Electrolytic Deposition Behavior of Mo in Molten NaCl-KCl-Li₂MoO₄

Abstract

The electrolytic deposition behavior of Mo in molten salt has been studied using the equimolar NaCl-KCl molten salt, which contains Li₂MoO₄ as a molybdenum source. In the equimolar NaCl-KCl molten salt containing only Li₂MoO₄, a high cathodic current corresponding to the reduction reaction of Li₂MoO₄ was observed under cathodic polarization. Under this polarization, the deposition of Mo could not be observed, but the deposition of Li₂Mo₂O₅ which grew perpendicular to the substrate surface was observed. On the other hand, in the equimolar NaCl-KCl molten salt containing B₂O₃, AlF₃ or K₂SiF₆ as the second addition agents in addition to the Li₂MoO₄, a higher cathodic current was observed under cathodic polarization, showing that the cathodic reaction was more active. Under the cathodic polarization in the molten salt containing B₂O₃ or AlF₃ as the second addition agent, the deposition of MoO₂ occurred without depending on the polarization potential. On the contrary, under the cathodic polarization in the molten salt containing K₂SiF₆ as the second addition agent the deposition material was changed with the polarization potential. Thus, in the molten salt containing K₂SiF₆, MoO₂ was deposited at high potentials, while Mo was deposited at low potentials. Consequently, it was found that in the equimolar NaCl-KCl molten salt containing Li₂MoO₄ and K₂SiF₆, Mo was deposited under the cathodic polarization at low potential.