Preparation and properties of Al-Ni composite anodic films on aluminum surface

Ni element was introduced to aluminum surface by a simple chemical immersion method, and Al-Ni composite anodic films were obtained by following anodizing. The morphology, structure and composition of the Al-Ni anodic films were examined by scanning electron microscopy (SEM), energy disperse spectroscopy (EDS) and atomic force microscopy(AFM). The electrochemical behaviors of the films were studied by means of polarization measurement and electrochemical impedance spectroscopy (EIS). The experimental results show that the Al-Ni composite anodic film is more compact with smaller pore diameters than that of the Al anodic film. The introduction of nickel increases the impedances of both the barrier layer and the porous layer of the anodic films. In NaCl solutions, the Al-Ni composite anodic films show higher impedance values and better corrosion resistance.