Corrosion evaluation and resistance study of alloys in chloride salts for concentrating solar power plants

Thermal energy storage (TES) systems based on molten salt are widely used in concentrating solar power (CSP) plants. The investigation of the corrosion behavior of alloy materials in molten salt is crucial for the correct selection of alloy materials and the design of TES systems. In this study, the corrosion behavior of 304, 310S, 316, and In625 alloys in molten chloride salts (27 mol% NaCl-22 mol% KCl-51 mol% MgCl₂) was investigated. The evolution of mass loss of the alloy samples with corrosion time and temperature and the analysis of the experimental results by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and X-ray diffraction (XRD) revealed the corrosion mechanism of the alloy samples in molten chloride salts. The main factors affecting the corrosion of the alloy samples were further analyzed. It was found that the loose multi-layer corrosion was formed on the surface of the corroded alloy samples with the increase in corrosion degree. Moreover, the experimental results showed that Mo played a positive role in improving the corrosion resistance of the alloy samples because the presence of Mo could inhibit the outward diffusion of alloying element Cr. This work enriches the molten salt corrosion database and provides a reference for the selection of alloy materials for TES systems with potential application in CSP plants. Graphical abstract: (Figure presented.)