Study On Ni-doped Graphene And Its Reinforced Bulk Nickel Matrix Composites

Ni-doped graphene was synthesized by hydrothermal,and Ni-doped graphene reinforced nickel matrix bulk composites were prepared by powder metallurgy.Ni-doped graphene was characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）and X-ray photoelectron spectroscopy（XPS）.Ni-doped graphene reinforced bulk nickel matrix composites were analyzed by optical microscopy（OM）,scanning electron microscopy（SEM）,energy dispersive spectrometry（EDS）and X-ray diffraction（XRD）,and the density and hardness tests as well.The following conclusions can be obtained from above investigation.（1）Ni-doped graphene was successfully synthesized by chemical reduction reaction in water bath at water-bath for hydrazine hydrate as reducing agent.With the increase of NiSO₄6H₂O,the number of nickel particles between the layers of graphene sheets increased,and inhibit the agglomeration of graphene from strong to weak.Compare three kinds of reducing agents,hydrazine hydrate,ascorbic acid and sodium borohydride and two reduction methods of water bath and autoclave,the best effect of the Ni-doped graphene by hydrazine hydrate and water bath.（2）Ni-doped graphene was successfully synthesized by chemical reduction reaction in water bath at water-bath,in which nickel particles in the form of speckled and spherical shape are uniformly distributed in the interlayer of graphene nano-plates,and NiSO₄·6H₂O、NiCl₂·6H₂O、Ni（NO₃）₂·6H₂O and hydrazine hydrate as nickel particles precursors and reducing agent,respectively.The oxygen functional groups on graphene oxide were removed effectively by chemical reduction reaction,and the oxygen content of graphene oxide decreases from28.98at%to 12.35at%.（3）After mixing powder,Ni-doped graphene is uniformly distributed among the nickel powders,nickel particles loaded between layers of graphene.With the increase of the sintering temperature,the size of nickel grain becomes larger.At the sintering temperature of 750℃,the density and the hardness of the 0.5wt%Ni-doped graphene reinforced bulk Ni matrix composite are 99.88%and 178HV,respectively.（4）With the increase of the size of nickel powder,the density of Ni-doped graphene reinforced bulk nickel matrix composites increases,while hardness decreases.When the particle size of nickel powder is 50nm,the hardness is 223HV.With the increase of Ni-doped graphene,the relative density of the bulk nickel matrix composites decreases and the hardness increases.At 3wt%Ni-doped graphene,the hardness and relative density of bulk Ni matrix composite are196HV and 97.97%,respectively.