Porous silica ceramics with uniform pores from the in-situ foaming process of silica poly-hollow microspheres in inert atmosphere

A novel way has been reported to fabricate porous silica ceramics, which is based on the in-situ foaming process of densely packed silica poly-hollow microspheres (SPHMs) at elevated temperature and inert atmosphere. The results show that sintering atmosphere and temperature have great effects on the formation and evolution of the porous structure. The original holes inside or between SPHMs could grow up to form uniform pores as the sintering temperature increases under inert atmosphere, and the optimal sintering temperature for well homogeneous microstructure could be 1575 °C. This novel method is facile and efficient, by which porous silica ceramics with the compressive strength ranging from 0.60±0.28 MPa to 29.77±2.28 MPa and the porosity of 39.0-77.2% have been prepared.