Effects of the Starting Powders on Microstructure and Properties of Porous Silica Ceramics

Porous silica ceramics with above 70% porosity were fabricated by gelcasting process using tert-butyl alcohol (TBA) as solvent. Two types of starting powders, α-silica and fused silica, were chosen to fabricate porous silica ceramics. According to XRD analysis, only single α-cristobalite phase can be identified in the sintered samples. SEM observation showed that highly porous skeleton formed by the bonding of molten ceramic particles in porous silica ceramics. Comparing to the samples using α-silica as starting materials, a compressive strength of 6.30MPa was achieved at a porosity of 70.7% when using fused silica as starting materials. A relatively high specific surface area higher than 10m2/g was obtained for both samples, which should be suitable for catalysis applications as catalyst supports.