Cellular silica-based ceramics prepared by direct foaming at high temperature

Cellular silica-based ceramics, including Si3N4/SiO2 composite ceramics and monolithic silica ceramics, with dense shell and closed cells with dense and crack-free cell wall inside was prepared by the direct foaming of the green-compacts at 1310–1370 °C. The influences of the heat-treatment temperature on the relative density as well as the mechanism of the cell formation were investigated. The porosity of the obtained cellular silica and Si3N4/SiO2 ceramics was within 60.0–84.0%, the cell size distribution was in the range of 10–120 μm, and the flexural strength was 9.7–16.3 MPa.