Effects of the oxidants H2O and CrF3 on the corrosion of pure metals in molten (Li,Na,K)F

The effects of two oxidizing species, H2O and CrF3, on the corrosion of pure metals Ni, Fe and Cr in molten (Li,Na,K)F at 700 °C were investigated by potentiodynamic polarization and electrochemical impedance spectroscopy. The results indicated that Ni, Fe and Cr were all in active dissolution state at the corrosion potential and the corrosion current densities were significantly increased when 2% H2O was introduced. However, the addition of CrF3 only accelerated the dissolution of Cr and Fe. Based on the impedance results, the diffusion coefficient of Cr3+ in the melt has been calculated to be 6.25 × 10−4 cm2 s−1.