Research On Preparation,Microstructure And Properties Of Copper Graphite/Graphene Composites

Copper-carbon composites are copper matrix composites made of copper and carbon materials,which are widely used in the field of electrical contact.However,the wettability between copper and carbon is very poor.The interface between them is mechanical bonding and the bonding strength is low.In addition,in composites with high carbon content,the agglomeration of carbon in copper matrix will also have an adverse impact on its comprehensive properties.Therefore,it is necessary to optimize the process to control the interface bonding,structure,content and spatial distribution characteristics of carbon materials in copper matrix,and fully combine the advantages of copper and carbon in order to obtain copper-carbon composites with excellent comprehensive properties.Based on the principle that copper oxide and cuprous oxide will react with carbon materials at high temperature,new copper-graphite composites（Cu₂O-Gr）and copper-graphene composites（Cu-G-MO）were prepared by in-situ formation method,and their microstructure and properties were analyzed and studied.The main conclusions are as follows:（1）Compared with Cu-Gr composites prepared by copper powder and graphite,Cu₂O-Gr composites showed higher mechanical properties and similar conductivity.The compressive strength of Cu₂O-55Gr and Cu₂O-70Gr composites reached 141 MPa and 67 MPa respectively,about 40%and 25%higher than that of Cu-55Gr and Cu-70Gr composites.（2）The strength of Cu/C interface in Cu₂O-Gr Composites was significantly higher than that in Cu-Gr Composites.The in-situ reaction made some graphite particle lamellae in the matrix thinner and its size smaller,which significantly improved the phenomenon of graphite agglomeration.（3）Cu₂O-Gr composites showed better mechanical friction and wear properties than Cu-Gr composites.The wear mechanism of Cu-Gr composites was mainly abrasive wear and fatigue wear,and there were obvious signs of tear and breakage on the friction surface.The wear mechanism of Cu₂O-Gr composites was typical abrasive wear,and the friction surface was in the shape of furrow.Cu₂O-Gr composites had better mechanical properties and stronger surface deformation resistance,which made them have better wear resistance.Fine and evenly distributed graphite particles were conducive to the formation of continuous and complete lubrication film,so that they can obtain better lubrication effect.（4）Under the power-on condition,Cu₂O-55Gr composite showed better wear resistance than Cu-Gr composite,and its wear rate was 25～50%lower than Cu-55Gr composite.The current increased the local temperature of the friction surface,reduced the strength of the sub surface layer and intensified the adhesion.At the same time,the current accelerated the falling off speed of graphite,which promoted the lubrication and reduced the wear of abrasive particles.The main wear mechanisms of materials were adhesive wear and arc ablation.（5）Compared with copper-graphene composites（Cu-G-MO）prepared by copper powder and graphene,copper-graphene composites（Cu-G-MO）prepared by micro copper oxide powder and graphene in situ showed higher mechanical properties and conductivity.In the sintering process,micro copper oxide powder can react with multilayer graphene in situ.While Cu was formed in situ,the multilayer graphene was thinned and the bonding of Cu/C interface was strengthened.