Corrosion resistance and anti-soiling performance of micro-arc oxidation/graphene oxide/stearic acid superhydrophobic composite coating on magnesium alloys

Magnesium (Mg) alloys, the lightest metal construction material used in industry, play a vital role in future development. However, the poor corrosion resistance of Mg alloys in corrosion environments largely limits their potential wide applications. Therefore, a micro-arc oxidation/graphene oxide/stearic acid (MAO/GO/SA) superhydrophobic composite coating with superior corrosion resistance was fabricated on a Mg alloy AZ91D through micro-arc oxidation (MAO) technology, electrodeposition technique, and self-assembly technology. The composition and microstructure of the coating were characterized by scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy, and Raman spectroscopy. The effective protection of the MAO/GO/SA composite coating applied to a substrate was evaluated using potentiodynamic polarization, electrochemical impedance spectroscopy tests, and salt spray tests. The results showed that the MAO/GO/SA composite coating with a petal spherical structure had the best superhydrophobicity, and it attained a contact angle of 159.53° ± 2°. The MAO/GO/SA composite coating exhibited high resistance to corrosion, according to electrochemical and salt spray tests.