Corrosion behavior and elements interdiffusion between a Ni coating and GH3535 alloy with and without a CrN barrier in molten fluoride salts

Abstract

CrN barrier was deposited between a Ni-electroplating and GH3535 alloy with the goal of prohibiting elements interdiffusion and increasing corrosion resistance in molten FLiNaK (LiF-NaF-KF: 46.5-11.5-42.0 mol%) salt. Results indicate that the Ni-coating apparently improves corrosion resistance of GH3535 in molten fluoride salts, but Cr and Fe diffuse constantly from the alloy to the Ni-coating. They are finally dissolved into the molten salt, causing corrosion of the GH3535 alloy. With a CrN diffusion barrier, however, elements interdiffusion has been completely suppressed and the corrosion resistance is further improved by more than eight times comparing to the CrN-free Ni-coated alloy.