Comparison between the oxidation of iron in oxygen and in steam at 650-750 °C

Oxidation of iron was investigated in oxygen and in steam at 650-750 °C by TGA, OM, SEM, and XRD. In oxygen, parabolic kinetics and multilayer oxide scales composed of typical three iron oxides were observed. Noticeably, the scale adhesion was very poor. In steam, linear-parabolic shape kinetics and multilayer oxide scales with fewer pores were found. As indicated by Pt marking, inward-growing process in steam was considered to result in the improvement of scale contact. Based on the experimental results, scaling mechanism of iron in steam was discussed.