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

Thermally sprayed WC-Co coatings are characterized by outstanding wear resistance, excellent abrasion and corrosion protection under heavy loads. 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 coating spraying itself. Thus is a great interest the spraying of smooth near-net-shape carbide coatings. In addition, less coating would have to be removed; the required sprayed coating thicknesses can be reduced, thus saving costs and resources at the same time.

This contribution proposed an investigation on the development of WC-12%Co coatings obtained by suspension HVOF spraying technology. Significant work was dedicated to the development and characterization of appropriate water-based suspensions starting from commercially available WC and Co raw powders. The developed suspensions were sprayed using HVOF process in order to produce fine- structured carbide coatings. The coating properties, i.e. microstructure, phase composition, mechanical stability of the S-HVOF sprayed coatings were evaluated and compared to that of conventional HVOF coatings. This work shows the potential of suspension spraying to produce dense, finely structured WC-12Co coatings with smooth surfaces and improved coating properties.