Corrosion behaviours of Ni-Mo-Cr alloy and 316 stainless steel in molten NaCl-KCl-AlCl3 salts at high temperature

The corrosion behaviours of Ni-Mo-Cr alloy and 316 stainless steel samples after immersing in NaCl-KCl-AlCl3 salt at 400.0°C for 168 h were investigated. The surface of Ni-Mo-Cr alloy basically kept its pre-corrosion morphology, with only a few corrosion pits. While NaCl-KCl-AlCl3 salt had stronger corrosivity to 316SS. After corrosion, the grain boundary of the surface of 316SS alloy was clearly visible, and the Fe and Cr atoms on the surface of 316SS were selectively corroded, leaving a Ni- rich layer of about 6.5 µm on the outmost surface of 316SS. At the temperature of 400.0°C, the corrosion resistance of Ni-Mo-Cr alloy to molten NaCl-KCl-AlCl3 salt was better than that of 316SS.