Enhanced Nonlinear Conductivity Properties of Epoxy Resin-Based Composites via Filler Design Using Donor-Doping

Epoxy matrix composites with nonlinear conductivity properties can effectively regulate the electric field distribution at the end of the motor, thus suppressing the corona phenomenon. In this study, ZnMn2O4and Al3+doped ZnMn2O4powders were successfully prepared by the coprecipitation method, and then added into epoxy resin according to different mass fractions for the preparation of composites. The microstructure and dielectric properties of the composites were systematically studied. The results show that ZnMn2O4/EP and Al3+doped ZnMn2O4/EP composites exhibit nonlinear conductivity properties with certain filler content. The nonlinear coefficient of Al3+doped ZnMn2O4/EP composites with 10 wt.% is 3.42, and the breakdown strength is close to that of pure epoxy resin. The tunneling effect and space charge limiting current effect are responsible for the conductive behavior. The filler design through donor-doping is an effective route to enhance the nonlinear conductivity of the composite.