Characterization of Oxide Scales on Super-Alloy HR120 at 1000 °C in Air and Steam Environments

Abstract

Oxidation resistance of super-alloy HR120 in air and steam environments at 1000 °C was investigated. Scanning electric microscopy and X-ray diffraction analysis were used to characterize the corrosion products. The results show that weight gain in steam was much higher than that in air. Oxide scales formed in air were MnCr2O4 and Cr2O3, whereas oxides developed in steam were NiFe2O4, (Cr, Fe)2O3 and little internal Cr-Si oxides. Steam can increase the corrosion rate and fine the oxides formed on the sample’s surface. Moreover, enhanced oxidation of HR120 in steam was mainly attributed to the evaporation of chromium oxyhydroxides.