Improvement of Cyclic Oxidation Resistance of Fe-23 mass% Cr Alloy by Molten Salt Electrodeposition of Lanthanum

Abstract

A La-containing surface layer was formed on a Fe-23 mass% Cr alloy by electrodepositing La and alloying it with the alloy in molten salt. The electrodeposition of La was carried out using a potentiostatic polarization method at constant potential in an equimolar NaCl-KCl melt containing La₂O₃ and NH₄Cl at 1023 K. EPMA analysis of the cross-section of the alloy after the electrodeposition showed that a surface region containing La of less than 1 mass% was formed. The cyclic oxidation test showed that the La-electrodeposited alloy was more resistant than the bare alloy to cyclic oxidation. On the La-electrodeposited alloy after cyclic oxidation, formation of a thin scale consisting of Cr₂O₃ was observed.