Improvement of microstructures and properties of copper-aluminium oxide coating by pulse jet electrodeposition

Cu-Al2O3 nanocomposite coatings were jet electrodeposited using a direct current and pulse current to enhance the quality of the deposition and its mechanical properties. The composite coating prepared with a pulse current exhibited a smooth surface morphology, dense microstructure and good mechanical properties compared with those of the coatings obtained under direct current conditions. The effect of the pulse parameters, including the current density and pulse frequency, on the morphologies, microstructures, grain growth, and properties of the coatings was also examined. The results show that a high pulse frequency and appropriate current density improved the quality of the deposition and its mechanical properties. A dense nanocomposite copper-alumina deposited coating with an average refined grain size of 26 nm was fabricated with a pulse current density of 400 A dm−2 and a pulse frequency of 5000 Hz. The microhardness and tensile strength of the nanocomposite coating attained maximum values of 2.37 GPa and 692 MPa, respectively, when the optimum deposition conditions were used.