Investigations on Reaction Pathway and Microstructure Transformations during Electrochemical Reduction of Cr2O3 in Molten CaCl2

The reaction pathway and microstructure transformations in the electrochemical reduction of chromium oxide (Cr2O3) to chromium (Cr) metal in CaCl2 molten salt were investigated. Some partially electrolyzed products and Cr metal were prepared by terminating the reduction process after different time periods, which were further characterized by means of XRD and SEM et al. Calcium chromite (CaCr2O4) was chemically in-situ synthesized in CaCl2 molten salt using Cr2O3 and CaO as raw materials, and its cyclic voltammogram test and electrolysis process were examined. The reaction pathway in the electrochemical reduction of Cr2O3 was hence demonstrated to proceed through a number of well-defined reaction steps, one of which involved the chemical formation and decomposition of CaCr2O4. Meanwhile, themicrostructures changed dramatically with the process progresses. An observation-based assumption was proposed to account for the different morphologies of cubic and nodular Cr particles formed at the early and later stages, respectively. (C) 2016 The Electrochemical Society. All rights reserved.