Abstract

With the purpose of improving the protection of steel ASTM A36 from corrosion, in this paper the use of tannin as an inhibitor was studied by incorporating it in an epoxy resin along with zinc oxide nanoparticles functionalized with 3-aminopropyltriethoxysilane (APTES) in concentrations of 1, 3, and 5%w/w. Electrochemical techniques such as polarization curves and EIS for the characterization of the anticorrosive properties, SKP for the study of coating delamination with the substrate, contact angle measurement and other standardized methods were used for the evaluation of the properties of the film. The results of the polarization curves revealed that the corrosion current density of the steel (i(corr)) decreases markedly with the addition of the tannin extract by changing the cathodic behavior without affecting the active anodic behavior. Likewise, the EIS analysis showed that the coatings with surface modified nanoparticles provide an excellent protection against corrosion that is complemented by the protective layer of the tannin-iron complex formed and the same was confirmed by FTIR spectroscopy after exposing the plates to accelerated corrosion tests in salt spray and weathering chamber. Finally, it could be demonstrated that the incorporation of zinc oxide nanoparticles in the coating formulation subtly improves the film properties and likewise, partially increases the hydrophobicity.