EFFECTS OF CONCENTRATION AND AVERAGE VALENCE OF TITANIUM SUBCHLORIDES ON THE ELECTRO-CRYSTALLIZATION OF TITANIUM

The effects of concentration and average valence of titanium subchlorides onthe electrocrystallization of titanium in a NaCl-KCl melt have been investigated.When the Ti ion concentration was about 2% and the average valence was nothigher than 2.4, the crystals obtained were coarse. A possible explanation of thisphenomenon is as follows: In NaCl-KCl melts, complex ions of Ti will form, andchemically, the Ti~(2+) complex ions are less stable as compared to the Ti~(3+) complexions. This will lead to comparatively small overpotential in electrodeposition. There-fore, lower average valence is conductive to the formation of rather coarsercrystals. With a view to improving the current efficiency and the quality of Tiin the electrolysis of TiCl_4 by basket cathode, measures which can raise theconcentration of titanium subchlorides as well as lower the average valence, suchas adding Ti to the gas-melt interface in the basket should be adopted.