BN表面沉积纳米Sn对BN/环氧树脂复合材料导热绝缘性能的影响

采用液相还原法，制备了BN表面沉积纳米Sn粒子(BN-Sn NPs)杂化材料，用于环氧树脂(EP)的导热绝缘填料。BN-Sn NPs表面纳米Sn的粒径和熔点分别为10~30 nm 和166.5~195.3℃。BN表面沉积纳米Sn后，粉体Zeta电位及压片的导热系数增加，EP滴在压片表面的接触角降低。在BN-Sn NPs/EP复合材料固化过程中，BN-Sn NPs表面纳米Sn熔融烧结，有利于填料相互桥联在一起，降低接触热阻，并改善界面性能，从而提高BN-Sn NPs/EP复合材料的导热系数。当填料体积含量为30vol%时，BN-Sn NPs/EP复合材料的导热系数达1.61 W(m·K)?1，比未改性BN/EP复合材料的导热系数(1.08 W(m·K)?1)提高了近50%。Monte Carlo法模拟表明，BN和BN-Sn NPs在EP基体中的接触热阻(R_c)分别为6.1×106 K·W?1和3.7×106 K·W?1。与未改性BN/EP复合材料相比，BN-Sn NPs/EP复合材料的介质损耗增加，介电强度及体积电阻率降低，但仍具有良好电绝缘性能。 

Effects of BN surface deposited with nano Sn on thermal conductivity and electrical insulation of BN/epoxy composites

Hybrid materials composed of Sn nano particles deposited on BN surface (BN-Sn NPs) were constructed as thermal conductive and electrical insulating fillers for epoxy(EP) by liquid-phase chemical reduction method. The diameter and melting point of Sn nano particles on BN-Sn NPs surface are 10–30 nm and 166.5–195.3℃, respectively. Both the Zeta potential of BN-Sn NPs powder and thermal conductivity of BN-Sn NPs pressed sheet increase, while the contact angle of EP droped on BN-Sn NPs pressed sheet decreases after BN surface deposited with nano Sn. During the curing process of BN-Sn NPs/EP composites, the nano Sn particles on BN-Sn NPs surface melt and sinter, simultaneously bridge the individual fillers, which results in the lower thermal contact resistance between the fillers, and the improved interfacial behavior. The feature of enhanced thermal conductivity reflects in BN-Sn NPs/EP composites. When the filler volume fraction is 30vol%, the thermal conductivity of BN-Sn NPs/EP composites reaches 1.61 W(m·K)?1, nearly 50% higher than that of the pristine BN/EP composites (1.08 W(m·K)?1). The results of Monte Carlo simulation demonstrate that the thermal contact resistance (R_c) of BN and BN-Sn NPs in the EP matrix are 6.1×106 K·W?1 and 3.7×106 K·W?1, respectively. The BN-Sn NPs/EP composites exhibit higher dielectric loss and lower dielectric strength and volume resistivity than that of the pristine BN/EP composites, while still have good electrical insulating properties.