Direct preparation of V-Al alloy by molten salt electrolysis of soluble NaVO3 on a liquid Al cathode

Abstract

Vanadium-aluminum (V-Al) alloy, the master alloy for the well-known Ti-6Al-4V alloy, is mainly produced via aluminothermic reduction process of V2O5 over the past decades. However, the reaction rate is too fast and it is difficult to control the product quality. Moreover, the utilization of aluminum is very low due to the production of Al2O3. In this work, a new method is proposed to prepare V-Al alloys by molten salt electrolysis of soluble NaVO3 on a liquid aluminum (Al) cathode in molten NaCl-KCl melt. The results show that VO3− ions can be reduced to metallic V-Al alloys on the liquid Al cathode during electrolysis process. Furthermore, thermodynamic and electrochemical analysis indicate that the reduction of VO3− ions on the liquid Al cathode results from the combined effect of electroreduction and aluminothermic reduction. In this process, the liquid Al can not only reduce VO3− ions to V, but also to combine with vanadium to form V-Al alloys. However, unlike the traditional aluminothermic reduction process, alumina produced due to the aluminothermic reduction will be in-situ electro-reduced to aluminum, which will be helpful to increase the utilization of aluminum. As a result, when the electrolysis voltage is enough large, VO3− ions will be completely reduced. Al3V alloy without alumina can be obtained.