Oxide Films Formed on MoSi 2 Anode in Molten MgCl 2 –NaCl–CaCl 2 and Molten LiCl–KCl

The anodic formation of an oxide film on MoSi2 in molten MgCl2–NaCl–CaCl2 containing oxide ions has been investigated based on our former study, and the compatibility as an inert anode in the melt is discussed in contradistinction in molten LiCl–KCl. A small anodic current flew continuously during potentio-static electrolysis, and gas bubble generation was seen. The weight of MoSi2 was changed by the electrolysis, and an oxide film consisting of SiO2 and MgSiO3 was formed by the electrolysis above 1.9 V (vs. Mg/Mg2+). The current contributions estimated from the weight change and the film thickness indicate that the reaction other than the Mo dissolution and the oxide film formation enlarged with the increase in the electrolysis duration and the raise in the electrolysis potential. The current contribution other than the Mo dissolution and the oxide film formation became above 90%, which suggests MoSi2 is promising as an inert anode. A SiO2 film was formed on MoSi2 in molten LiCl–KCl containing oxide ions, but most of the current was consumed for the Mo dissolution and the oxide film formation. It is considered that the formation of MgSiO3 influences the anodic behavior of MoSi2.