Filler Size Effect on Tuning Electrical, Mechanical, and Thermal Properties of Field Grading Composites

A field-grading composite with a low switching field, stable nonlinear conductivity performance, and excellent mechanical and thermal properties was prepared by using hybrid ZnO micro-spherical varistors of different particle sizes as the fillers and silicone rubber as the matrix. The hybrid effects of particle size on the electrical, mechanical, and thermal properties of ZnO micro-spherical varistors composites are investigated. An increase in the ZnO micro-spherical varistor size in the composites will lower the switching field but lead to degradation of the mechanical properties and stability of the nonlinear conductivity properties. The silicone rubber is incorporated with a mixture of hybrid ZnO micro-spherical varistors of different sizes at an optimal mass ratio range exhibited low switching field, stable nonlinear conductivity performance, and excellent mechanical and thermal properties. Our findings are helpful to comprehensively regulate performance of advanced field-grading materials and increase stability and durability of electronic and electrical devices.