Vertical particle alignment of boron nitride and silicon carbide binary filler system for thermal conductivity enhancement

Thermally conductive BN/SiC binary filler and epoxy composite materials were fabricated via magnetic alignment. The magnetic iron oxide particles on the surface of the filler allowed particle re-orientation under the external magnetic field. Owing to its anisotropy, the vertically aligned BN composite had a high thermal conductivity and generated a vertical heat flow path. When the SiC nanoparticles were added to the binary filler, they hindered BN-particle aggregation and led to the formation of a three-dimensional heat conduction path, thereby resulting in increased thermal conductivity. The maximum thermal conductivity (5.77 W/mK) was obtained with an addition of SiC filler, and was 3.08-fold and 1.1-fold higher than that of randomly mixed BN and vertically aligned BN composites, respectively. The additional SiC–Fe3O4 particles resulted in significant aggregation of the filler, which in turn led to a decrease in the thermal conductivity. The measured storage modulus of the BN–Fe3O4/SiC binary filler composite was also higher than those of the BN–Fe3O4 and BN–Fe3O4/SiC–Fe3O4 composites, owing to the aggregation of particles.