Study on the pulsed vacuum surface flashover characteristics of epoxy composites with micro TiO2 and Al2O3•3H2O fillers

Micro TiO₂ and Al₂O₃·3H₂O fillers were loaded into the epoxy resin by mixing different weight ratio. The flashover studies were conducted using 20 ns (rise time)/1.5 μm (half-height width time) pulse under 5 × 10^-3Pa vacuum. The surface flashover properties of micro TiO₂ and Al₂O₃·3H₂O/epoxy composites were presented. In addition, their dielectric spectrum and thermally stimulated depolarization current (TSDC) were measured. Results showed that when the weight percentage of the two fillers was both 10%, the flashover strength of the composite material was 28.4% higher than the epoxy resin´s. Considering the influence of the dielectric constant, the conductivity, the trap energy and the trap density, the flashover mechanism was discussed. It was found that the flashover characteristics were strongly correlated with the TSDC properties.