Molten Salt Corrosion in Energy Systems: A Comprehensive Review on the Effects of Media and Material States

ABSTRACT Corrosion limits structural reliability in molten salt Concentrated Solar Power (CSP) systems. This review categorizes mechanisms into chemical, electrochemical, and mechanical modes. Chemical corrosion varies by environment: nitrate salts enable protective oxide films (e.g., Cr₂O₃, FeCr₂O₄) on Cr‐steels, while chloride systems require Ni‐based alloys with high Mo/W and strict impurity control to suppress Cr volatilization. Electrochemical corrosion is impurity‐driven in chlorides (H₂O/O₂/Cl⁻ causing film breakdown and acidification) but milder in nitrates. Notably, welded joints are vulnerable; microstructural inhomogeneity induces galvanic cells, accelerating Heat‐Affected Zone (HAZ) erosion. Mechanical corrosion involves flow delamination, thermal flaking, and stress‐corrosion, where initial Cr diffusion eventually promotes intergranular cracking. Since static testing underestimates synergistic effects, future research must prioritize dynamic coupled testing and multiscale modeling to ensure high‐temperature reliability.