High temperature corrosion of superalloys in a molten salt under an oxidizing atmosphere

Abstract

The electrolytic reduction of spent oxide fuel involves the liberation of oxygen in a molten LiCl electrolyte, which results in a chemically aggressive environment that is too corrosive for typical structural materials. So, it is essential to choose the optimum material for the process equipment for handling a molten salt. In this study, corrosion behavior of Inconel 713LC, Nimonic 80A and Nimonic 90 in a molten LiCl–Li 2O salt under an oxidizing atmosphere was investigated at 675 °C for 72–216 h. Inconel 713LC alloy showed the highest corrosion resistance among the examined alloys. Corrosion products of Inconel 713LC were Cr 2O 3, NiCr 2O 4, Ni and NiO, and those of Nimonic 80A were Cr 2O 3, LiFeO 2, (Cr, Ti) 2O 3 and Li 2Ni 8O 10 while Cr 2O 3, (Cr, Ti) 2O 3, LiAlO 2 and CoCr 2O 4 were produced from Nimonic 90. Inconel 713LC showed a local corrosion behavior and Nimonic 80A, Nimonic 90 showed a uniform corrosion behavior.