Refractory composites of alumina and boron nitride

This patent describes a composite produced by heating and compressing a mixture of particulate alumina and boron nitride. The composite consists essentially of between about 50 and about 90 weight percent alumina having a purity of at least 99.90 weight percent, and between about 10 to about 50 weight percent boron nitride having a purity of at least 99 weight percent. The composite has a density not more than about 93% of the theoretical density, and a Rockwell R hardness less than 130