Production and characterization of WC-10Co-4Cr-xGr composite coating produced by thermal spraying method

One of the most widely used methods to Improving the surface resistance of industrial parts is applying composite coatings such as WC-10Co-4Cr. But this coating, despite its excellent corrosion resistance, does not have a good tribological behavior compared to other tungsten carbide base coatings. For this purpose, in this research, by adding graphite in two amounts of 7% and 14% by weight to WC-10C-4Cr powder and applying coatings by thermal spraying on the steel substrate, their tribological behavior was compared. Investigations were carried out with the help of SEM images, XRD test, roughness measurement and hardness measurement. Pin-on-disk test was also used to evaluate the wear resistance behavior of coatings and substrate. The results showed that despite the relative decrease in hardness and increase in the roughness of the tungsten carbide base coating, graphite leads to a significant improvement in the tribological behavior of the substrate and the tungsten carbide coating. Among the coatings, coating with 7% graphite It had the best wear resistance due to the combination of suitable hardness, low porosity and low friction coefficient. The wear mechanism of the coatings was also investigated with the help of SEM images and EDS analysis. It was found that the dominant mechanism of coatings containing graphite, dellamination and WC-10Co-4Cr coating was adhesive. The most important reason for increasing the tribological properties of coatings in the presence of graphite was the formation of a protective layer of these reinforcing particles in the wear path and around the pin.