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聚酰亚胺薄膜(polyimide,PI)以其卓越的介电性能广泛应用于变频电机匝间绝缘,纳米掺杂能改善PI膜的绝缘性能.为研究方波条件下纳米 Al2O3对 PI 膜表面放电特性的影响,文中将粒径为60nm的Al2O3纳米粒子作为无机填料添加到PI基体中,制作了掺杂量为1%,2%,5%,7%, 10%的 PI 薄膜.测量了 PI/Al2O3薄膜耐电晕性能和局部放电次数随温度的变化,用扫描电镜(scanning electron microscope,SEM)观察了放电前后PI/Al2O3薄膜微观形貌.利用傅里叶红外光谱(Fourier transform infrared spectroscopy,FTIR)测试了复合薄膜老化前后的化学键情况.研究结果表明:纳米 Al2O3 在 PI 基体中弥散分布, PI/Al2O3复合薄膜的红外吸收峰与纯 PI 膜基本一致,但吸收峰深度有所加强.老化4h后PI/Al2O3分子链上的C-O-C (醚键)以及C-N-C(酰亚胺环)消失,其余化学键吸收峰有所减弱;Al2O3纳米粒子的掺入提高了复合薄膜的耐电晕性能并减少了局部放电次数.并且温度的上升会导致局部放电次数减少.表面放电导致的化学键断裂是复合薄膜降解的主要原因,纳米粒子所引入的两相界面以及其优良的导热性能提高了复合薄膜的绝缘性能.“,”Polyimide (PI) films are widely used in the insulation of pulse width modulation(PWM)inverter motors with its excellent dielectric properties. Nano filler is great helpful to improve the insulation property of PI. A PI film with the nano alumina (60nm) content was made for researching the PI films surface discharge property under the square impulses. The content of alumina was 1%,2%,5%,7%,10%. Under the different temperatures the number of partial discharge and the corona-resistance of PI/Al2O3films were tested. The microstructure of the PI/ Al2O3 film before and after discharge was observed by scanning electron microscope. The chemical bonds of pure PI and PI/ Al2O3 were also tested by Fourier transform infrared spectroscopy. The results show that, the nano Al2O3 is diffusely distributed in the PI film. Compared with pure PI films, the characteristic absorption peaks of PI/Al2O3 is reinforced. After 4 h aging, the C-O-C and C-N-C are disappearing. Other absorption peaks are weakening. Nano Al2O3 fillers are improving the corona-resistance of the composite film and are reducing the number of partial discharge. The number of partial discharge is decreasing with the increasing of temperature. Chemical bond rupture is the main reason of degradation of the composite film under the surface discharge. The interface from doping of the nano particles and its good heat-conducting can improve the insulation property of PI films.