Effects of pre-treatment on the growth rate and morphology of hard anodic films on aluminium (EN AW-6082)

Abstract

For qualitative statements concerning influences of the substrate's surface on thickness and morphology of the films different surface states were prepared. Aluminium alloys (6000 series alloy) were applied as substrate for the hard anodization. The characterization (thickness, surface morphology) of the alumina films implies significant correlations between surface states of the substrate and film thickness. The results of the film thickness were confirmed with two investigation methods independently. Using Atomic Force Microscopy (AFM) the surface morphologies of both as-received and polished surface states were shown. The obtained roughness values correspond to the values by the conventional roughness measuring station. The comparison between the bare and the subsequently anodized surface morphologies implies an increasing film thickness growth rate with a decreasing roughness of the substrate. All experimental parameters for the hard anodizing process were maintained. Smooth surfaces of the substrate result in less rough anodized films. The effects of pre-treatment on the growth rate and morphology of hard anodized aluminium oxide films on AlSi1MgMn-alloy were summarized in a “hard anodization map”.