Wear and corrosion properties of Cu-AlN composite coatings deposited by cold spray

Copper and copper alloy are commonly used to fabricate ship propellers and sealing valves that encounter harsh corrosion and wear. To improve their service life, Cu coating and Cu-AlN composite coatings with different volume content of AlN (10%, 20%, 30%) were prepared by cold spraying. The investigation focused on analyzing the coatings` microstructure, microhardness, resistance to wear, and corrosion. Results show that the composite coatings with AlN have fewer pores and denser microstructure than the Cu coating. The coating demonstrates a relatively low deposition efficiency, resulting in the attainment of only 3.8 vol.% of AlN when the feedstock AlN powder content was 30 vol.%. The microhardness of Cu-3.8AlN coating is 159.7 HV, about 53.1% higher than that of Cu coating. The specific wear rate of Cu-3.8AlN coating is reduced by about 73.5% compared to that of Cu coating, measuring at 1.69×10-3 mm3/(N·m). Compared with other coatings, Cu-3.8AlN has the highest corrosion resistance (Ecorr=−0.199 V, Icorr=1.2 μA/cm2, Rct=3200 Ω·cm2). The Cu-3.8AlN coating exhibits superior wear and corrosion resistance among the four coatings, attributed to its highest level of densification and the presence of AlN particles.