The molten CaCl 2 -CaMoO 4 system was investigated, and the electrodeposition of protective Mo coatings on Ni plates was demonstrated. The results confirm the high solubility of solid CaMoO 4 and the electrochemical reactivity of MoO 4 2– ions in molten CaCl 2 . The eutectic temperature and composition of the system are identified as 1021 K and 4.74 wt.% CaMoO 4 , respectively. Under constant-current electrolysis conditions of -10 mA/cm 2 at 1123 K, uniform and dense Mo coatings are obtained on Ni plates with up to 90.31% efficiency. Increasing the current density raises the overpotential, leading to refined grains and decreased roughness. The Mo-coated Ni plate exhibits a significant improvement in hardness and corrosion resistance. Microhardness increases from HV 46.00 to HV 215.10 after coating, and the corrosion rate in a 20 wt.% NaCl solution at room temperature decreases to 0.1% that of the bare plate. These findings enhance our understanding of the molten CaCl 2 –CaMoO 4 system and emphasize the potential of innovative Mo coating technologies.
Cheng et al. (Thu,) studied this question.