RGO modified ZnAl-LDH as epoxy nanostructure filler: A novel synthetic approach to anticorrosive waterborne coating

The reduced graphene oxide‑zinc‑aluminum layered double hydroxides (rGO-ZnAl-LDH) micro-nano fillers were prepared via a one-step process, then modified by 3-aminopropyl triethoxysilane and incorporated into a waterborne epoxy (EP) matrix to produce M-rGO-ZnAl-LDH/EP composite coating. The effects of the M-rGO-ZnAl-LDH hybrid on the corrosion resistance of the coating were studied by adjusting the ratio of GO: ZnAl-LDH and also the adding amount of M-rGO-ZnAl-LDH hybrid. The anticorrosive nature of the M-rGO-ZnAl-LDH/EP composite coating had been investigated by potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS) and salt spray test. The results indicated that the corrosion resistance of the coating was improved remarkably when the ratio of GO: ZnAl-LDH was 2:1 and the adding amount was 0.5 wt% into EP. The corrosion current density (icorr) was only 0.0733 μA/cm2 and the coating resistance (Rc) was up to 2.77E4 Ω cm2 for M-rGO-ZnAl-LDH/EP (2:1–0.5 wt%), while the icorr for pure EP was 0.469 μA/cm2 and the Rc for pure EP was 2.10E3 Ω cm2, which suggested that the M-rGO-ZnAl-LDH micro-nano fillers had a higher anticorrosion properties relative to the waterborne epoxy resins.