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Silicon film on brass suppresses partial discharge
Researchers demonstrate that a silicon-containing film deposited on brass by an atmospheric-pressure plasma jet can suppress partial discharges caused by metallic contamination. The near-superhydrophobic coating raises the flashover voltage and increases the surface work function of the electrode.
Gas-insulated electrical equipment is susceptible to operational failures caused by metallic particle contamination, which can trigger surface discharges. A recent study proposes a dynamically rotating film deposition strategy in which brass electrodes are treated with an atmospheric-pressure plasma jet (APPJ) to enhance their insulation performance. Using an Ar/hexamethyldisiloxane (HMDSO) plasma, the authors generate active species — including Ar* and silicon-containing fragments — that deposit a silicon-based film on the electrode surface.
The dynamic rotation ensures a uniform siloxane network coating across the brass substrate. The researchers developed a plasma nanosecond-pulse-driven deposition system integrated with plasma diagnostic techniques, allowing detailed investigation of discharge characteristics on treated substrates under both forced zero-potential and floating potential conditions, using a combination of simulations and experiments.
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Reduced discharge activity and near-superhydrophobic surface
Partial discharge (PD) measurements on the coated electrodes demonstrated a marked reduction in discharge activity. At applied voltages of 5 kV and 8 kV, the number of PD events decreased by 36.5 % and 32.3 %, respectively, while the average amplitude was reduced by 37.5 % and 23.8 %, and the maximum amplitude decreased by 13.8 % and 34.5 %. In parallel, the flashover voltage increased by 0.6 kV, indicating improved dielectric performance under electrical stress.
The treated brass surface also changed from hydrophilic — with a water contact angle of around 60° ± 6° — to near-superhydrophobic at 146° ± 3°. Furthermore, the surface work function increased by 0.114 eV. Based on physicochemical characterisation and electric field simulations, the authors attribute the observed suppression of discharge to the combined effect of altered dielectric properties, higher surface work function and increased hydrophobicity. The findings suggest that APPJ-based silicon film deposition offers a viable route to enhance insulation performance in gas-insulated equipment and to mitigate risks associated with metallic contamination.
Source: Cheng, H. et al., Silicon film deposition on brass with atmospheric-pressure plasma jet for suppressing metallic contamination-induced partial discharge. Progress in Organic Coatings (2026). https://doi.org/10.1016/j.porgcoat.2026.110303
