| Copper is one of the most important metals for the human production and life. It has excellent electrical conductivity, thermal conductivity and mechanical processing performance. However, its poor mechanical properties hinder its wider application. For graphene has excellent mechanical properties, electrical conductivity, thermal conductivity, it is a good reinforcement of metal matrix composites. So, graphene received wide attention and study around the world, since discovered in 2004,. Thus, graphene reinforced copper matrix composites show attractive prospects for development in Electrical contact materials, electronic packaging materials and other field. However the poor dispersion of graphene in copper matix composite hinder the its production. In this paper, we choose graphene as reinforcement, prepare graphene/Cu composite powder by different mothods to study the effect on dispersion of graphene in copper matix composite. The composite were sintered by these powders and the properies and enhancement mechanism of composites with different methods were studied.Graphene/Cu composite powder is prepared by low energy ball milling method, and the effect of different milling speeds and milling times on composite powders and composites are also studied. The results show that, the composite powder prepared with the 100rpm’s ball milling speed and the ball milling time is 4 hours has less defeats. The composite produced by this powder has a yield strength of 378 MPa and its conductivity is 70.4%IACS.RGO/Cu composites with different volume fraction are prepared by typical molecule level mixing method(MLM method) and MLM method with high-shear mixing(M-H method). The results show that the composite powders produced by M-H method have less agglomeration than composite powders produced by MLM method. The composite with 2.4%vol. RGO produced by M-H method has a yield strength of 501 MPa, more than 3 times of that of copper(150MPa). The composite with 0.6%vol. produced by M-H method has a Apparent enhancement coefficient of 322, which shows that RGO has outstanding enhancement effect on copper matrix composite.Graphite, sub-micron and nanometer copper powder as the substrate material are used to prepare FLG/Cu composite powder by particle assisted exfoliation method. The results 1,3-Butyleneglycol with suitable surface energy and high viscosity, and it can effectively peel graphene from graphite than 1,3-propanediol and ethanol. Thus 1,3-Butyleneglycol is suitable solvent to prepare graphene/Cu composite powders with the particle assisted exfoliation method. The thickness of FLG sheets are main in 5-10 nanometers, which shows that the particle assisted exfoliation method is useful to peel the graphite into FLG.The morphology of composites produced by particle assisted exfoliation method were analyzed and found that FLGs exist between copper crystal boundaries, this structure could hinder copper particle growing up during sintering process and movement of dislocations, enhance the mechanical propeties of composite. Meanwhile during the spark plasma sintering, some FLG converted into graphene film and carbon particles appear in the grain boundaries and triangle grain boundaries,respectively. this carbon materialcould improve the mechanical properties of composite. The composites produced by particle assisted exfoliation method have excellent mechanical properites, The composite with 2.5%vol. FLG has a yield strength of 494 MPa, and the composite after hot rolling has a tensile strength of 388 MPa, more than that of composite enforence by CNT with same volume percent.The graphene produced by particle assisted exfoliation method as enhencement and copper particle as matrix, using the particle assisted mixing method to produce graphene/Cu composites. The results of analyse shows that the copper particles are packed by graphene, the graphene is well disperse in composite powders. The composite with 0.42%vol graphene has a yield strength of 381 MPa and its apparent enhancement coefficient reach 367. |
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