Evaluation of surface pretreatment stages of Al 1050 to obtain nanostructured anodic films

The growth and ordering of the anodic aluminum oxide layer depend strongly on the initial roughness of the substrate and consequently on the different pretreatment stages. The objective of this study was to select the best combination of surface pretreatment stages of Al 1050 to synthesize self-ordered anodic films. The average roughness of the substrate after the pretreatment was used as a selection parameter. Also, the effect of the selected pretreatments on the porous structure obtained by anodic oxidation was evaluated by means of scanning electron microscopy images and Fast Fourier Transforms analysis. The results showed that the consecutive pretreatments Grinding + Polishing + Electropolishing + Acid etching at appropriate conditions presented a degree of synergism that significantly reduced the surface roughness of the Al 1050 substrate to 0.062 mu m, allowing the development of a nanoporous film of self-ordered aluminum oxide.