A shark skin for high temperature applications

SPP 1299

Bild Forschungsprojekt

Hochtemperaturofen in Betrieb

Period: 2007-07-01 to 2014-02-15
Funder: German Research Foundation (DFG)
Project Manager: Dr. Raluca Pflumm
Research Group: High Temperature Materials

This project is part of the "HAUT"-program funded by the DFG. The research topics are surfaces which can adapt to the surrounding atmospheric conditions at temperatures over 600°C similar to a living skin (in German "Haut"). The project  "A shark skin for high temperature application" is about structuring the surface of substrates by using the natural oxidation behaviour of the material at temperatures up to 1000°C. The pattern of the structures is similar to that of a shark skin. These structures decrease the aerodynamical losses due to shear strain at the surface of a solid moving in a flow. This improvement in the flow conditions is applicable to turbine blades of an aeroplane engine for example. Lower aerodynamical losses lead to more economic usage of fuel, decrease the CO2 emission into the atmosphere and reduce the acoustic emission. These are very important aspects for environmental protection. On the other hand, aeroplane engines operate at temperatures between 500 and 1000°C and strong temperature gradients. Therefore the surface structuring process should not prevent the growth of the right kind of oxide layer, necessary to protect the material against high temperature corrosion.

Together with our project partners from DLR Köln, BTU Cottbus, TU Berlin and MTU Aero Engines München, we investigate the efficiency of different experimental methods (geometrical, chemical, precursor-methods) that lead to surface structuring. Materials used in the industry were chosen as a substrate. The study of the nucleation process, the time stability of the structures at constant temperature or in a temperature gradient and investigations of the aerodynamical behaviour of structured surfaces are the tools used for the characterisation of the structures in order to determine the applicability of the used methods.
At DFI substrates made of Gamma-TiAl alloys (Al content between 45 and 50 at%) are structured using chemical methods based on the halogen effect.

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