The migration and reaction of ions during the oxidation of Fe-Si alloy with 0.5 wt% Si at 1000–1200 °C

Abstract

In order to investigate the oxidation mechanism during physical state transformation of Fe-Si alloys in details, the oxidation tests in dry air were carried out at 1000 °C, 1100 °C and 1200 °C for 120 min. The migration of iron ions was prevented due to the formation of a stable Fe2SiO4 layer in the scale-alloy interface at 1000 °C and 1100 °C. The formation of FeO + Fe2SiO4 eutectic in liquid state enhanced the iron diffusion at 1200 °C. It promoted the oxidation rate to a higher value. The thickness of oxide scale and the oxidation rate were significantly higher at 1200 °C compared to those at lower temperatures. The oxidation kinetics of Fe-Si alloys followed a parabolic-linear law instead of parabolic due to the physical state transformation and iron diffusion from 1000 °C to 1200 °C.