Electrodeposition of titanium–vanadium alloys from chloride-based molten salts: influence of electrolyte chemistry and deposition potential on composition, morphology and microstructure

Abstract

In the present study, we demonstrate co-deposition of titanium and vanadium from a eutectic LiCl-KCl electrolyte enriched with VCl 3 and TiCl 2 at 700 K. While the addition of metallic titanium to the electrolyte caused vanadium depletion by a displacement reaction, metallic vanadium addition created and stabilized divalent vanadium ions in the melt, which are supposed to positively affect the deposition process. Various electrochemical experiments were carried out with different electrolyte concentrations, and a relationship between applied potential, electrolyte concentration and composition of the deposit was established. The composition and the morphology of the obtained deposits were strongly affected by the electrolysis conditions. Electrodeposited vanadium-rich Ti-V alloys were found to grow as dendrites, whereas the titanium-rich alloys exhibited a dense cauliflower-like surface morphology. In contrast to deposits of the single elements, which are composed of comparably large faceted crystals, the Ti-V alloys obtained in this study were very fine grained, especially those with vanadium contents around 10-15 at%. Transmission electron microscopy revealed that, depending on the composition of the deposit, either a biphasic α + β microstructure in the case of low vanadium contents or β-(V,Ti) with small amounts of ω phase for high vanadium contents were found.

Pulsed-Potential Electrodeposition of Zirconium in a Molten LiCl–KCl Salt: Improvements in the Selectivity and Adhesion Strength

“…It is expected to be filled with randomly oriented, poorly grown crystals. 44 Contrarily, R4-PPED exhibits plain hexagonal plate structures that are stacked (Fig. 7b).…”

Thermodynamic and Electrochemical Study of Vanadium Solutions: Towards Vanadium Recovery From a Spent Catalyst

“…Guo et al (2015) achieved the deposition of Ni over glassy carbon at -1.25 V. For Ti, the electrodeposition occurs in a similar route at very negative potentials using complex agents and basic electrolytes (Rao and Triveti 2005). Gussone et al (2020) carried out the electrodeposition of Ti in molten salt medium at -0.4 V and 700 ºK indicating that the eletrodeposition of Ti is extremely endothermic and, at room temperature, the electrodeposition is impossible and competitive with the hydrogen evolution. (pentavanadyl cation) in aqueous medium at low pH values (< 3.6) at 10 mM concentration but, when the concentration increases to 1 mM, the pH decreases to 1.3 promoting the formation of V 2 O 5 between pH 1.3 and 3.6.…”

Recent Studies on Titanium Refining: 2017–2020

“…Considering the production of titanium powder from titanium sponge as the raw material, the shuttle reactions due to disproportionation (the backward reaction of Ti 2+ to Ti 3+ and Ti metal) were studied at 1023 K in molten NaCl KCl by Lu et al 103) and in molten MgCl 2 LiCl by Wu et al 104) Their results showed that Ti 2+ is more stable in these molten salts than in fluoride melts. A Ti-rich TiV alloy with a cauliflower-like morphology was deposited from LiClKCl at 700 K. 105) Fig. 5 Mechanism of Mg reduction in MgCl 2 melt proposed by Fang et al 87,88) A d v a n c e V i e w Kumamoto et al 106) chose the eutectic LiClKClCsCl system to conduct the electroreduction of Ti 2+ to Ti at low temperatures such as 573 K. The addition of F ¹ increases the current density of electrodeposition because of the increase in the total concentration of soluble Ti ions in the molten salt.…”