Nanostructured wear resistant WC-Co coatings deposited by HVOF

Nanocrystalline WC-Co coatings were deposited by high velocity oxy-fuel (HVOF) using nanostructured composite powders with the aim of increasing coating performance, especially in terms of wear and corrosion resistance. HVOF processing parameters (fuel flow rate, length of the torch barrel and spraying distance) were optimized on the basis of a surface response approach, as specified by design of experiments (DOE) methodologies. Nanostructured coatings were characterized and compared with conventional WC-17%Co coatings in terms of average size of carbides after spray, index of carbide retention (from XRD results), microstructural features (porosity, interface quality), microhardness, fracture toughness, friction coefficient and wear resistance. Significant improvements of coating mechanical properties were evidenced