Study of Corrosion Performance and Mechanisms of P91, 304SS and IN625 Alloys in Molten Nitrate Salts Used for Thermal Energy Storage System

The corrosion performance of P91, 304SS and IN625 alloys was evaluated in simulated Solar Salt at 565 degrees C for up to 15 days. Results revealed that IN625 exhibited the best corrosion resistance with the evolution of thin and compact dual-structured oxide scales. 304SS experienced a great corrosion rate at the initial stage, but showed protective behavior in the later period. A linear mass gain rate was observed for P91, which may result in breakaway corrosion during prolonged immersion time. Finally, the underlying corrosion mechanisms were revealed, providing important guidelines for selecting applicable materials for corrosion mitigation in thermal energy storage (TES) system.