Electrochemical deposition of nickel graphene composite coatings: effect of deposition temperature on its surface morphology and corrosion resistance

Abstract

The present work describes the fabrication of Ni–graphene composite coatings on carbon steel at different deposition temperatures (15 °C, 30 °C, 45 °C and 60 °C, respectively) by an electrochemical codeposition method. The surface morphology, compositions, roughness and phase structures were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), atomic force microscopy (AFM) and X-ray diffractometer (XRD), respectively. The polarization test and electrochemical impedance spectroscopy (EIS) were used to study the electrochemical properties of composite coatings. The results showed that the Ni–graphene composite coatings deposited at 45 °C exhibit coarser surface morphology with increased carbon content, refined grain sizes, high micro hardness and better corrosion resistance performance. At lower temperature relatively flat Ni–graphene composite coatings were obtained and the same characteristics of the coatings were investigated at higher than the peak value of the bath temperature. Thickness increased with the increasing of deposition temperature. The linear changes in composition and surface morphology of the Ni–graphene composite coatings were observed when the deposition temperature reached up to 45 °C.