Regensburg 2007 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 35: SYBM Bioinspired Materials
MM 35.1: Vortrag
Donnerstag, 29. März 2007, 14:45–15:00, H16
Reflection of water jets on biological and bio-inspired artificial surfaces — •Michael Scharnberg1, Vladimir Zaporojtchenko1, Rainer Adelung1, Srdjan Milenkovic2, and Achim Walter Hassel2 — 1Chair for Multicomponent Materials, Technical Faculty, University of Kiel, Germany — 2Electrochemistry and Corrosion, Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
Water jets impinging on a nasturtium leaf, a biological ultrahydrophobic surface (lotus effect), were observed to flow across the surface for a distance in the order of several jet diameters before it is reflected off the surface as a coherent jet under an angle that is close to or smaller than the angle of incidence. Design and technical applications of ultrahydrophobic surface require understanding of the physical processes involved, however biological surfaces often have defects and irregularities like leaf veins that impede experiments. A ds-NiAl-W alloy, microstructured by etching and coated with a sputtered polytetrafluoroethylene (PTFE) thin film is also ultrahydrophobic (contact angle > 160°). Due to the regular microstructure of its surface that can also be easily varied by controlling the needle length, this ultrahydrophobic material system is well suited for investigation of the water jet reflection phenomenon. In this presentation the influence of the microstructure, the water pressure and the angle of incidence will be discussed.