Microstructure and Mechanical Properties of HVOF-Sprayed NiCrBSi-WC(Co) Coatings

In this paper, the effect of changing the spray distance in the high-velocity oxy-fuel (HVOF) spray method to apply NiCrBSi-WC(Co) coatings on the resulting microstructural changes and also on the mechanical properties of the coating (including adhesion strength, hardness and wear resistance) are discussed. The SS304 stainless steel sheet was used to make substrates. In the range of 200-300 mm, where the spraying distance was changed, with increasing spray distances, more suitable and homogeneous layered microstructure, having less porosity and less melted particles, as well as a better distribution of carbide particles in the coating structure, was obtained. The NiCrBSi-WC(Co) coating applied by HVOF gun at a distance of 300 mm indicated the most suitable structure meanwhile the highest adhesion strength to the substrate, the highest hardness, and the lowest wear rate.