Electrochemical Deoxidation of Titanium in Molten MgCl₂–YCl₃

A new electrochemical deoxidation process for Ti, where a mixture of magnesium chloride and yttrium chloride (MgCl₂–YCl₃) is used as flux, was developed. In the new process, Ti and carbon were used as the cathode and anode, respectively. By elucidating the system using an E-pO²⁻ diagram and the experimental results, the reaction mechanism was proposed. Mg is deposited on the Ti cathode and reduces the oxygen in Ti to oxide ions (O²⁻). The activity of the generated O²⁻, \(a_{\text O^{2-}}\), in the system is effectively kept at a low level by the formation of yttrium oxychloride, and is further decreased by the electrochemical oxidation reaction on the anode. The process effectively deoxidizes Ti to the level of 100 mass ppm of oxygen concentration at 1200 K. In addition, the oxygen concentration in the Ti sample was maintained at the level of 500 mass ppm O even with the addition of O²⁻ sources. Furthermore, a new concept of the industrial Ti-recycling process based on this new deoxidation process was depicted. The obtained results indicate that this new deoxidation technique can be applied in the recycling process of Ti scrap containing a large amount of oxygen.