Preparation of Porous Mullite Ceramics Using Fly Ash Cenosphere as a Pore-Forming Agent by Gelcasting Process

Porous mullite ceramics were fabricated from an industrial grade mullite powder by gelcasting process using fly ash cenospheres (FAC) as a pore-forming agent. The influence of content of FAC and sintering temperature on the density and strength was evaluated. The microstructure showed that FAC can act as a sintering aid and a pore-forming agent. When the sintering temperature at 1200 degrees C, porous mullite ceramics with a relatively high porosity (48.1-72.2%), low density (0.84-1.64 g/cm(3)), low thermal conductivity (0.16-0.22 W/m . K), and high compressive strength (6.21-14.70 MPa) have been obtained.