Fabrication and properties of porous anorthite/mullite ceramics with both high porosity and high strength

Porous anorthite/mullite ceramics with both high porosity and high strength have been successfully fabricated by foam‐gelcasting and pressureless sintering technology, using α‐Al 2 O 3 , SiO 2 , and CaCO 3 as starting materials and MnO 2 as sintering aids. The porous mullite ceramics prepared in this study had 83.3% porosity and 0.3 W/m·K thermal conductivity, exhibited compressive strength value as high as 6.1 MPa. The samples fabricated with mullite content of 30 mol% possessed 79.4% porosity and 5.9 MPa compressive strength showed thermal conductivity as low as 0.19 W/m·K. With the addition of MnO 2 , the properties of the prepared materials varied slightly when mullite content changed in a large scale. The results showed that the addition of MnO 2 promoted the reaction, affected sintering and grain growth, and contributed to high strength and low‐thermal conductivity.