Nonlinear conductivity and breakdown strength characteristics of silicon carbide and hexagonal boron nitride co-doped epoxy resin composites

In this study, the method of co-doping semi-conductor silicon carbide (SiC) and insulating inorganic phase hexagonal boron nitride (h-BN) in epoxy resin (EP) composites has been proposed for considering both the nonlinear conductivity and the breakdown strength. First, the epoxy-based composites were fabricated and prepared by hot press vulcanization. Then, the phase structure and the microstructure of the composites were characterized by XRD and SEM. Finally, the nonlinear conductivity and the breakdown strength of the composites were tested. The results indicate that the breakdown strength of the 1 wt. % h-BN/3 wt. % SiC/EP composite reaches 115.6 kV/mm, which is 4 times higher than that of the single-doped 3 wt. % SiC/EP composite. More importantly, the appropriate h-BN and SiC contents of the co-doped EP composites still exhibit excellent nonlinear electrical conductive properties. The results indicate that both the nonlinear conductivity and the breakdown strength have been obtained by the semi-conductor and insulator co-doping strategy.