The growth behavior and properties of orientated LDH film composited with reduced graphene oxide

Oriented reduced graphene oxide-MgAl layered double hydroxides (rGO-LDH) films were prepared on Mg alloy with pre-sprayed rGO-Al coating by in-situ growth method. Characteristics of orientated LDH films were detected through field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FT-IR) and Raman spectroscopy. The orientation mechanism was dicussed. Corrosion behavior of the coatings was investigated using potentiodynamic polarization curves, electrochemical impedance spectroscopy and full immersion test. Ball on disc test was carried out for measuring the anti-wear performance. Results indicate that the nanosheets in LDH film tend to parallel to the substrate under low pH value, and nanosheets in LDH film tend to perpendicular to the substrate under high pH value. Parallel oriented LDH films exhibit excellent shielding and lubrication ability. And the rGO has a strong anchoring effect on perpendicular oriented LDH film, which results in higher anti-corrosion and anti-wear performance (load capacity) for the film. The orientation mechanism of films and the relationship between orientation and performance were discussed.