Ni–Co duplex coatings were cladded onto Cu to improve the antiwear properties of Cu products. Prior to laser cladding, n-Al₂O₃/Ni layers were introduced as interlayers between laser cladding coatings and Cu substrates to improve the laser absorptivity of these substrates and ensure defect-free laser cladding coatings. The structure and morphology of the coatings were characterized by scanning electron microscopy and optical microscopy, and the phases of the coatings were analyzed by X-ray diffraction. Their hardness was measured using a microhardness tester. Experimental results showed that defect-free composite coatings were obtained and that the coatings were metallurgically bonded to the substrates. The surface of the Ni–Co duplex coatings comprised a Co-based solid solution, Cr₇C₃, (Fe,Ni)₂₃C₆, and other strengthening phases. The microhardness and wear resistance of the duplex coatings were significantly improved compared with the Cu substrates. The average microhardness of the cladded coatings was 845.6 HV, which was approximately 8.2 times greater than that of the Cu substrates (102.6 HV). The volume loss of the Cu substrates was approximately 7.5 times greater than that of the Ni–Co duplex coatings after 60 min of sliding wear testing. The high hardness of and lack of defects in the Ni–Co duplex coatings reduced the plastic deformation and adhesive wear of the Cu substrates, resulting in improved wear properties.

Ni-Co/ZrO₂ composite coatings were fabricated by electrochemical deposition from sulfamate solutions containing zirconia nanoparticles. The main purpose of this research was to evaluate the effect of mechanical stirring and ultrasonic agitation in plating solutions on the structure and properties of Ni-Co/ZrO₂ composite coatings. The morphology, microstructure, microhardness, anti-corrosion and wear resistance of the composites were investigated via scanning electron microscopy, X-ray diffraction, Vickers microhardness testing, electrochemical workstation utilization and friction wear testing. The hardness, friction coefficient, wear loss, corrosion rate of the composite coating prepared with mechanical stirring, and ultrasonic agitation were 533 and 680 HV; 0.40 ± 0.02 and 0.35 ± 0.02; 2.15 × 10⁻⁵; 0.85 × 10⁻⁵ g·m⁻¹; and 0.36 and 0.07 mm/year, respectively. In comparison to mechanical stirring, ultrasonic agitation could more uniformly disperse the zirconia nanoparticles to obtain Ni-Co/ZrO₂ composite coatings, which has simplicity and compactness.