Effect of the in-situ SiC whiskers on the alkali attack resistance mechanism of mullite-SiC foam ceramics

In this study, five mullite foamed ceramics were prepared with industrial alumina, white clay, and varying Si powder contents. The effect of the in-situ SiC whisker generation content controlled by the varying Si powder contents on the compressive strength, alkali attack resistance, and thermal conductivity of the ceramics was investigated and the optimal SiC whisker generation content was confirmed. With a rise in Si powder content, the porosity of the foamed ceramics decreased, the thermal conductivity increased, and the compressive strength increased first and then decreased. The alkali corrosion resistance improved by decreasing the diffusion rate of alkali vapor and improving the stability of ceramic matrices. Taking mechanical properties, thermal insulating properties, and alkali attack resistance into consideration, the optimized product was a specimen with 10 wt% Si powder content.