Characteristic comparison of stacked WC-based coatings prepared by high-velocity oxygen-fuel spray and electric contact strengthening

Abstract

Homogeneous stacked WC-based coatings were prepared by high-velocity oxygen-fuel spray (HVOF) and electric contact strengthening (ECS). The microstructure, porosity, interfacial adhesion, phase composition and mechanical properties were investigated and evaluated. The thermal shock test was carried out to test the service performance under simulated thermal cycling working condition, and the interfacial bonding strength of the coating was indirectly compared. The results showed that the pores concentrated at the skin of ECS prepared coating, while those evenly distributed throughout the whole HVOF sprayed coating. With the layer stacked by ECS process, the existed pores in previous coating area were healed. The porosity of three-layer ECS coatings was 2.45%, which was much lower than that of HVOF coating. The interfacial bonding strength of ECS prepared coating was much better, according to morphology, scratch peaks, failure cycling times and residual interfacial phase in thermal shock test.