Electrodeposition, microstructure, friction and electrochemical behavior of diamond-like carbon (DLC) films with Ni/Cu interlayer

Diamond-like carbon (DLC) films containing single copper (Cu), nickel (Ni) and double Ni/Cu interlayers were fabricated on LY-12 aluminum alloy by electrodeposition. The influences of different interlayers on the microstructure, microhardness, friction and wear properties and electrochemical behavior of the films were investigated respectively. The morphologies results show that the porosity of DLC films was reduced and the particles were refined after the introduction of double interlayer. Raman and XPS results confirm that the amorphous characteristics of DLC films containing nickel and copper interlayers were enhanced, and the content of sp3-C in the films was increased. In addition, the optimal micro-hardness of 210.67 HV was achieved due to the high sp3-C content of double Ni/Cu-DLC film. Meanwhile, the Ni/Cu-DLC film possessed excellent wear resistance which benefits from the synergistic effect of copper and nickel interlayer. The nickel as the supporting layer and copper as the lubricating layer alleviated the wear and friction of the film. Simultaneously, the deposition of double interlayer increased the density of the film, which further prevented the invasion of corrosion ions，so the film had superior electrochemical properties.