Corrosion resistance of a self-healing micro-arc oxidation/polymethyltrimethoxysilane composite coating on magnesium alloy AZ31

摘要

A micro-arc oxidation (MAO)/polymethyltrimethoxysilane (PMTMS) hybrid coating was fabricated via MAO processing and subsequent sealing with alkaline treatment and PMTMS. The surface morphologies, chemical compositions and corrosion resistances of the coatings were investigated using FE-SEM, FTIR, XRD and electrochemical and hydrogen evolution measurements. The results indicated that the alkaline treatment was beneficial to the silane treatment and that the MAO coating was efficiently sealed by the PMTMS film. The MAO/PMTMS coating significantly enhanced the corrosion resistance of the AZ31 alloy due to its self-healing function. Additionally, we suggest and discuss a corrosion mechanism for the coating. (C) 2017 Elsevier Ltd. All rights reserved.