In Situ Composite Reduced Graphene Oxide/Layered Double Hydroxide Growth on AZ31 Magnesium Alloy: Anticorrosion Performance and Protection Efficiency

Magnesium alloys are among the most promising engineering materials due to their excellent mechanical properties. However, because of the high surface activity, the magnesium alloys can be degraded easily in the corrosive medium which restricts their further application. Layered double hydroxide (LDH) coating is one of the promising methods to enhance the corrosion resistivity of these alloys. Also, integrating graphene derivatives i.e., rGO, as corrosion inhibitors into LDH coating can improve the performances synergistically. In this research, rGO/LDH coatings were applied to the magnesium by one-step hydrothermal method. The characterization results showed that GO reduces into rGO during hydrothermal processes, and LDH nanosheets grow on both sides of the rGO surface as well as the surface of the substrate. The structural composition and morphology of rGO/LDH coatings were confirmed by x-ray diffraction, Fourier-transformed infrared spectroscopy (FT-IR), and scanning electron microscopy (SEM). The potentiodynamic polarization curves reveal that the rGO/LDH coatings show superior corrosion resistance with lower current density (6 x 10(-9) A/cm(2)) due to the unique anion-exchange ability of labyrinth-structured LDH coating and the barrier effect of rGO. The optimum rGO/LDH coating exhibits an impedance value of (10(6 )Omega cm(2)) at 0.01 Hz, demonstrating superior anticorrosion properties. As immersion time increases, the decrease in the |z|0.01 Hz value for the optimum rGO/LDH coating sample becomes slower, which has been attributed to a reduced rate of degradation and delamination.