间位芳纶绝缘纸孔隙结构与浸油性能的构效关系研究

A Study on the Structure-Property Relationship Between the Pore Structure and Oil Absorption Properties of Meta-Aramid Insulation Paper

关键词:  间位芳纶  CT扫描  孔隙  渗透性能

Key Words:meta-aramid  Micro-CT  pore  permeability

摘要:间位芳纶绝缘纸具有优异耐热性和电气绝缘性能，在牵引变压器及高温绝缘系统中具有应用潜力，其油浸充分性直接影响油-纸复合绝缘结构的可靠性。本研究选取3种典型工业级间位芳纶绝缘纸（克重40.7-47 g/m2）为研究对象，开展动态浸油实验，并利用Micro-CT三维成像结合图像预处理与灰度分析的局部阈值分割方法，实现了纤维与孔隙的准确识别，进而重构三维孔隙结构，提取孔隙率、孔径分布、平均配位数、分形维数等参数，进一步采用孔隙尺度渗流模拟计算不同方向绝对渗透率。结果表明，间位芳纶绝缘纸的油浸渍性能并非由总孔隙率单一决定，而是受有孔径分布、孔喉连通性及厚度方向孔隙非均匀性的共同影响；其中，连通孔隙和低阻力渗流通道对油液输运能力具有主导作用。研究结果揭示了间位芳纶绝缘纸三维孔隙结构调控油浸行为的作用机制，可为油浸式高压电气设备用芳纶绝缘纸的孔隙结构设计、浸油工艺优化及材料筛选提供依据。

Abstract:Meta-aramid insulation paper possesses excellent heat resistance and electrical insulation properties, offering potential applications in traction transformers and high-temperature insulation systems, and the adequacy of its oil impregnation directly affects the reliability of oil-paper composite insulation structures. In this study, three typical industrial-grade meta-aramid insulating papers (basis weight 40.7-47 g/m²) were selected as test specimens for dynamic oil impregnation testing. Using Micro-CT 3D imaging combined with image preprocessing and a local threshold segmentation method based on grayscale analysis, accurate identification of fibers and pores was achieved. This enabled the reconstruction of the 3D pore structure and the extraction of parameters such as porosity, pore size distribution, average coordination number, and fractal dimension. Furthermore, pore-scale seepage simulations were employed to calculate the absolute permeability in different directions. These findings reveal the mechanism by which the three-dimensional pore structure of meta-aramid insulating paper regulates oil-impregnation behavior, providing a basis for the design of pore structures, optimization of oil-impregnation processes, and material selection for aramid insulating paper used in oil-immersed high-voltage electrical equipment.