC) and hydrated alumina (ρ-Al₂O₃),firing at 1 450 ℃ for 3 h.The effect of the ρ-Al₂O₃-CAC addition (2.5%-20%,by mass) on the phase composition,microstructure,and properties of porous SiC ceramics was studied.The results reveal several key findings:ρ-Al₂O₃-CAC facilitates the oxidation of silicon carbide and reacts in situ with SiO₂ produced by the oxidation of silicon carbide,forming a glass-mullite composite;bubbles are introduced into the composite phase,with their size increasing with the rising ρ-Al₂O₃-CAC addition;at an ρ-Al₂O₃-CAC addition of 12.5%,the prepared porous SiC ceramics exhibit the optimal comprehensive properties:the apparent porosity is 39.1%;the flexural strength is 39.3 MPa;the air permeability reaches 26.74 m³·h^-1·kPa^-1·m^-2,and the thermal shock resistance is the best.

Key words: porous silicon carbide ceramics, ρ-Al₂O₃-CAC, glass-mullite composite combination, thermal shock resistance, air permeability