Fabrication of calcium hexaluminate‐based porous ceramic with microsilica addition

Calcium hexaluminate ( CA 6 )‐based porous ceramic was prepared with α‐alumina powders and nanometer‐sized calcium carbonate using a direct foaming technique with the addition of calcium aluminate cement and microsilica. The microsilica leads to the acceleration of CA 6 formation. Moreover, the shrinkage, densification, and elastic modulus at room temperature were enhanced with increasing microsilica content. But the hot elastic modulus showed obvious reduction between 1100°C and 1200°C if the microsilica content was over 0.5 wt%. Furthermore, α‐Al 2 O 3 appeared in the specimens with and without microsilica after treatment at 1550°C, and the proportion of CA 6 grains having a high aspect ratio increased after microsilica addition.