Investigation On Modification Of Graphene And Graphene Reinforced Silver Matrix Composites

Ag-doped graphene and N-doped graphene compound powders were synthesized by chemical reduction method and hydrothermal method, respectively. The microstructures of Ag-doped graphene and N-doped graphene were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy (Raman) and X-ray photo electron spectroscopy (XPS).The Ag-doped graphene reinforced silver matrix blocky composites and N-doped graphene reinforced silver matrix blocky composites were fabricated by powder metallurgy. Microstructures were characterized by optical microscopy (OM),scanning electron microscopy (SEM),energy dispersive spectrometer (EDS), transmission electron microscopy (TEM), and the density, hardness and electrical conductivity were tested as well. The following conclusions can be drawn from above investigations.(1) Silver ions and graphene oxide (GO) can be reduced effectively by hydrazine hydrate at 90 ? for 2h and most of oxygen functional groups on the Ag-doped graphene can be removed. Ag doping effectively inhibits the ordered stacking of graphene, and reconstructs the conjugated structure of graphene.(2) At the hydrothermal temperature of 160? for 6h, graphene oxide (GO) are reduced effectively, and 4.74at% nitrogen is synchronously doped into the graphene. Besides partial overlapping and wrinkle, the replacement of nitrogen atoms in graphene gives rise to the distortion of N-doped graphene.(3) The addition of Ag-doped graphene can effective enhance the properties of the composites. With decrease of Ag-doped graphene content, the hardness and electrical conductivity increase. Compared with pure silver, the hardness and electrical conductivity of 0.5wt% Ag-doped graphene reinforced sliver matrix blocky composites are increased by 55.4%and 2.78%, respectively. The coarse Ag particle size decreases the hardness, but increases the electrical conductivity. The Ag-doped graphene reinforced Ag matrix blocky composites prepared by 100nm Ag powders has the maximum hardness and electrical conductivity, which are 89.4HV and 95.69%IACS, respectively.(4) With increase of the sintering temperature, the hardness and electrical conductivity of Ag-doped graphene reinforced sliver matrix blocky composites increase and then decrease. The optimum sintering temperature is 600? for the preparation of Ag-doped graphene reinforced sliver matrix blocky composites. The hardness and electrical conductivity are 89.4HV and 95.69%IACS, respectively.(5) The addition of a small amount of N-doped graphene into Ag matrix can strengthen the properties of N-doped graphene reinforced sliver matrix blocky composites. Compared with pure Ag, the hardness and electrical conductivity of Ag matrix blocky composite with the addition of 0.1 wt% N-doped graphene are increased by 64.8% and 3.71%, respectively.However, excessive N-doped GNP addition reduces the hardness and electrical conductivity.(6) Fine Ag powders are favorable for the enhancement on the hardness of composites and decrease on the electrical conductivity. The largest hardness value of 94.6HV can be obtained for the N-doped graphene reinforced Ag matrix blocky composite prepared by 100nm Ag powders. The Ag matrix blocky composites prepared by different Ag powders have excellent electrical conductivity with above 96%IACS.