Process strengthening for electrochemical reduction of solid TiO2 to Ti in situ

Abstract

In this paper, a new electrolysis device was presented with corundum crucible as an electrolytic cell in place of a graphite crucible, and in the corundum crucible a sleeve with a cathode pellet with a fluted base placed flat in it was adopted to separate the cathode and anode. The process of electrochemical reduction of solid TiO2 to Ti in situ was studied and characterized by the time–current curves and X-ray diffraction (XRD) patterns of the electrochemical reduction products. The influence of CaCl2 doping in the cathode and the electrolysis device structures on electrochemical reduction mechanisms and the process strengthening was systematically studied. The results show that the oxygen content in the obtained Ti is reduced to 0.51% with a cathode pellet sintering temperature of 1000 °C, sample preparation pressure of 20 MPa and CaCl2 doping amount of 30%. Tiny holes are formed in the cathode pellet by CaCl2 doping in the electrochemical reduction process, which could increase the contact area between the electrolyte and cathode and improve the electrode reaction efficiency. The new electrolysis device could reduce the carbon content in the molten salt, cathode polarization and the electrode reaction overvoltage, inhibit the chances of secondary reactions, increase the contact area between the produced Ca and cathode and strengthen the thermal reduction of TiO2 by Ca.