Optimization of tartaric/sulphuric acid anodizing process using Doehlert design

The aim of this study was to investigate the influence of tartaric/sulphuric acid anodizing parameters (bath temperature, anodic current density, sulphuric acid and tartaric acid concentrations) on the anodic oxide layer properties. A Doehlert design was implemented to optimize this process. Four responses were retained, namely: growth rate, microhardness, dissolution rate and weight loss after abrasion of the anodic oxide layer. A multicriteria optimization using desirability function was performed in order to find a compromise between maximization of growth rate and microhardness and minimization of dissolution rate and weight loss after abrasion. the determined optimal anodizing conditions (Ctart = 23.1 g L− 1, 8.6 °C, 2.1 A dm− 2, Csul = 151 g L− 1), the estimated response values were 0.59 μm min− 1, 3.64 g m− 2 min− 1, 446 HV and 70 g m− 2 for growth rate, dissolution rate, microhardness and weight loss after abrasion, respectively. The morphology and the composition of the anodic oxide layer were examined by scanning electron microscopy, atomic force microscopy and glow-discharge optical emission spectroscopy.