High thermal conductivity and mechanical properties of Si@Graphite/Aluminum nitride/aluminum composites for high-efficiency thermal management

To obtain high performance composites for thermal management fields, we adopt a new route to prepare the graphite flakes (Gf)/aluminum (Al) composites via vacuum pressure infiltration process. In this study, aluminum nitride (AlN) particles were used as supporting particles to obtain infiltration pathways for the penetration of the molten Al matrix. Gf, starch, urea and AlN were mixed evenly in the mass ratio of 1: 0.035: 0.058: 0.3 and then sintered at 330 °C to prepare porous preforms. It was observed that these substances had excellent chemical compatibility using characterization equipment. The improvement of the thermal transfer and mechanical properties of the composites for silicon coating was also studied. When the volume fraction of graphite was about 54%, compared with the samples without coating, the samples with SiC coating displayed an excellent thermal conductivity (TC) of 467.8 W/m·K and a promising bending strength of 58.8 Mpa, which increased about 82.1 and 238.0%, respectively. The coefficient of thermal expansion (CTE) of composites also decreased about 23.3% from 2.19 × 10⁻⁵ K⁻¹ to 1.68 × 10⁻⁵ K⁻¹ from room temperature to 380 °C.