Preparation and thermophysical properties of hexagonal boron nitride-cubic boron nitride/epoxy composites

Epoxy resin (EP) has low thermal conductivity, and EP-based insulate equipments will failure due to their poor heat dissipation and heat re-sistance in long-term use. A composite insulating material with high heat resistance and high thermal conductivity was prepared by adding micron boron nitride (BN) to EP, and the thermal conductivity and heat resistance of the composite material were studied. The results show that when the mass fraction of hexagonal boron nitride (hBN) is 30wt%, the thermal conductivity of the composite is 0.444 W/(m·K), which is 2.3 times that of pure EP. When the filler mass fraction is 30wt%, the thermal conductivity of the composite mater-ial prepared by using KH560 modified hBN is 0.456 W/(m·K), which is slightly higher than that of the unmodified material. For the hBN-cBN/EP hot-pressed composite material, when the filler mass fraction is 30wt%, the in-plane thermal conductivity is 1.32 W/(m·K), which is much greater than the normal thermal conductivity. The hBN/EP composite materials with two particle sizes (1, 5-10 μm) were prepared by blending. The results show that filler blending can significantly improve the heat resistance of the material. Two cubic boron nitride (cBN) with two particle sizes (1, 5-10 μm) were added to prepare composite materials and their hot-pressed composite materials. The results show that the addition of cBN and hot-pressing can improve the heat resistance of the composite materials.