A novel functionally graded Ni-graphene coating and its corrosion resistance

Functionally graded Ni-graphene coatings with both graphene content and grain size increasing in the thickness direction are electrodeposited by altering the duty cycle in a one-pot plating bath. X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) are used to investigate the microstructure and element content. The prepared coatings are tested in synthetic seawater, CO2-structured synthetic seawater, and a simulated condition of gathering pipelines (temperature: 40 °C, partial pressure of CO2: 2 MPa, flow rate: 0.5 m/s). The corrosion resistances of the coatings are studied using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and surface observations. These results demonstrate the excellent corrosion resistance of functionally graded Ni-graphene coatings, which potentially provides a promising pathway to mitigate the corrosion problems in the oil and gas industry. [Display omitted] •A novel functionally graded Ni-graphene coating is prepared.•Both graphene content and grain size increase in the thickness direction.•The FG Ni-Gr coating provides excellent corrosion inhibition for mild steel.