Effect of high temperature-assisted ultrasonic surface rolling on the friction and wear properties of a plasma sprayed Ni/WC coating on #45 steel substrate

To improve the friction and wear properties of a plasma-sprayed Ni/WC coating on a #45 steel substrate and explore the influence of spindle speed on the friction and wear properties of the coating in the process of hightemperature assisted ultrasonic rolling (HT/USR), The HT/USR processing of the Ni/WC coating was conducted under various spindle speeds (173, 248, and 360 r/min). The results showed that the pores and cracks in the Ni/ WC coating after HT/USR treatment were reduced, giving the coating a compact structure. The surface performance of the coating was the best when the spindle speed was 173 r/min. Compared with the untreated sample, the surface roughness of the coating treated by HT/USR-173 r/min was reduced by 49 %, and the surface hardness was increased by 38.4 %. The residual tensile stress was transformed from tensile stress to compressive stress, reaching 404.2 MPa. The wear mechanism of the coating after HT/USR treatment changed from abrasive and fatigue wear to abrasive and oxidation wear. The friction coefficient and wear amount decreased with decreasing spindle speed. The average friction coefficient and wear amount of the coating with a spindle speed of 173 r/min were the lowest, 0.03094 and 5.4 mg, respectively, which are 69.23 % and 64.23 % lower than those of the untreated sample. Therefore, HT/USR effectively improved the surface properties of the plasma-sprayed Ni/WC coatings, as well as their friction and wear properties.