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1504 |
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Tools for online monitoring of failure evolution
of thermal barrier coatings
in gas burner thermal cycling rig environment |
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Daniel E. Mack* / Forschungszentrum Jülich GmbH,
Institute of Energy Research (IEF),
IEF-1: Materials Synthesis and Processing, GER Robert Vaßen/ Forschungszemtrum Jülich, Institute of Energy Research (IEF), IEF-1: Materials Synthesis and Processing, Germany Detlev Stöver/ Forschungszemtrum Jülich, Institute of Energy Research (IEF), IEF-1: Materials Synthesis and Processing, Germany |
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One major shortcoming of thermal barrier coatings applied to gas turbine components is the spallation of the ceramic coating under mechanical stress developing during thermal cycling environments. In order to study the evolution of failure and the expectancy of lifetime under realistic conditions cycling burner rig tests are a well established matter of choice. In the same way the techniques of acoustic emission (AE) testing and infrared (IR) thermography have been widely proofed to provide insight to microscopic crack formation and localization of hidden delaminations, respectively. Both techniques can be utilized to record the evolution of microscopic and macroscopic defects in advance to the apparent failure. Indirectly, this knowledge allows to verify and to improve lifetime models. The aim of this study is to expand the use of AE and IR testing as a rugged in-situ monitoring tools for combustion driven cycling rigs and to provide spatial resolved information on thermal load and failure evolution of the TBC in those tests. For a successful application to an experiment using a gas fired and air cooled burner rig some it is necessary to overcome some limitations which are mainly due to the high level of interfering signals under those experimental conditions. In the case of the AE technique a discrimination of signals originating from different sources of the setup is necessary. For the IR thermography the evaluation of data recorded from transient states can be used to eliminate variations due to the inhomogeneous combustion heating. |