Investigation On Ag-doped Graphene Reinforced Silver Matrix Composites

Ag-doped graphene was synthesized by chemical reduction method,the Ag-doped graphene and nano-sized silver powder were mixed by ultrasonic treatment and three dimensional blending,and Ag-doped graphene reinforced silver matrix bulk composites were prepared by spark plasma sintering(SPS).The Ag-doped graphene powder was characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),Raman spectroscopy(Raman)and X-ray photo electron spectroscopy(XPS),and the microstructures of Ag-doped graphene reinforced silver matrix bulk composites were characterized by optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffraction(XRD),and the density,hardness and electrical conductivity were tested as well.The following conclusions can be drawn from above investigations.(1)When the mass ratio of graphene oxide(GO)and silver nitrate is 1:2,the desired Ag-doped graphene compound powder can be obtained using ascorbic acid as reducing agent.The silver particles are uniformly distributed and the reduced graphene oxide exhibits a typical thin and transparent structure.The uniformly distributed silver particles are introduced into the graphene lamellar layer.(2)GO and Ag+can be effectively reduced by ascorbic acid and removed most of the oxygen-containing functional groups from the silver-doped graphene at 90? in water bath for 3h.Most oxygen-containing functional groups from graphene oxide are removed,oxygen content decreases from 31.42 at%to 15.55 at%,Ag+particles,with the size of 40-100 nm are uniformly introduced in the transparent graphene sheets.(3)The relative density,electrical conductivity,hardness of the silver matrix bulk composite decreases with increase of Ag-doped graphene.At 0.5wt%Ag-doped graphene,the hardness and electrical conductivity of the silver matrix bulk composite are 78.5 HV and 98.79%,respectively.Compared with pure Ag,the hardness and electrical conductivity are increased by 39.43%and 2.32%,respectively.(4)With increase of sintering temperature,the relative density,electrical conductivity,hardness of the silver matrix composites increases and then decreases.At the range of the experiments,Ag-doped graphene reinforced silver matrix bulk composites sintered at 450? has uniform distribution of Ag-doped graphene and the best comprehensive properties.The hardness and electrical conductivity were 78.5HV and 98.79%IACS,respectively.(5)The hardness and electrical conductivity of silver matrix composites decrease with increase of silver particle size.When Ag particle size is 100 nm,the relative density,hardness and electrical conductivity are 98.74%,81.2 HV and 98.62%IACS,respectively.