Improving the wear resistance of HVOF sprayed WC-Co coatings by adding submicron-sized WC particles at the splats' interfaces

• The submicron-sized WC particles are bound with WC-Co powders by ball mill method.
• The even distribution of WC particles at the interfaces of WC-Co splats is achieved.
• The presence of WC particles changes the stress state at the splats' interfaces.
• The WC particles at the splats' interface inhibit the propagation of microcracks.
• The addition of WC particles enhances the microhardness and sliding wear resistance.

In this paper, the submicron-sized WC particles (~ 300 nm) with the content of 3 wt.% and 5 wt.% are incorporated into high velocity oxy-fuel (HVOF) sprayed WC-Co coatings with the aim of improving properties of the coatings. XRD analyses suggest a small amount of decarburization of the incorporated WC phase after the composite coating deposition. The SEM microstructure showed even distribution of WC particles at the interfaces of WC-Co splats, indicating significantly enhanced wear resistance of the coatings with the wear rate as much as ~ 10− 7 mm3/N·m. The content of submicron-sized WC particles plays an important role in determining the wear performances of the coatings. The increment of submicron-sized WC particles causes a decrease in wear rate from 6.09 × 10− 7 mm3/N·m to 5.15 × 10− 7 mm3/N·m. Also, the Vickers microhardness of the coatings enhances as the increasing of WC particle ratio (reaches 1365 HV with the content of the WC particles of 5 wt.%). The wear failure analysis gives further insight into the mechanism of the property enhancement. The change of stress state and crack initiation at splats' interfaces act as the predominant mechanism, which is caused by the presence of submicron-sized WC particles at splats' interfaces.