Study On Fabrication And Mechanical Properties Of Laminated GNPs/Cu Composites

In this dissertation,the fundamental process of graphene/copper composites with nanolaminated architecture fabricated by electrophoretic deposition(EPD)was explored.According to the macroscopic morphology and microstructure,the influence of pickling process,the thickness of copper,the content of active carrier on the dispersion of graphene was confirmed in the preparation of EPD.That is to say,pickling process with 50?m thickness of copper,0.1g of Al(NO3)3 was beneficial to the dispersion of graphene.And then the influence of technological parameters in the EPD-SPS-Rolling process,the time of EPD and rolling deformation,which influenced microstructure and mechanical properties of GNPs/Cu composites with nanolaminated architecture,were analyzed in detail.According to the results of micro structural analysis and mechanical tests by Scanning Electron Microscope(SEM),Transmission Electron Microscope(TEM),Raman spectrum and Electron Back-Scattered Diffraction(EBSD),after the ajustmengt of the parameters repeatly,the best technological parameters of graphene/copper composites with nanolaminated architecture fabricated by electrophoretic deposition(EPD)were confirmed.The analysis of microstructural and mechanical properties of GNPs/Cu composites with nanolaminated architecture showed that With the increase of the time of EPD,the content of graphene and the cover area of graphene in composites increased,which was beneficial to enhance the strength,but when the content of graphene was too much,it occurred to agglomerate,and the cover area of graphene was too much to have a good interfacial bonding.With the increase of the rolling deformation,the mechanical properties of GNPs/Cu composites with nanolaminated architecture were enhanced,and the interlamellar spacing was decreased,with the structure of graphene being destroyed and the nanolaminated architecture getting fuzzy if the rolling deformation was too large.In this paper,the best technological parameters were 75 s of the time of EPD and 75% of rolling deformation,when the yield strength of GNPs/Cu composites with nanolaminated architecture had a promotion of 21.6% and the tensile strength had a promotion of 6.2%.The analysis of microstructural and interfacial properties of GNPs/Cu composites with nanolaminated architecture showed that graphene/copper composites with nanolaminated architecture fabricated by EPD had architecture of “brick-and-mortar”,the graphene was evenly distributed between the metal lamellae.With its excellent mechanical properties,the crack deflection and load transfer improved the mechanical properties of the composites,and there was dislocation mismatch at the interface,which indicated that the existence of graphene hinders the dislocation motion,and the critical stress of dislocation motion was increased to induce the strengthening effect.Compared with pure copper,the grain size of the composites had a tendency to refine,but because of the grain growth during the high temperature process,the effect of fine grain strengthening of the composites was weak.The main strengthening mechanisms of graphene/copper composites with nanolaminated architecture fabricated by EPD were: load transfer,second phase strengthening and fine grain strengthening.While the crack deflection ersureed its toughness.In conclusion,compared to the matrix copper material,the yield strength and tensile strength of graphene/copper composites with nanolaminated architecture had a big promotion,which showed that graphene was dispersed uniformly,and controlled nanolaminated architecture made the graphene play its advantages of small mount-high performance,improving its strength,at the same time,retaining its toughness.