Effect of rare oxide coating in improving the cycle oxidation resistance of chromia forming alloys

Abstract

The use of rare earths to increase high temperature oxidation resistance of chromium dioxide and alumina forming alloys is well known. The rare earths can be added as elements (or oxides) to the alloys or applied as an oxide coating to the alloy surface. The sol-gel technique is very efficient to apply fine oxide particle coatings. The influence of various rare earth oxide gels such as La2O3, CeO2, Pr2O3, Nd2O3, Sm2O3, Gd2O3, Dy2O3, Y2O3, Er2O3, and Yb2O3 on cyclic oxidation behavior (RT-900ºC) of Fe20Cr alloy has been studied. The morphology and coverage of the rare earth oxide gels varied with the type of rare earth. The cyclic oxidation resistance increased with increasing rare earth ion radius, increasing coverage and gel crystallites in the form of cuboids or needles.