Preparation and properties of Al2O3–MgAl2O4 ceramic foams

In this work, a series of alumina (Al2O3)–magnesium aluminate (MgAl2O4) ceramic foams (AMCFs) were fabricated from powders of fused white corundum and magnesia (MgO) by a polymeric foam replication method combined with a reaction sintering process. The effects of MgO content and sintering temperature on the sintering properties and post-sintering properties of the AMCFs such as phase composition, appearance, microstructure, cold compressive strength and thermal shock resistance have been investigated. During the sintering process, MgO reacted with Al2O3 to form MgAl2O4 ceramic phase, which contributed to the improvement in sintering properties, cold compressive strength and thermal shock resistance of the AMCFs. The AMCFs doped with 8 wt% MgO and sintered at 1450 °C for 2 h displayed high cold compressive strength of 0.89 MPa, good sintering properties and thermal shock resistance. Although their apparent porosities were about 87%, the cold compressive strength of as-prepared foam was about 1.3 times higher than that of commercial Al2O3 foam.