Corrosion of metallic scandium in molten halides

The mechanism of corrosion of scandium metal was studied in chloride and chloride-fluoride melts. Scandium metal dissolves in the melts according to the reaction 3 Na(I) + Sc(0) ⇔ 3 Na(0) + Sc(Ⅲ) Formation of passivating oxide film on surface of scandium metal leads to the decrease in corrosion rate. The presence of scandium cations in chloride melts results in the increase of corrosion rate due to competing reaction of formation of scandium oxide between scandium metal and scandium cations. Effect of fluoride-ions on the corrosion rate is discussed.