XPS characterization of the oxide scale on fully processed non-oriented electrical steel sheet

• Published in: Materials characterization 2011-05, Vol.62 (5), p.503-508
• Main Authors: Petrovič, Darja Steiner, Mandrino, Djordje
• Format: Article
• Language: English
• Subjects: ARGON IONS; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Ferrous alloys; IRON; IRON COMPOUNDS; IRON IONS; LAYERS; MATERIALS SCIENCE; Non-oriented electrical steel; Oxide scale; OXIDES; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; REDUCTION; Sheet metal; SHEETS; Solidification; SPUTTERING; STEELS; SURFACE CONTAMINATION; SURFACES; X-RAY PHOTOELECTRON SPECTROSCOPY; X-rays; XPS
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2011.03.011

An X-ray photoelectron spectroscopy analysis of the surface of fully processed, non-oriented, electrical steel sheet was performed in an attempt to elucidate the chemistry of the complex oxide scale. Ar + sputtering was used to clean the surface contamination. Not only Fe 2+, but also Fe 0 states were detected in addition to the Fe 3+ in the top several tens of nanometers of the 1–5-μm-thick complex oxide scales. This reduction of iron was explained as being due to the preferential sputtering of the oxygen atoms from the iron compounds in the Ar + sputtering process. A fayalite reduction mechanism is proposed to account for the reduction of the iron down to Fe 0. The results of the study indicate that X-ray photoelectron spectroscopy is limited to the determination of thick, complex oxides in multicomponent iron alloys. ► XPS analysis of the 1–5-μm-thick oxide scales of NO-electrical steel was performed. ► Not only Fe 3+ and Fe 2+, but also Fe 0 were detected in the very subsurface layers. ► A fayalite reduction mechanism is proposed for the reduction of the iron to Fe 0.