Effect of magnetic field–assisted jet electrodeposition on the microstructure and properties of Cu–Al₂O₃ composite coatings

This study addresses the issue of nanoparticle agglomeration and the resulting inhomogeneous structure and performance degradation in Cu–Al₂O₃ composite coatings prepared by jet electrodeposition. To improve particle dispersion and optimize coating properties, magnetic field–assisted jet electrodeposition was employed to systematically investigate the effects of Al₂O₃ particle concentration (10, 15, and 20 g/L) and magnetic field intensity (0 and 400 mT) on the microstructure and tribological behavior of the coatings. Surface morphology, particle distribution, and crystal structure were characterized by SEM and XRD, while microhardness and friction–wear performance were evaluated. The results show that, in the absence of a magnetic field, the coatings tend to form porous and loosely packed structures with significant particle agglomeration. Under a 400 mT magnetic field, however, coating densification is enhanced, particle dispersion is improved, and grain refinement becomes evident. With increasing Al₂O₃ concentration, both hardness and wear resistance first increase and then decrease. Optimal overall performance is achieved at a concentration of 15 g/L, where the maximum microhardness reaches 190.1 HV, the lowest coefficient of friction is 0.27, and the minimum mass loss is 3.3 mg. This study demonstrates that, through magnetic field assistance and appropriate particle concentration control, nano-Al₂O₃ agglomeration can be effectively suppressed. The combined effects of MHD-enhanced mass transfer, grain refinement, and dispersion strengthening significantly improve the wear resistance of Cu–Al₂O₃ composite coatings