The long-term operation of motors induces substantial alterations in the surface conductivity and nonlinear coefficient of anti-corona paint, diminishing its efficacy and jeopardizing the longevity of large motors. Hence, the development of high-performance anti-corona paint holds paramount importance in ensuring motor safety. In this study, we integrate two nano-fillers, namely silicon carbide (SiC) and organic montmorillonite (O-MMT), into a composite matrix comprising micron silicon carbide and epoxy resin (SiC/EP). Subsequently, three distinct types of anti-corona paint are formulated: SiC/EP, Nano-SiC/EP, and O-MMT/SiC/EP. Remarkably, O-MMT/SiC/EP exhibits a glass transition temperature about 25 °C higher than that of SiC/EP, underscoring its superior thermal properties. Moreover, the introduction of nano-fillers markedly augments the surface conductivity of the anti-corona paint. Aging tests, conducted across varying temperatures, unveil a notable reduction in the fluctuation range of surface conductivity post-aging. Initially, the nonlinear coefficients exhibit a declining trend, succeeded by an ascending trajectory. The O-MMT/SiC/EP composite displays a maximum nonlinearity coefficient of 1.465 and a minimum of 1.382. Furthermore, the incorporation of nanofillers amplifies the dielectric thermal stability of epoxy resin composites, with O-MMT/SiC/EP showcasing the pinnacle of thermal endurance. Overall, our findings elucidate the efficacy of nano-fillers in enhancing the performance and longevity of anti-corona paint, particularly highlighting the exceptional attributes of the O-MMT/SiC/EP composite in bolstering motor safety through improved thermal stability and electrical properties.

To solve the problem of corona discharge generated by the stator wire rod of large high-voltage motors, anti-corona technology should be developed rapidly to ensure the safe operation of power generation systems. A nonlinear anti-corona material is often used to coat the primary insulation at the end of the stator rod to improve the unevenness of the electric field and to reduce the problem of shortening the service life of the primary insulation caused by the uneven phenomenon of field strength. It is imperative to study composites with good nonlinear electrical conductivity properties. In this paper, Tetra-needle-like ZnO whiskers (T-ZnOw) with a three-dimensional four-needle three-dimensional structure was added to the montmorillonite/silicon carbide/epoxy (MMT/SiC/EP) composite system to improve the electrical properties of the hybrid system, and T-ZnOw/MMT/SiC/EP micro-nanocomposites were prepared. The result of dispersion and interfacial overlap of inorganic fillers in the matrix was shown by scanning electron microscope. The conductivity, breakdown, and dielectric properties of the composites were tested. The results show that T-ZnOw can constitute an excellent conductive path inside the composite and reduce the threshold field strength of the composite. It improves the electrical conductivity and nonlinear coefficient of the composite. The content of T-ZnOw is 1 phr, which can effectively enhance the breakdown field strength of the composite. Its range of 9 phr reduces the relative dielectric constant and the dielectric loss angle tangent value.

In this paper, SiO2 particles with three particle sizes of 60 nm, 2 mu m, and 25 mu m were added as fillers into the composites prepared by epoxy resin and micron silicon carbide to investigate the mechanism of SiO2 particle size on the nonlinear electrical conductivity and breakdown characteristics of the composites. Compared with SiC/EP composites, the smaller the added SiO2 particle size, the lower the current density at high fields and the higher the breakdown field strength of SiO2/SiC/EP composites. The nonlinear coefficients of SiO2/SiC/EP composites increased slightly with the addition of 1phr 25 mu m SiO2 and 4phr 2 mu m SiO2, and the breakdown field strengths were increased by 55.36% and 66.77%, respectively. The SiO2/SiC/EP composites with the addition of 4phr 60 nm SiO2 particles showed the most significant attenuation of the conductivity current and the most prominent enhancement of the breakdown field strength, but the nonlinear coefficient was reduced by 24.6%. With the increase of SiO2 doping amount, compared with the composites with the same particle size and low doping amount, the larger the SiO2 particle size, the decrease of the current density of the composites under high field intensity is more obvious, and the dielectric constant drops even more.

具有非线性电导特性的电介质被广泛应用于解决许多领域的高能放电问题(如航天器充电和电机绝缘).本文通过在含有SiC和蒙脱土(MMT)微纳米复合体系中继续添加零维或一维纳米材料来进一步优化复合材料的非线性电导特性及其他电学性能.通过X射线衍射仪对MMT有机化改性前后的层间距进行了表征;通过扫描电子显微镜对复合材料内部各填料的分散情况以及界面状态进行了表征;通过对复合材料进行电导、击穿和介电频谱测试来研究纳米填料的维度对电学性能的影响规律.实验结果表明,在MMT-SiC/EP复合体系中添加一维四针状氧化锌(T-ZnOw)比零维颗粒状ZnO,可以更加有效增加体系中界面重合率,更加容易在复合材料内部构成良好的载流通路,能够在有效降低复合材料的阈值场强,提高复合材料的电导率和非线性系数,使得复合材料具备优越非线性电导特性的同时,不仅可以保证击穿场强不会太低,还可以降低复合材料的相对介电常数和介质损耗角正切值.

Nonlinear composite materials serve to homogenize electric fields and can effectively improve the local concentration of the electric field in power systems. In order to study the nonlinear surface conductivity properties of micro-nano epoxy composites, two types of epoxy micro-nano composite specimens were prepared in the laboratory using the co-blending method. The surface conductivity of the composites was tested under different conditions using a high-voltage DC surface conductivity test system. The results show that the surface conductivity of micro-nano structured composites increases and then decreases with the rise of nanofiller doping concentration. The nonlinear coefficient was 1.781 at 4 wt% of doped nanostructured SiC, which was the most significant nonlinear coefficient compared to other doping contents. For the same doping concentration, the micro-nano structured composites doped with nanostructured SiC have more significant surface conductivity at the same test temperature with a nonlinear coefficient of 1.635. As the temperature increases, the surface conductivity of the micro-nano structured composite increases significantly, and the threshold field strength moves towards the high electric field. Along with the increase in temperature, the nonlinear coefficients of micro-nano composites after doping with nanostructured SiC showed a gradually decreasing trend. The temperature has little effect on the nonlinear coefficients of the micro-nano structured composites after doping with O-MMT.