Microstructure and Tribological Properties of HVOF-Sprayed Nanostructured WC-12Co/Fe3O4 Coatings

Due to wear and improper operation, many machine parts become useless, which is why issues of friction and wear remain constantly relevant across all industrial sectors. This paper presents the results of research on the microstructure and properties of a nanostructural composite coating containing solid lubricant. The coating was deposited from a mixture of nanostructural WC-12Co powder and nanostructural Fe3O4 powder using HVOF spraying. Despite significant differences in grain size and density of both powders, the deposited coating consisted of WC-12Co matrix containing evenly distributed Fe3O4. The XRD analysis of the coating confirmed the presence of both components and the presence of W2C, which resulted from the decarburization of WC due to the high temperature during the spraying process. Furthermore, the microstructure analysis of the coatings confirmed that they contained both nanostructural WC and Fe3O4 grains that were present in the feedstock. The coefficients of friction, microhardness, and wear of the nanostructured composite coatings were determined using an experimental binomial program. Based on the ANOVA conducted, it was determined that the most significant impact on the friction coefficient is the Fe3O4 content in the sprayed mixture, while the oxygen to propane ratio affects the microhardness. For the wear of nanostructural composite coatings, the most important parameter is the spraying distance.