Structure And Dielectric Properties Of Modified Nano-alumina Hybrid Three-Layer PI Composite Films

PI film has a broad and important application for its excellent electrical properties in the electromechanical industry.More and more people pay attention to the research of nano-materials modified PI films' corona resistant with the rapid development of nano-materials' research.But the research that introducing other elements to modify nano-alumina which be used to dope PI for further improve the dielectric properties of the film has been rarely reported.The nano-alumina particles dispersions modified jointly by different contents of zirconium(Zr)and titanium(Ti)were made by the micro emulsion-hydrothermal method.Inorganic nanometer oxide doped total of 24 wt%which was fixed.When converted into oxides,titania(TiO2)and zirconia(ZrO2)doped inorganic total accounted 10 wt%.A sequence of three-layer composite films doping nano-alumina particles which modified by different contents of Ti and Zr were prepared by in-situ polymerization.The microstructure of films and dispersion were analyzed by transmission electron microscopy(TEM),and the dielectric properties of films were measured respectively by breakdown strength measuring system,electrical current experiment device and corona resistance measuring system.It can be seen from the TEM that the average particle size of inorganic nano-dispersion was less than 20 nm;and inorganic particles-dispersed well in composite films.Under the same conditions,the conduction current density of the composite films has no obvious change with different contents of TiO2.The electrical degradation threshold of composite films showed increase trend at first and decrease afterward with the content of TiO2 increasing,and the maximum appeared when the content of TiO2 was 4 wt%.The dielectric filed strength of the composite film showed increase trend at first and decrease afterward with the content of TiO2 increasing,and the maximum appeared when the content of TiO2 was 6 wt%.When the power frequency was 50 Hz and the electric field strength was 80 kV/mm,from the result of the corona resistant life of hybrid PI composite films doping nano-alumina particles modified by different contents of Ti and Zr at 30 ? and 155 ?,we got a fact:the corona resistant property of composite films has increased as a result of introducing Ti02,and the corona resistant life showed increase trend at first and decrease afterward with the content of TiO2 increasing,but the maximum of the corona resistant life emerged on different doping ratio in distinct measure temperature;The corona resistance test of the composite films which TiO2 doping amount is 6 wt%in different temperature showed that the corona resistant life presented a index fell trend as the temperature increases;The corona resistance test of the hybrid composite films which TiO2 doping amount is 4 wt%in different voltage showed that the corona resistant life also presented a index fell trend as the voltage increases.