Nd Based Surface Modification to Prevent High Temperature Oxidation of a Ferritic Stainless Steel

Abstract

Fe-Cr stainless steels have experienced a formation of chromia scale when exposed to an oxidising atmosphere at elevated temperatures. The oxidation will reduce the electrical conductivity of the steel for the high resistivity of the Cr oxide layer grown. In addition, the Cr containing scale may result in a poisoning of the air electrode in solid oxide fuel cells (SOFCs), which is led by volatile Cr species released from the surface. Therefore, it is required to avoid or prevent the scale growth to improve the oxidation resistance and electrical conductivity by the application of a protective coating or a surface modification onto the steel surface. In this study, an influence of Nd based surface modification onto a commercial ferrtie stainless steel was examined on the microstructure evolution, high temperature oxidation, and area specific resistance. It was revealed that the Nd modification suppressed chromia scale growth and thus reduced area specific resistance because of the formation of an Nd and Cr containing secondary phase possessing a conductivity than that of the Cr scale.