Abstract: The kinetics of La-Co alloy film in acetamide-urea-NaBr molten salt electrolyte at 353K was investigated. It is shown that the reduction of Co(Ⅱ) to Co is irreversible reaction with the transfer coefficient of 0.28 and the diffusion coefficient of 7.46×10^-5 cm²/s. While La(Ⅲ) cannot be reduced to La directly; but can be codeposited with cobalt. The content of La in the uncrystallized La-Co alloy film increases with increasing cathodic overpotential, molar ratio of La³⁺ to Co²⁺ and electrolysis time as well, and reaches the maximum of 66.32%.

Key words: La-Co alloy film; acetamide-urea-NaBr  molten salt electrolyte; electroreduction; inductive co-deposition; rare earth elements