Wear and Corrosion Behavior of Plasma-Sprayed Nickel-Based Coatings on the Surface of Aluminum Alloy

Ni 60+35% WC alloy coating was prepared on the surface of 7075 aluminum alloy substrate by plasma spraying technology. The morphology and mechanical properties of the coating were characterized by optical microscopy and digital microhardness tester. The friction test was carried out on the substrate and coating samples by UMT-5 friction tester. By flushing nitrogen into an autoclave to simulate different hydrostatic pressure conditions, the corrosion resistance of the coatings in 3.5% NaCl solutions with different hydrostatic pressures conditions was tested in combination with electrochemical technology. The results showed that Ni 60+35% WC coating had a dense structure with few pores and cracks, and the combination of coating and aluminum alloy belonged to mechanical bonding. The hardness of coating was much higher than that of aluminum alloy substrate. The wear rate of coating was much lower than that of aluminum alloy substrate. With the increase of hydrostatic pressure, the corrosion resistance of both coating and substrate in 3.5% NaCl solution decreased.