A Stable Super-Hydrophobic and Self-Cleaning Al Surface Formed by Using Roughness Combined with Hydrophobic Coatings

Abstract

A stable super-hydrophobic and self-cleaning surface with a high contact angle above 150° and the contact angle hysteresis below 3° were produced by using roughness combined with hydrophobic coatings, which were also confirmed to exhibit extreme water repellence and self-cleaning properties which facilitate removal of contaminant particles. To fabricate micro-patterened aluminium surface, the aluminium was etched with hydrochloric acid. A very thin polytetrafluoroethylene (PTFE) film was coated on the etched aluminium surface in order to achieve the super-hydrophobic surface. Roughness factors on the aluminium surfaces coated with PTFE were calculated as a function of etching time, based on the homogeneous interface (Wensel model). A critical roughness factor on the super-hydrophobic surface of the aluminium coated with PTFE was found to be 1.51 which can be formed on the surface of the aluminium etched over 10 min with hydrochloric acid of 7 wt.%.