20 October 2009 Degradation of thermal barrier coated superalloy component during service
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Proceedings Volume 7493, Second International Conference on Smart Materials and Nanotechnology in Engineering; 74932C (2009) https://doi.org/10.1117/12.843404
Event: Second International Conference on Smart Materials and Nanotechnology in Engineering, 2009, Weihai, China
Abstract
The time dependent degradation of first-stage blades for gas turbine was investigated. First, Two used blades were prepared from the operating facilities, and their operating hours were 25,000 and 52,000 hrs, respectively. Microstructural comparison of coating surfaces showed that exposure to the environment increased thickness of TGO (Thermally Grown Oxide) and β depletion region, and then debonding and spallation of TBC (Thermal Barrier Coating) occurred finally. In the case of substrate, Ni-based superalloy, the shape and size of γ' were changed with increasing operating time. Especially, in the leading and trailing edges of blades, the size of γ' was bigger and the shape was more elliptic than other region. It can be thought that the leading and trailing edges of blades can be the starting point of degradation in first-stage blades. Second, TBC failed blade used for 22,000 hrs was prepared and compared with other two blades. Large interfacial cracks were formed between top and bond coat, and TGO was not uniform and continuous. The chemical composition analysis on bond coat showed that low chromium content is responsible for the formation not only of Al oxide but also of Co, Cr, Ni oxides.
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Han-Sang Lee, Han-Sang Lee, Doo-Soo Kim, Doo-Soo Kim, Jine-sung Jung, Jine-sung Jung, Keun-Bong Yoo, Keun-Bong Yoo, } "Degradation of thermal barrier coated superalloy component during service", Proc. SPIE 7493, Second International Conference on Smart Materials and Nanotechnology in Engineering, 74932C (20 October 2009); doi: 10.1117/12.843404; https://doi.org/10.1117/12.843404
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