Microstructure and tribological behavior of plasma spray Ni60 alloy coating deposited on ZL109 aluminum alloy substrate

Abstract

This paper investigated the microstructure and tribological behavior of Ni60 alloy coating prepared on the surface of aluminum alloy (ZL109) by plasma spray. The ANSYS software was applied to compare the deformation and temperature of nickel-based alloy coating deposited on aluminum alloy piston with the thickness of 300 µm, 400 µm and 500 µm. X-ry diffraction (XRD) and Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS) were used to characterize the phase, microstructure and chemical composition of Ni60 alloy coating. Besides, fractal theory was used to study the geometric morphology of materials. The tribological properties of the coating were investigated under oil-lubrication at 100 °C through the circular cyclic test with Si3N4. The result shows that the piston skirt deformation was the smallest when the coating thickness was 300 µm. Multiple phases such as chromium carbide and Ni3Fe phases were contained in the coating, and Si element was dispersed in the Ni60 alloy powders with the form of silicon oxide, which enhanced the hardness and oxidation resistance of the coating. The porosity of the coatings prepared under three power conditions (P = 40 kW, P = 50 kW and P = 45 kW) were 1.58%, 1.47% and 0.97%, respectively. When the load increased from 80 N to 100 N, the depth and width of the wear scar increased and the wear volume added from 1.54 × 108 μm3 to 3.45 × 108 μm3. The friction coefficient of the coating increased with the increment of load. By comparison, the coating with moderate spraying power has less weight loss and better wear resistance under higher wear load.