Study Of Low-Temperature Plasma Polymerized Modifying Coatings For Enhancing The Vacuum Flashover Strength Of Polymers

Vacuum-solid insulation is widely used in vacuum circuit breakers,pulse power equipment,microwave dielectric windows and other equipment.Polymers are widely used in vacuum-solid insulation systems because of their good mechanical properties,excellent electrical properties and low-cost Manufacture of solid insulation materials.With the continuous improvement of voltage levels,stronger local electric field distortions appear on polymer insulation materials.Strong electric field distortions can easily cause flashover accidents of polymers.Flashover accidents will seriously damage the stability and reliability of vacuum equipment Sex and bring huge economic losses.The existing polymer material modification methods have gradually failed to provide a higher anti-flashover improvement effect.Therefore,efficient,easy-to-industrial,and environmentally friendly surface insulation modification methods need to be proposed urgently.First,this article describes two novel and efficient polymer surface insulation modification methods based on low-temperature plasma polymerization-coatings.The first method is to fabricate a non-smooth plasma polymerized methyl methacrylate(p PMMA)plasma polymerization modified coating with low surface resistance on the surface of polypropylene by atmospheric pressure plasma jet deposition.The second method is to prepare a dodecafluoroheptyl-methacrylate(DFHMA)-p PMMA plasma polymerization modified coating on the surface of polystyrene by glow discharge plasma,which can modify the surface chemical molecular structure.These two modification methods increase the vacuum flashover voltage of the polymer through physical morphology optimization and chemical molecular structure modification,respectively.Then,this article discusses the physical morphology,chemical composition and electrical characterization results of the samples before and aftermodification by the two modification methods,respectively.For the first optimizing physical morphology modified coating,when the deposition time is 5minutes,the surface roughness of the coating reached the maximum.At the same time,the non-smooth p PMMA coating introduces polar groups into the polypropylene surface.In electrical characterization results,compared with untreated PP,the introduction of non-smooth p PMMA coating increases the surface potential attenuation rate of polypropylene by 26% and the secondary electron emission rate by 30.2%.Under theses combined effects,the vacuum flashover voltage is increased by 35.5%.For the second chemical molecular structure modification coating,DFHMA successfully introduces C-F bonds to the surface of polystyrene.At the same time,the surface roughness of polystyrene do not change much before and after DFHMA-p PMMA coating.In electrical results,the introduction of C-F bonds greatly increases the rate of dissipation of surface charges,which increases the vacuum flashover voltage by 39%.In conclusion,these two methods proposed in this paper to stably increase the vacuum flashover voltage of polymer surfaces through low temperature plasma polymerization modified coatings have opened up new research ideas for the field of electrical insulation,and may be applied to other more important fields.