Anticorrosive properties of chitosan-derivatives coatings on Mg AZ31 alloy in Hank's Balanced Salt Solution.

This study describes the preparation of chitosan-derivatives coatings on AZ31 Mg alloy for corrosion protection in Hank's Balanced Salt Solution (HBSS). The derivatives were prepared by reacting chitosan with natural aldehydes (vanillin, benzaldehyde and cinnamaldehyde) and the coatings were characterized by means of water contact angle, scanning electron microscopy and swelling essays. The corrosion behavior of the samples was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy and hydrogen evolution essays. All derivatives present superior corrosion protection than neat chitosan and the best performance is observed for the vanillin derivative with the highest modification degree, which present hydrogen evolution rate of 0.05 mL cm-2 day-1, below the tolerance limit for biomedical application, and |Z|max in the order of 104.6 Ω cm2 even after 14 days of exposure to the corrosive solution.

New relations between modification degree, swelling and impedance in anticorrosion chitosan-derivative coatings on magnesium alloy AZ31.

Environmentally friendly coatings of chitosan-derivatives with natural aldehydes were investigated for corrosion protection of magnesium AZ31 alloy. The derivatives were characterized using FTIR and UV-Vis, and the swelling degree of their films was determined in 3.5 wt% NaCl solution. The coated samples were characterized using scanning electron microscopy, potentiodynamic polarization and electrochemical impedance spectroscopy. The results indicated that, as the modification degree increases, the corrosion current density and the swelling degree decrease, whereas the impedance modulus increases. For the first time it was proposed relations between |Z| and swelling with the modification degree.