Preparation of mullite bonded porous SiC ceramics by an infiltration method

A powder compact of α-SiC and α-Al2O3 was infiltrated with a liquid precursor of SiO2, which on subsequent heat treatment at 1500 °C produced a mullite bonded porous SiC ceramics. Results showed that infiltration rate could be estimated by using weight gain measurements and theoretical analysis. The bond phase was composed of needle-shaped mullite which was observed to be grown from a siliceous melt formed during the process of oxide bonding. The porous SiC ceramics exhibited a density and porosity of 2 g cm−3 and 30 vol%, respectively, and also a pore size distribution in a range of 2–15 μm with an average pore size of 5 μm. No appreciable degradation of room temperature flexural strength (51 MPa) was observed at high temperatures (1100 °C).