| With the rapid development of electronic technology,electronic devices are continuously becoming smaller,more functional,and integrated,which puts higher demands on heat management.Heat management materials are the foundation of thermal design,and copper/diamond composite materials,with their high thermal conductivity and controllable thermal expansion coefficient,are one of the representative new electronic packaging heat management materials.Currently,Ti,Cr,W and other elements are mainly used to solve the micro-interface connection between copper and diamond,and the thermal conductivity of the corresponding composite materials is limited to around 800 W/mK,making it difficult to further improve.Two-dimensional graphene materials with high thermal conductivity have the potential to further improve the performance of copper/diamond composite materials.In this study,molecular dynamics simulation and finite element method were used to study the heat transfer properties of graphene-reinforced copper/diamond composites at multiple scales,and the results were compared with the existing experimental results.The main research results obtained are as follows:The interface binding strength of the copper/diamond system and the copper/graphene/diamond system was characterized using the interface binding energy.The copper(111)and diamond(111)were determined as the most stable surfaces through calculations of the surface energy of different crystal faces of copper and diamond,and a copper/diamond model was constructed,with an interface binding energy of 2.09 J/m2.On the basis of the original system,single-layer graphene was used to modify the copper/diamond interface.The interface binding energy of copper/graphene and diamond/graphene in this system was 0.37 J/m2 and 1.22 J/m2,respectively.The effects of graphene and TiC as interlayer on interface binding energy were further compared.The calculation results showed that the energy required for the formation of the copper/graphene and diamond/graphene interfaces was lower than that of the copper/diamond interface,and energy required for the formation of the copper/graphene/diamond interfaces was lower than that of the copper/TiC/diamond interface.The addition of graphene can improve the low binding strength of the copper and diamond interface.The interface thermal transfer properties of the copper/diamond system and the copper/graphene/diamond system were explored.The phonon coupling degree at the copper/diamond interface was low in both the in-plane and out-of-plane directions,and the interface thermal conductivity was 33.17 MW/m2K.This study systematically investigated the influence of factors such as the number of graphene layers and the crystalline orientation of the matrix material on the boundary thermal conductivity,and it was found that the highest interface thermal conductivity of the copper/graphene/diamond system was 467.68 MW/m2K.Simulation results showed that the addition of graphene effectively improved the interface thermal conductivity of the copper/diamond composite material.The simulation results of molecular dynamics interface thermal conductivity were used as input parameters for the numerical simulation of the macroscopic copper/diamond heat transfer process.The results showed that the use of graphene for interface modification significantly increased the heat flux through the diamond particles.The thermal conductivity of the copper/diamond composite material first increased and then decreased with the increase of graphene content.Linear fitting was performed on the calculation results of different gradient diamond volume fraction models,and the results showed that the thermal conductivity of the diamond/copper composite material without interface modification could reach 640.64 W/mK when the diamond volume fraction was 70%,while the thermal conductivity of the composite material modified with titanium carbide increased to 873.34 W/mK.The thermal conductivity of the composite modified with graphene can reach up to 1054.51W/mK. |
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