Investigation of chromium and vanadium carbide composite coatings on CK45 steel by Thermal Reactive Diffusion

In the present study the possibility of formation of chromium and vanadium carbide composite coatings on CK45 steel by Thermal Reactive Diffusion method was studied. Two different baths (metal and oxide) and different substrates (CK45 steel and pure iron) were used. Composite carbide coatings including a base phase of chromium carbide (Cr23C6, Cr7C3), and reinforce of vanadium carbide (V8C7) were formed on CK45 steel. Also the complex carbide phase of Cr2VC2 has been formed in the carbide coating layer based on XRD results. The ratio of reinforce to the base phase was 0.37 and 0.47, respectively for metal bath and oxide bath. Phase distribution of vanadium carbide in the chromium carbide base phase in metal bath was more homogeneous than in oxide bath. The thickness of the composite carbide coating was 6 μm greater in metal bath than in oxide bath. In addition to carbon, iron diffusion has also occurred from the substrate into the coating. Results indicate that composite chromium and vanadium carbide coatings were successfully formed on CK45 sample in the borax baths consisting of either chromium/vanadium metal powders, or chromium/vanadium oxide powders.