Effects of cerium and manganese on corrosion of Fe–Cr and Fe–Cr–Ni alloys in Ar–20CO2 and Ar–20CO2–20H2O gases at 650 °C

Abstract

Model alloys Fe–9Cr, Fe–20Cr and Fe-20Cr–20Ni (wt.%) with 0.1% Ce or 2% Mn were exposed to Ar–20CO2 and Ar–20CO2–20H2O gas mixtures at 650°C. Ferritic alloys underwent breakaway oxidation in both gases. Manganese additions significantly improved the oxidation resistance of Fe–20Cr in dry but not wet CO2. Water vapour accelerated internal oxidation of Fe–(9, 20)Cr. Austenitic alloys were more protective during corrosion in wet CO2. Cerium/manganese improved Fe–20Cr–20Ni performance in dry but not wet CO2. Most alloys carburised beneath their scales in both gases. Breakaway resistance is discussed in terms of Wagner’s criteria for selective chromia scaling.