Numerical Simulation on the Optimization of the Anisotropic Thermal Conductivity of Hexagonal Boron Nitride/Nanofiber Composite Films

Understanding the relationship between the physical properties of composite components and thermal conductivity is conducive to optimize the overall heat-dissipation performance. Herein, we conduct a numerical simulation to investigate the anisotropic thermal conductivity and heat flux distributions of hexagonal boron nitride (h-BN)/nanofiber composite films. The critical issues to be considered include the effect of the intrinsic thermal conductivity of the nanofiber matrix and h-BN filler, the geometric size and orientation of the h-BN filler, and the interface thermal resistance. The results demonstrate that increasing the intrinsic thermal conductivity of nanofiber matrix is beneficial to bridge the straightforward h-BN pathway along the directional heat transfer, and the thermal barrier can be effectively inhibited by tuning the interface thermal resistance below 10–8 m2·K·W–1. As for the h-BN fillers, increasing their intrinsic thermal conductivity and length have very limited contributions to the improvement of anisotropic thermal conductivity. But raising the aspect ratio of h-BN and regulating the orientation of the well-stacked layered h-BN filler toward the heat source transfer direction are conducive to enhance the directional thermal conductivity. Based on these comprehensive mathematical analyses of all of the influencing factors, we propose an optimized equation for effectively predicting the anisotropic thermal conductivity of h-BN/nanofiber composite films. The findings are expected to guide the design of highly anisotropic thermal conductive materials.