The manufacturing of hydrophobic and anti-icing surfaces makes it possible to develop new technological and economic fields. For example, surface with these properties are relevant for refrigeration and wind energy technology as well as for the aviation industry. The removal of water and ice leads on the one hand to an increased material wear and energy consumption and on the other hand it is associated with an impairment of safety aspects. A further point is the decreasing environmental impact caused by the saving of chemicals that are used for de-icing.
Many innovations of the 21st century can be attributed to the targeted surface topography and/or surface chemistry of various materials, so that it is becoming increasingly important to research this area. Natural examples, such the lotus leaf (nelumbo nucifera) have shown to serve as a perfect template for a water repellent functional surfaces. This information can be used for the treatment of technical surfaces such aluminum alloys and thus preventing wetting and icing if micrometer-sized structures are produced.
In this study, laser based technologies were used for producing these functional structures using pulsed infrared laser radiation with a fundamental wavelength of 1064 nm. As material, electrolytically polished aluminium EN AW-1050 was selected, since this metal is of particular interest for the above-mentioned economic and industrial fields. More specifically nanosecond pulsed direct laser writing (DLW) and picosecond pulsed direct laser interference patterning (DLIP) have been utilized. These methods enables a one-step manufacturing process without the requirement of any kind of post-processing. Different geometries like line or cross-like patterns with a spatial period (repetitive distances) between 1 µm and 10 μm (DLIP) and hexagonal honeycomb arrays with a sizes between 50 µm and 500 μm (DLW) were generated and investigated.
For the surface examination with regard to the water repellency of the surface, water contact angle measurements were used primarily. The surface topography was characterized by confocal microscopy and scanning electron microscopy.