Effect of Iron Purity on Oxidation Kinetics at 600 °C to 900 °C

Abstract

The effect of iron purity on oxidation kinetics was examined at 600 °C to 900 °C under oxygen pressure of 0.1 MPa using a commercial electrolytically purified iron (ET-Fe. 99.9 wt pct) and a solvent extraction and anion-exchange refined iron (AE-Fe, >99.999 wt pct). ET-Fe oxidizes slower than AE-Fe. Oxidation of AE-Fe follows the parabolic oxidation rate law, but a downward deviation from the parabolic relationship was observed for ET-Fe. Analysis shows that the difference between AE-Fe and ET-Fe is attributable to a concentrated impurity layer at the FeO/Fe interface and to dissolution of copper, silicon, nitrogen, and carbon dissolved in FeO for ET-Fe. [PUBLICATION ABSTRACT]