Ice accretion on external aircraft surfaces due to the impact of supercooled water droplets can negatively affect the aerodynamic performance and reduce the operational capability and, therefore, must be prevented. Icephobic coatings capable of reducing the adhesion strength of ice to a surface represent a promising technology to support thermal or mechanical ice protection systems. Icephobicity is similar to hydrophobicity in several aspects and superhydrophobic surfaces embody a straightforward solution to the ice adhesion problem. Short/ultrashort pulsed laser surface treatments are proposed as a viable technology to generate superhydrophobic properties on metallic surfaces. However, it has not yet been verified whether such surfaces are generally icephobic under representative icing conditions. This study investigates the ice adhesion strength on Ti6Al4V, an alloy commonly used for aerospace components, textured by means of direct laser writing, direct laser interference patterning, and laser‐induced periodic surface structures laser sources with pulse durations ranging from nano‐ to femtosecond regimes. A clear relation between the spatial period, the surface microstructure depth, and the ice adhesion strength under different icing conditions is investigated. From these observations, a set of design rules can be defined for superhydrophobic surfaces that are icephobic, too.

The evaporation of water/ethanol drops with different mixing ratios was investigated at controlled vapor pressure of water (relative humidity) and ethanol in the background gas. Therefore, a drop of about 1 μL was deposited on a hydrophobized silicon substrate at room temperature in a closed cell. With a microscope camera we monitored the contact angle, the volume and the contact radius of the drops as function of time. Pure water drops evaporated in constant contact angle mode. The evaporation rate of water decreased with increasing humidity. In mixed drops ethanol did not evaporate completely at first, but a fraction still remained in the drop until the end of evaporation. Depending on ethanol concentration in the drop and on relative humidity in the background gas, water vapor condensed at the beginning of the evaporation of mixed drops. Also, at a high vapor pressure of ethanol, ethanol condensed at the beginning of the evaporation. The presence of ethanol vapor accelerated the total evaporation time of water drops.

A sessile droplet can deform the surface of a soft solid not only with its weight. The surface tension pulls up a ridge at the perimeter of the drop, and the capillary pressure embosses a quasi-spherical dimple underneath the drop. This holds for the case of a bulk solid. However, if the solid forms a film with thickness comparable to the deformation scale the shape and the depth of the dimple are strongly distorted. We investigated dimples on elastomer films with a Young's modulus of 25 kPa and thickness in the range 4–104 µm embossed by sessile ionic liquid droplets. The films are supported by an undeformable glass slide. Below a certain critical film thickness, the dimple is shallower and the ridge at the drop rim is less elevated than for the bulk elastomer. The deviations are more pronounced for thinner films. Further, troughs form at the two sides of the ridge. Their distance from the rim is equivalent to the layer thickness. The measurements are qualitatively reproduced by an analytical model and quantitatively by numerical simulations. A consistent physical picture of the deformation on the bulk elastomer and of the distortions on the thin films is given.