Magnesium Aluminate Spinel Ceramics Containing Aluminum Titanate for Refractory Applications

The thermal shock resistance of alumina-rich magnesium aluminate spinel refractory ceramics with aluminum titanate as second phase was investigated. First, suitable thermal conditions for the formation of aluminum titanate from corundum and rutile were determined. Ground pre-synthesized aluminum titanate was added to the spinel powder. According to another route, alumina and titania powder were mixed with the spinel raw material in order to form the aluminum titanate in situ during sintering. Test bars were prepared by means of slip casting and sintered at 1650 degrees C. The bending strength of both types of as-sintered samples with aluminum titanate was significantly lower in comparison with pure spinel ceramic, but their thermal shock resistance was improved. When the test bars were quenched five times from 950 or 1150 degrees C, the retained strength of the materials with aluminum titanate was higher than that of the pure spinel samples.