Epoxy resin is widely deployed as a high voltage electrical insulation material when compounded with inorganic fillers. However, in the laboratory, the filler prevents visual observation of the long-term degradation known as electrical treeing. To date therefore, much laboratory testing has been conducted on unrepresentative unfilled materials. Here, the impact of micro-sized fillers on the treeing phenomenon in an epoxy system has been explored. Sub-micrometre resolution 3D reconstructions of electrical trees are reported from X-ray computed tomography (XCT) using an advanced ‘pink beam’ synchrotron light source imaging system. The role of filler particles between 1 and 10 μm in size on tree channel propagation is reported. In highly filled materials (30% by weight) a radical change in tree growth behavior is seen, leading to bush tree rather than branch tree growth. The dielectric breakdown time at constant stress was also found to increase as the square root of the filler level. The change in geometry of tree growth may explain the extended life of filled materials in high voltage applications.

中文翻译：

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微硅填充环氧树脂中的电树生长

当与无机填料复合时，环氧树脂被广泛用作高压电绝缘材料。然而，在实验室中，填充物会阻止目视观察长期退化的现象，称为电树。因此，迄今为止，已对不具代表性的未填充材料进行了大量实验室测试。在这里，研究了微尺寸填料对环氧树脂体系中树状现象的影响。使用先进的“粉红色光束”同步加速器光源成像系统，通过 X 射线计算机断层扫描 (XCT) 报告了电树的亚微米分辨率 3D 重建。报告了尺寸在 1 到 10 微米之间的填料颗粒对树形通道传播的作用。在高度填充的材料（按重量计 30%）中，可以看到树木生长行为的根本变化，导致灌木树而不是树枝树的生长。还发现恒定应力下的介电击穿时间随着填料含量的平方根而增加。树木生长几何形状的变化可以解释填充材料在高压应用中的寿命延长。