Dissolved Valence State Of Iron Fluorides And Their Effect On Ni-Based Alloy In Flinak Salt

In this study, the stable dissolved valence state of iron fluorides in molten LiF - NaF - KF (FLiNaK) salt and their effect on GH3535 alloy were systematically investigated. Results of in situ ultraviolet-visible (UV-Vis) absorption spectroscopy and electrochemical analysis indicated that Fe (II) in molten FLiNaK salt is unstable and gets converted to more stable Fe (III) through the disproportionation reaction: 3 Fe (II) = 2 Fe (III) + Fe. Thus, the corrosion of GH3535 alloy is aggravated by the addition of iron fluorides due to the redox reaction: Fe (III) + Cr = Fe + Cr (III), resulting in the formation of the Cr-depletion layer and Fe-rich layer.