Design On Interface Construction And Research On Microstructure And Properties Of High Thermal Conductivity Diamond/Aluminum Composite

With the rapid development of electronic equipment,the power consumption and heat generation of electronic system and components increase rapidly.Therefore,it is very important to solve the heat dissipation problem of electronic equipment.Due to the advantages of low density,high thermal conductivity and adjustable coefficient of thermal expansion,diamond/aluminum composite has become a research hotspot of new thermal management materials.In this paper,diamond/aluminum composites were prepared by pressureless infiltration.The effects of infiltration temperature and diamond particle surface coating on the structure and thermal physical properties of the composites were studied.Hasselman Johnson?H-J?model was used to calculate the effect of diamond particle size on the thermal conductivity of the composite.Based on the research results,the diamond particles with an average particle size of 113.26?m were selected in the experiment.The temperature range of pressureless infiltration process was determined by analyzing the graphitization law of diamond and thermodynamic law of wettability and interfacial reaction between diamond and aluminum matrix.With the decrease of infiltration temperature,the structure defects of diamond/aluminum composite increase.Combined with the thermodynamic analysis of two-phase wetting angle,the main reason is that the wettability of diamond and aluminum liquid decreases with the decrease of infiltration temperature,weakening the interface bonding state,resulting in the decrease of thermal conductivity of the composite.The thermal conductivity of diamond/aluminum composite decreased from388.33 W/?m·K?to 204.3 W/?m·K?with the infiltration temperature decreasing from950?to 850?.The obvious increase of thermal expansion coefficient of diamond/aluminum composite prepared at 850?is related to the decrease of diamond particle volume fraction.In order to inhibit the interface reaction between diamond and aluminum,the diamond particles were coated on the surface.Combined with the acoustic mismatch model?AMM?,the differential effective medium model?DEM?and the H-J model,the effects of coating type,coating thickness,particle size and volume fraction on the thermal conductivity of diamond/aluminum composite were analyzed,and the best metal coating materials were W and mo.Most of the Mo coating in the Mo coated diamond/aluminum composite is coated on the surface of the diamond particles.In addition,there are a small amount of white block phase around the diamond particles.EDS spectrum analysis shows that the main elements include Al,Mo and Si.In the W-coated diamond/aluminum composite,almost all of the W coating changes into white block phase and gathers around the diamond particles,and the main elements include Al,W and Si On the one hand,the existence of the white block phase reduces the inhibition of the coating on the diamond aluminum interface reaction,and the composite still has the Al₄C₃brittle phase.On the other hand,it increases the interface thermal resistance of the composite,which reduces the thermal conductivity of the coated diamond aluminum composite,and the thermal conductivity of the coated Mo and W composite are 322.24 W/?m·K?and 338.64 W/?m·K?,respectively.