Characterization of the Fluorinated Surface Layer of the Alumina-filled Epoxy Insulator

In order to promote the possible application of direct fluorination for the performance improvement of epoxy spacers, the alumina-filled composite epoxy samples were prepared with the same formulation and technology as those for commercial epoxy spacers and were fluorinated. Surface physicochemical characteristics and basic properties of the fluorinated epoxy sample layer were investigated. ATR-IR analysis and SEM cross section observation do not show obvious differences in chemistry and thickness of the fluorinated layer between the composite epoxy sample and the unfilled “pure” epoxy sample, while SEM surface observation clearly indicates the influence of alumina particles on surface morphology of the fluorinated layer due to the likely fluorination of the particles and the interface damage. Surface potential decay measurements show that the fluorination led to an increase in surface conduction of the composite epoxy sample, similar to but not as significant as the case of the pure epoxy sample. Contact angle measurements show that the fluorination decreased the water contact angle on the composite epoxy sample, but increased the diiodomethane contact angle, also similar to the pure epoxy sample, showing a small influence of the particles on the wettability. The influences of the particles on surface physicochemical characteristics and properties should be closely associated with fluorination condition.