| Electrical contact material is the most important material in the process of current conduction and conversion.Because this kind of material requires very high technical content,the electrical contact materials used before are very expensive alloys of Au,Ag,Pt and their composites,which are not only expensive in cost,but also short in service time.The discovery of graphene provides a good solution to this problem,and its excellent properties make it possible for graphene-copper matrix composites to become a new generation of electrical contact materials.The interface is the link between the reinforcing phase and the matrix in composite materials,and it is also the bridge for the reinforcing phase to play an effective role.The bonding properties of the interface have an important impact on the properties of composite materials.Therefore,the research on interface strengthening and toughening is an important basis for the development of high-performance composite materials.GO is very easy to gather together in layered stacking mode,mainly because of van der Waals force between molecules,poor wettability and high surface energy,and it is extremely difficult to combine with other materials.In this paper,Cu atoms are used to modify the surface of graphene oxide,introducing wrinkles on the surface of graphene oxide,improving the dispersibility and wettability of graphene oxide,enhancing the interfacial bonding ability between graphene oxide and copper matrix,discussing the mechanism of Cu atom sputtering on the surface modification of graphene oxide,and studying the microstructure and properties of graphene oxide copper matrix composites.The main research results are:(1)The morphology of composite powder under different ball milling time and different ball milling speed was compared by scanning electron microscope.Under the conditions of 250r/min and ball milling time of 4 h,copper powder changed from spherical shape with diameter of 50 μm to flake structure with diameter of about 30 μm,and a part of graphene oxide was coated on the copper flake structure,while a small amount of graphene oxide was embedded in the copper flake structure.The composite powder was sintered by SPS.By comparing the properties of composites at different temperatures and pressures,it is found that the properties of composites reach the best when the sintering temperature is 800℃ and the sintering pressure is 45 MPa.When the content of GO is 0.15 %vol,the comprehensive properties of the material are the best.(2)By comparing the sputtering modification of Cu atoms with different energy and time,a smooth and flat copper film was prepared to cover the graphene oxide surface.The experimental results show that the sputtering time is 10 min and the power is 50 w,which is the best process,and the GO surface is wrinkled.(3)The mechanism of Cu atom sputtering modified graphene oxide was studied.Oxygencontaining functional groups on the surface and edge of graphene oxide undergo deoxidization reaction under the sputtering of Cu atoms.XRD results show that copper oxide and cuprous oxide are formed.XPS results show that oxygen in coordination bond Cu-O gets electrons.After sputtering by Cu atoms,the interfacial energy and surface energy of graphene oxide decrease.(4)Graphene oxide sputtered by Cu atoms is more evenly dispersed in copper matrix,and agglomeration is reduced.The comprehensive properties of graphene oxide copper matrix composites have been improved,including hardness,electrical conductivity,density,friction and wear coefficient decreased obviously,and corrosion potential changed greatly.At the same time,the friction and wear behavior of the composites and its mechanism were studied in detail.After Cu atom sputtering,the interface bonding between graphene oxide and copper substrate was improved,and the fatigue crack phenomenon was reduced by SEM photos.In the sputtering process of Cu atoms,the oxides produced also play a role in lubrication. |
