Effects of CeO 2 applied to preformed oxide scales on subsequent oxidation of Fe–20Cr at 1000°C

Abstract

In order to explore the relationships between rare earth elements existing in oxides and growth rate and adhesion of oxide scales, CeO₂ thin films were prepared on Fe–20Cr alloys after pre-oxidation at 1000°C; subsequent isothermal and cyclic oxidation was carried out, and the oxide adhesion was determined by using the tensile pull test. The results demonstrated that similar to the effects of CeO₂ on the as polished Fe–20Cr alloy, the application of CeO₂ to the preformed oxides could decrease the subsequent oxidation rate, improve the cyclic oxidation resistance of the alloy and raise the adhesion strength of the oxide scales. These beneficial effects of the applied CeO₂ decreased with increasing pre-oxidation time. The fact that virtually none of CeO₂ applied on the preoxidised preformed layer reached the metal/oxide interface suggests that the ‘sulphur trapping effect’, through which CeO₂ may act, is minimal in the present system.