h-BN/聚酰亚胺纳米复合绝缘介质界面区导热特性和机理的研究

The poor thermal conductivity of electrical insulation systems severely restricts the miniaturization and performance of power equipments and devices. Although the nanodielectrics, as the developing direction on the insulating materials, have shown excellent insulation performances, how to improve the thermal conductivity of nanodielectrics stays as the important issue in the research field. The key factors limiting the improvement of thermal conductivity of nanodielectrics are the characteristics of nanoparticle, the shape of nanoparticle, and the interface in nanodielectrics. In the present proposal, the nano hexagonal boron nitride (h-BN), two-dimensional nanoparticles, is chosen as thermally conductive filler due to its excellent insulation behavior as well as high thermal conductivity. The layer-by-layer method will be empolyed to tailoring-synthesize regularly arranged h-BN/polyimide nanodielectrics. Interfacial structures will be constructed by functional graft h-BN with different functional groups. Study the thermal conductivity of nanodielectrics with different interface, and then reveal the thermal conductivity mechanism of interface region will effectively accelerate the development of thermally conductive nanodielectric. Eventally, it is important to miniaturization and performance improvement of electrical equipment and devices.

电气绝缘系统的导热性差严重制约着电力设备和器件的小型化和性能提高。纳米电介质代表着电气绝缘材料的发展方向，尽管其性能优异，仍存在导热性能难以提高的问题。限制纳米电介质导热性能提高的关键因素是纳米粒子的特性、形状和排列，以及纳米电介质中的界面。本项目选择高导热和高绝缘的六方氮化硼二维纳米粒子，采用逐层有序的方式复合后聚合来可控地制备六方氮化硼二维纳米粒子规整排列的纳米复合介质。通过表面功能化接枝氮化硼，构造出不同的界面结构。研究具有不同界面结构的纳米复合介质的导热特性，研究界面区的热导率、热容等特性参数，研究纳米粒子表面性质、与基体的复合状态、界面区厚度等因素与导热特性的关联，揭示界面区对复合介质导热的作用机理。为提高具有优异电气绝缘性能纳米电介质的导热性能，发展高性能、小型化电力设备和器件提供理论和技术指导。

电力设备绝缘系统的导热性能一直是高电压与绝缘技术领域的基础前沿问题，聚合物绝缘材料导热效率低是制约电力设备向高性能、小型化发展的技术瓶颈之一。研究聚合物绝缘材料的导热特性和机理，对提高其导热性能，进而提高电力设备的可靠性具有重要意义。将聚合物基体与导热填料复合是制备高导热复合材料的主要方法。复合材料中，纳米粒子虽然粒径很小，但相对于分子来说仍然具有较大的体积。因此，在纳米复合绝缘材料中实际存在两相，具有相界面。界面的性质决定了各个作用在两相之间的传递与转换，对于材料的整体性能具有重要影响。因此，研究不同界面与复合材料导热性能之间的关系，对于制备高导热绝缘材料，进而对于提高电力设备绝缘系统的导热性能具有重要的理论支撑意义。针对研究h-BN/聚酰亚胺纳米复合绝缘介质界面区导热特性和机理这一目标，本项目主要完成了以下工作：建立了聚酰亚胺薄膜的制备方法；成功构筑了不同的界面区结构；确认了界面区结构的不同对复合材料导热性能有影响；研究了微观物理界面对复合材料导热性能的影响；研究了界面区特性对复合材料导热性能的影响；研究了材料导热性能与耐烧蚀特性之间的关系。