Research On The Fabrication, Microstructure And Properties Of Diamond/Al Composites

Diamond/Al composites have advantages of high thermal conductivity,low thermal expansion coefficient and light weight,which are ideal for a new generation of electronic packaging materials.In this paper,Diamond/Al composites were fabricated by gas pressure infiltration.The effects of matrix and the coating on diamond and the fabrication process on the microstructure and properties were studied systematically.The main research results are as follows:?1?The effects of matrix material and diamond coating on the structure and properties of the composite were studied.The results show that the Diamond/Al-Si composites have high thermal conductivity,but the interface product Al₄C₃ is harmful to the stability of the composites.Ti plating on diamond surface can prevent the formation of interfacial products,improve the stability of composites and reduce their thermal expansion coefficient,but it can increase the interfacial thermal resistance of composites and reduce their thermal conductivity.?Ti?Diamond/Al composites prepared by pure aluminium instead of aluminium-silicon can improve the thermal conductivity of the composites while ensuring good interface bonding and stability,but increase the thermal expansion coefficient.?2?The effects of gas pressure infiltration on the structure and properties of?Ti?Diamond/Al composites was studied.The results show that the infiltration temperature is too low,the holding time is too short,the wetting between diamond and liquid aluminium is insufficient,and the interface bonding is poor.Increasing the infiltration temperature and prolonging the holding time are conducive to the full wetting between diamond and aluminium matrix and the strengthening of interface bonding.However,the higher the infiltration temperature and the longer the holding time,the lower the properties of the matrix and the composites.The larger the diamond particle size,the less the thermal resistance of the interface,the better the properties of the composites.Composites fabricated by Al matrix which has the purity of 99.6 wt%and 165?m diamond with Ti coating,under the fabrication process,infiltration temperature 780⁸00?,gas pressure 1.5MPa,holding5min,can acquire high interfical bonding and thermal conductivity 520 W/?m·K?,coefficient thermal expansion less than 9×10^-6/K,which meet the performance requirements of high thermal conductivity electronic packaging materials.The preparation and testing of diamond/aluminium composites were discussed:The effects and mechanism of die materials and coatings on the properties of the composites were discussed.The change rule and analysis of thermophysical properties of the composites with temperature rise were discussed.The surface treatment methods of the composites were also discussed.