Abstract

A Mg-Al-layered double hydroxide (LDH) coating modified with methyltrimethoxysilane (MTMS) and cerium nitrate was prepared on AZ31 magnesium alloy substrate via a hydrothermal process and subsequent the immersion treatment. The surface morphologies and chemical compositions were investigated using FE-SEM, XRD, FT-IR and XPS. These results indicated that the composite coatings were consisted of polymethyltrimethoxysilane (PMTMS) and CeO2. The adherence between the PMTMS/CeO2 coating and the LDH coating was significantly improved with the formation of Si-O-Si and Si-O-Mg chemical bonds. Electrochemical tests and hydrogen evolution illustrated that the optimum corrosion resistance of the composite coating was obtained in presence of 10−3 mol/L cerium nitrate. In addition, experimental data proved that addition of an excess of cerium nitrate was bad for coating formation. Finally, the coating corrosion mechanism was proposed and discussed.

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