ABSTRACT To enhance the corona resistance and dielectric properties of polyimide (PI), this study designed and fabricated Si‐B‐Mg/PI nanocomposites. The relative magnesium content was investigated for its effect on the electrical insulation properties of the Si‐B‐Mg/PI nanocomposite. A composite with a specific doping level of 27.5 wt% Si‐B‐Mg/PI was prepared by adjusting the Mg addition ratio. The composite material underwent performance testing and microstructural characterization, including corona discharge lifetime, dielectric properties, volume resistivity, conductive current, and breakdown field strength. The influence of Mg content on the insulating properties of the Si‐B‐Mg/PI composite was systematically analyzed. Experimental results indicate that when the molar ratio of Si‐B‐Mg composite oxides is 12:3:0.8, the composite exhibits minimal dielectric loss and the longest corona resistance lifetime. At 155°C, 60 kV/mm, and 50 Hz, this lifetime reaches 510.4 min‐2.67 times that of the pure PI film. At 155°C, 60 kV/mm, and 10 kHz, it reached 140 min, representing a 11.67‐fold increase over the pure PI film. The incorporation of magnesium effectively enhances the corona resistance lifetime and reduces dielectric loss in Si‐B‐Mg/PI composite materials.
Zhao et al. (Tue,) studied this question.