Evaluation of Corrosion Resistance of Ni-Co/Gr Nanocomposite Coating Applied on Carbon Steel Substrate by Electro-Deposition Method under Pulse-Reverse Current

In this research, Ni-Co/Gr nanocomposite coating was applied on a low carbon steel substrate based on electrodeposition method under pulse-reverse current using watt plating solution in the presence of saccharin with 0.05 g/L graphene. For better graphene distribution, the plating solution was sonicated. The microstructure of the coating was examined by scanning electron microscopy, atomic force microscopy, and X-ray diffraction, and its corrosion resistance was assessed by polarization and Electrochemical Impedance Spectroscopy (EIS) analysis. The results showed that the coating included Ni-Co/Gr alloy with a smooth surface morphology and contained about 26 % by weight of cobalt. Graphene reinforcing particles were co-deposited on the surface. The average grain size of the Ni-Co/graphene composite coating was obtained as about 7 nm, indicating the formation of a very fine-grained structure. The hardness value of the sample increased from 220 HV (microhardness of the substrate) up to 496 HV followed by nanocomposite coating application. The results of the corrosion tests showed that the corrosion resistance of the coated sample was much higher than that of the uncoated steel. As a result of applying this coating, the corrosion rate decreased from 0.611 mm/y to 0.0029 mm/y.