High-temperature corrosion behavior of al-coated ni-base alloys in lithium molten salt for electroreduction

Abstract

The electrolytic reduction of a spent oxide fuel involves the liberation of oxygen in a molten salt LiCl–Li2 O electrolyte, which creates a corrosive environment for typical structural materials. In this study, the corrosion behaviors of Al–Y-coated specimens in a Li molten salt kept under an oxidizing atmosphere at 650◦ C for 72 and 168 h were investigated. The weight loss fraction of the coated specimen to bare specimen was approximately 60% for 3% Li2 O and 54% for 8% Li2 O at 72 h, and approximately 38% for 3% Li2 O and 30% for 8% Li2 O at 168 h. Corrosion was induced in the LiCl–Li2 O molten salt by the basic oxide ion O2− via the basic flux mechanism, and the corrosion product was found to be dependent on the activity of the O2− ion. The increase in weight loss may have been caused by the increase in the O2− concentration due to the increase in the Li2 O concentration rather than being because of the increased reaction time. The Al–Y coating was found to be beneficial for hot corrosion resistance, which can be useful for handling high-temperature lithium molten salt under an oxidizing atmosphere.