ZnO压敏微球/硅橡胶复合材料介电弛豫特性

控制高压设备内部电场均匀分布是有效防止高压设备绝缘材料老化及故障的关键，ZnO压敏微球/硅橡胶(Si R)复合材料因其非线性电导和介电特性，常用于高压设备均压结构中。该文制备ZnO体积分数为5%～40%的ZnO/SiR复合材料，在0.1Hz～1.0MHz频率范围以及-40～160℃温度范围内，利用宽频介电谱仪获得不同ZnO体积分数的ZnO/SiR复合材料的弛豫过程，可知ZnO/SiR复合材料中存在β弛豫、内部偶极极化(intermediate dipolar effect,IDE)弛豫和α弛豫3种弛豫形式，分别由硅橡胶基体的粘流态转变、聚合物支链运动以及ZnO压敏微球引起。通过对IDE弛豫时间对数与温度倒数的线性拟合可知，ZnO/SiR复合材料IDE弛豫的产生机制为ZnO压敏微球内部热激活载流子的迁移与积累。研究结果为ZnO/SiR复合材料的弛豫过程提供了基础数据，并为该复合物在高压设备中的应用提供参考。

Dielectric Relaxation Characteristics of ZnO Microvaristor/silicone Rubber Composite

Keeping uniform distribution of electric field in high voltage equipment is an effective method to prevent the insulation materials from aging or failure.ZnO microvaristor/silicone rubber(SiR)composites have been used in electric field grading structures for high voltage equipment due to the nonlinear conductance and dielectric properties.In this paper,ZnO/SiR composites with volume fraction of 5%~40%ZnO were prepared.The relaxation processes of ZnO/SiR composites with different volume fractions of ZnO have been obtained by using broadband dielectric spectroscopy(BDS)in the frequency range of 0.1Hz~1.0MHz and the temperature range of-40℃~160℃.Three kinds of relaxations have been found,i.e.βrelaxation,IDE relaxation andαrelaxation,which are caused by the movement of polymer branch chain,ZnO microvaristor,and the transition to viscous flow state of silicone rubber,respectively.By linear fitting the logarithm of IDE(intermediate dipolar effect)relaxation time and inverse of temperature,it reveals that the mechanism of IDE relaxation in ZnO/SiR composite is the migration and accumulation of thermally activated carriers in ZnO microvaristor.This work provides basic data for the relaxation process of ZnO/SiR composites and supplies reference for the application of ZnO/SiR composites in high voltage equipment.