Volkmar Stenzel

Anti-icing and anticontamination properties of coatings induced by surface structure

The development of the first model coatings with innovative surface structures, anti-icing, and anticontamination properties could be implemented in the EU-project CleanSky. A porous aluminum alloy structure created by anodization was filled with fluid silicon oil polydimethylsiloxane. At the surface, the silicon oil was modified with vacuum ultraviolet-light to form a thin and solid hydrophobic layer. For further investigations, laser-structured metal surfaces were copied and reproduced with a coating and afterward filled with fluoro-modified oils. Additionally, aluminum alloy AA2024 samples were pickled and treated with hot water to create micro- and nanostructures at the surface. These samples were also filled with different fluoro-modified and nonmodified oils. After application, the surface properties were analyzed with special tests for functionality regarding anti-ice and anticontamination properties.

Investigation of the wear properties of a riblet paint structure on an Airbus A300-600ST Beluga

While the application of drag reducing riblets on aircraft in the past was done by an adhesive film, a new promising technique was developed by the Fraunhofer Institute IFAM. The riblets are imprinted very precisely into the paint on the aircraft. To investigate the durability of such a riblet structure, free flight tests on an Airbus A300-600ST Beluga were performed. According to a specified time schedule, samples from the aircraft were taken. This riblet samples were prepared to measure the aerodynamic properties in an appropriate test facility, the DLR oil channel. The preparation of the test samples consists of several steps like moulding, casting, three dimensional surface measurements and a rapid prototyping technique. The sample preparation chain is evaluated by means of a common numerical method. Results of the experimental investigation show the influence of the wear during the flight tests on the riblet surface.

Selbstheilende Beschichtungen im maritimen Bereich

In den letzten Jahren ist das Interesse an selbstheilenden Materialien, die auch Beschichtungssysteme mit einschließen, stark gestiegen /1/. Im Projekt „ThroughLife“ hatten sich unter Koordination von Meyer Werft 17 europäische Partner zusammengeschlossen, um die Nutzungsdauer von Schiffen durch innovative, umweltfreundliche Technologien und neue Geschäftsmodelle zu verlängern und so die Kosten bezogen auf den Lebenszyklus eines Schiffs zu verringern. Ziel war es, durch den Einsatz selbstheilender Beschichtungen in Ballastwassertanks von Schiffen die Korrosion in diesem sehr stark durch Feuchtigkeit, Salz und wechselnde Temperaturen belasteten Bereich zu minimieren (Bild 1). Dies gelang durch ein Heilungsreagenz, das schon bei kleinsten Beschädigungen der Beschichtung freigesetzt und so der Untergrund vor beginnender Korrosion geschützt wird. Dadurch lassen sich Wartungszyklen und Lebensdauer der Bauteile verlängern und Kosten für Reparatur und Instandhaltung reduzieren.

Development and Testing of Icephobic Materials: Lessons Learned from Fraunhofer IFAM

The effective development of icephobic coatings requires test scenarios that simulate relevant icing conditions in the desired application field. Because of a lack of available standardized tests, developers rely on comparative tests, comparing results with pre-defined benchmark systems. In this context, tests need to be conducted under very stable conditions without allowance for fluctuation. This guarantees a development process with stepwise material improvement. Fraunhofer IFAM in Germany began working on icephobic materials over 10 years ago, seeking to develop not only the materials but also adequate test methods. This chapter describes the development process and results of these activities, as well as proposals to improve efficiency further in the future development of icephobic materials.