Sustainable smart coatings of chitosan and LDH loaded with natural inhibitors for corrosion protection of Mg AZ31 alloy

In this study, sustainable smart coatings based on chitosan and layered double hydroxides (LDH), loaded with natural anions, were developed to enhance the corrosion resistance of AZ31 magnesium alloy. The LDH was synthesized using the co-precipitation method, loaded with natural inhibitors (vanillate, gallate and citrate anions) by an anion exchange process and characterized by various techniques, such as scanning electron mi-croscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis. The kinetics of inhibitor release was investigated at different pH and the results show higher rates as the pH increases. The corrosion resistance offered by the sustainable smart coatings was determined by electro-chemical impedance spectroscopy and hydrogen evolution tests, while the coating morphology, before and after the corrosion tests, was analyzed by SEM and optical microscopy, respectively. All of the results demonstrated that the smart coating containing gallate ions significantly improved the corrosion resistance of AZ31 magnesium alloy