Corrosion Behavior and Mechanism of High-Oxidation-Potential Cu-Modified V2SnC in Chloride Molten Salts

Abstract

High-temperature molten salt systems are essential for energy storage and molten salt reactors, but their corrosiveness limits the durability of structural materials. MAX phases offer excellent high-temperature stability and oxidation resistance, yet the selective dissolution of A-site atomic layers in molten salts leads to structural degradation. Here, by introducing high-oxidation-potential non-noble metal Cu into the A-site, we enhanced interlayer bonding and suppressed A-site dissolution. Using V2SnC as a model, corrosion tests in MgCl2−NaCl−KCl molten salt at 700 °C showed that Cu incorporation transformed the corrosion behavior from mass loss (5.46% for V2SnC) to mass gain (4.80% for V2(Sn0.7Cu0.3)C) and drastically reduced the corrosion rate by 89.8%. Mechanistic analysis revealed that Cu inhibits Sn dissolution and volatile SnCl4 formation, strengthens M-A bonding, and promotes a dense MgO protective layer. Electrochemical measurements further confirmed enhanced corrosion resistance, with self-corrosion potential shifting positively and induced current density decreasing significantly. This work provides a cost-effective strategy to improve MAX phase structural stability in molten salt environments, advancing their application in high-temperature systems.