Restraining the Cr-Zr interdiffusion of Cr-coated Zr alloys in high temperature environment: A Cr/CrN/Cr coating approach

In this study, a Cr-CrN-Cr coating was fabricated on Zr alloys to restrain the Cr-Zr interdiffusion of Cr-coated Zr alloys. The early stage diffusion, decomposition, and oxidation behaviors of the coating sample are investigated by a tube furnace equipped with a “fast-in & fast-out” tool. The outer and inner Cr layer was transferred into Cr₂N by nitrogen, which was formed by the decomposition of the CrN layer. A Zr₂N layer formed at the interface between the residual coating and Zr substrate, which acted as a diffusion barrier. After oxidation in a steam environment, the coating structure can be divided into Cr₂O₃, CrN, Cr₂N, and Zr₂N (from outside to inside).