| The polytetrafluoroethylene(PTFE)PTFE has excellent mechanical properties and is an important insulating material in pulse power equipment.However,under the high electric field and complex environment,its surface is prone to accumulate a large amount of charge,which can easily cause flashover along the surface and may cause insulation failure,equipment failure and safety problems and economic losses.Whether it is the development direction of compact and miniaturized equipment size,or the development direction of high-power and high-voltage equipment performance,there are increasing requirements for the surface voltage resistance of solid insulating media.Therefore,studying the surface charge accumulation and dissipation characteristics of solid insulating materials,and using this as a theoretical basis to find a way to improve the voltage resistance of the material along the surface,is of great significance to the further development of pulse power technology.In order to suppress the accumulation of charge on the surface of PTFE material,in this work,radio frequency nitrogen plasma was generated to perform plasma immersion ion implantation(PIII)on its surface to improve its surface properties.And through various tests and analysis of its surface composition and performance,to explore the relationship between the surface factors of the material and the surface charge accumulation and dissipation characteristics.This article mainly has the following innovations:(1)A plasma immersion ion implantation system was developed and constructed,and PTFE samples were uniformly implanted in all directions;(2)Through various testing methods,the plasma immersion ion implantation was used to analyze the changes in the chemical composition and physical properties of the surface of the Teflon sample;(3)A set of surface potential measurement system was developed and constructed.The measurement results intuitively reflected the changes in surface charge accumulation and dissipation characteristics of the PTFE sample after plasma immersion ion implantation treatment,and based on this The surface trap characteristics of PTFE samples were analyzed,and the characteristics of surface charge accumulation and dissipation were analyzed from the mechanism.X-ray photoelectron spectroscopy(XPS),Fourier transform infrared spectroscopy(FTIR),water contact angle measurement,surface resistivity measurement and surface potential attenuation measurement were performed on the samples of PTFE material before and after injection to analyze the changes in surface composition and physical properties of PTFE samples after ion implantation treatment.Based on the theory of isothermal surface potential attenuation,the energy levels and density distributions of the surface traps are calculated.The results showed that after nitrogen ion implantation,the main change in the chemical composition of the surface of the PTFE material is the destruction and conversion of its own molecular structure,and part of the CF2 structure is transformed into the CF and CF3 structures,resulting in shallower trap levels on the sample surface.And the analyzed results also showed that the water contact angle rose to about 140°,which is about 27° higher than that of the unprocessed sample.The surface resistivity drops to 3×1015 ?/?,which is two orders of magnitude lower than unprocessed samples.After 1 minute of corona discharge on the surface,the amount of accumulated charge on the surface of the PTFE material processed with nitrogen ion implantation decreased,and the rate of dissipation increased.This is because the shallower surface trap level is conducive to surface charge trapping,and the reduction in surface resistivity also promotes the dissipation process of surface charge along the surface.The distribution curve of the trap energy level on the surface of the PTFE sample intuitively reflected that the surface trap energy level became shallower and the density decreased,which also confirmed this argument. |
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