Rapid Treatment with Pulsed Gliding Arc Plasma in Ambient Air to Increase the Hydrophobicity of Silicone Rubber for Electrical Insulators

Hydrophobicity of silicone rubber (SR) is important for its anti-ice and anti-pollution property and the pollution flash-over performance of electrical insulators in transmission lines. In this work, a pulsed high-voltage source is used to generate gliding arc (GA) with ambient air flow, combining the advantage of high reactivity and low power consumption. This plasma source is adapted for enhancing the hydrophobicity of SR. Contaminating suspension composed of Kaolin and NaC1 solution with different non-soluble deposit density (NSDD, from 0.125 to 1 mg/cm
²
) is imposed on SR. With NSDD of 0.125 mg/cm
²
and only 1-min treatment with pulsed GA, the water contact angle (WCA) of SR increases from ~68° to 145° and excellent wearing performance is achieved. As a comparison, natural migration takes tens of hours to reach a similar WCA. For higher NSDD, longer plasma-treatment time is needed, while the best WCA achieved is smaller. Optical emission spectroscopy from pulsed GA illustrates that O atoms have the highest emission intensity and quenching of excited N
2
by O2 contributes to a high O2 dissociation degree. Assisted with Fourier transform infrared analysis of clean, contaminated, and plasma-treated SR surface, it is speculated that high-density O atoms generated by pulsed GA accelerate the migration of hydrophobic component in contaminant. This work proposes a rapid, low-cost, and environmental-friendly treatment method for increasing SR hydrophobicity, showing a good potential for application in engineering field.