Electrolytic reduction of mixed solid oxides in molten salts for energy efficient production of the TiNi alloy

摘要

Direct electrochemical reduction of mixed TiO_2 and NiO powders to TiNi alloy has been successfully demonstrated in molten CaCI_2 at 900 deg C by constant voltage electrolysis. The electrolysis energy consumption was as low as 23.4 kWh/kg-TiNi, although the current efficiency was 20.5 percent in the preliminary experiments. During the process, NiO was first reduced to Ni at high speed, accompanied by TiO_2 being perovskitized to CaTiO_(3_x) which was gradually reduced to Ni_3Ti and TiNi, assisted by the depolarization of the preformed Ni. The cell voltage for preparation of the TiNi alloy was lower than that for Ti. Adjusting the cell voltage not only affected the reduction speed, but also offered a convenient access to the preparation of the nickel/perovskite composite.