Oxidation studies were conducted on Al2O3-SiC composites at 1375-1575˚C in O2. The composites were prepared by hot pressing mixtures of Al2O3 and SiC powders. The reaction products contained alumina, mullite, an alumino-silicate liquid, and gas bubbles. The parabolic rate constants were about 3 orders of magnitude higher than those expected for the oxidation of SiC particles alone. Higher rates are caused by higher oxygen permeabilities through the reaction products than through pure silica. Our results suggest that oxygen permeabilities are comparable in three condensed phases observed in the reaction products.

Oxidation studies were conducted on Al2O3-SiC composites at 1375-1575˚C in O2. The composites were prepared by hot pressing mixtures of Al2O3 and SiC powders. The reaction products contained alumina, mullite, an alumino-silicate liquid, and gas bubbles. The parabolic rate constants were about 3 orders of magnitude higher than those expected for the oxidation of SiC particles alone. Higher rates are caused by higher oxygen permeabilities through the reaction products than through pure silica. Our results suggest that oxygen permeabilities are comparable in three condensed phases observed in the reaction products.