Potential of Suspension Spraying for Development of Dense WC-12Co Coatings

Outstanding wear resistance, excellent abrasion, and corrosion protection under heavy loads characterize thermally sprayed WC-Co coatings. However, the good wear resistance of these coatings requires high post-processing costs (grinding, polishing) which are estimated to be up to 3-4 times higher than the spray coating process itself. Thus, a great interest of spraying smooth near-net-shape carbide coatings exists. In addition, less of the coating must be removed and the required sprayed coating thicknesses can be reduced, offering saving of costs and resources at the same time. This contribution is an investigation on the development of WC-12Co coatings obtained by suspension HVOF spraying technology. Significant work was devoted to the development and characterization of appropriate water-based hardmetal suspensions starting from commercially available WC and Co raw powders feedstock. The developed suspensions were sprayed using HVOF process to produce fine-structured carbide coatings. The S-HVOF coatings properties, i.e., microstructure, phase composition, and microhardness were evaluated and discussed.