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

ABSTRACT 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.