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- 2012 (2) (entfernen)
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Schlagworte
Thermal barrier coatings allow increasing the operating temperature and efficiency of land-, sea-, or air-based turbines. As failure of the coating may result in serious damage of the turbine, reliable estimation of its lifetime is essential. To assess the lifetime, cyclic tests are conceived to combine thermal loading by heating the surface of the coating with laser irradiation and nondestructive methods for damage determination. Using laser irradiation allows a high reproducibility of the thermal load. The temperature of the sample surface during thermal loading is determined by an infrared-camera which also enables the possibility to detect damage in the coating via thermography. Additionally, four acoustic sensors, attached to the experimental setup, are used to detect damage in the sample and determine the source of acoustic events. Results of acoustic emission correlate well with thermographic images that visualize the formation and evolution of damage through delaminations in the samples.
Study of elastic properties of aero-engine metallic materials is of paramount importance because it forms one of the foundations of engineering design of components. Nine isotropic aero-engine metallic materials were studied for their elastic properties for a temperature range varying from ambient to operating limit. Test was carried out in vacuum to prevent oxidation of specimens. Dimensional corrections of the specimen due to thermal expansion were taken into account. Dynamic elastic modulus was evaluated as the average of the moduli that was obtained through first flat and edge flexural mode frequencies. Dynamic shear modulus was established through the first torsional mode of frequency.