Fabrication and microstructural characterization of porous SiC membrane supports with Al2O3–Y2O3 additives

Porous silicon carbide membrane supports were prepared using alumina and yttria additives (1–4 wt%) with various weight ratios of Al2O3/Y2O3 (23/77–60/40) and sintering at 1500–1800 °C. The relationships between the processing factors and the porosity, pore size and microstructure were examined. Variation of the sintering temperature, the amount of additive used and the ratio of Al2O3/Y2O3 were found to be effective for control of the pore size and microstructure. The pore size and grain size of membrane support with 1 wt% additive increased with the sintering temperature. For SiC membrane supports containing 4 wt% additive, pore size and grain size were dependent on the alumina ratio in additive. Smaller grains and fine pores around 200–300 nm were detected for specimens with higher Al2O3 content (60/40) in the additive. In contrast, for specimens with low Al2O3 content (23/77) in the additive, the grain and pore sizes were enlarged. This difference was attributed to the effect of Al2O3 content on the temperatures of liquid phase formation during sintering.