Microstructure and polarization behavior of Ni/WC plus GO (graphene oxide) composite cladding fusion coating

Ni/WC/graphene oxide (GO) composite cladding fusion coatings were fabricated through the vacuum cladding technique on a medium carbon structure steel (45# steel) substrate whose carbon content was 0.45 +/- 0.03%. The microstructural characteristics, phase composition, and electrochemical polarization characteristics of the composite cladding fusion coatings were analyzed with scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, and the electrochemical workstation CHI660E. Results show that the microstructure was compact and was micro-crack free, and without inclusions or other defects. It was comprised of four micro-zones, namely, the composite, transition, diffusion fusion, and diffusion-affected zones with thicknesses of approximately 4 mm, 1 mm, 20 mu m, and 250 mu m, respectively. The main phases of the composite coating were gamma-Ni solid solution, WC, Cr7C3, Ni2.9Cr0.7Fe0.36, Cr23C6, Ni3Fe, Ni3Si, Ni3B, W2C, and C. The self-corrosion potential of the composite coatings had increased by 0.3269 V compared with that of the substrate, and the corrosion current density of the composite coatings had decreased by nearly two orders of magnitude. The Ni-based solid solution region with relatively high C and Cr contents was difficult to dissolve.

Automated summary

Ni/WC/graphene oxide (GO) composite cladding fusion coatings were fabricated on medium carbon structure steel substrate through vacuum cladding technique, showing compact microstructure without cracks or inclusions. The main phases of the composite coatings include gamma-Ni solid solution, WC, Cr7C3, with improved corrosion resistance compared to the substrate.