Preparation of vanadium powder and vanadium-titanium alloys by the electroreduction of V 2 O 3 and TiO 2 powders

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ling Ma College of Chemistry and Life Science, Hubei University of Education, Wuhan 430205, People’s Republic of China

Xianbo Jina) College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, People’s Republic of China (Received 18 November 2015; accepted 8 January 2016)

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.

I. INTRODUCTION

Vanadium is a soft and ductile, silver-grey metal. It has good resistance to corrosion by alkalis, sulfuric, and hydrochloric acid. Vanadium has good structural strength and a low fission neutron cross section, making it useful in nuclear applications. Approximately 80% of vanadium produced is used as ferrovanadium or as a steel additive, others used in specialty stainless steel, superconducting magnets, catalyst, lithium vanadium oxide1–4 and so on. By far the greatest proportion of the world’s vanadium production is sourced from vanadium-bearing magnetite found in ultramafic gabbro bodies. From these ores vanadium can be calcined to form ferrovanadium, or can be recovered from the vanadium steel smelting process which is widely used in Russia and China.5,6 Titanium has unique good mechanical and physical properties and is widely used in turbine components, such as high tension, low density, strong corrosion resistance, and good welding capacity.5–10 The vanadium alloys especially V–Ti–Cr–Fe-series alloys have a good hydrogen Contributing Editor: Jürgen Eckert a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.18 J. Mater. Res., Vol. 31, No. 3, Feb 15, 2016

storage properties, and have a wide range of applications in fuel cells, hydrogen storage, and transportation.11 As the preparation of vanadium–titanium alloys should generally take a vacuum induction furnace or a vacuum arc furnace, the adiabatic temperature could be up to 2584–28