Elaboration of Al2O3/PTFE icephobic coatings for protecting aluminum surfaces

In order to protect aluminum ground wires and phase conductors of overhead power lines against ice adhesion and excessive accretion, for ensuring safe and reliable power transmission during winter periods, a new coating with icephobic characteristics and satisfactory mechanical properties was developed. The method consisted in depositing an extremely adherent poly(tetrafluoroethylene) or PTFE coating on an Al₂O₃ underlayer produced by anodisation in either a phosphoric or an oxalic acid electrolyte. PTFE impregnation was carried out at low temperature (320 °C) and coating adhesion was assessed using tape and bend tests. These treatments resulted in highly hydrophobic surfaces with water contact angles lying between 130° and 140°. Ice shear stress was reduced by almost 2.5 times, and the PTFE coatings remained active after several ice shedding events. Morphologies and chemical compositions were studied using scanning electron microscopy, energy dispersive X-Ray analysis, as well as Fourier Transform Infra Red and X-Ray photoelectron spectroscopy.