Study On Preparation And Performance Of Electro-brush Plating Ni-graphene Composite Coatings

Due to its extraordinary mechanical,thermal,optical and electrical properties,graphene is an enhanced phase for the preparation of metal matrix composites with broad prospects for development.In this paper,the graphene was added to the rapid nickel electro-brush plating bath to obtain a graphene suspension uniformly dispersed nickel-graphene composite electro-brush plating bath,Ni-graphene composite coating was prepared on 1045 steel by electro-brush plating.The microstructure and morphology of graphene and composite coatings was analyzed by scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,Raman spectroscopy,X-ray diffraction（XRD）and atomic force microscopy（AFM）,the relationship between the amount of graphene in the plating solution and the graphene content in the composite coating was also studied,properties of friction and wear,and corrosion resistance of the composite coating were also studied.The mechanical properties,thermal conductivity,electrical conductivity and absorbing properties have also been studied.At the same time,a variety of methods are used to try to reduce the friction coefficient of the composite coating.Results show that the graphene in the composite coating exists in three forms in different parts of the coating.When the addition amount of graphene is 0.5g/L,the content of graphene in the composite coating is the highest,which is 0.163wt%,compared with nickel coating and other composite coatings,the composite coating has the highest density and the least defects such as cracks and pores.The mechanical properties,properties of friction and wear,corrosion resistance of all composite coatings are improved.The composite coating prepared by the addition of graphene at 0.5g/L is the maximum improvement.,the microhardness is increased by 15.2%,the elastic modulus is increased by 31.4%and the wear loss is reduced by 81%The self-corrosion potential increased by 9.5%,the self-corrosion current density decreased by 66.2%,and the charge transfer resistance increased by 2.1 times.The corrosion loss in the immersion test of 3.5 wt%NaCl solution in 168 h decreased 57.4%compared with that of nickel coating.It is also found that the thermal conductivity,electrical conductivity and microwave absorbing performance of the composite coating are obviously improved compared with that of nickel coating.In addition,when adding 0.4 g/L Y（NO₃）₃·6H₂O in the composite plating solution with 0.5g/L graphene,the friction coefficient of the composite coating can be reduced to the same as that of the nickel coating,and the wear loss is 67.3%less than that of nickel plating.