Corrosion of Al2O3/Cr and Ti2O3/Cr composites in flowing air and CO2 at 750°C

Hot-pressed Al2O3/Cr and Ti2O3/Cr composites were exposed to synthetic air or CO2 at 750 °C. The Al2O3/Cr composites formed external Cr2O3 scales, and exhibited slow parabolic oxidation kinetics, in both gases. The Cr2O3 scales formed in CO2 possessed finer grains, and thickened at a faster rate, than Cr2O3 scales formed in air. The Ti2O3/Cr composites formed thick external TiO2 scales with internal oxidation zones that also contained Cr2O3 scales on subsurface Cr grains. After 20 h at 750 °C, the Ti2O3/Cr composites exhibited parabolic oxidation kinetics in both gases, although the oxidation rates were significantly higher than for the Al2O3/Cr composites.