Study on the vacuum surface flashover characteristics of epoxy composites with microTiO2 fillers under steep high-voltage impulse

With the tendency towards higher power, higher capacity and less scale of the pulsed-power devices, the vacuum surface flashover strength turns to be a primary limitation of the development of the pulsed-power equipments, as it is much lower than the vacuum breakdown strength. To improve the different capabilities of the epoxy composite material, different kinds of micron inorganics are filled to the epoxy resin. TiO₂ (TO) is a typical kind of oxide ceramic, as well as an important sort of broad band-gap oxide semiconductor material. With its unique optical and electrical properties, excellent chemical stability, high dielectric constant and semi-conductive properties, it is widely applied to enhance the performance of the organic composite material. In this article, the experimental results of vaccum surface flashover characteristics of epoxy resin and epoxy resin cast with 1 mum powdered TO samples are presented. In addition, their dielectric spectrum and thermally stimulated depolarization current (TSDC) are measured. Considering the influence of the dielectric constant, the conductivity, the trap energy and the trap density, associated with the interface theory, the article analyzes the influence mechanism of micro-scale TO fillers on the vacuum flashover voltage of epoxy composite material.