INFLUENCE OF ALUMINA REACTION TUBE IMPURITIES ON THE OXIDATION OF CHEMICALLY-VAPOR-DEPOSITED SILICON-CARBIDE

Pure coupons of chemically vapor deposited (CVD) SiC were oxidized for 100 h in dry flowing oxygen at 1300 degrees C. The oxidation kinetics were monitored using thermogravimetry (TGA). The experiments were first performed using high-purity alumina reaction tubes, The experiments were then repeated using fused quartz reaction tubes. Differences in oxidation kinetics, scale composition, and scale morphology were observed. These differences were attributed to impurities in the alumina tubes, Investigators interested in high-temperature oxidation of silica formers should be aware that high-purity alumina can have significant effects on experimental results.