Influences of Electrical Aging on the Electrical Properties of Epoxy/Silicon Carbide Composites

ABSTRACT For the purpose of studying the impacts of electrical aging on nonlinear resistive field grading materials, epoxy silicon carbide composites were manufactured under varying electrical aging field and time. The microscopic morphologies of the samples were characterized. The dielectric properties, breakdown strength, conductivity, and trap density were tested. The findings show that the permittivity (along with loss tangent) of the samples increased significantly with the elevation of aging electric field and extension of aging time. Similar phenomena also occurred in the trap density. The breakdown strength of aged composites was reduced relative to unaged counterparts, and for nonlinear conductivity, elevated aging electric field (or prolonged aging time) led to a decreased switching electric field and an increased nonlinear coefficient. A higher nonlinear coefficient is beneficial to optimizing the electric field uniformity within power equipment, but the reduced switching electric field and breakdown strength induced by electrical aging endanger the reliability of the composites. The present study establishes a fundamental basis for elucidating the long‐term stability of epoxy/SiC composite‐based nonlinear resistive field grading materials.