Protective Metallic Molybdenum Coatings on 12Kh18N10T Steel for Fluoride Melts. Deposition, Certification, and Efficiency

Abstract—The successful use of molten alkali metal fluorides as electrolytes for high-temperature plants requires the creation of reactors materials that have high corrosion resistance in melts with the compositions that are typical of a mixing molten salt reactor (MSR-M). This is one of the most important unresolved problems. One of the effective ways to decreases corrosion losses is to create a layer on the metal surface in order to protect the metal from the aggressive effects of the environment. In this work, molybdenum insulating coatings on 12Kh18N10T steel, which are deposited in molten salts of various compositions using various methods, are analyzed. Experiments are conducted to perform the electrodeposition of molybdenum coatings on an iron-based structural material (12Kh18N10T steel). The electrochemically deposited coatings are heterogeneous and easily flaking. The thicknesses of the molybdenum coatings deposited on steel in molten salts are 8.15 and 20.34 μm in the FLiNaK and LiCl–KCl melts, respectively. Corrosion tests have shown the inefficiency of the molybdenum coatings deposited from both chloride and fluoride melts. The corrosion rate of 12Kh18N10T steel in the FLiNaK/(FLiNaK + 5% CeF₃) melts at 650°C for a holding time of 100 h decreases in the following row: 12Kh18N10T + Mo (0.75/0.77 mm/year) > 12Kh18N10T (0.45/0.50 mm/year).