Enhanced surface insulation of micron alumina/epoxy composites brought by plasma co‐hydrothermal fluorination of filler

Abstract Epoxy resin filled with micron alumina (micro‐Al₂O₃/ER) has been widely used in the manufacture of basin insulators for its excellent mechanical and thermal properties. However, charge dissipation properties of micro‐Al₂O₃/ER are too poor to ensure its surface insulation on strength under long‐term action of a DC electric field. In this paper, the modification method of plasma cohydrothermal fluorination of filler was proposed to improve its surface charge dissipation performance. The surface morphology and the element content of Al₂O₃ were observed, and the flashover voltage and charge characteristics of different composites were tested. Finally, the trap distribution was calculated by isothermal current attenuation method. Self‐comparison analysis with single‐step modification of plasma treatment shows that the cofluorination method has a high graft rate of fluorine element and an ideal modification effect on surface insulation, with its technical means convenient to be applied in the insulator manufacturing industry.