STUDIES OF CHROMIUM CARBIDE ELECTRODEPOSITION IN MOLTEN FLUORIDES

The chemistry and electrochemistry related to the electrodeposition of chromium carbide from fluoride melts has been explored. Plating of chromium metal and chromium carbide was attempted where the source of chromium was varied from chromate (Cr042) to anodized chromium to chromium(II) fluoride. Chromate cannot be reduced up to the cathodic limit of the melt; however, an oxidation was observed via cyclic voltammetry. The oxidation must be coupled with chemical steps since multiple re-reduction processes occur. Neither chromium metal nor chromium carbides could be obtained when anodized chromium was the source of ionic chromium. The simultaneous reduction of Cr(II), from CrF2, and C032- at 850°-900°C leads to chromium carbide formation, although an acid-base reaction between these two substances somewhat interferes with the process. X-ray photoelectron spectroscopy (XPS) was used to probe the chemical nature and environment of quenched melt samples and of the chromium carbide coatings. © 1990, The Electrochemical Society, Inc. All rights reserved.