Study of the wettability behavior of stainless steel surfaces after ultrafast laser texturing

The interest in superhydrophobic surfaces has grown exponentially over recent decades. Since the lotus leaf dual hierarchical structure was discovered, researchers have investigated the foundations of this behavior and many methods have been developed to obtain superhydrophobic surfaces. In this paper the possibility to use ultrafast laser treatments to obtain hydrophobic and superhydrophobic stainless surfaces was investigated on a AISI 316L stainless steel, ranging the total energy doses provided to the surfaces from 178 to 1143 J/cm2. As SEM-FEG images reveals, different surface microstructures can be obtained at the increasing values of energy dose. Independently on the specific values of laser treatment, all the obtained samples showed hydrophobic values of static contact angle. However, only particular surface microstructures allowed obtaining a self-cleaning surface characterized by low values of both contact angle hysteresis and roll-off angle. The obtained results led to define the effect of the laser parameters on the morphological, chemical and wetting surface properties allowing one to design new textures with the desired wetting properties, from “lotus effect” surfaces to “rose petal effect” surfaces.