Short-term corrosion behavior of 316 stainless steel in molten salt LiCl KCl-CaCl2 as high temperature thermal storage medium

The effects of alkaline earth metal salts on the corrosion of Fe-Cr alloys are not clear up to now. The ternary chloride salts are the potential high-temperature thermal energy storage medium for future application. In this study, the short-term corrosion behavior of two ternary chloride salts LiCl–KCl–CaCl2 with different content CaCl2 on 316 stainless steel (316 SS) are investigated by immersion experiments at 650 ºC. The effect of CaCl2 content on the formation and evolution of corrosion products are revealed by the kinetics, microstructure and chemical analysis of corroded 316 SS. Meanwhile, the effects of 316 SS before and after corrosion on salt chemistry and thermal properties are also characterized by ICP-OES and infrared spectroscopy, respectively. The results indicate that the dissolution of Fe-Cr into the ternary chloride salt cannot change the chemical properties of the ternary chloride salt LiCl–KCl–CaCl2. However, the dissolution of Fe-Cr reduces the melting temperature of ternary chloride
salts LiCl–KCl–CaCl2. These findings provide new ideas for molten salts design and corrosion control for high-temperature thermal energy storage medium of concentrated solar power.