2025 Szabo Phytic Acid Zinc Coating

The aim of this work was to develop composite silica/phytic acid hybrid coatings on zinc, by using TEOS as a silicon precursor and the sol–gel method. The silica/PA-coated samples were prepared at two different immersion/withdrawal speeds of the zinc wafers in the sol, and at various PA contents. SEM was used to analyze the morphological and surface characteristics of the PA/silica coatings. The corrosion resistance efficiency of the coated zinc wafers was evaluated using electrochemical impedance spectroscopy measurements and polarization tests in a 0.2 g/L Na2SO4 solution. Equivalent circuits (EC) were fitted to the impedance data and allowed the calculation of the electrochemical parameters of the coatings. The presence of PA in the silica coating has generally a beneficial effect on the anti-corrosion resistance of zinc. Potentiodynamic measurements put in evidence that both electrochemical processes (metal dissolution and oxygen reduction) are hindered in the presence of PA, suggesting that the organic compound acts as a mixed-type inhibitor. This could be due to increased crosslinking within the silica network of the organic phosphate compound, as was put in evidence by FT-IR measurements. As expected, thicker layers protect better than the thinner ones. The high protective effect noticed at 0.05 M and 0.1 M PA suggests the existence of an optimal concentration domain of PA. The wettability and the thickness of the coatings were evaluated in relation to the preparation conditions, and the optimal conditions were established.