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

• Published in: Journal of nuclear materials Vol. 514; pp. 348 - 357
• Main Authors: Wang, Chengxu, Chen, Wei, Chen, Minghui, Chen, Demin, Yang, Ke
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.02.2019; Elsevier BV
• Subjects: Chromium nitride; Coatings; Corrosion; Corrosion resistance; Corrosion resistant alloys; Diffusion barriers; Electroplating; Fluorides; High temperature corrosion; Interdiffusion; Iron; Lithium fluoride; Molten salts; Nickel base alloys; Nickel coatings; Protective coatings; Salts; Superalloys; Superalloys; High temperature corrosion; Molten salts
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2018.12.018

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. •Ni-coating greatly improves corrosion resistance of alloy in molten fluoride salts.•CrN barrier can inhibit elements interdiffusion and enhance corrosion resistance.•CrN layer remains intact and adheres well to the alloy and coating after corrosion.