Hardness of Oxide Scales on Fe-Si Alloys at Room- and High-Temperatures

Abstract

Hardness of oxide scales on Fe-(0, 0.5, 1.5, 3.0)Si alloys was studied at room temperature after oxidation at 1273 K for 18 ks in oxygen, and at 1073 and 1273 K for 180 and 1080 ks in dry air, by micro-Vickers hardness measurements. After oxidation at 1273 K for 18 ks, high-temperature hardness of oxide scales on Fe-(0, 1.5, 3.0)Si alloys was also measured at 1273 K. Oxide scales on Fe-Si alloys were mainly Fe2O3, Fe3O4, FeO and Fe2SiO4. Hardness of Fe2O3, Fe3O4 and FeO on Fe was 6.7, 4.0 and 3.5 (GPa), respectively, and hardness of Fe2O3 on Fe-Si alloys slightly increased with increasing silicon content at room temperature. At 1273 K, hardness of Fe3O4 and FeO on Fe was 0.08 and 0.05 (GPa), respectively, and hardness of Fe2O3 on Fe-1.5Si alloy was 0.32 (GPa), and that of Fe2O3 and Fe2SiO4 on Fe-3.0Si alloy was 0.53 and 0.63 (GPa), respectively.