Nonlinear Electrical Conductance Triggered by Partial Discharge of Fluorinated Carbon Nanotube Clusters and Its Applications in Field Grading

Materials with nonlinear conductivity are promising for electric field grading in various electrical and electronic devices because of their self-adaptability. In this study, we reported a nonlinear mechanism in fluorinated multi-wall carbon nanotube (F-MWCNT) clusters based on partial discharge in their porous structure. Excellent nonlinear conductivity featuring a low threshold electric field of around 2 kV/mm and a wide range of switching fields was observed after loading an ultra-low F-MWCNT loading ratio of 0.5 wt% into the UV-cured resin. Both experimental and theoretical analyses were performed to explain the underlying nonlinear mechanism. The improved electric field mitigation effect of the composite with F-MWCNT compared with the conventional inorganic fillers like SiC was validated by a flashover test in compressed SF6 gas. Simulations were also conducted to explain the flashover threshold improvement considering the generation of seed electrons for ionization, which was in agreement with the experimental results.