Effects Of Graphene Content On Microstructure And Properties Of Ni-Co-graphene Composite Coatings

In this paper,Ni-Co-graphene composite coating is prepared on the copper surface,assisted by ultrasonic and mechanical stirring,by using DC electrodeposition technology.The effects of different graphene content,different cobalt content and different graphene types on the composite coating were studied.The surface morphology,composition changes,crystal structure,micro-hardness,micro-friction and wear and corrosion resistance of the composite coating were examined and analyzed.The coating performs a series of tests by the utilize transmission electron microscope(TEM),scanning electron microscope(SEM),energy spectrometer(EDS),X-ray diffractometer(XRD),micro hardness tester,micro-nano material mechanics comprehensive test system(UMT1)and the electrochemical workstation(VersaSTAT3).The results of Co-Ni-graphene composite coating show that when the slurry graphene added to the electrolyte is 1 g/L,the coating performance is the best overall.At this time,the surface structure of the composite coating is fine and crystalline,and the crystal structure is mainly densely packed hexagonal.The micro hardness of the coating is 678 HV at the highest,the friction coefficient is at least 0.15,and the corrosion resistance is also the best.The surface of the Ni-Co alloy coating and its graphene composite coating is better than that of the Co-Ni alloy coating and graphene composite coating.The crystal structure is face-centered Cubic,corrosion resistance is also stronger than the high cobalt content composite coating,but in terms of micro hardness and wear resistance,Co-Ni-graphene composite coating is better.The results of Ni-Co-graphene composite coatings show that the performance of the composite coatings is different with different graphene powders added.When the graphene content is 0.05 g/L,the coating surface is flat;when the content is 0.1 g/L,the microhardness is high and the corrosion resistance is good.The more graphene powder content in wear resistance,the lower the friction coefficient.Ni-Co-graphite composite coating crystals grow on the(111)crystal plane.When the graphite powder content is 0.4g/L,the surface morphology is the smoothest.The microhardness is the highest at 0.1 g/L,and the corrosion resistance is also the best;the friction coefficient is the lowest when the surface of the composite coating is uneven.The results of composite coatings of different graphene types show that the smallerthe size of the graphene powder used,the less the graphene content required for good overall performance.The graphene powder in the agglomerated state showed similar performance results as the graphite powder composite coating.Since slurry graphene is easier to incorporate into the composite plating layer,it has the best performance in terms of corrosion resistance and wear resistance.