Dependence of Titanium Deposition upon Its Ionic State in Molten Salt
The ionic valence of Ti changed with electrorefining process of Ti in a bath equi-molar mixture of NaCl-KCl containing TiCln (n=2 or 3); The average valence was about 2.3 initially, and became about 2.1 after electrolysis. The cathodic current efficiency was getting better with electrolysis. It should be necessary to maintain the average ionic valence lower for efficient electrolysis in the molten salt. The dominant Ti ion and its electrode reaction changed with the addition of NaF-KF in the molten salt; The average valence shifted from about 2 to about 3, and the total amount of Ti in the bath decreased. The result indicates the disproportionation reaction: 3Ti2+ = Ti + 2Ti3+ is induced by the fluoride addition. The quantity of electricity for Ti deposition changed consequently, and the purity of the Ti deposit was also affected.
S.-G. Kang and T. Kobayashi
T. Takenaka et al., "Dependence of Titanium Deposition upon Its Ionic State in Molten Salt", Materials Science Forum, Vols. 449-452, pp. 453-456, 2004