Low-temperature sintering of SiC reticulated porous ceramics with MgO–Al2O3–SiO2 additives as sintering aids

SiC reticulated porous ceramics (SiC RPCs) was fabricated with polymer replicas method by using MgO–Al2O3–SiO2 additives as sintering aids at 1,000~1,450 C. The MgO–Al2O3–SiO2 additives were from alumina, kaolin and Talc powders. By employing various experimental techniques, zeta potential, viscosity and rheological measurements, the dispersion of mixed powders (SiC, Al2O3, talc and kaolin) in aqueous media using silica sol as a binder was studied. The pH value of the optimum dispersion was found to be around pH 10 for the mixtures. The optimum condition of the slurry suitable for impregnating the polymeric sponge was obtained. At the same time, the influence of the sintering temperature and holding time on the properties of SiC RPCs was investigated. According to the properties of SiC RPCs, the optimal sintering temperature was chosen at 1,300 C, which was lower than that with Al2O3–SiO2 additives as sintering aids.