Study on Breakdown Strength and Nonlinear Conductivity Characteristics of BN and SiC Co-doped SiR Composite Dielectrics

Silicon rubber (SiR) is widely used in the field of electrical engineering because of its good electrical insulation, corrosion resistance, and mechanical properties. The modified SiR composite is helpful to solve the problem of an uneven electric field of high voltage direct current (HVDC) cable accessories. In this paper, SiR was selected as the matrix, semiconductive silicon carbide (SiC), and boron nitride (BN) were selected as inorganic fillers. SiC and BN were added into SiR by in-situ polymerization combined with high-speed dispersion technology to prepare composite dielectric samples. The electrical properties of pure SiR, SiC/SiR composite dielectrics with 5 wt.%, 10 wt.%, 15 wt.%, and SiC/BN Co-doped SiR composite dielectrics were systematically studied. The results show that when the doping content of SiC is greater than 10 wt.%, the composite dielectrics show significant nonlinear conductivity characteristics. And when doped with SiC and BN at the same time, the SiC/BN/SiR composite dielectric maintains good nonlinear conductivity and breakdown strength.