Improving the thermal conductivity of epoxy resin composites by magnetic orientation of boron nitride nanosheets

Preparation of high thermal conductivity epoxy resin (EP) composites can effectively solve the heat dissipation problem of windings of new energy vehicle drive motors. In this study, the high thermal conductivity of the vertical plane of boron nitride nanosheets (BN) was utilized, and the CoFe
2
O4 (CFO) prepared by hydrothermal method was attached to the exfoliated BN surface by van der Waals attraction and Dopamine (PDA) coating. The EP composites were prepared by magnetic orientation of BN, which improved the thermal conductivity of EP and achieved higher thermal conductivity enhancement at lower content. As the content of 6.81 vol.%, the thermal conductivity of the oriented BN@CFO composites reached 0.65 W/m.K, which is 263 % of EP. The thermal conductivity of the composites with different magnetic orientation times were compared, and it was found that the extended magnetic orientation time was beneficial to improve the thermal conductivity of the composites. In addition, it was confirmed using simulation that BN orientation is more favorable for heat transfer. This study provided an effective approach for the preparation of high thermal conductivity epoxy resin composites.