Comparative study of the effects of methionine and tartaric acid in sulfuric acid anodizing

This work investigates the comparative analysis of anodic oxide films formed in sulfuric acid with and without tartaric acid or methionine. The corrosion performance was evaluated using immersion and salt spray tests complemented by electrochemical impedance spectroscopy. The results indicated that the addition of tartaric acid or methionine in a sulfuric acid bath led to a lower anodizing current density, a thinner oxide layer, and more ordered surface morphology. Additionally, glow-discharge optical emission spectroscopy (GDOES) analysis suggests the incorporation of methionine components in the anodized layer, which provides active inhibition during corrosion tests. The tartaric acid and methionine-based anodic oxides presented a higher corrosion performance than anodic oxides formed in sulfuric acid without additives.