Ermittlung des Verformungs- und Schädigungsverhaltens von Wärmedämmschichtsystemen

Heckmann, S.

Dissertation / PhD Thesis/Book

Ermittlung des Verformungs- und Schädigungsverhaltens von Wärmedämmschichtsystemen

Heckmann, S. (Corresponding author)FZJ*

2003
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Jülich : Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag, Berichte des Forschungszentrums Jülich 4077, 163 p. (2003) = Aachen, Techn. Hochsch., Diss., 2003

Please use a persistent id in citations: http://hdl.handle.net/2128/309

Report No.: Juel-4077

Abstract: The application of gas turbines for the generation of electricity bas significantly increased over the past decades. In order to reduce emissions and to conserve fossil fuels, the thermal efficiency of stationary gas turbines should be increased. This can be achieved mainly by higher turbine inlet temperatures and by reduction of the cooling air flow. The use of thermal barrier coatings (TBCs) has great potential for increasing the thermal efficiency, while at the same time limiting metal temperatures of the blades. The exploitation of the potential of TBCs has, however, been hampered by the lack of systematic data concerning the damage development, and of the material properties that affect it. In the present work, the damage development in a TBC system has been investigated under simulated service conditions. The system consisted of an atmospheric plasma sprayed, yttrium stabilized zirconium oxide; a bond coat (BC) layer of NiCoCrAlY (balance Ni, 21.1%Co, 17.1%Cr, 12.6%Al, 0.61%Y, 0.4%Hf) that also acts as a corrosion protection; and a substrate of the polycrystalline turbine blade alloy IN 792 CC or the single crystalline CMSX-4. For the isothermal low cycle fatigue (LCF) testing, additional means for the heating of coated specimens were developed and for the thermomechanical fatigue (TMF) tests, completely new test techniques were necessary. The manufacture of specimens of the isolated coating and compression testing of these specimen were successfully carried out. The results obtained show that there are significant differences in the damage development in TMF loading and in isothermal (LCF) loading. In TMF loading with maximum and minimum temperatures of 950 and 450°C, shorter fatigue lives than those in the LCF tests were measured. Investigations of the damage in the TBC using acoustic emission and calculation of the stress in the TBC have contributed to the understanding of the damage processes. To obtain data for the analysis of the mechanical behaviour, the time-dependent deformation behaviours of both TBC and BC and the elastic modulus of the TBC were determined. Based on these data, a deformation model was derived, which interpreted the deformation under compressive stress as a change in the defect structure of the TBC.

Note: Record converted from VDB: 12.11.2012
Note: Aachen, Techn. Hochsch., Diss., 2003

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