Mechanical properties and residual stress of HVOF sprayed nanostructured WC-17Co coatings

Nanostructured WC-17Co, 2C-12Co coatings and conventional WC-17Co coating were prepared by High Velocity Oxygen Flame (HVOF) spray technique. The elastic modulus, fracture toughness and crack spread path were studied. The residual stress, different phases, microstructure from surface to the depth of coatings were also analyzed. While the nanostructured WC-12Co coating showed the highest elastic modulus, the nanostructured WC-17Co coating has the highest fracture toughness. The compressive residual stress of the nanostructured coatings was higher than the conventional coating. Both WC and W₂C phases showed compressive residual stress, but Co₆W₆C phase showed tensile stress. The distribution of residual stress showed that the stress is the lowest at the surface and the highest close to the interface.