Fabrication and characterization of Mg-M layered double hydroxide films on anodized magnesium alloy AZ31

Highly oriented Mg-M layered double hydroxide (LDH) films were firstly fabricated by a facile in-situ growth method on anodized magnesium alloy AZ31. It is proved to be an effective method to seal the porous anodic oxide film. M presents metal cations, such as Al3+, Cr3+ and Fe3+. The characteristic structure, morphology and composition of the LDH films were investigated via field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), fourier transform infrared spectrometer (FT-IR) and energy dispersive spectrometer (EDS) respectively. Besides, the corrosion resistance of the LDH films on magnesium alloy was investigated by using potentiodynamic polarization and electrochemical impedance spectroscopy. The result demonstrates that anodic oxide film can be sealed by the formation of LDHs with nano-container structures. The corrosion resistance of anodized magnesium alloy is remarkably improved by Mg-M LDHs, especially by Mg-Al LDHs. Finally, the protection mechanism of Mg-M LDHs was proposed.