Preparation of Metal-Gr Composite Coatings Via Electro-Plating for High Corrosion Resistances

1) Preparation of Fe-Gr composite coating via DC electro-plating for high performances. In this work, the iron-graphene (Fe-Gr) composite layer was prepared by using an electro-plating method. The performance of the composite was varied with the concentrations of GO in the electrolyte. The layer’s microstructures were systematically characterized by SEM, TEM, Raman, FT-IR, and the micro-hardness and its corrosion resistance were evaluated for getting desired properties. The experimental results revealed that: 1) the Gr could be scattered homogeneously in the Fe layer when dispersible graphene oxide (GO) was added in the electrolyte; 2) comparing with pure Fe layer, the micro-hardness and corrosion resistance of the Fe-Gr composite layer were greatly enhanced; 3) it was found that there was an optimal GO addictive amount (0.4 g/L) in the electrolyte, which increased the properties involving the micro-hardness up to HV 248, 2.07 times higher than that of pure iron layer(HV 120); 3.75 times of anti-corrosion rate(0.1353 mmy-1) and 5.38 times of the charge transfer resistance(1456 /(Ω·cm2) higher than that of pure iron layer(0.5076 mmy-1, 270.5 /(Ω·cm2). 2) Preparation of Zn-Gr composite coating via pulse reverse electro-plating for high corrosion resistances. In this work, a kind of the Zn-Gr composite layer is successfully prepared on iron substrate via pulse reverse electro-plating method from a chloride aqueous solution. The experimental results revealed that: 1) By adding GO in the electrolyte, Gr sheets can be incorporated homogenously in the Zn plating layer during electro-plating, and the reduction from GO into Gr occurs due to the Zn and GO co-deposition. 2) Due to increasing of the nucleation sites, Gr incorporation changes the growth mechanism of Zn crystal, i.e., makes the main preferred orientations from (112) and (101) crystal planes in the pure Zn layer into (103), (102) and (110) planes in the Zn-Gr composite layers. 3) As a corrosion protection barrier layer, Gr sheets play an important role on the corrosion resistance of the Zn-Gr composite plating layers in simulated seawater environment. The highest corrosion resistant properties occur in an optimal range 0.3 – 0.5g/L GO adding amount in the electrolyte, at which the corrosion current density just be a hundredth comparing with that of pure Zn layer. 4) The present method for preparing Zn-Gr composite, with advantages of simple, controllable, scalable, etc., is likely to be industrialized.