Corrosion behavior of Incoloy 800H/HT in the fluoride molten salt FLiNaK + MFx (MFx = CrF3, FeF2, FeF3 and NiF2)

Abstract

The impact of the addition of CrF₃, FeF₃, FeF₂ and NiF₂ to the molten eutectic mixture FLiNaK (46.5 mol% LiF–11.5 mol% NaF–42 mol% KF) on the corrosion behavior of Incoloy 800H/HT was studied by static tests. The mass losses imply that initial corrosion increases upon addition of metal fluorides. Otherwise, the mass losses of alloys in FLiNaK with the same concentration of different additives obey the sequence Cr(3+) < Fe(2+) < Fe(3+) < Ni(2+) which represents the elements' standard electrode potential order. Chromium is acting as a sacrificial element in the cases of addition of FeF₂, FeF₃ and NiF₂ to corrosion media. At the same time chromium and iron act as sacrificial elements in the case of NiF₂ addition.