The Effect of Graphene as a Hydrophobic Additive on the Pollution Performance and Accelerated Ageing of Coatings when Applied to AC High Voltage Ceramic Insulator Materials

This study focuses on developing and testing a modified ceramic insulator Room-Temperature Vulcanised Silicone Rubber (RTV SR) coating either doped with Pristine Graphene (PG) or Nanoplatelet Graphene (NPG) at varying weight percentages (wt%). Key properties, comprising of surface resistivity, hydrophobicity and accelerated ageing tests, were investigated to assess the modified RTV SR coating’s pollution performance and practicality in the field. RTV SR coating samples doped with over 3 wt% NPG exhibited a significant reduction in surface resistivity compared to the control RTV SR coating. The study also revealed promising results regarding hydrophobicity, hydrophobicity recovery, and hydrophobicity transfer properties when increasing the NPG weight percentage. A 10 wt% NPG fraction resulted in a 10% increase in static Contact Angle (CA) measurements with reference to the control, even after pollution application, suggesting NPG sheets may also transfer to the surface with the Low Molecular Weight (LMW) silicones. Tracking and erosion results from the Inclined Plane Tester (IPT) indicated that NPG lowered the combustion temperature of the Aluminium Trihydrate (ATH) filler, leading to ignition of the RTV SR coating accelerated by electrical dry band arcing events. Therefore, the NPG doped RTV SR coating is impractical for field application.