Electroreduction of solid V2O3 pellets (∼0.7 g) to V in molten CaCl2 at 900 °C has been studied by cyclic voltammetry and potentiostatic electrolysis, together with scanning electron microscopy, energy dispersive x-ray, and elemental analyses. The intermediate products of the potentiostatic electrolysis are various, forming some lower valence state compounds (VO, V16O3, V7O3, VO0.2) and higher valence state which are likely VO2, CaVO3, or CaV2O5. At potentials more negative than −0.6 V versus Ag/AgCl, fine vanadium powder (aggregates of nodular ∼500 nm particles) can be prepared by electrolysis of porous solid of the V2O3 pellets. The current efficiency and energy consumption were satisfactory, about 53.4% and 2.5 kW h/(kg V) at −0.6 V versus Ag/AgCl, respectively. Moreover, V-20Ti alloys were electrochemically synthesized by constant voltage electrolysis at the indicated potentials, the control of composition as well as the reduction optimization of the mixtures were demonstrated. This electrochemical route is efficient and offers a product with controlled stoichiometry, with particular advantage of manufacturing of low cost alloys and intermetallics directly from mixed oxide precursors, and has potential to produce functional vanadium alloys.
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We acknowledge the financial support from the National Natural Science Foundation of China (Grant Nos. 21303045 and 21173161), Natural Science Foundation of Hubei Province (2014CFA527), 2014 Young Talents Development Plan of Hubei Province, Wuhan Chenguang Project (2015070404010212). We thank the Center for Electron Microscopy at Wuhan University for helps in taking the TEM and high-resolution TEM images for the materials.
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Wu, T., Ma, X. & Jin, X. Preparation of vanadium powder and vanadium-titanium alloys by the electroreduction of V2O3 and TiO2 powders. Journal of Materials Research 31, 405–417 (2016). https://doi.org/10.1557/jmr.2016.18