Galvanic corrosion of pure metals in molten fluorides

The corrosion of structural materials is a great challenge for the development of a molten salt reactor using molten fluorides as fuel or coolant. The corrosion of materials in molten fluorides occurs mainly through the dissolution of alloying elements into the melt. In the present investigation, the galvanic corrosion behavior of pure Ni, Fe, and Cr as the common alloying constituents in an eutectic LiF–NaF–KF melt at 700 °C has been investigated. The experimental results indicate that the corrosion potential of the three metals decreases significantly by the order of Ni, Fe and Cr, with the largest potential difference observed between Ni and Cr. Their great potential differences lead to the occurrence of significant galvanic corrosion. The galvanic corrosion effects of the couples Ni/Cr, Ni/Fe and Fe/Cr are significantly larger than 1, with the most remarkable effectiveness obtained for the couple Ni/Cr, then Fe/Cr and Ni/Fe.