Effects of O2- additive on corrosion behavior of Fe-Cr-Ni alloy in molten fluoride salts

Corrosion behavior of 316 stainless steel (316SS) was studied in molten FLINAK and FLINAK + O2- salts at 650 degrees C by weight loss measurement, electrochemical methods and characterization techniques including scanning electron microscopy (SEM), X-Ray diffraction (XRD), electron probe micro-analyzer (EPMA) and Raman spectroscopy. The results showed that 316SS suffered corrosion attack in molten FLINAK. Notable corrosion products Cr2O3 and Fe3O4 were detected on the surface of 316SS in addition to subsurface voids. When O2- was added, the corrosion product changed to LiCrO2, which protected the alloy constituents from diffusion into the salt.