Corona Resistance of Polyimide Films Modified by Nano-Al2O3 in LN

Polyimide (PI) films have been widely concerned for their excellent thermal and insulating properties. There are many reports about the electrical characteristics of PI films. However, the corona resistance of nanocomposite PI films in liquid nitrogen (LN) is rarely reported. $\mathrm{PI} / \mathrm{Al}_{2} \mathrm{O}_{3}$ films with different mass fractions were fabricated by in-situ polymerization in this study. SEM was employed to observe the surface microstructure of the samples. The corona resistance) of the samples was tested at normal temperature and in L N, respectively. It indicates that the corona-resistant lifetime for the samples modified with 7 wt % nanoparticles is five times longer than the pure ones in LN. Nanoparticles and low temperature can prevent corona to improve the corona resistance for the PI films.