The electrochemical process of the solid titanium dioxide develops in the complex system: TiO2 (solid, sintered cathode) � CaCl2 (liquid, electrolyte) � C (anode, graphite). As a consequence of the chemical and electrochemical reactions which take place in this system, with determined conditions of temperature and potential, are finally formed solid metallic titanium (at the cathode) and oxygen (at the anode). The general reaction of the process is: TiO2(s) = Ti(s)+O2(g). A series of other reactions, implying the presence of other components (elements and compounds), as Ca, CaO, CaTiO3, C, CO, CO2, etc., are possible in certain conditions and stages of the process. In the paper are analyzed the main reactions which occur in the process, by their thermodynamic study. Through mathematical processing of thermodynamic data for the main reactions in the system, recently published in the literature, there was determined the temperature dependence of the Free Gibbs Energy, and based on it the values of the electrode potential were computed. In this manner was possible to prove that chemical reactions that could not spontaneously evolve, can develop in the electrochemical process by means of a corresponding voltage applied on the electrolysis cell.
Reduction of Titanium Dioxide to Metallic Titanium by Thermal Decomposition via Titanium Disulfide
