Enhanced corrosion resistance and biofunctionality of Zn–Al layered double hydroxide coating on micro-arc oxidized ZK60 Mg alloy via ion exchange

In this work, zinc-aluminum layered double hydroxides (Zn–Al LDHs) were prepared on the surface of micro-arc oxidized ZK60 magnesium (Mg) alloy by a hydrotreatment in a Zn(NO3)2 solution. Scanning electron microscopy, X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), laser scanning confocal microscopy and Fourier-transform infrared spectroscopy (FT-IR) were applied to analyze the coating characteristics. Ion exchange experiments were performed on the optimized LDHscoatings with 0.1 M methionine (Met) and cysteine (Cys) solution for 4 h at 60 °C. Methionine and cysteine were successfully inserted into the interlayer structure of LDHs. The LDHs-Met and LDHs-Cys coatings are distributed in a petal shape by hexagonal nanosheets, and their distributions on the surface of the MAO are dense and uniform. The porosity, surface roughness, hydrophilicity, and corrosion resistance of LDHs-Met and LDHs-Cys coatings are increased compared to MAO and MAO/LDHs coatings. The amino acids in the LDHs could play an influential corrosion inhibition role, improving the corrosion resistance of the MAO effectively. The ion exchange layer has a more substantial protective effect on the substrate and better biocompatibility than MAO and MAO/LDHs coatings. [Display omitted] •Zinc-aluminum layered double hydroxides (LDHs) were prepared on micro-arc oxidized (MAO) coatings.•Amino acids was loaded on MAO/LDHs coatings by hydrothermal treatment.•Corrosion resistance of coatings after ion exchange were increased.•Ion exchange coatings showed better biocompatibility than MAO/LDHs coatings.