Wear Resistance of Plasma Sprayed Ni-Based Alloy Coating on ZL109 AluminumAlloy Surface for Engine Piston

A Ni60CuMo alloy coating was prepared by plasma spraying on the surface of ZL109 aluminum alloy for engine piston. The microstructure, phase composition, microhardness and wear resistance under different conditions of the coating were studied. The results show that the coating was composed of alternately overlapping Cr-rich zone and Ni-rich zone, and the bonding mode between coating and substrate was mechanical bonding. The porosity of the coating was 2.48%. The average microhardness was 792.91 HV and was about more than 6 times that of the substrate. The friction coefficient and wear mass loss decreased with increasing test temperature from 25 ℃ to 450 ℃. Under 450 ℃ oil lubrication condition, the average friction coefficient of the coating was 0.037, and the wear mass loss was 7.35 mg, which was only about 1/4 of the substrate. With increasing test temperature, the wear mechanism of the coating changed from peeling failure to oxidation wear and adhesive wear under dry friction condition, and from abrasive wear to abrasive wear and adhesive wear under oil lubrication condition, and finally to adhesive wear.