Research On The Preparations Of Graphite Flakes Reinforced Aluminum Matrix Composites By Pressure Infiltration Method

With the rapid development of high power electronic devices、laser technology、 LED lighting and electronic products trend of miniaturization, the request of thermal management materials puts forward higher, it is urgent for us to develop a new generation of high performance heat dissipation material. Aluminum/carbon composites consists of high crystalline graphite flakes and aluminum alloy, with high thermal conductivity, low thermal expansion coefficient, low density of graphite flakes and machinability of metal, it is a typical representative of a new generation of heat dissipation material.In this study, Graphite flakes(Gf)/aluminum composites were prepared by pressure infiltration method. Firstly we used the particles of SiC and Al to make perform with graphite flakes by cold pressing, which could make pores in the perform by using particles isolate graphite flakes, and it could help the liquid of Al infiltrate into perform. Then metal melt was put into the sample by high pressure, which could solve the problem of the Poor wettability between carbon and melt Al. We study the influence of the different preheating temperature on the mold. Meanwhile the thermal properties and the microstructure of the composites could be found by changing the volume fraction of the graphite flakes in the composite. In addition, Si and AlN were used, which have better performance, to replace the SiC to make composites. And we try to use GO to improve the properties of the A1N.The results showed that 500℃ was the best preheating temperature. The XRD test found that graphite flakes were lined with (002) basal plane in the composites. And Al4C3 could hardly be fund. We could find that the stacking of the graphite flakes increased with the volume fraction increased in the composites from the SEM images. The results showed that graphite flakes could increase the in-plane thermal conductivity and decrease the coefficient of thermal expansion and density of the composite. The density decreased from 2.71 g/cm3 to 2.33 g/cm3, and the in-plane thermal conductivity of composite increased from 234 W/mK to 403 W/mK by the graphite flakes volume fractions increasing from 23.9% to 73.4% in the composite.After successfully master the technology, we tried to use Si and AlN to replace SiC to make composites. The test showed that the thermal diffusion coefficient of the Si/Gf/Al composites is better than SiC/Gf/Al composites. But the AlN/Gf/Al composite is lower than former, so we try to use GO to change the properties of AIN.