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

Abstract

The oxidation behaviors of Fe-3.0 wt%Si non-oriented electrical steel were studied in the high-purity Ar, compressed dry air, Ar-H 2 O mixed, and Air-H 2 O 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 O 2 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 H 2 O-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, H 2 O and O 2 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-H 2 O atmosphere because of above conditions. This research lays the groundwork for a more in-depth investigation of silicon steel oxidation behavior. • Annealed with the hybrid atmosphere was applied to study the oxidation mechanism of Fe-3.0 wt%Si electrical steel. • The synergistic effect of H 2 O and O 2 leads to the cross-wrap structure appearing between the oxidized particle layer and the outermost oxide layer.