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

Abstract

Nonlinear resistive field grading material presents nonlinear electrical conductivity, and self-homogenizes the electric field distribution. The nonlinear conductivity is closely associated to the filler distribution, which can be modulated by the electric field assist during the material preparation. In this paper, the effects of the direct current (DC) electric field assist on the filler distribution and nonlinear conductivity of the nonlinear resistive field grading materials were studied for the first time. The silicon carbide (SiC)/low-density polyethylene (LDPE) composites were prepared under different DC assisted electric field. The composites’ microstructure, dielectric spectra and DC conductivity were characterized, respectively. Results illustrate that the DC electric field assist leads to the gradient distribution of SiC filler in the matrix, and also contributes to the SiC particles’ chains. Compared with the untreated SiC/LDPE composite, the electric-field assisted composites show more distinct nonlinear conductivity characteristics when the DC assisted electric field exceeds 0.3 kV mm−1, which is attributed to the percolation phenomenon of SiC particles. This work is helpful to design the dielectric functionally graded materials, and to self-homogenize the electric field distribution in power apparatus and electronic devices.