Effect of nano-fillers on electrical treeing in epoxy resin subjected to AC voltage

In the study, various amounts of nano- and micro-scale zinc oxide particles (62 nm and 1 /spl mu/m average diameter) were systematically introduced into an Araldite epoxy resin matrix for reinforcement purposes. The influence of these particles on the electrical treeing breakdown resistance was investigated experimentally. Samples of point-plane geometry were made and tested under 10 kV and 15 kV AC voltage. Comparative results are presented which show that the addition of a small amount (0.5 to 1 wt.%) of zinc oxide particles in the epoxy resin can make significant improvements in breakdown resistance by increasing the treeing time to breakdown, and nano-ZnO/epoxy composites are far more resistive to treeing breakdown than that of micro-ZnO/epoxy composites and neat epoxy resin. The possible reasons why and how smaller particles should improve the electrical treeing resistance are discussed.