Microstructure, morphology and electrochemical properties of ZnFe-Graphene composite coatings

Zinc-Iron (Zn-Fe) and Zn-Fe-Graphene (Zn-Fe-G) coatings were electrodeposited on mild steel from acidic sulphate electroplating bath. Electrochemically exfoliated graphene was dispersed in Zn-Fe plating bath to produce Zn-Fe-Graphene composite coatings containing different amount of graphene. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques were used to characterize the coatings. Addition of graphene refined the grain size and altered the morphology of the Zn-Fe-G coatings. Influence of change in morphology and microstructure on the electrochemical corrosion behavior of the coatings was studied by Tafel polarization and electrochemical impedance spectroscopic (EIS) methods. Incorporation of graphene into the Zn-Fe matrix enhanced the corrosion resistance of the coatings up to a certain concertation of graphene. Further addition of graphene, enhanced the corrosion rate indicating an ``optimum'' with respect to the addition of graphene into the composite coatings for enhancement in the corrosion resistance performance. (C) 2018 Elsevier B.V. All rights reserved