Study on improving the space charge behavior in insulating paper by depositing nanostructured alumina on its surface via magnetron sputtering

Abstract

A nanostructured alumina (AlOx) layer was coated on an insulating paper surface to improve space charge behavior by suppressing space charge injection from electrodes. Samples with various coating times were prepared and characterized. The space charge behavior of the samples was measured with a pulsed electroacoustic device. Results showed that all samples coated with AlOx had a lower amount of charge accumulation than the blank paper. In particular, the paper coated for 60 min possessed the lowest charge accumulation among the samples. Its total charge accumulation was 34.8% lower than that of the blank paper and resulted in a 47.5% reduction of the electric field distortion rate in the insulating paper. During injection, the AlOx layer introduced an extra barrier that increased the contact barrier between the electrodes and paper. Moreover, the absorption current results showed that the AlOx film suppressed the injection of space charge by increasing the scattered electron amount on the sample surface. The micromorphology of the sample surface was also investigated as a crucial factor in studying injection.