Study On Suppressing Surface Charge Accumulation Of Epoxy Resin Treated By Low Temperature Plasma

Epoxy resin is widely used in high-voltage electrical equipment for its excellent mechanical and electrical properties.However,in the DC high voltage electric field,the surface charge is easy to accumulate on epoxy resin material at the triple junction of metal,insulating material and gas.It would result in the decrease of insulating strength and even lead to flashover accident,seriously affecting the safe operation of electrical equipment.Therefore,the low-temperature plasma is used to deposit SiO₂-like film on the epoxy resin surface in order to improve the surface electrical properties and suppress the accumulation of surface charge without affecting the bulk material of epoxy resin.In this paper,a set of insulating material surface depositing treatment experiment system was established based on atmospheric pressure plasma enhanced chemical vapor deposition technology.Dielectric barrier discharge,atmospheric pressure plasma jet and sliding discharge were used as plasma source and tetraethyl orthosilicate was used as reaction precursor.The precursor reacted in the plasma and the SiO₂-like film deposited on the epoxy resin surface.Through a series of physical,chemical and electrical properties test,the surface insulation properties of the epoxy resin materials before and after deposition treatment were compared and analyzed.Then the accumulation,distribution and dissipation of the surface charge on epoxy resin were studied by the self-built surface potential test system.Finally,the mechanism of suppressing surface charge accumulation by deposition treatment was discussed by the experimental results obtained by various measurement methods.After the deposition treatment,a dense and homogeneous SiO₂-like film with a thickness of more than 200 nm was formed on the epoxy resin surface.The main composition of film was Si-O-Si and Si-OH groups and its micro-particles were coral-like distribution,completely covering the flaws of original surface.The surface wettability increased and roughness decreased.Besides,the surface andvolume conductivity of epoxy resin were greatly improved and the surface falshover voltage increased by more than 25%.Therefore,its insulation performance and withstand voltage were improved.After the positive and negative DC corona and pulse corona discharge,the initial surface accumulating potential of the deposited epoxy resin was reduced,the potential decay rate was accelerated and the potential distribution was more uniform compared with the untreated sample.The depth of surface charge traps energy level was more shallow and the density was smaller,which is beneficial to enhance the insulation performance of epoxy resin.With the increase of deposition treatment time,the effect of suppressing surface charge accumulation was also improving.In summary,the plasma deposition treatment can suppress the accumulation of surface charge on epoxy resin and it has important reference significance and practical value on enhancing the insulation performance of the epoxy resin in insulation devices.