Effect of B4C addition on microstructure and tribological performance of laser cladded WC−10Co4Cr coatings

WC −10Co4Cr−5% B4C, −10% B4C, and −15% B4C coatings were fabricated on Cr12MoV steel by laser cladding (LC) to improve its wear resistance. The effect of B4C mass fraction on the phases, morphologies, and chemical elements of obtained coatings were investigated using an X-ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive spectroscopy (EDS), respectively, and the tribological performance was evaluated using a ball–on–disk tester. The results show that the average COFs and wear rates of WC−10Co4Cr−5% B4C, −10% B4C, and −15% B4C coatings are increased with the increase in B4C mass fraction, and the WC−10Co4Cr−5% B4C coating has the best wear resistance among the three kinds of coatings, which is attributed to the effects of grain refinement and solid solution strengthening. The excessive B4C particles cause a large decomposition of WC, and the coating microstructure becomes coarse when the B4C mass fraction exceeds 5%, which results in the tribological performance decreasing. Moreover, the wear mechanism of WC−10Co4Cr−5% B4C and −10% B4C coatings is abrasive wear, while that of WC−10Co4Cr−15% B4C coating is abrasive wear and adhesive wear.