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.

Electric Field Assist on Enhancing the Electrical Breakdown Strength of Cross-Linked Polyethylene for Power Cable Insulation

“…An approximation is used in the ranking of the breakdown strength and is defined as follows: P false( E normalb false) = false( i − 0.44 false) / false( n + 0.25 false) where n is the total number of breakdown strength ( i = 1, 2, 3, ..., n ).…”

DC assisted electric field on the improvement of the nonlinear electrical conductivity of SiC/LDPE field grading composites

“…Whereas with the growth of the DC assisted electric field (>0.3 kV mm −1 ), the curve of the current density against the electric field for the field assisted composites goes further away from that of the untreated composite. For the nonlinear resistive field grading material, the relationship between the current density and the electric field is often expressed as below [37].…”

Effect of Aged Nonlinear Resistive Field Grading Material on Electric Field Distribution of DC Cone Spacer

“…A DC breakdown test device with a maximum output of 60 kV was used to measure the DC breakdown strength of aged samples at 25 ± 1 • C. The sample was placed between two ball electrodes of 25 mm in diameter. In order to prevent surface flashover, the whole electrode system was immersed in silicon oil [16]. During the measurement, the voltage was applied to the sample at an increasing rate of 1 kV/mm until the breakdown occurs.…”