Wear and Corrosion Resistance of Chromium-Vanadium Carbide Coatings Produced via Thermo-Reactive Deposition

Chromium carbide, vanadium carbide, and chromium-vanadium mixture coatings were deposited on AISI D2 steel via the thermo-reactive deposition/diffusion (TRD) technique. The carbides were obtained from a salt bath composed of molten borax, ferro-chrome, ferro-vanadium, and aluminum at 1020 degrees C for 4 h. Analysis of the morphology and microstructure of the coatings was done via scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The hardness of the coatings was evaluated using nano-indentation, and the friction coefficient was determined via pin-on-disk (POD) testing. The electrochemical behavior was studied through potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS). The XRD results show evidence of the presence of V8C7 in the vanadium carbide coating and Cr23C6 and Cr7C3 in the chromium carbide coating. The hardness value for the vanadium-chromium carbide coating was 23 GPa, which was higher than the 6.70 +/- 0.28 GPa for the uncoated steel. The wear and corrosion resistance obtained was higher for the niobium-chromium carbide coating, due to the nature of the ceramic carbide produced.