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

Abstract

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. (C) 2015 Elsevier Ltd. All rights reserved.