Fast transition from hydrophilic to superhydrophobic, icephobic properties of stainless steel samples after femtosecond laser processing and exposure to hydrocarbons

Abstract

Femtosecond laser processing is a key technology for surface modification and can be used to trigger superhydrophobic behavior through a combination of topographical and chemical effects. Nevertheless, immediately after laser processing, steel samples appear superhydrophilic and evolve into a hydrophobic state over a period of several days to weeks. To reduce the wetting transformation time down to hours, the sample can be stored in a vacuum chamber. In the chamber, the absence of atmosphere and thereby water vapor leads to an increased adsorption of hydrocarbons by the surface. In this study, we investigate an alternative and less demanding approach for shortening the wetting transformation time significantly by exposing the laser treated samples to a hydrocarbon liquid/atmosphere. This not only leads to a faster transformation, but also to an improved deicing performance. Both effects are analyzed for various hydrocarbon liquids and different laser patterns with respect to the surface chemistry.