The improved corrosion resistance of anodic films on aluminum by nickel ions implantation

Abstract

The influence of nickel ions implantation on the corrosion resistance of porous anodic films on aluminum was studied. Nickel ions were implanted into anodic films on 1070 aluminum using a MEVVA source at an energy of 40 keV with doses of 1.0×1017 and 5.0×1017 ions/cm2, respectively. Atomic force microscope (AFM) observations showed that the implantation of nickel ions made the surface structure of the anodic films more uniform. XPS analysis revealed that nickel is present in the states of metallic nickel and NiO on the surface of the anodic film. Electrochemical tests showed that anodic films with nickel ion implantation provided relatively higher corrosion resistance both in acidic and in basic solutions. Nickel ion implantation mainly affects the property of porous layer, which is characterized by the capacitance Cp and the resistance Rp. After nickel ions implantation, Rp values increased and Cp values decreased, which shows a more difficult penetration of the aggressive electrolyte into the anodic film. The concentration of nickel and formation of NiO on the surface of anodic film, which block the pores in the film, should be the main reason for better corrosion resistance of the implanted samples.