The relationship between surface flashover properties and trap characteristics of nanocomposites

It is known that nanocomposites may have better surface flashover properties, which are important to the use of dielectrics in electrical equipment. By changing the content of nanoparticles added into polymers, the surface flashover voltage of nanocomposites can be increased by 30 %. One reason is that the changing of nanoparticles makes a contribution to different trap characteristics. As the density and level of electron and hole type traps in nanocomposites, especially at the thickness less than 2 µm of the surface, differ with the varying particles, it is of great value to study the relationship between trap characteristics and surface flashover properties. In this paper, epoxy nanocomposite samples with different trap characteristics are prepared. The trap characteristics are controlled by changing the content of Al2O3 nanoparticles (0 wt %, 0.5 wt %, 1 wt %, 3 wt %, 5 wt %). Distribution of electron traps can be obtained with negative corona charging and thus we obtained the isothermal surface potential decay characteristics of different kinds of samples. Surface flashover voltages in vacuum under DC voltage were tested. The results we obtained implied the connection between trap characteristics and surface flashover properties. It shows that two types of electron traps (shallow trap and deep trap) can be obtained by controlling the particle content. The level and density of traps make different contribution to electron transport and electron emission at the surface, which influences the surface flashover of nanocomposites.