Study On Preparation And Properties Of Copper Matrix Composites With High Thermal Conductivities

With the rapid development of network communications,the heat production power per unit of electronic components has increased,requiring thermally conductive materials to have higher heat dissipation capabilities.Traditional metal thermal conductive materials?such as copper,aluminum,etc.?have gradually failed to meet the requirements of use,and the development of new thermal conductive materials is imminent.Carbon materials?such as natural flake graphite,graphene paper,etc.?have the advantages of high thermal conductivity and low thermal expansion coefficient,and are considered to be ideal thermally conductive fillers.Because of its adjustable thermal expansion coefficient,excellent thermal conductivity,and high strength,carbon-based/copper composite materials have become promising thermally conductive composite materials in contemporary thermal management systems.The prepared carbon-based/copper composite material will have problems such as difficulty in aligning the heat-conducting reinforcement in the copper matrix,uneven distribution,poor interface bonding,etc.,resulting in unstable performance of the composite material,which cannot achieve the expected strength and thermal conductivity.The natural flake graphite reinforced copper matrix composite material with oriented structure is prepared by casting process and vacuum hot pressing technology,which solves the problems of difficult orientation and difficult uniform distribution of natural flake graphite in the matrix.The experimental results show that copper powder and natural flake graphite can be prepared into copper powder film and highly oriented flake graphite film by casting process,and cast copper powder film and uniform and highly oriented flake graphite film,and then by vacuum hot pressing process Highly oriented flake graphite/copper composite materials were prepared.The highly oriented flake graphite/copper composite material has higher performance than the flake graphite/copper composite material prepared by the traditional process,and has excellent high temperature stability.50 vol%highly oriented flake graphite/copper composite material,its thermal conductivity is 556 W/?m·K?,the flexural properties of XY plane and Z plane are both over 60 MPa,and its thermal expansion coefficient is 13.2×10^-6m/k at room temperature is much lower than the thermal expansion coefficient of pure copper.When the flake graphite content is 70 vol%,the thermal conductivity of the highly oriented flake graphite/copper composite material reaches 685 W/?m·K?,which is 5%higher than that of the flake graphite/copper composite material,and its XY plane flexural strength is increased by 3%.A new graphene paper/copper composite material with micro-zebra structure was prepared by surface treatment process and hot pressing technology.As a result,the use of large-size graphene paper instead of graphene can avoid problems such as agglomeration and unevenness of graphene in the copper matrix.Using surface chemical treatment to roughen and oxidize the surface of graphene paper can improve the wettability between graphene paper and copper.The graphene paper/copper composite material with zebra structure can eliminate the interface thermal resistance of the XY plane,so that it has higher strength and thermal conductivity than the highly oriented flake graphite/copper composite material.In addition,the surface-treated graphene paper and copper powder film increase the interfacial bonding force of the composite material,and a polycrystalline region with a thickness of 10 to 25 nm can be formed at the interface.In addition,the micro zebra structure improves the mechanical properties of the XY plane,making the graphite Ethylene-copper composite material has both high thermal conductivity and bending resistance.When the volume fraction of graphene paper is 40%,the thermal conductivity of graphene paper/copper is 581 W/?m·K?and the flexural strength is106.9 MPa.When the volume fraction of graphene paper is 70%,the thermal conductivity of graphene paper/copper is 581 W/?m·K?and the flexural strength is106.9 MPa,which is higher than the thermal conductivity and bending resistance of highly oriented flake/copper composite 41%and 60%,respectively.