Deposition of SiO2 and TiO2 Films on Electrode Materials to Suppress Space Charge Injection

Abstract

Liquid dielectrics are widely used in high-voltage transformers owing to their excellent insulation properties. Space charge injected from electrodes can damage power systems. It is believed that space charge dynamics are related to the electrodes surface closely. In this study, surface modifications of copper and stainless-steel electrodes deposited by SiO2 and TiO2 nanostructured films with radio frequency magnetron sputtering were investigated. The films were characterized. The effects of the films on the breakdown voltage and space charge dynamics characteristics of the propylene carbonate were studied. These results indicate that when a TiO2 nanostructured film was deposited on the stainless-steel electrode, the breakdown voltage of the propylene carbonate increased by 7.3%, and when SiO2 and TiO2 films were deposited on the copper electrode, the increases were 7.4% and 10.2%, respectively. Furthermore, the amount of charge injection of the stainless-steel electrode was lower than that of the copper electrode, and the nanostructured films markedly suppressed the space charge. Both the TiO2 and SiO2 nanostructured films sputtered on the electrode surface changed the barrier height of the solid–liquid interface and reduced the depth and amount of charge injection. Compared with a sputtered SiO2 film, the TiO2 film had a better space charge suppression effect.