Enhanced switching electric field and breakdown strength of epoxy composites with core-shell silicon carbide nanoparticles

Abstract

Silicon carbide (SiC) is widely used to improve the non-linear conductivity of non-linear resistive field grading composite. In this paper, the SiC nanoparticles are modified into core-shell nanoparticles with silica (SiO2) coating on the surface and are characterised by transmission electron microscopy and X-ray diffraction, respectively. The 7 wt% SiC@SiO2/epoxy nanocomposite is then prepared, and the pure epoxy and 7 wt% SiC/epoxy nanocomposite are prepared as a contrast. The relative permittivity, thermally stimulated current, conductivity and breakdown strength are studied, respectively. The presence of SiO2 shell around SiC nanoparticles has a great effect on the relative permittivity and trap distribution. The epoxy nanocomposites show non-linear conductivity characteristics, compared with pure epoxy. The 7 wt% SiC@SiO2/epoxy nanocomposite has higher switching electric field and breakdown strength than the 7 wt% SiC/epoxy nanocomposite, which is helpful for the application of non-linear resistive field grading composite in higher-voltage equipment or components.