Porous mullite ceramics prepared by hollow glass microspheres and its properties

Porous mullite ceramics were prepared by pressing molding and sintering method, using coal gangue and bauxite as raw materials, hollow glass microspheres as pore-forming agent. The effects of addition amount of hollow glass microspheres and sintering temperature on phase composition, microstructure, flexural resistance and acid and alkali corrosion resistance were studied. The results show that increasing the amount of hollow glass microspheres can increase the porosity of porous ceramics; the addition of hollow glass microspheres can promote the formation of mullite phase and reduce the sintering temperature. In a certain temperature range, increasing the sintering temperature can also increase the porosity, but when the sintering temperature is over 1350 ℃, the porosity begins to decline. Porous mullite ceramics with porosity of 33.23% and flexural strength of 56.41 MPa can be obtained by keeping the molar ratio of Al2O3∶SiO2=3∶2 and adjusting the addition amount of hollow glass microspheres to 1.68%(mass fraction) and sintering at 1350 ℃ for 2 h, which has good acid and alkali corrosion resistance.