Corrosion Behavior of Ni-Base Alloys in a Hot Lithium Molten Salt under an Oxidizing Atmosphere

摘要

The electrolytic reduction of a spent oxide fuel involves the liberation of the oxygen in molten LiCl electrolyte, which is a chemically aggressive environment that is excessively corrosive for typical structural materials. Accordingly, it is essential to choose the optimum material for the processing equipment that handles the molten salt. In this study, the corrosion behaviors of Haynes 263, Haynes 75, Inconel 718 and Inconel X-750 in a molten LiCl-Li_2O salt under an oxidizing atmosphere were investigated at 650 deg C for 72 to 216 hrs. The Haynes 263 alloy showed the best corrosion resistance among the examined alloys. The corrosion products of Haynes 263 were Li(Ni,Co)O_2 and LiTiO_2; those of Haynes 75 were Cr_2O_3, NiFe_2O_4, LiNiO_2 and Li_2NiFe_2O_4; while Cr_2O_3, NiFe_2O_4 and CrNbO_4 were identified as the corrosion products of Inconel 718. Inconel X-750 produced Cr_2O_3, NiFe_2O_4 and (Cr,Nb,Ti)O_2 as its corrosion products. Haynes 263 showed a localized corrosion behavior while Haynes 75, Inconel 718 and Inconel X-750 showed a uniform corrosion behavior.