Effects of second particles on nonlinear resistance properties of microvaristor-filled composites

Microvaristors are used particularly as lightning arrestors. In addition, they are used as electric field grading materials and stress control devices to reduce the localization of electric fields in various electric equipment. Nonlinear resistance properties are generally attributed to the high-loading of microvaristor fillers in the resin. However, high-loading is prone to cause aggregation and sedimentation of microvaristor fillers in the resin. This tendency adversely affects nonlinear resistance properties based on microvaristor fillers. Therefore, secondary particles should be provided as a disperser and then these particles can help the microvaristor to disperse homogeneously. In addition, the secondary particles can act as conducting paths between microvaristor particles. In recent research, we developed an effective way to improve the nonlinear resistance properties of a microvaristor-filled composite material. In the method, we focused on the adding of the semi-conductive whiskers as secondary particles to the resin. We chose the candidates of the second particles based on the shapes and the electrical properties. We finally determined the semi-conductive whiskers with the tetrapod-like shape. The effects of secondary particles on the nonlinear resistance properties of microvaristor-filled materials are investigated in this paper.