High-temperature oxidation mechanism of Fe-3.0 wt%Si electrical steel with hybrid atmosphere

The oxidation behaviors of Fe-3.0 wt%Si non-oriented electrical steel were studied in the high-purity Ar, compressed dry air, Ar-H2O mixed, and Air-H2O mixed atmosphere when annealed at 1200 °C for 200 min. The oxide layers generation and transformation mechanism of electrical steel during the high-temperature annealed process was characterized and discussed systematically by means of the XRD, SEM, EDS, and XPS analysis methods. Under compressed air conditions, only O2 participates in the oxidation reaction. And the oxide layer has a typical three-layer structure. The oxidized particle layer only could be observed in the H2O-containing atmosphere, and the particle size and morphology of the oxide layer present an obviously evolution process. During the oxidation reactive process between Fe, Si and O, H2O and O2 could play a synergistic effect. In addition, this synergistic effect leads to the cross-wrap structure appearing between the oxidized particle layer and the outermost oxide layer. The oxide layer thickness increases significantly in the Air-H2O atmosphere because of above conditions. This research lays the groundwork for a more in-depth investigation of silicon steel oxidation behavior. © 2022 Elsevier B.V.