Electroplating preparation of Ni–Al2O3 graded composite coatings using a rotating cathode

In order to develop a new technique for fabricating Ni–Al2O3 graded coatings, a polyhedron cathode was used, which is composed of eight pieces of copper foil fixed on the side faces of a regular octagonal nylon prism. The stirring rate was 350 rpm. For pure nickel deposition, the coating thickness difference between different side faces is increased when the electrolyte is stirred. The particle concentration has no evident effect on the coating thickness, but affects the particle content in different coatings. The largest difference of particle contents appears while the Al2O3 particle concentration of the electrolyte is 80 g/L. Based on these results, the graded composite coating was fabricated through rotating the cathode.