The Effect Of Reinforcement Constitutes And Copper Element In Aluminum Matrix On Thermo-physical Properties Of SiCp/Al Composites

This paper studied the effect of structure form of SiC(Single, double particles, foam ceramic of continuous), SiC mixed second phase particles(diamond or aluminum nitride) on the thermal physical properties of SiCp/Al composites; The effect of the addition of Cu element on the thermal physical properties and electrical conductivity of SiCp/Al composites was also studied. X-Ray Diffraction(XRD) and Scanning electron microscopy(SEM) were used to analysis the material composit ion and observe the morphology. Through the thermal conductivity instrument and thermal expansion instrument measure the thermal physical properties of materials, to explore the effect of different factors on composite property.The SiCp/Al composite was fabricated by powder natural accumulation with pressureless infiltration, it can improve volume fraction of SiC by double size distribution, when the mass ratio of 220?m to 70?m is 3:1, the volume fraction of SiC was maximum value, at 63.5%. The thermal conductivity of composite was reduced with the pore density increases of foam ceramic, the coefficient of thermal expansion of composite was also declined. When the volume fraction was the same, diffuse distribution structure's thermal conductivity of composite was the highest, the network interpenetrating structure's thermal conductivity of composite was higher than Dual structure distribution. In the aspect of thermal expansion, it was the same as the rule of thermal conductivity.When the silicon carbide and diamond(Dia) mixing reinforced aluminum matrix composites, diamond contents lower than 20% of the total volume fraction of reinforcement, with the total volume fraction of reinforcement was rose, the thermal conductivity of composite was reduced. But the diamond contents greater than 20% of the total volume fraction of reinforcement, the thermal conductivity was increased with the total volume fraction of reinforcement rising. When the volume fraction was the same, the thermal conductivity of composites mixed with Dia particles was higher than aluminum nitride(AlN). When the volume fraction was the same, SiC particle size is greater than Dia, The growth rate of thermal conductivity of SiCp-Dia/Al composites was the largest at the volume ratio of the SiC particles to the diamond particles is 8:2, But the diamond particle size should not be too small. When SiC particle size is smaller than diamond, the growth rate of thermal conductivity of SiCp-Dia/Al composites was the largest at the volume ratio of the SiC particles to the diamond particles is 2:8. In order to obtain the thermal conductivity of composites was greatly improved, while the cost increases little, the diamond particle size should be less than SiC size and can't too small, the content of diamond was optimum in the 20%~30% of the total volume fraction of reinforcement.When the addition of copper element in aluminum matrix, the thermal conductivity, coefficient of thermal expansion(CTE) and electrical conductivity of Al-Cu alloy with the increase of copper content was gradually decreased. The thermal conductivity, coefficient of thermal expansion and electrical conductivity of SiC/Al-Cu composite was also decreased. When the copper content was 8%, the thermal conductivity of composite was the fastest decline. When the copper content was 4%, the CTE of composite was declined markedly, reach the minimum.