Study On Preparation And Properties Of C_f-Si/Al Composites

In the field of electronic packaging materials,ultra-high silicon aluminium alloys have very important application value in aerospace and microelectronics industry because of their low thermal expansion coefficient,high thermal conductivity,low density and certain strength.Al-70Si fully meets the above physical performance requirements,but because of the high content of Si,poor continuity of Al matrix,low fracture strength of materials,poor machinability,easy collapse of materials,high cost,it can not be widely used.In order to improve the properties of silicon-aluminium alloys,carbon fibers are introduced as reinforcements to replace 70Si alloys.In this paper,carbon-aluminium?Cf-Si/Al?composites were fabricated by powder metallurgy combined with two-punch step-by-step compression method.The properties of carbon fibers and Al-Si alloys with different mass fractions were investigated at different sintering temperatures.Feedback process was used to determine the optimal process parameters.In this experiment,OM,SEM and XRD were used to analyze the microstructures of the composites.The optimum mass fraction and sintering temperature were predicted through experiments and theoretical analysis.The thermophysical properties,mechanical properties,density,air tightness,thermal fatigue properties and mechanical processing properties of the composites were characterized.The results show that the composite material of 5%carbon fibers and Al-35Si sintered at 680?for 2 hours has the best properties,the thermal expansion coefficient is 7.75×10^-6/K,the longitudinal thermal conductivity is 85.632 W/m·K,the tensile strength is 116.6 MPa,the density is 2.300g/cm³,and the composite material of 10%carbon fibers and Al-27Si sintered at 680?for 2 hours has the best properties and thermal expansion system.The number is 6.04×10^-6/K,the longitudinal thermal conductivity is 87.799 W/m K,the tensile strength is 104.2 MPa,and the density is2.371g/cm³.The two composites exhibit excellent thermophysical properties and can basically replace Al-70Si.basically replace Al-70Si.The optimum sintering temperature for carbon fibers and high silicon aluminium alloys is 680?.