氮化铝/氮化硼/碳纳米管/硅橡胶复合材料的力致填料取向对导热性能的影响

随着科学技术的发展，电子元器件发热量大幅度增加，因此开发兼具高导热和高绝缘性能材料日益迫切。以甲基乙烯基硅橡胶（SR）为基体，碳纳米管（CNTs）、六方氮化硼（BN）以及氮化铝（AlN）为导热填料，通过机械共混法制备导热复合材料。研究3种导热填料复配对复合材料的导热性能、绝缘性能和力学性能的影响，研究填料取向对复合材料导热性能的影响，研究材料表面温升与加热时间的关系。采用Agari模型预测复合材料的理论热导率。通过热红成像、扫描电子显微镜、X射线衍射分析、热重分析等对复合材料进行表征。结果表明：随着复配导热填料中AlN用量的减少，BN和CNT_S用量的增加，复合材料的热导率逐渐升高；当AlN为80 phr，BN为68 phr，CNTs为2 phr时，复合材料的垂直热导率为1.857 W·m^-1·K^-1，平行热导率为2.853 W·m^-1·K^-1，体积电阻率为2.18×10¹² Ω·cm，拉伸强度达4.3 MPa，复合材料的综合性能较好。

Effect of filler orientation induced by force on thermal conductivity of AlN/BN/CNTs/SR composites

With the development of technology,the amount of heat generated by electronic components has increased significantly.Therefore,it is increasingly urgent to develop materials with high thermal conductivity and high insulation properties.Thermally conductive composites were prepared by mechanical blending using methyl vinyl silicone rubber(SR)as the matrix,and some particles including carbon nanotubes(CNTs),hexagonal boron nitride(BN)and aluminum nitride(AlN)as thermally conductive fillers.The effect of hybridization of three kinds of fillers on the thermal conductivity,electrical insulation and mechanical properties of the composites was studied.The influence of the filler orientation on the thermal conductivity of the composites was investigated.The effect of the heating time on the surface temperature of the composites was also investigated and the theoretical thermal conductivity of the composites was fitted according to Agari model.The composites were characterized by an infrared thermal image,scanning electron microscopy(SEM),X-ray diffraction(XRD)and thermogravimetric analysis(TGA).The results show that with the decreased addition of AlN and the increased loadings of BN and CNTs,the thermal conductivity of the composites is gradually increased.When the content of AlN,BN and CNTs is 80,68 phr and 2 phr respectively,the composites show better overall performance,where the out-plane and in-plane thermal conductivity of the composites is 1.857 W·m^-1·K^-1 and 2.853 W·m^-1·K^-1,and the volume resistivity and the tensile strength is 2.18×10¹²Ω·cm and 4.3 MPa,respectively.