Robust superamphiphobic coatings with gradient and hierarchical architecture and excellent anti-flashover performances

Biomimetic superhydrophobic (SH) coatings have emerged as a promising alternative to traditional room temperature vulcanizing (RTV) silicone rubber coatings for improving the flashover strength of insulators. However, organic contamination occurs in outdoor applications and thus a superamphiphobic (SAP) surface is more desirable but not yet reported for improving flashover performance. Herein, we developed a novel anti-flashover technique by fabricating robust SAP coating with unique gradient and micro-nanoscale hierarchical architecture. The SAP coating was fabricated by sequentially spray-depositing a resin-based primer and a silica-based topcoat on substrates (i.e., glass slides and insulators). The primer not only functions as an adhesive offering strong adhesion to the substrate but also offers a micromastoid-like structure facilitating the subsequent formation of hierarchical micro-nanostructure. The appropriate spraying pressure leads to a diffusion of the fluorocarbon-modified silica nanoparticles into the primer to form a unique gradient structure, by analogy to inserting bullets into a wood. These features render the SAP coating excellent robustness with strong abrasive resistance, excellent ultraviolet (UV) resistance, and excellent chemical and thermal stability. Pollution flashover property of the SAP coating was explored and compared with that of SH and RTV specimens, from which a novel organic-contamination model to evaluate the flashover performance was proposed. The coated SAP glass insulator demonstrated 42.9% pollution flashover voltage improvement than RTV-coated insulator. These stated unique features reveal the convincing potential of the present SAP coatings to be applied for not only outdoor transmission line insulators for anti-flashover but also other fields for self-cleaning, anti-fouling, and anti-icing.