Study on interface insulation properties of Al2O3 epoxy composites using plasma jet‐fluorinated etching/SiOx deposition

Abstract

AbstractDue to their superior mechanical and electrical characteristics, Al2O3 epoxy composites (Al2O3/EP) are extensively utilized in producing insulation devices. However, Al2O3/EP is prone to accumulating a large amount of charge under a direct current (DC), which threatens the operation of the power system. In this article, we conducted surface fluorinated etching and SiOx deposition on the material by atmospheric pressure plasma jet (APPJ). Various testing methods were used to investigate the impacts of plasma modification on the physicochemical characterization of Al2O3/EP, and the changes in superficial conductivity, flashover voltage, charge dissipation rate, and trap distribution were experimentally tested. The influences of two plasma modification methods on the physicochemical characterization of Al2O3/EP were analyzed. The enhancement mechanism of Al2O3/EP flash behavior by fluorinated etching and SiOx deposition is summarized. The findings demonstrate that the insulation behavior of Al2O3/EP results from a combination of a few dominant and multiple factors. Fluorinated etching enhances the degree of roughness and the relative proportion of the F element, provides chemically deep traps, and raises the flashover voltage by up to 19%. SiOx deposition boosts the dispersion of charges by forming SiOx layers on the surface, reducing the degree of roughness and increasing the content of the silicon–oxygen element, making it more difficult for charges to accumulate and increasing the flashover voltage by up to 15%. This study will reveal the internal relationship between gas–solid interface and surface flashover, and provide a possible scheme for suppressing surface flashover.Highlights Modifications substantially increase the flashover voltage. Modifications allow a wide range of interface parameters to be adjusted. The effects of modifications on physicochemical properties are compared. The enhancement mechanism of flashover voltage by modifications is compared. The overall effect of multiple factors on insulation properties is analyzed.