Preparation And Properties Of High Volume Fraction Of Sic Particulate Reinforced Al Matrix Composites

SiC/Al composites with high volume fraction have the properties of high thermal conductivity,low density and high mechanical properties, which can also be adjusted by the reinforcement according to their usage. Therefore,SiC/Al composites have received great interest as potential materials for most the electronic packaging and thermal management. However,as the high workability of the SiC/Al composites with high volume fraction,to develop a new method to manufacture the composite pasts with near-net shape and complex geometry have become a hot point in this composite area.In this work,powder injection molding and pressure infiltration have been employed to manufacture the SiC/Al composites with high volume fraction and near-net shape.Firstly,the SiC perform with the desired volume fraction was prepared by powder injection molding.The feedstock with high powder(65 vol.%)is easy to obtain by the means of using the SiC power with bimodal particle size and a new binder system. Most of the binder is extracted after 9 hours' solvent debinding at 60℃, which can avoid the appearance of the defects during the thermal debinding.Secondly,the molten alloy was pressure infiltrated into the pores among the performs to form the dens composites.The as-prepared SiC/Al composite(65 vol.%)with the properties of density 3.00g·cm^-3, coefficient of thermal expansion 7.18×10^-6·K^-1(30～100℃),thermal conductivity 175W/m.K and bending strength 431MPa can fully meet the requirements of the electric package.The composites have been investigated by the means of Metallographic analysis,XRD,Emerge spectrum,SEM and TEM.The major conclusion in the current paper is introduced as follows:the SiC preforms have the desired volume fraction and high open pores ratio.The coarse and fine SiC particles distribute evenly dense composites,and there is no interface reaction observed according to the XRD and TEM analysis.The mechanical properties are desired by the size of the coarse particles,the larger of the coarse particles,the worse of the mechanical properties.The thermal conductivity of the composites is accounted according to Hasselman and Johnson equation,and the results show the same rules among the composites.Finally,effects of the temperature,the volume fraction and particle size of the reinforcement and the cryogenic treatment on the coefficient of thermal expansion was investigated.