Superhydrophobic and high-flashover-strength coating for HVDC insulating system

Abstract In high voltage power equipment especially those for outdoor applications, the surface of dielectrics suffers from various problems such as flashover, raining, contamination, and ultraviolet illumination, which becomes the weak link in the whole insulating system. However, a high-throughput, flexible, and low-cost approach to simultaneously improve these properties of surface insulation was not reported yet. Here, a “binding polymer + nanofillers” based multifunctional nanocoating was fabricated by spray-coating of ZnO particles and multiwalled carbon nanotubes (MWCNT) dispersed in a poly(dimethylsiloxane) (PDMS) elastomer solution. The ZnO/MWCNT/PDMS coating plays multiple roles including inhibiting charge injection from electrodes due to the introduced deep interfacial traps, accelerating charge dissipation for the enhanced surface conductivity, and forming a micro-nanoscale hierarchical surface structure. As a result, the coatings endowed various dielectric materials such as epoxy resin, polymethyl methacrylate and silicone rubber with multifunctionality of high DC flashover strength (maximum 54% flashover voltage increase), superhydrophobic surface (water contact angle >150°), self-cleaning capability, good abrasive resistance, ultraviolet-resistance, and anti-icing performances. The ZnO/MWCNT/PDMS coating is well suitable for the surface modification of dielectrics in both indoor and outdoor HVDC insulating system. The present approach provides a new insight for simultaneously improving the multiple surface properties of dielectric insulation.