Fig. 3 shows the variation of bulk density and apparent porosity of porous mullite/corundum ceramics with sintering temperature. As sintering temperature increased from 1350 ฐC to 1500 ฐC, apparent porosity of samples decreased, while bulk density increased. As sintering temperature increased from 1500 to 1550 ฐC, apparent porosity increased, but bulk density decreased. The variation of bulk density and apparent porosity with sintering temperature was small, which was related to the small linear shrinkage.