For promoting the preparation and application of graphene-based composite materials, graphene/nickel composite coating and pure nickel coating were prepared on the surface of carbon steel substrate by electrodeposition method. The morphology of coating was observed and analyzed by scanning electron microscope (SEM), and the phase of the coating was analyzed by X-ray diffractometer (XRD). The mechanical properties of the coating were evaluated by hardness tester. Results showed that the introduction of graphene refined the nickel based crystal grains for graphene/nickel composite coating under the same preparation conditions. Due to the higher conductivity of the graphene than the Ni, Ni ions tended to be preferably deposited on the surface of the graphene sheets during electrodeposition process, leading to formation of bumps, while pure Ni coating without graphene exhibited a smooth and flat surface and a coarse grain structure. XRD results showed that no phase transformation occurred during electrodeposition process, and the addition of graphene resulted in the smaller crystal grains and the denser surface microstructure of deposited Ni. Raman spectrum results indicated that the smaller the deposition current, the greater the intensity ratio of 2D peak to G peak of deposited graphene, and the better the dispersion effect. Moreover, the hardness of the nickel coating with graphene was significantly higher than that of the coating without graphene, and the highest hardness could reach about 530 HV4.9 N. The above results showed that the electrodeposition method could be an effective way to introduce graphene in the metal substrate as the second phase to prepare high-performance graphene/metal composite materials.
