The Study On Preparation And Strengthening Methods Of Flake Graphite/Aluminum Composites With High Thermal Conductivity

With the rapid development of the Internet technology,the data and commands that electronic products need to process become more and more complex,requiring electronic chips to have higher frequency and faster processing speed,which will bring a lot of heat,which requires modern thermal management systems to have better heat dissipation.Graphite/aluminum composite is a new composite used in modern thermal management systems.It has high heat dissipation efficiency,but insufficient mechanical properties.The research of this paper is to strengthen the mechanical properties of graphite/aluminum composites by different strengthening methods and preparations,ensuring there owing high thermal conductivity.Details as follows:?1?The surface of the graphite is subjected to a coating treatment to improve the interface bonding of the graphite-aluminum interface,which can improve the thermophysical properties.The graphite was coated with Si and Ni,respectively.The results showed that 242 nm SiC nano-layer coating,and 985 nm metallic Ni nano-layer coating were formed on the graphite surface.Both coatings could improve the interface between graphite and aluminum.When the graphite volume fraction is 30%⁷0%,the Si-coated graphite/aluminum composite exhibits better thermophysical properties,and the thermal conductivity increases from 268⁶43 W/?m·K?to328⁷25.W/?m·K?,and the bending strength is increased from 72³3MPa to 90⁴5MPa;while the Ni-coated graphite/aluminum composite exhibits better bending strength,the thermal conductivity is lower than that of uncoated graphite/aluminum composite.?2?Based on the graphite strengthen by the coating process,the mechanical strength of the graphite/aluminum composite are improved by adding copper meshes.The physical bearing of the copper mesh makes the graphite have a good alignment between the copper meshes,and the copper mesh also serves as the second phase reinforcement to improve its bending strength.The results show that after adding copper mesh,the graphite orientation inside the silicon-coated graphite/aluminum composite is better,and the structure of the graphite sheet is highly aggregated,which not only improves the bending strength of the silicon-coated graphite/aluminum composite,but also the graphite volume fraction.The thermal conductivity of the silicon-coated graphite/aluminum composite is improved at a lower temperature.When the silica-coated graphite with a volume fraction of 40%was added,the thermal conductivity of the composite reached 512 W/?m·K?,the flexural strength was as high as 127 MPa,and the comprehensive performance was optimal.The thermal expansion coefficient was 14.4×10^-6m/K.?3?Based on the graphite strengthen by the coating process,a graphite/silicon carbide/aluminum ternary composite was prepared by adding silicon carbide particles,in order to solve the shortcomings of insufficient mechanical strength of graphite/aluminum binary composites.The effects of silicon carbide particle size and volume fraction on micro-morphology,thermal conductivity and bending strength were analyzed,and the thermal conductivity model of three-phase composites was established.The results show that the addition of silicon carbide particles will reduce the thermal conductivity of the composite in the x-y plane to some extent,but it will contribute significantly to the improvement of mechanical properties.When the amount of silicon carbide added is 12 vol%,the thermal conductivity of graphite/silicon carbide/aluminum composite can still be maintained at 512 W./?m·K?,the bending strength is 121 MPa at this time.At this time,then the coefficient of thermal expansion is 10.8×10^-6m/K.