Ultra-low corrosiveness molten LiCl-KCl-Li salt solution with dissolved metallic Li component

Purpose Chloride salts are highly hygroscopic, which can lead to severe corrosion of metallic materials at elevated temperatures, greatly limiting their practical applications. This paper aims to evaluate the impact of impurity moisture on the metal corrosiveness of molten salt and achieve complete removal of impurity moisture. Design/methodology/approach Here, the authors choose the dissolution corrosion of nickel metal in LiCl-KCl eutectic salt as a research model. The authors prepared LiCl-KCl eutectic salt and further synthesized molten LiCl-KCl-Li salt solution containing dissolved metallic Li component using it as raw material. The static corrosion test of nickel in molten LiCl-KCl-Li and LiCl-KCl was applied to evaluate their corrosiveness. Findings The Ni sheet in LiCl-KCl undergoes obvious dissolution corrosion, and the generated Ni2 + ions mainly exist in the form of KNiCl3 complex with a small amount of dissolved NiO. In contrast, LiCl-KCl-Li solution shows ultra-low corrosiveness toward metal Ni, and no significant Ni content was detected in the LiCl-KCl-Li sample that reacted with a Ni sheet at 600°C for 7 days. Originality/value Through near-ideal controlled experiments, the study deeply explored the impact of residual moisture in chlorine salts after heat treatment on metal corrosion. The research results reveal that the impurity moisture in LiCl-KCl plays a crucial role in the Ni corrosion, and can be completely removed by using an excess of metallic Li, resulting in a molten-salt solution with almost no corrosivity.