Electrodeposition of Titanium in a Water-Soluble KF–KCl Molten Salt

Abstract

A new method of electrodeposition of Ti using a water-soluble KF–KCl molten salt electrolyte has been proposed. The electrochemical behaviors of Ti(III) ions in a KF–KCl molten salt to which 0.1 mol% K₂TiF₆ and an excess amount of sponge Ti were added have been investigated by cyclic voltammetry at 923 K. Anodic currents corresponding to the oxidation of Ti(III) ions were observed from 1.5 V (vs. K⁺/K) at a glass-like carbon rod electrode. In the negative potential region, cathodic currents were seen from 0.3 V, indicating the deposition of Ti metal from Ti(III) ions. When a nickel flag electrode was used, cathodic currents due to the formation of Ti–Ni alloys were observed, in addition to the current of deposition of Ti metal. The analyses of the electrodeposits by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffractometry confirmed that dense and smooth films of Ti metal with 20 μm thickness were obtained at current densities of 2.5 × 10⁻²–1.0 × 10⁻¹ Acm⁻².