Analysis of the Anticorrosive Properties of Castanea sativa Tannin and Its Application in a Primer for Aluminum 1050 Protection

The present investigation examines the corrosion inhibition properties of chestnut tannins on AA1050 aluminum alloy, evaluating their efficacy both as a direct inhibitor in near-neutral chloride solutions and as a pigment within a polyvinyl butyral wash primer. Electrochemical analyses conducted in NaCl solutions revealed that chestnut tannin functions as a mixed-type inhibitor, significantly attenuating both cathodic and anodic reaction rates. SEM-EDS and XPS analyses confirmed the formation of thin, tannin-containing passive layers and the exclusion of chloride ions on tannin-exposed surfaces. A chestnut tannin-based primer was formulated, and its anticorrosive performance on aluminum was assessed. It demonstrated efficacy comparable to a standard zinc tetraoxychromate primer in both electrochemical and humidity chamber evaluations. This study highlights the potential of chestnut tannin to provide a sustainable and effective alternative to chromate-based coatings, offering a promising solution for environmentally friendly aluminum corrosion protection.