Dielectric barrier discharge in atmospheric air for glass-surface treatment to enhance hydrophobicity

Experiments of a material-surface treatment using the nonthermal plasma generated by the dielectric barrier discharge (DBD) at atmospheric pressure in ambient air are carried out on a laboratory scale to see if the DBD can be used in enhancing the surface hydrophobicity. It is well known that the DBD can react with the material surface and induce physical and chemical changes to improve the surface wettability. The main purpose of this paper, however, is to look into the possibility of using the same experimental setup to do the opposite, i.e., to improve the surface hydrophobicity for a better insulation performance, which can be judged by the contact-angle and surface-resistance measurements, and verified by the wet flashover voltage test. To enhance the surface hydrophobicity, the glass surface is sprayed with a silicon liquid before it is exposed to the DBD treatment, and it is found that the formed hydrophobic coating is stable enough to endure both the thermal and chemical aging tests. The improvement of hydrophobicity depends on the DBD voltage and treatment time. It seems that there exists an optimum treatment time for a certain applied voltage of the DBD. Possible interaction between the DBD plasma and the material surface is discussed.