Optimization of mechanical and chemical properties of sulphuric anodized aluminium using statistical experimental methods

Abstract

We described a three-step strategy to achieve simultaneous optimization of mechanical and chemical properties of an anodic aluminium oxide layer elaborated in a sulphuric acid solution. In the first two steps, a Doehlert design was carried out and then the canonical analysis has been conducted to study the four fitted models of the responses, namely: dissolution rate, Vickers microhardness, weight loss after abrasion and deflection at failure of the anodic oxide layer. Canonical analysis showed that the experimental conditions where the optima are found for each individual response are just opposite, so it is required to look for a certain compromise, which was achieved using the desirability function, in the last step. The morphology and the composition of “optimum” layer was examined by scanning electron microscopy (SEM), atomic force microscopy (AFM) and glow-discharge optical emission spectroscopy (GDOES).