Effect of electron beam irradiation on surface molecule and flashover voltage of epoxy composites

The unsatisfactory insulating properties of solid–gas interfaces seriously restrict the development of high-voltage electrical equipment and threaten their power supply stability. Electron-beam irradiation (EBI) can effectively improve the surface flashover voltage of dielectrics. However, the underlying mechanism of EBI in tailoring the surface trap and improving the flashover voltage remains unclear. In this study, the surface morphologies and chemical compositions of epoxy composites treated with EBI were investigated. In addition, the surface wetting properties, surface charge migration parameters, and surface flashover voltages were experimentally characterised. It was found that EBI aggravated the surface morphology, changed the surface chemical components, and repressed surface charge transportation. As a result, the contact angle was reduced from 103.7° to 78.43°, and the flashover voltage in SF₆ was increased from 35.26 to 38.90 kV. DFT calculations showed that the newly generated C–O–H and C=O bonds on the surface molecules after EBI formed charge centres at the molecular electrostatic potential, which enhanced the trapping effect of the surface deep trap. As a result, surface charge migration was repressed, and the surface flashover voltage was improved. This study could promote the further development of EBI on materials modification.