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2781 |
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Wednesday, September 28, 2011, Saal C2.2 4:25 PM Pre- & Post-Treatment 1 |
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Thermal barrier coatings on surfaces with micro-machined roughness profiles |
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Philipp Seiler* / Institut für Werkstoffe
Technische Universität Braunschweig, Germany Martin Bäker / Institut für Werkstoffe, TU Braunschweig, Germany Joachim Rösler/ Institut für Werkstoffe, TU Braunschweig, Germany Mario Schweda/ IEF-2, Forschungszentrum Jülich, Germany Tilmann Beck/ IEF-2, Forschungszentrum Jülich, Germany |
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Thermal barrier coating systems are used to enhance the temperature resistance of hot section components in gas turbines. The coatings protect the underlying nickel based components and consist of the bond coat (BC) the thermal barrier coating (TBC) and a thermally grown oxide (TGO) between the BC and TBC. The coating systems fail in service at or near the TBC/TGO interface. The failure mechanisms are not fully understood, yet. A simplified coating system is introduced which consists of a MCrAlY bond coat material as the substrate, an artificial TGO, and a yttria-stabilised zirconia TBC as a top coat. The TBC is applied by atmospheric plasma spraying on top of specimens with different roughness profiles. The profiles are manufactured by micro machining processes. The main advantage of micro machining is a defined interfacial roughness between TBC and BC in contrast to sandblasted specimens. Furthermore, a FEM simulation of the coating system was developed which approximates the interface by sinusoidal functions. This simplified model system and additional FEM calculations provide insight into the failure mechanisms of real thermal barrier coating systems. |