High temperature corrosion of pure Fe, Cr and Fe–Cr binary alloys in O 2 containing trace KCl vapour at 750 °C

Abstract

Pure Fe, Cr and Fe–Cr binary alloys were corroded in O 2 containing 298 ppm KCl vapour at 750 °C. The corrosion kinetics were determined, and the microstructure and the composition of oxide scales were examined. During corrosion process, KCl vapour reacted with the formed oxide scales and generated Cl 2 gas. As Cl 2 gas introduced the active oxidation, a multilayer oxide scales consisted of an outmost Fe 2O 3 layer and an inner Cr 2O 3 layer formed on the Fe–Cr alloys with lower Cr concentration. In the case of Fe–60Cr or Fe–80Cr alloys, monolayer Cr 2O 3 formed as the healing oxidation process. However, multilayer Cr 2O 3 formed on pure Cr.