Abstract
A method combining ultrasonic impact treatment with electrospark was developed to fabricate ceramic coatings on Ti–6Al–4V alloy. In this paper, the mechanism of the combined process is described in detail. The microstructure, chemical states, phase composition and surface residual stress of the ceramic coated titanium alloy were presented. The coatings mainly consist of carbides of titanium. The hardness of the coating increased significantly owing to the existence of the ceramic phase. Further, the impact process and the narrow space that the shock ball traverses decrease the surface roughness of the sample after the combined process. Finally, the surface residual stress of the sample treated by the combined process is compressive stress.
Acknowledgements
The authors are grateful for the support by the National Natural Science Foundation of China (grant nos. 51275343 and 51375331).