Enhanced DC Surface Insulation of Al 2 O 3 /ER Brought by the Permeability of Fluorine-Containing Release Agent

The objective of this paper is to propose an equivalent fluorination method to improve the DC surface insulation strength of Al 2 O 3 /ER composites using fluorine-containing release agent (F-RA). By replacing the conventional silicon series release agent with a fluorine-containing one, the DC flashover voltage is, at best, raised to 1.2 times of the original value, and the surface charge characteristics are modified for better suppressing the distortion of surface electric field. The trap depth of the material is shallow, and the surface conductivity is reduced. The modification mechanism is explained from the perspectives of surface conductivity and fluorine electronegativity.