Is crosslinked pectin a suitable material for efficient corrosion protective coatings? A study with AZ31 Mg alloy

In this study, coatings of pectin crosslinked with Ba2+ or Ca2+ions were prepared on sheets of AZ31 magnesium alloy, and their properties were investigated by means of infrared spectroscopy, electronic microscopy, energy dispersive spectroscopy, contact angle measurements and swelling essays. The corrosion behavior of the coated samples was characterized by means of electrochemical impedance spectroscopy. The prepared coatings were dense, with a thickness of ca. 13 μm and reached initial impedances in the order of 105 Ω cm2. Additionally, it is demonstrated that coatings crosslinked with Ba2+present lower swelling and better corrosion protection in the first days of exposure to the corrosive solution. All these results indicate that pectin is a suitable polymer for the preparation of efficient, sustainable and biodegradable coatings for Mg alloys.