Preparation And Microstructure Of Rare Earth Modified Graphene Oxide Reinforced Copper Matrix Composites

At present,the application range of copper is increased by adding reinforcements to the copper matrix,which improve the properties of the material.Although the traditional reinforced phase improves the mechanical properties of composite materials,it has poor conductivity,heat conduction and wear resistance.The special structure of graphene makes it excellent in conducting,conducting,lubricating and mechanical properties,and is widely used in the reinforced phase of composite materials.The development of a new type of silver free copper based electrical contact material is a new hot spot in the study,using the excellent conductivity,heat conduction and good lubricating properties of graphene.Due to the poor wettability,interfacial bonding and dispersion in the metal matrix,graphene should be modified.After modified,the dispersion and compatibility of graphene have been improved,and the comprehensive properties of the composites enhanced.Since it polarized in the hybrid system,Rare earth elements with special electronic structure can be used as surfactant and shallow penetration into the elements of defective parts of graphene oxide or surface active groups to graphene oxide,thereby improving the combination of graphene and the substrate.In this paper,copper/graphene composite was prepared by ball milling and SPS discharge plasma sintering with the surface modification of graphene using rare earth.Graphene-copper based composite material preparation and properties were studied,the different content of graphene added Cu matrix composite was analyzed by XRD,SEM,EDS and carried on the theoretical analysis of the density,hardness,conductivity,friction and wear,corrosion and performance mechanism.The preparation and modification mechanism of rare earth modified graphene were discussed,and the modified graphene was analyzed by SEM,XRD,FT-IR,XPS and TEM.The effect of rare earth modified graphene on the microstructure and properties of copper matrix composites was investigated and compared.The main results are as follows:?1?Comparing different ball milling speeds,the results show that the effect of graphene dispersion in copper matrix is better under the condition of 200r/min ball milling.Composite materials were prepared by SPS spark plasma sintering method.The effects of sintering conditions at 800?,850?,920?,and different graphene additions on the microstructure and properties of the composites were studied.The results showed that the performance of the composites was excellent at 850?When the addition amount is 0.2vol%GN,the grain of the composite is fine,the porosity is low,the hardness is high,and the corrosion resistance is good.When the addition amount is 1vol%GN,the friction coefficient of the composite is the lowest and the most stable.The wear form is two forms of adhesive wear with abrasive wear?2?modified graphene was prepared by different modifiers CeCl₃ and LaCl₃ and different modification methods?heating modifier and wetting method?.SEM/TEM results showed that the modification effect of rare earth modifier CeCl₃ is better than LaCl₃.The dispersibility of the modified graphene oxide prepared by the heating modifier is better than that of the infiltration method.XPS/FT-IR/EDS results indicate that rare earth elements react with the oxygenated functional groups of graphene oxide,forming new functional groups,reducing the interfacial energy and surface energy of graphene oxide,thereby improving the dispersion of graphene oxide.?3?The principle of the action of rare earth modified graphene was studied.The interaction between rare-earth elements and functional groups of graphene oxide causes coordination reaction between the two compounds.FT-IR results show that the peak positions of functional groups of graphene oxide are red shifted and Ce-O bonds are formed.In the coordination reaction,XPS shows that the oxygen element in the rare earth coordination bond Ce-O gets the electron,and XRD shows the new phase of the CeO₂.After rare-earth modified,the interfacial energy and surface energy of graphene oxide are reduced,thus improving the dispersivity of graphene oxide.?4?The rare earth modified graphene oxide has more uniform dispersion in the copper matrix,and the agglomeration phenomenon is less.The hardness,conductivity and density of the composites increased,the friction system decreased and the corrosion potential changed little.At the same time,the friction behavior and mechanism of the composite are studied.After rare-earth modification,the interfacial bonding of graphene and copper matrix has been improved,and the fatigue crack is reduced.In the process of rare-earth modification,the lubrication of the complexes in the process of friction is also an important factor for improving the friction and wear properties.