Corrosion resistance of a ceria/polymethyltrimethoxysilane modified Mg-Al-layered double hydroxide on AZ31 magnesium alloy

• Published in: Journal of alloys and compounds Vol. 764; pp. 913 - 928
• Main Authors: Yao, Qing-Song, Zhang, Fen, Song, Liang, Zeng, Rong-Chang, Cui, Lan-Yue, Li, Shuo-Qi, Wang, Zhen-Lin, Han, En-Hou
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 05.10.2018; Elsevier BV
• Subjects: Cerium nitrate; Cerium oxides; Chemical bonds; Chemical composition; Corrosion mechanisms; Corrosion resistance; EIS; Hydrogen evolution; Hydroxides; Iridium; Magnesium; Magnesium alloy; Magnesium base alloys; Morphology; Organic chemistry; Pitting corrosion; Polymer coating; Polymers; Protective coatings; SEM; Silicon; Submerging; Substrates; X ray photoelectron spectroscopy; XPS; Pitting corrosion; SEM; XPS; Polymer coating; EIS; Magnesium alloy
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2018.06.152

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. •The addition of Ce(NO3)3 improved the corrosion resistance of the coating.•The system modified with 10–3 mol·L−1 Ce(NO3)3 had the best corrosion resistance.•The composite coating had rose effect and self-healing performance.