Ultralight and high-strength bulk alumina/zirconia composite ceramic foams through direct foaming method

The mechanical strength of highly porous ceramic foams shows significant attenuation with the increase of porosity, especially for ceramic foams with very high porosity level above 95%. Ultra-light bulk composite ceramic foams were fabricated via introducing 20 wt% zirconia in alumina-based cell wall, aiming at improving mechanical strength of alumina based ceramic foams. The preparation and stability of alumina and zirconia particles synergistically stabilized foams were investigated. The obtained bulk ceramic foams manifested an exciting combination of both high porosity above 96% and excellent specific compressive strength, due to their closed pore structure, defect-free cell wall with uniform thickness, and uniformly distributed zirconia grains in alumina matrix. The alumina/zirconia composite ceramic foams with porosity of 96.7% exhibited compressive strength of 1.11 +/- 0.07 MPa, which was much higher than that of alumina ceramic foams in the case of same porosity.