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This paper investigates the effect of nano-scale SiO 2 on the tracking failure properties of nanocomposites. Test samples were made by dispersing nano-scale SiO 2 powder in epoxy with the weight ratios of 0, 1, 3, 5, 7, 9 wt%. AC voltage was applied on a pair of needle-plate electrodes at the surface with the insulation distance of 10 mm. The time to tracking failure and discharge current were recorded. In order to distinguish the change of the tracking resistance from the confusing discharge current, a recurrence plot (RP) analysis of discharge current has been used. The patterns of the tracking failure were analyzed with fractal dimension (FD) method to quantify the carbonization degree. The results reveal that 3 wt% of nano-scale SiO 2 filler greatly increase the resistance to tracking failure of epoxy/SiO 2 nanocomposite.

Epoxy resin has become an integral part of electronic and electrical devices where the material is exposed to pulse stress. Surface charge accumulation and decay of charged dielectric materials are very important parameters related to the electrical properties of the material. Nano-composite technology makes it possible to improve electrical properties of insulating materials. Therefore, it is important to investigate the dynamic behavior of surface charge decay influenced by the nano filler on epoxy resin. In this paper, it was attempted to clarify the effect of pulse stress on the electrical properties of epoxy resin nanocomposites focused on the surface charge accumulation and decay based on the TiO 2 nano-filler. Prior to test, the samples were prepared by dispersing nano-scale TiO 2 into epoxy resin by mixing with shear force. Corona charging and decay tests were independently performed at room temperature with the same humidity. The surface charge distribution was measured by means of an electrostatic voltmeter. Obtained results show the dependence of the accumulated charge density as well as the charge decay rate upon the different nano filler loading that is varied as a function of the rise time of pulse stress. It is suggested that the charge dynamics is dependent upon the characteristics of localized surface states that are altered by the nano filler induced chemical reactions.