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°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.