Corrosion resistance of ceria/polymethyltrimethoxysilane modified magnesium hydroxide coating on AZ31 magnesium alloy

A magnesium hydroxide/polymethyltrimethoxysilane (PMTMS)/CeO2 hybrid coating was fabricated via hydrothermal treatment method and subsequent sealing with PMTMS and CeO2. The surface morphologies, wettability, microstructures and chemical compositions of the samples were investigated using FE-SEM, FT-IR, XRD, XPS and contact angle (CA). The corrosion resistance of the composite coatings was evaluated using the electrochemical and hydrogen evolution measurements. The results demonstrated that the magnesium hydroxide coating was sealed by the PMTMS and CeO2. The Mg(OH)2/PMTMS/CeO2 coating had a thickness of approximately 12.86 ± 0.01 μm and significantly enhanced the corrosion resistance of the AZ31 alloy. The influence of the existence of the ceria on the corrosion resistance was investigated. Additionally, a corrosion mechanism of the coating was proposed and discussed.