Formation Mechanism Of Graphene/Copper Composite Powder By Electrochemical Deposition And Its Application In Graphene-Strengthened Copper-Based Composite

Graphene is believed to be an attractive candidate for the strengthening agent of copper-based composite owing its high-strength and high-conductivity.Whereas,the major hindrances to developing graphene-strengthened copper-based composite are the non-uniform dispersion of graphene flakes within copper matrix and the low bonding strength of the interface between graphene flakes and copper matrix.In the present paper,graphene nanoplatelets reinforcing copper matrix composites with different contents of graphene were fabricated by a simple electrochemical deposition and atmosphere sintering.The microstructure,element composition,crystal structure and phase structure of graphene/copper composite powders and composites were studied by XRD?FTIR?XPS?SEM and TEM.Mechanical properties and electrical conductivity of graphene/Cu composites were tested by vivtorinox hardness tester and eddy current conductometer.The results show that when the addition of graphene oxide?GO?in electrochemical deposition solution is 25.0 mg/L,the graphene/Cu composite powders show homogenous dispersion of graphene in the matrix,without agglomerate and the copper grains are spherical with an average particle size of only20 nm.After hydrogen reduction,the oxygen-containing functional groups such as C-O-C and O-C=O in graphene/Cu composite powders are greatly reduced,and Cu₂O is completely removed.Only a small amount of oxygen is contained in the composite powders.XPS and FTIR results show that Cu-O-C bonds are formed during electrochemical deposition,and oxygen atoms change from interstitial oxygen atoms to oxygen atoms combined by covalent bonds or ionic bonds.By analyzing the electron diffraction images of graphene/Cu composite powders,the crystal orientation relationships of???? 1????_Cu//?10???0?_Grapheneand?222?_Ni//?10???0?_Grapheneis observed,and the lattice misfit?*of Cu and graphene is 2.1%.It shows that Cu and graphene are completely coherent,and interfacial bonding between Ni and graphene form.The bond strength between Cu and graphene is increased by Ni-Graphene,Cu-O-C and the coherent crystal orientation relationship.Taking advantage of the graphene/Cu composite powders prepared by electrochemical deposition to prepare the composites,the results show that when the content of graphene is 11.8 wt.%,the graphene/Cu composite have the best properties,with hardness of 111.2 HV and conductivity of89.2%IACS.