Enhanced Thermal Conductivity of Epoxy Composites by Introducing 1D AlN Whiskers and Constructing Directionally Aligned 3D AlN Filler Skeletons

With the miniaturization of current electronic products, ceramic/polymer composites with excellent thermal conductivity have attracted increasing attention. For regular ceramic particles as fillers, it is necessary to achieve the highest filling fraction to obtain high thermal conductivity, yet leading to higher production cost and reduced mechanical properties. In this paper, AlN whiskers with a high aspect ratio were successfully prepared using a modified direct nitriding method, which was further paired with AlN particles as fillers to prepare the AlN/epoxy composites. It is indicated that AlN whiskers could form bridging links between AlN particles, which favored the establishment of thermal pathways inside the polymer matrix. On this basis, we constructed the 3D AlN skeletons as a thermal conductivity pathway by the freeze-casting method, which could further enhance the thermal conductivity of the composites. The synergistic enhancement effect of 1D AlN whiskers and directional filler skeletons on the composite thermal conductivity was further demonstrated by the actual heat transfer process and finite element simulations. More significantly, the experimental results showed that the addition of one-dimensional fillers could also effectively improve the thermal stability and mechanical properties of the composites, which was beneficial for preparing high-performance TIMs.