Oxidation Resistance and Corrosion Resistance of Molybdenum-Chromium Nitride Layer

Abstract

For Mo-Cr nitride layer prepared by NH3 gas nitriding of pure Mo subjected to Cr-diffusion treatment, the oxidation behavior in air and corrosion behavior in boiling sulfuric acid were investigated. The surface nitride layer consisted of γ-Mo2N type solid solution of which Mo-Cr ratio was almost 1 : 1 on the surface. Although γ-Mo2N layer obtained by nitriding pure Mo was oxidized at temperatures above 773 K, Mo-Cr nitride layer exhibited superior oxidation resistance up to 1073 K. The corrosion resistance of Mo-Cr nitride layer in boiling sulfuric acid was as excellent as that of γ-Mo2N layer.