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Effect of nano-TiO2/EP composite coating on dynamic characteristics of surface charge in epoxy resin

As a modification method, surface coating is considered to be an effective method in regulating the surface state of the epoxy resin, thus suppressing the accumulation of surface charge. In this paper, epoxy resin coated with nano-TiO2/EP composite coating was prepared and two electrode systems which were respectively dominated by normal and tangential electric field component were designed. Surface potential distributions of samples at different time under two electrode systems were studied by electrostatic probe method, volume and surface conductivities of the samples were tested by capacitance probe method. The effects of nano-TiO2 particle content (1, 3, 5, and 7%) on the surface charge dynamic characteristics of epoxy resin were obtained. The results showed that the surface charge was mainly accumulated near the electrode when the normal electric field component was dominant, and the accumulation region was related to the material. When the content of nano-TiO2 particles in the coating was 1 and 3%, the charge mainly accumulated near the high voltage electrode. When the content of nano-TiO2 particles in the coating was 5 and 7%, the charge was mainly accumulated near the ground electrode. On the other hand, when the tangential electric field component was dominant, the surface charge would be dissipated, and the dissipation rate of the surface charge near the high voltage electrode was faster than the surface charge accumulated near the ground electrode. Taking the dynamic process of surface charge into account, it was found that the coating of which nano-TiO2 particle content was 5% showed the most significant effect on restraining charge accumulation.