Optimization of Thermal Conductivity of Alumina-Filled Composites by Numerical Simulations

Understanding the correlation between the physical features of composite components and thermal conductive pathway is beneficial to optimizing the overall heat-transfer performance. Herein, we conduct numerical simulation to investigate the thermal conductivity and heat flux distributions of alumina (Al 2 O 3 )-filled composites. The finite element model was verified by both experimental data and theoretical models. The crucial factors include the influence of the interface thermal resistance, the intrinsic thermal conductivity of the matrix and Al 2 O 3 filler, and the size effect of Al 2 O 3 fillers were investigated. For single Al 2 O 3 -filled composites, the results indicate that increasing the intrinsic thermal conductivity of the matrix is conductive to bridge the Al 2 O 3 pathway along heat-transfer direction, but there are very limited contributions by enhancing the intrinsic thermal conductivity of Al 2 O 3 filler, tuning the size of Al 2 O 3 filler, and reducing the interface thermal resistance. After introducing the multiscale fillers, it is found that the high thermal conductivity can be achieved by regulating their size matching effect. At the optimal binary ratio of 70:30 (40 µm:15 µm) and ternary ratio of 55:35:10 (40 µm:15 µm:10 µm), the heat-conduction network presents the dominant skeleton of large-sized filler and the bridging branch of small-sized fillers features, which facilitates the formation of a complete and continuous thermal conductive network. This study gives a practical guidance for the thermal conductive design of Al 2 O 3 -filled composites.