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1269 |
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Monday, June 02, 2008, Room 05 3:40 PM Powders, Wires, Gases 2 New powder mixtures and cored wires, support and distribution of industrial gases for thermal spraying |
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High temperature functionality of surfaces: drag reduction and self-cleaning |
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Simon Jahn* / TU Ilmenau, Germany Johannes Wilden / TU Ilmenau, Germany Victor Drescher/ TU Ilmenau, Germany Markus Dolles/ TU Ilmenau, Germany |
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Increasing requirements on technical components for high-temperature-applications (e.g. turbine blades) demand new developments in surface engineering. Selective combination of materials with positive and negative thermal expansion coefficient (NTE) will lead to a reversible activation of the surface depending on surface temperature: The generation of a riblet structure (shark skin) in operation condition by thermal expansion of the matrix and shrinkage of the NTE-ceramic and self-cleaning of the surface at cool down as a result of the reversal of the process. Due to its hygroscopicity the chosen NTE-ceramic Y2W3O12 cannot be used by itself. Therefore a feedstock powder consisting of MCrAlY, WO3 and Y2O3 is mechanically alloyed in a high-energy ball mill. The powder is deposited on substrates by thermal spraying (VPS and HVOF) as well as laser cladding. After the coating process a position- and depth-selective ion implantation of Tungsten, Yttrium and Oxygen will force nucleation in prede-fined areas. A following heat treatment of the specimens supports the in-situ-formation of Y2W3O12. This paper deals with the first results of the feedstock powder production and coatings. |