Effect of ultrasonic impact on the microstructure and properties of 30% WC-Ni ceramic coatings by laser cladding

In this study, 30%WC-Ni coatings were prepared using the laser cladding process. Ultrasonic impact treatment (UIT) was performed on the surface of the coatings with different UIT time to systematically investigate the effects of UIT on the microstructure and properties. The results showed that surface plastic deformation became more pronounced as UIT time increased. The matrix phase exhibited grain refinement and lattice distortion, inducing work-hardening effects. After UIT, the coating surface displayed a dispersed distribution of numerous broken WC particles. Furthermore, UIT significantly reduced the size and number of pores in the coating, enhancing its density. These combined effects significantly improved the microhardness and wear resistance of the coatings. The surface microhardness and wear resistance increased with UIT time. After UIT with the time of 20 min, the microhardness of the coating surface is the highest, 759.4 HV0.3, and the wear resistance of this coating was also optimal, with a wear rate of 4.09 x 10-3 mu m3 N- 1 mu m- 1. In addition, more Cl-intrusion channels can be generated due to broken WC particles, grain refinement, and internal cracks of WC particles, which results in specimens being prone to micro electro-coupling and the formation of a corrosion mechanism for the exfoliation of WC particles after UIT. The findings can offer experimental insights and a basis for the effects of UIT process on metal-ceramic alloys.