In this paper, 60.5–68.0 vol.% SiCp/Al composites were prepared by infiltrating liquid aluminum into preforms. The average diameters of SiC particles used in the particles packing experiments were 45, 8 and 2 µm for the group I preforms, and 75, 8 and 2 µm for the group II preforms. The thermal-mechanical properties of the composites were investigated. The mechanical properties test showed that the tensile strength of the composites was in the range of 212–349 MPa, and the elastic modulus of the composites was greater than 150 GPa. For a given SiC volume fraction, the tensile strength and elastic modulus of the group I composites were greater than that of the group II composites. The thermal properties test revealed that the coefficient of thermal expansion of the composites was in the range of 10.33–12.32 × 10–6/℃, and the measured thermal conductivity of the composites was greater than 85.6 W/(m·℃). The change of the particle size distribution had no effect on the coefficient of thermal expansion, and the coefficient of thermal expansion decreased linearly with the increase of SiC content. An average diameter approach for estimating the thermal conductivity of the composites was proposed in the application of Hasselman-Johnson model. The results indicated that the predictions of the model were in good agreement with the measured thermal conductivity of the composites.

SiC particles reinforced aluminum matrix composites (SiC p /Al) with SiC content of more than 60%, without particle segregation for mirror substrate applications, are prepared by using the improved process. The improved process contains sintering process design, preform quality traceability, and equipment designing. The maximum SiC volume fraction of 70.4% is obtained by optimizing the selection of the following proportion: 71.4% coarse, 7.1% medium, and 21.5% fine particles. The variation of SiC volume fraction is correlated with the percentage of fine particles by using regression analysis. The preforms with the compressive strength above 10.34 MPa are prepared by sintering at 1600 C for 2 h. Results showed that no defects in the scale of more than 10 mm are observed in the preforms. Due to the generation of a SiO 2 layer during the sintering process, the formation of Al 4 C 3 phase was inhibited. As the SiC particle volume fraction increased from 65.6% to 70.4%, the bending strength increased from 483.2 MPa to 585.2 MPa. The elastic modulus also increased from 174.2 GPa to 206.1 GPa, while the coefficient of thermal expansion between 50 C and 350 C decreased from 11.02 Â 10 À6 / C to 9.53 Â 10 À6 / C.