High temperature molten salt corrosion of structural materials in UCl ₃ –LiCl–KCl

High temperature corrosion behaviour of 2.25Cr–1Mo, 9Cr–1Mo and SS 410 in molten UCl3–LiCl–KCl salt at 500 and 600°C under inert and reactive atmospheres for 24 h were studied by thermogravimetry. The results indicate marginal weight gains in all the alloys. In all conditions, except at 600°C under reactive atmosphere, the weight gains were higher in initial period of exposure. The weight gain was continuous for samples studied at 600°C under reactive atmosphere. The 2.25Cr–1Mo showed higher weight gain in an inert atmosphere, whereas SS 410 showed more weight gain at 500°C and 9Cr–1Mo at 600°C under reactive atmosphere. The weight gains were attributed to the formation of γ-FeOOH, α-Fe2O3, Fe3O4, FeCr2O4 and Cr2O3 as confirmed by Raman spectra analysis. The oxide films formed are neither uniform as evidenced from SEM-EDS analysis nor protective, attributed to the corrosive and aggressive nature of molten chloride salts.