Influence of alkaline earth metal CaCl2 on early-stage corrosion behavior of 316 stainless steel in high-temperature molten salt

Abstract

Ternary chloride salts containing alkaline earth metal salts are potential hightemperature thermal energy storage (TES) media for future applications. However, the effect of alkaline earth metal salts on the corrosion of 316 stainless steel (SS) is still not well understood. In this paper, the short-term corrosion behavior of two ternary chloride salts, LiCl–KCl–CaCl₂, with different CaCl₂ contents on 316 SS at 650 ºC was studied through a combination of experiments and first-principles molecular dynamics simulations. The effect of impurity water introduced by CaCl₂ on the formation and evolution of corrosion products was revealed by experimental methods. The dynamic interaction between impurity water introduced by the chloride salts and the salt mixture LiCl–KCl–CaCl₂ with different components was studied by molecular dynamics simulations. The experimental and simulation results show that the impurity water introduced by CaCl₂ promotes the corrosion of 316 SS. These findings provide new insights for molten salt design and corrosion control of high-temperature TES for concentrated solar power.