Synergistic Effects of Electric Field Assist and Micro/Nano SiC Particles on the Nonlinear Conductivity of Epoxy Composites

Nonlinear conductivity makes the polymer composite self-homogenize the electric field distribution, and it can be regulated by micro and nano semiconducting particles or the electric field assist. The micro/nano particles and electric field assist may have a synergistic effect on the nonlinear conductivity, but this is rarely paid attention to. In this paper, the electric field assisted epoxy composites containing micro and nano SiC particles were prepared together with the untreated micro-composite and nano-composite. The microstructure was characterized by Fourier-transform infrared spectroscopy (FTIR) and energy dispersive spectroscopy (EDS). The dielectric spectra, DC conductivity, surface potential decay and flashover voltage were tested. The results show that, the electric field assist makes the filler particles arrange in chains in the epoxy matrix, forming the conductive paths. Compared to the untreated composites, the field-assisted composites shows significant nonlinear conductivity, and the nonlinear coefficient increases greatly. Furthermore, the micro/nano particles and the assisted electric filed synergistically enhances the surface potential decay speed and flashover voltage. The surface flashover voltage of the field-assisted composite increases by a factor of 1.4 than that of the nano-composite. This work provides a basis for the development of the nonlinear resistive field grading material.