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DBD device provides large-area hydrophobic coating for insulators
Researchers have developed a large-area dielectric barrier discharge system with transparent water-tungsten wire mesh electrodes to achieve uniform hydrophobic surface treatment of epoxy insulators. Integrated visual and distributed diagnostics ensure homogeneous plasma processing and reliable coating deposition.
High-voltage electrical equipment operating in humid environments faces accelerated ageing of insulating barriers and an increased risk of flashover, both of which threaten operational reliability. A recent study proposes an in-situ plasma-based protection strategy to achieve uniform hydrophobic surface modification of large-area epoxy insulating barriers, addressing a common bottleneck in the treatment of complex insulator geometries.
The authors developed a large-area dielectric barrier discharge (DBD) device incorporating water-tungsten wire mesh electrodes together with quartz observation windows. This design enables both homogeneous plasma generation and simultaneous visual observation and distributed diagnostics of the discharge process. By systematically optimising the applied voltage and argon flow rate, homogeneous plasma was achieved at 12 kV and an Ar flow of 1 L/min, as confirmed by grayscale image analysis and spatially resolved optical emission spectroscopy.
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Hydrophobic coating deposition and mechanistic insights
Using a nanosecond pulsed power supply at atmospheric pressure with hexamethyldisiloxane (HMDSO) as precursor, the team deposited a uniform hydrophobic coating on epoxy resin (EP) laminates within 20 minutes of plasma treatment. The average water contact angle increased from 74.5° ± 0.2° on the untreated surface to 130.2° ± 3.9° after treatment, corresponding to a 74.7 % improvement in hydrophobicity.
Mechanistic analysis showed that the enhanced hydrophobicity results from the synergistic effect of increased surface roughness and the deposition of a dense silicon-containing coating derived from HMDSO. The reaction pathways during discharge and the formation mechanisms of the hydrophobic layer were systematically analysed to support process optimisation. According to the authors, the integration of visual inspection and distributed diagnostic techniques ensures uniform treatment across large surface areas, providing a scalable strategy for enhancing the moisture resistance and long-term reliability of insulating components in high-voltage equipment.
Source: Huang, J. et al., Achieving uniform surface treatment on large-area epoxy resin via a transparent water-tungsten wire mesh electrode DBD with integrated visual and distributed diagnostics. Progress in Organic Coatings (2026). https://doi.org/10.1016/j.porgcoat.2026.110297
