High-temperature electrochemical corrosion evaluation of 2.25Cr–1Mo alloy in eutectic LiCl–KCl molten salt

Abstract

The Cr–Mo ferritic steels are candidate structural materials for the pyrochemical reprocessing applications due to desirable high-temperature strength, resistance to oxidation, and etc. The corrosion resistance of the alloys in molten salts depends on the moisture, impurities, oxidising nature of the electrolyte and temperature. In the present study, in order to monitor the corrosion behaviour of 2.25Cr–1Mo steel in LiCl–KCl molten salt under inert argon atmosphere at 500°C for 200 h duration, electrochemical measurements like open-circuit potential (OCP), linear polarisation resistance, and electrochemical impedance spectroscopy have been carried out. On increasing the duration of exposure to molten salt, the OCP is shifted to the noble direction, and the polarisation resistance increased. The electrochemical impedance spectra exhibited three time constants attributed to the intermittent oxide layer, which was also evident from the surface morphology. The XRD analysis did not reveal the formation of oxide films.