We have studied the fabrication of line-like and pillar-like periodic microstructures on stainless steel by means of direct laser interference patterning. A picosecond (10 ps) pulsed Nd:YAG laser operating at 1064 nm wavelength was used to produce the microstructures with spatial periods ranging from 2.6 μm to 5.2 μm. By varying the laser parameters (laser fluence, pulse-to-pulse overlap) structure depths ranging from 500 nm to nearly 11.5 μm could be obtained. Furthermore, low and high frequency laser induced periodic surface structures (LIPSS) have been generated, resulting in three-level multi-scaled patterns. The orientation of the laser induced periodic structures with respect to the interference patterns could be adjusted by controlling the laser beam polarization. Finally, static water contact angle measurements are performed to investigate its correlation with the surface morphology. The treated surfaces are characterized using confocal and scanning electron microscopy

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.can reduce dramatically lift and increase drag, influencing the maneuverability of the aircraft. Ice protection systems (IPS) are installed to allow aircraft flying safely in icing conditions. At the present time, IPS are not supported by coatings or surfaces that facilitate the ice removal-due to the still too low maturity and robustness of such technological solutions. Yet, surface functionalization is a promising strategy for manufacturing icephobic surfaces [3] aiming to delay ice accretion and/ or to reduce ice adhesion [4,5] and therefore to reduce the electrical or thermal energy required by the IPS.In the last two decades, several approaches for producing icephobic surfaces were presented in literature. For example, it has been proven that polishing the surfaces can reduce the mechanical interlocking with the accreted ice, hence facilitating the ice removal. [5] Coatings can lower the surface free energy and thus reduce the strength of the bonding between ice and surface. [6] On slippery liquid-infused porous surfaces the supercooled water droplets impinge on a liquid instead of a solid surface, which offers a double advantage: interfacial slippage of water or ice occurs (nonzero slip velocity)-which reduces ice adhesion [7] -and interlocking of ice with a liquid interface cannot occur. However, employing coatings or chemicals to

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