Double layer HVAF-sprayed WC-CoCr coatings for optimal properties

A double layer High-Velocity Air Fuel (HVAF) sprayed WC-CoCr coating was designed as a protective coating for the harsh wear resistant parts. Microstructure, morphology and mechanical properties of the double layer coating structure were comparatively studied with the single layer systems. The results show that the double layer coating offers better wear resistance or fracture toughness than the single layer ones. A modified cupping test was conducted to verify the fracture toughness improvement of the double layer structure and the corresponding mechanism was developed. The application verification findings show that the harsh wear resistant parts with double layer structured coatings inhibited the formation of the coating cracks at the working conditions, which prolonged their service life limit.