Study On Preparation And Thermophysical Properties Of High Volume Fractions Graphene Reinforced Copper Composites

Research on the factors affecting the thermophysical properties of graphene-copper composites is in process.This topic used molecular-level mixing methods to prepare graphene/copper-based composites,and studied the effects of graphene volume fractions,drying temperature and sedimentation time on the structure and morphology of composite powders,the structure of composite materials,and the thermophysical and mechanical properties of materials.I also pre-strained the prepared material,and studied the effect of pre-strain on the thermophysical and mechanical properties of the material.In this paper,a molecular-level mixing method is used to prepare graphene/copper composite powder.The composite powder is composed of copper oxide and graphene oxide,and the composite sheets of the copper oxide and graphene oxide group are gathered together and arranged in layers in a microscopic state.The volume fractions of graphene are 20%,35%,and 50%.When the volume fraction of graphene is 20%,graphene has the best dispersibility and a lower degree of agglomeration.The composite material with a drying temperature of 100~oC and a settling time of 0h and 3h is prepared.The composite powder prepared with sedimentation time of 3h was more self-assembled and has smaller particles size.The composite material is prepared by the electric spark sintering method.The composite material is composed of a light-colored carbon-poor phase and a long strip of dark carbon-rich phase.When the graphene volume fraction is 20%,the drying temperature is 40~oC,and the sedimentation time is 3h,the aspect ratio of the dark phase is the largest.Perform thermophysical performance tests on materials.The thermal expansion coefficient is mainly affected by stress changes,the yield strength of the matrix and the bonding of the graphene/copper interface.This paper discusses the relationship between the thermal expansion coefficient and the thermal mismatch stress.As the drying temperature of the material decreases and the sedimentation time increases,the interface bonding between graphene and copper is better.Test the mechanical properties of the material.The elastic modulus and compressive strength of the parallel sintering and pressing direction are significantly higher than the vertical sintering and pressing direction,which is caused by the orientation of graphene.When the graphene volume fraction is 20%,the drying temperature is 40~oC,and the sedimentation time is 3h,the composite material has the highest compressive strength and elastic modulus,which are 497MPa and 115GPa,respectively.Pre-straining can improve the orientation of graphene,change the interface bonding between graphene and copper,and improve the thermophysical and mechanical properties of the material.After compressing to yield along the parallel sintering pressure direction,the graphene volume fraction is 20%,the drying temperature is 60~oC,and the settling time is 3h for the composite material,the interface bonding becomes better.After being compressed to yield,the compressive strength and elastic modulus of the composite material are significantly improved.The graphene volume fraction is 20%,the drying temperature is 60~oC,and the settling time is 3h.The compressive strength of the composite material is increased by 14.3%to 501MPa,and the elastic modulus is increased.25.7%to 176GPa.Because under the action of pre-strain,the graphene is aligned in the vertical direction of pressure,and the orientation becomes better.Moreover,the pores at the interface between graphene and copper are healed,the interface is strengthened,and the mechanical and thermophysical properties of the material are improved.