Effects of Temperature, Ti(III) Ion Concentration, and Current Density on Electrodeposition of Ti Films in LiF-LiCl Melt

Abstract

The effects of temperature, Ti(III) ion concentration, and current density on the electrodeposition of Ti films were investigated in the eutectic LiF–LiCl melt at 823–973 K. The Ti(III) ions were prepared by adding Li₂TiF₆ and Ti metal to the melt. The diffusion coefficients of Ti(III) were 1.4, 1.8, 2.3, and 3.2 × 10⁻⁵ m² s⁻¹, at 823, 873, 923, and 973 K, respectively. Galvanostatic electrolysis was conducted at 823–973 K. The surface roughness (Sa) of the Ti films decreases with decreasing temperature. Thus, the electrodeposition of Ti films was conducted at the lowest temperature of 823 K with various Li3TiF6 concentrations (0.55–7.1 mol%) and cathodic current densities (50–1200 mA cm⁻²). The Sa was lower at higher Ti(III) ion concentrations and lower current densities. The smoothest Ti films with a Sa of 1.23 μm and a thickness of 10 μm were obtained at a cathodic current density of 50 mA cm⁻² and Li₃TiF₆ concentration of 7.1 mol%.