Effect of deposition current density on the Co–Ni/SiO2 alloy composite coatings Using Scanning Jet Electrodeposition

Co–Ni/SiO2 alloy composite coatings were electrodeposited on copper substrate by scanning jet electrodeposition at various current densities to study its effect on the deposite morphologies, texture orientation, microhardness, adhesion force, wear resistance and corrosion resistance of Co–Ni/SiO2 alloy composite coatings. The structure and performance of the material were characterized using scanning electron microscope, XRD diffractometer, nanoindentation, scratch tester, friction and wear tester and electrochemical methods. The morphologies of the Co–Ni/SiO2 alloy composite coatings changed from sparse and slender structures to dense starfish structures with an increase in current density. A part of Co precipitated in the form of a face-centered cubic structure and formed a solid solution with Ni, while another part of Co precipitated in the structure of the composite coating in the form of a hexagonal close-packed structure. The Co–Ni/SiO2 alloy composite coating exhibited excellent adhesion force, wear resistance and corrosion resistance when the deposition current density was 130 A/dm2. Once the current density was exceeded, some microcracks appeared on the surface of the composite coating, after which the adhesion force and corrosion resistance decreased. The present study suggests that current density at 130 A/dm2 is more suitable than low current density for jet electrodeposition to prepare high-density and high-quality composite coating.