Influence of F− on the electrochemical properties of titanium ions and Al–Ti alloy electrodeposition in molten AlCl3–NaCl

Abstract

The present study reports the electrochemical properties of titanium ions in molten AlCl₃–NaCl with various concentrations of fluoride anions. Transient electrochemical techniques, such as chronopotentiometry, cyclic voltammetry and square wave voltammetry, were performed to reveal the diffusion coefficients of the electroactive species and reduction steps. Results suggest that there are three steps for titanium ion reduction in molten AlCl₃–NaCl: Ti(IV) → Ti(III), Ti(III) → Ti(II) and Ti(II) → Ti. The reduction processes transferred to Ti(IV) → Ti(III) and Ti(III) → Ti when NaF was added in the melt in increasing amounts. The influence of fluoride anions on the Al–Ti alloy deposition was also investigated. A constant potential electrolysis was carried out for depositing Al–Ti alloys and results illustrated that the Al–Ti alloys with different molar ratios were obtained under different amounts of NaF in the melt.