Electrochemical characteristics of surface of titanium formed by electrolytic polishing and anodizing

A clear surface was polished using electrolytic polishing (EP). The mean roughness (Rz) of the polished surface was 1.966 nm, as measured by atomic force microscopy (AFM) over a 2 × 2 um2 scan area. The various directions of the grains could be observed clearly following EP. The multiple beam interference effect generated various colors of the grains after anodic treatment at constant anodic voltage. A template with ordered nanochannel-array of anodic titanium oxide (ATO) was formed at 20 V. The template formed by self-assembly. The long-range ordered nanochannel had a thickness of 170 nm film, a pore size of 100 nm, an inter-pore distance of 120 nm, pore walls with a thickness of 25 nm, a pore density of 8× 109 pores/cm2, and a porosity of 68.2%, after anodizing for 90 s. When the applied voltage exceeded the breakdown voltage (90 V) of titania, the corrosion rate increased and the color of the titanium became as measured electrochemically by Tafel polarization and AC impedance methods, and observed by optical microscopy.