Direct electrochemical reduction of solid mixed oxides to produce Ti-Ta and Ti-Ta-Nb alloys in molten salt

摘要

Ti-Ta alloys have excellent corrosion resistance in hot nitric acid and are the ideal structural materials for spent nuclear fuel reprocessing facility over the current applied low carbon austenitic stainless steel, excepting for their high cost. In this paper, a simple way to prepare Ti-Ta alloy by direct reduction of solid oxides was investigated. TiO2, Ta2O5 and/or Nb2O5 mixed oxides pellets acted as cathodes and a graphite rod was used as anode in a molten salt electrolysis cell. The effect of the applied cell voltage, electrolysis time and the porosity of oxide pellet on the cathodic product were investigated. Ti-Ta and Ti-Ta-Nb alloy were directly prepared in CaCl2 molten salt at 850 °C. Comparing to the conventional methods, this new method has prominent advantages, not only higher energy efficiency, but also less pollutants emissions. Moreover, the energy consumption for 1 kg of Ti-5%Ta alloy was around 34 kW-h.