环氧树脂表面特性与界面电荷关联性及其表面等离子体梯度改性

Epoxy resin (EP) is often used as insulating support in extra high voltage electrical equipment, and in recent years its insulation performance under HVDC condition has been highly concerned by the domestic and foreign scholars. Studies have shown that the gas-solid interfacial charge characteristics and insulation properties can be improved if the surface properties of EP are properly modified. However, the relationship between the chemical and physical properties of the EP surface and the interface charge has not yet been explored clearly, which leads to the lack of theory and pertinence of the insulation performance control method based on surface modification. In this project, based on the chemical methods such as plasma chemical vapor deposition, multi-component surface characteristics that are different from the substrate properties will be obtained. On the other hand, multi-scale modification of the surface morphology for EP will be carried out with the use of methods such as plasma etching. Then the relationship among chemical composition, physical morphology, and interface charge and insulation properties will be studied quantitatively. Moreover, in order to improve the interface charge and field intensity distribution of EP, the gradient structure modification of the surface chemical and physical properties will be realized by controlling the processing mode, position, time and strength in surface modification process based on the correlation study results. After the non-uniform surface chemical and physical properties are obtained, the mechanism and effect of gradient modification on the insulation properties will be further explored. The implementation of this project can provide scientific basis for exploring the optimization of surface modification of EP and the guidance for the design of HVDC projects.

环氧树脂（EP）绝缘材料常用作超/特高压电气设备绝缘支撑，其高压直流工况下的沿面绝缘性能研究近年来受到国内外学者高度关注。研究表明，EP表面改性处理可以改善气固界面电荷特性与绝缘性能。但EP材料表面理化特性与其界面电荷的关联性尚未探索清楚，导致基于表面改性的绝缘性能调控方法缺乏理论性与针对性。本项目基于等离子体化学气相沉积方法获得有别于EP基体特性的多组分化学表面特性，利用等离子体刻蚀等方法实现EP表面多尺度物理形貌改性，定量研究EP表面化学组分、物理形貌与界面电荷及绝缘性能间的关联关系。基于关联性，以界面电荷、表面场强优化分布为目标，通过控制EP表面改性技术的处理方式与位置、作用时间与强度等关键变量，对EP表面实施梯度改性，获得非均一化的表面理化特性，进一步研究梯度改性对绝缘性能的作用机理及调控效果。项目实施可为探索EP表面优化改性方法提供科学依据，并为高压直流工程绝缘设计提供理论指导。

在过去四年的时间内，本课题组对承担的课题项目进行了深入研究，完成了任务书的相关研究工作。取得的成果如下：.1.得到了环氧树脂（EP）表面理化特性与界面电荷及绝缘性能的关联关系。利用等离子体改性方法实现了EP的等离子体氩气刻蚀、氟化和镀硅处理，通过改变等离子体处理时间、前驱物种类等参数可实现EP表面形貌和化学组分的定向调控，进而影响表面电导率、陷阱能级分布等电气参数，最终改变EP的界面电荷聚散和沿面闪络特性。.2.提出EP表面理化特性的等离子体梯度结构改性技术及方法。提出了针对极不均匀电场的等离子体表面阶跃型梯度改性方法，设计出表面阶跃型梯度刻蚀、梯度氟化和梯度镀硅的EP。相比于传统均一型等离子体改性，采用阶跃型梯度改性方案可以进一步提升EP在极不均匀电场下的沿面闪络性能。.3.获得EP表面组分-形貌及其梯度特性对绝缘性能的协同作用机理。设计出氟硅二元阶跃型梯度EP，可充分结合两种改性手段的优势，最大程度地提升了EP在极不均匀电场下的沿面闪络性能。此外，提出了适用于稍不均匀电场的等离子体表面离散型梯度改性方案，得到了最优表面组分-形貌梯度参数。.4.得到EP表面非均一化特性对界面电荷及绝缘性能的影响机制。通过仿真手段得到表面电导率呈梯度分布时EP界面电荷聚散和电场强度的变化规律，结合实验研究获得等离子体梯度改性手段、EP表面理化特性、EP电气性能三者的映射规律，发现对于非均匀电场下的EP，其沿面闪络性能取决于最大场强、最大表面电荷积聚量以及电极间的表面电荷迁移速率。.该项目重点研究EP表面特性与界面电荷关联性，并提出基于等离子体技术的EP表面梯度改性新方法，从而获得基于表面组分-形貌及其梯度特性协同作用的绝缘性能优化调控技术。项目成果能够进一步完善绝缘材料表面改性理论体系与方法，为促进我国高压直流气体绝缘设备的推广应用奠定理论与技术基础，具有重要的理论意义和工程价值。