Silicon carbide (SiC) is widely used to improve the non-linear conductivity of non-linear resistive field grading composite. In this paper, the SiC nanoparticles are modified into core-shell nanoparticles with silica (SiO₂) coating on the surface and are characterised by transmission electron microscopy and X-ray diffraction, respectively. The 7 wt% SiC@SiO₂/epoxy nanocomposite is then prepared, and the pure epoxy and 7 wt% SiC/epoxy nanocomposite are prepared as a contrast. The relative permittivity, thermally stimulated current, conductivity and breakdown strength are studied, respectively. The presence of SiO₂ shell around SiC nanoparticles has a great effect on the relative permittivity and trap distribution. The epoxy nanocomposites show non-linear conductivity characteristics, compared with pure epoxy. The 7 wt% SiC@SiO₂/epoxy nanocomposite has higher switching electric field and breakdown strength than the 7 wt% SiC/epoxy nanocomposite, which is helpful for the application of non-linear resistive field grading composite in higher-voltage equipment or components.

中文翻译：

---

核壳碳化硅纳米粒子增强环氧树脂复合材料的开关电场和击穿强度

碳化硅（SiC）广泛用于提高非线性电阻场分级复合材料的非线性电导率。本文将SiC纳米颗粒改性为表面具有二氧化硅(SiO _{2 )涂层的核壳纳米颗粒，并分别通过透射电子显微镜和X射线衍射对其进行了表征。}然后制备7 wt% SiC@SiO ₂ /环氧树脂纳米复合材料，并制备纯环氧树脂和7 wt% SiC/环氧树脂纳米复合材料作为对比。分别研究了相对介电常数、热刺激电流、电导率和击穿强度。_{SiO 2}的存在SiC纳米粒子周围的壳对相对介电常数和陷阱分布有很大影响。与纯环氧树脂相比，环氧纳米复合材料表现出非线性导电特性。7 wt% SiC@SiO ₂ /环氧树脂纳米复合材料比7 wt% SiC/环氧树脂纳米复合材料具有更高的开关电场和击穿强度，有助于非线性电阻场分级复合材料在更高电压设备或组件中的应用。