High-performance WC–Co coatings <i>via</i> HVOF: Mechanical properties of steel surfaces

Abstract This study aims to investigate the microstructural and wear properties of tungsten carbide and cobalt (WC–Co) coating deposited by high-velocity oxy-fuel spraying (HVOF) by optimising powders with different content ratios. Two different powders were used as coating powders, one containing 50 wt% Sulzer Metco 5810 (WC, 12 wt% cobalt powder) and 50 wt% Amdry 960 (nickel, chromium, and aluminium) and the other containing 50 wt% Woka 3653 and 50 wt% Amdry 960. The coating layer was examined using scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS), and X-ray diffraction analysis was performed on the coated surface. The hard phases occurred after the HVOF process, and the hardness values were measured on the cross-section of the coating layer. The coated surface’s hardness was found to be increased by five times (from 200 HV to 1,250 HV). The CSM wear test machine examined the changes in the wear properties of coated surfaces according to the ASTM G133 standard. Both coatings positively affected wear, and the wear resistance of the coated surface was increased after the HVOF process. The friction coefficients of samples decreased after the coating process. SEM–EDS analyses of worn surfaces were conducted, and a 3D surface topography test was applied to worn surfaces. Abrasive and adhesive wear were seen on the surface. It was observed that the mechanical and surface properties of the two groups of powder coatings were different.