Vanadium-based alloys are usually produced by alumino-thermic reduction of V2O5. In order to use it in hydrogen storage alloys, contained impurities such as aluminum and oxygen have to be removed by electron beam purification, increasing the alloy cost by one-order. In this work, we have developed an electro-slag remelting purification method for removing the impurities with low cost. In this electro-slag remelting process, a crude vanadium consumable electrode made by alumino-thermic reduction and flux of CaF2-CaO-Al2O3 are used. By applying high current, the vanadium electrode is partially melted, the contained impurity such as aluminum oxide is removed to the flux and a purified molten metal is dropped to bottom.
Removal ratio of the aluminum oxide is in proportional to the CaO content in the flux. Then, remained oxygen in the metal is removed by remelting with rare-earth metal as a reducing agent. The alloy prepared by this process shows the same hydrogen storage capacity as that prepared using high purity metal. The electro-slag remelting purification method is suitable for mass production with reasonable cost.
