Effect of SiO2 particle size scale on the electrical performance of epoxy-based nonlinear conductive composite

In this paper, SiO 2 particles with three particle sizes of 60 nm, 2 μm, and 25 μm were added as fillers into the composites prepared by epoxy resin and micron silicon carbide to investigate the mechanism of SiO 2 particle size on the nonlinear electrical conductivity and breakdown characteristics of the composites. Compared with SiC/EP composites, the smaller the added SiO 2 particle size, the lower the current density at high fields and the higher the breakdown field strength of SiO 2 /SiC/EP composites. The nonlinear coefficients of SiO 2 /SiC/EP composites increased slightly with the addition of 1phr 25 μm SiO 2 and 4phr 2 μm SiO 2 , and the breakdown field strengths were increased by 55.36% and 66.77%, respectively. The SiO 2 /SiC/EP composites with the addition of 4phr 60 nm SiO 2 particles showed the most significant attenuation of the conductivity current and the most prominent enhancement of the breakdown field strength, but the nonlinear coefficient was reduced by 24.6%. With the increase of SiO 2 doping amount, compared with the composites with the same particle size and low doping amount, the larger the SiO 2 particle size, the decrease of the current density of the composites under high field intensity is more obvious, and the dielectric constant drops even more.