Effect of nano-fillers on electrical breakdown behavior of epoxy resin

Epoxy resin is widely used in high voltage apparatus as insulation due to its excellent mechanical, electrical and chemical properties. In recent years, researches on epoxy resin/nanocomposites have shown that the presence of nano-size filler in epoxy resin system can improve electrical, thermal and mechanical properties significantly. In the present paper, the epoxy resin containing nanosize SiO₂ and Al₂O₃ fillers were prepared and the influence of nanosize filler on nanocomposites electrical properties was investigated. The epoxy resin (LY556), commonly used in power apparatus, was used as the base material and nano-sized fillers were mechanically mixed into the epoxy resin. The influence of filler type, filler size and filler concentration on nanocomposites ac breakdown strength and space charge accumulation were examined. In addition, traditional epoxy resin/microcomposites were also prepared and tested and the results were compared with those obtained from epoxy resin/nanocomposites. The present results show that the presence of nano-sized fillers affects space charge accumulation and ac breakdown strength shows a slight reduction. The dielectric properties are strongly influenced by the filler size type and concentration.