Corrosion behaviour of Alloy 800 in Molten Chloride Salt at 350 °C

Abstract

This study investigates the importance of salt impurities, moisture and oxygen, on the corrosion behavior of Alloy 800 in a ternary eutectic salt (LiCl 55% mol, KCl 40% mol, MgCl₂ 5% mol) at 350°C. Electron microscopy techniques were applied to evaluate the dealloying of Alloy 800 in two different salt conditions: low impurity salt exposed to (1) air, and (2) Ar in a glovebox. Results show that heat treating the salt decreases the impurity concentration which decreases corrosion of Alloy 800 substantially. However, exposure of Alloy 800 to the salt in air, even after heat treatment, results in dealloying and formation of a Ni-rich porous layer. In contrast, no sign of dealloying, at the micro-scale, was observed after exposure of Alloy 800 to salt inside the glovebox.