Effect of Co and Cr Matrix on Abrasive Wear Properties of Tungsten Carbide Coatings
Three WC composite coatings with Co and CoCr matrix mass fractions of 12％, 14.5％ and 17％ on 30CrMnSiA substrates were prepared by high velocity oxygen fuel(HVOF) process. The microstructure, phase composition and especially the effects of Co and Cr binder contents on the micro hardness and wear resistance of WC coating were investigated, the surface morphology of the coating before and after abrasive wear was observed by scanning electron microscope, the abrasive wear mechanism of WC composite coating was discussed. The results show that the microstructure of HVOF WC composite coating is compact, the coating is well bonded with the substrate, there are a small amount of inclusions, the porosity of the coatings are less than 1％, and there are a small amount of oxides in the coating; during the spraying process of powder materials, there are oxidation and decarburization, and a small amount of brittle phases W2C and Co3W3C are formed, a small amount of Cr3C2 is found in the coating containing Cr; in a certain range, with the increase of binder Co and Cr content, the micro Vickers hardness and the abrasive wear resistance of HVOF WC composite coating decrease, and among the three coatings, the abrasive wear resistance of coating with 12％ binder phase content is the best,and the coating with 17％ binder phase is the worst; and the abrasive wear mechanisms of WC composite coatings with a mass fraction of 12％, 14.5％, and 17％ of Co and CoCr bonding phases sprayed by HVOF in a white alumina abrasive environment are both micro cutting and fatigue peeling of large WC hard phases.
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