Enhanced corrosion resistance of LiAl-layered double hydroxide (LDH) coating modified with a Schiff base salt on aluminum alloy by one step in-situ synthesis at low temperature

Disodium vanillin L-aspartic acid modified LiAl-layered double hydroxide (LDH) coating was fabricated on A6N01-T5 Al alloy by the one step in-situ synthesis at relatively low temperature. The characteristics of the modified LiAl-LDH (VLDH) coating were characterized by X-ray diffractometer (XRD), Flourier transformation infrared spectrometer (FT-IR), Scanning electron microscopy (SEM), Energy dispersive spectrometer (EDS), Xray photoelectron spectroscopy (XPS) and Atomic force microscopy (AFM). The results showed that vanillin Laspartic acid anions were successfully intercalated into the interlayer of LiAl-LDH to form the smoother and more compact surface of the VLDH coating. The corrosion resistance of the VLDH coating was investigated by Scanning electron microscopy (SEM), Energy dispersive spectrometer (EDS), Elemental analyzer (EA), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. These results indicated that the VLDH coating possessed the excellent ion-exchange property and the better corrosion resistance than the unmodified LiAl-LDH (NLDH) coating in 3.5 wt% NaCl solution. The corrosion resistance mechanism of the VLDH coating was proposed in this paper.