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

In this paper, SiO2 particles with three particle sizes of 60 nm, 2 mu m, and 25 mu m were added as fillers into the composites prepared by epoxy resin and micron silicon carbide to investigate the mechanism of SiO2 particle size on the nonlinear electrical conductivity and breakdown characteristics of the composites. Compared with SiC/EP composites, the smaller the added SiO2 particle size, the lower the current density at high fields and the higher the breakdown field strength of SiO2/SiC/EP composites. The nonlinear coefficients of SiO2/SiC/EP composites increased slightly with the addition of 1phr 25 mu m SiO2 and 4phr 2 mu m SiO2, and the breakdown field strengths were increased by 55.36% and 66.77%, respectively. The SiO2/SiC/EP composites with the addition of 4phr 60 nm SiO2 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 SiO2 doping amount, compared with the composites with the same particle size and low doping amount, the larger the SiO2 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.