BN/Al_(2)O_(3)复合粉末及其聚合物基复合材料的制备与导热性能

Preparation and Thermal Conductivity of BN/Al_(2)O_(3)Composite Powder and Its EP-based Composites

采用固-液相共混法制备了多种BN/Al_(2)O_(3)复合粉末,通过冻融法和表面修饰法对BN进行了改性处理,改变表面修饰剂类型和摩尔比得到了前驱体和烧结态BN/Al_(2)O_(3)复合粉末,并利用机械混合法制备了聚合物基BN/Al_(2)O_(3)复合材料,并测试分析了其导热性能。结果表明,经冻融处理的BN分散性和界面相容性明显优于未经冻融处理的BN。多巴胺对BN的改性效果优于聚乙二醇。采用多巴胺作为表面修饰剂且BN与Al(NO3)3的摩尔比为1:1时,能够得到纳米Al_(2)O_(3)均匀包覆的微米BN粉末,即BN/Al_(2)O_(3)微纳复合粉末,其聚合物基复合材料的导热系数可达0.62 W·m^(-1)·K^(-1),是纯聚合物导热系数的3倍,是采用纯微米BN粉末制备的聚合物基复合材料导热系数的1.5倍。在BN表面附着的Al_(2)O_(3)可以形成层状热传导通道,能够有效提高聚合物基BN/Al_(2)O_(3)复合材料的热导率。

Several boron nitride(BN)/aluminum oxide(Al_(2)O_(3))composite powders were synthesized by liquid-solid phase co-mixture method.BN was modified by the freeze-thaw method and surface modification.The precursor and as-sintered BN/Al_(2)O_(3)composite powders were obtained by changing the type of surface modification materials and the molar ratios.Additionally,the thermal conductivity of the epoxy resin(EP)-based BN/Al_(2)O_(3)composite materials prepared by mechanical mixture was measured and analyzed.Results show that the dispersion and interfacial compatibility of BN after freeze-thaw process are obviously better than those without freeze-thaw process.The modification effect of dopamine on BN is better than that of polyethylene glycol.When the dopamine is used as the surface modification material and the molar ratio of BN to Al(NO3)3 is 1:1,BN powder at micro-level with uniform nano-Al_(2)O_(3)deposition can be obtained,namely the BN/Al_(2)O_(3)micro/nano-composite powder.The thermal conductivity coefficient of this EP-based BN/Al_(2)O_(3)composite reaches 0.62 W·m^(−1)·K^(−1),which is 3 times and 1.5 times higher than that of the pure EP composite and EP-based composite material prepared by pure micro-sized BN powder,respectively.The deposited nano-Al_(2)O_(3)on BN surface can form multiple thermal conduction paths,thereby improving the thermal conductivity of the EP-based BN/Al_(2)O_(3)composites.