Abstract: High temperature ultrasonic deep rolling (HT+UDR) was applied to plasma sprayed Ni/WC coating to improve its wear resistance. The wear resistance of the Ni/WC coating after HT+UDR was examined and analyzed by using scanning electron microscope with energy spectrometer, X-ray diffractometer, dimensional hardness tester and friction wear tester. The results show that the lamellar structure of the Ni/WC coating after HT+UDR is eliminated, the internal porosity and cracks are reduced and the coating is more compact. After HT+UDR, some new hard phases such as Cr₇C₃, Cr₂B₃ and CrB are generated on the surface layer of the coating, the half-height width of the X-ray diffraction peak is broadened, grain refinement occurs on the surface layer of the coating, and the hardness of the coating surface is increased by 185.9 HV0.2. The wear mechanism of the Ni/WC coating is mainly abrasive wear with fatigue wear, with less spalling and cracking on the worn surface. HT+UDR can effectively improve the wear resistance of the Ni/WC coating, the wear loss is 7.1 mg, which is 51.3% lower compared to that of the unrolled coating.

Key words: high temperature ultrasonic deep rolling (HT+UDR), Ni/WC coating, wear resistance, wear mechanism