Influence of alumina on the passive oxidation at low oxygen pressure of hot-pressed α-SiC

The influence of an alumina content (2 wt.%) on the oxidation behavior of hot-pressed α-SiC is studied. Sintering of α-SiC powder with alumina rests on the formation of a liquid phase corresponding to the eutectic composition in the SiO2-Al2O3 system. The oxidation kinetics of pure α-SiC at 1470 K under helium with an oxygen partial pressure of 0.1 Pa is linear, although silica is produced. The formation of Al-rich crystallized phase could be responsible for the slower oxidation kinetics of alumina-doped SiC. (authors)