Spherical aggregated BN /AlN filled silicone composites with enhanced through-plane thermal conductivity assisted by vortex flow

Thermal interface materials (TIMs) with high thermal conductivity and good insulation properties are in high demand for thermal management systems. Platelet-like materials such as BN and graphene usually orient horizontally in polymer composites, causing minor Through-plane thermal conductivity (TC) enhancement. Herein, aggregated BN (A-BN)/AlN/silicone rubber (SR) composites with enhanced through-plane TC are fabricated assisted by vortex flow during the planetary centrifugation process. It is found that BN platelets assembled into ABN with spherical AlN as cores based on concentric vortex. Due to the formation of spherical A-BN, throughplane TC of as-prepared composites with 40 wt% BN and 45 wt% AlN is as high as 6.56 W/(m center dot K) while it is only 4.62 W/(m center dot K) for composites without A-BN. Such high TC should mainly be attributed to the large-sized spherical BN interconnected structure which constructs an efficient thermally conductive path in the throughplane direction. The heat dissipation evaluation test also demonstrates the excellent performance of the A-BN/ AlN/SR composite. This work provides a facile strategy to produce large-sized BN agglomerates and gives insights into the vortex flow during the planetary centrifugation process.