| Microstructure Design and Thermal Durability of Thermal Barrier Coatings with Layered Structure |
| Yeon-Gil JUNG |
| Changwon National University |
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Now days the turbine inlet temperature of gas turbines has been increased to 1600¡ÆC, which is much higher than the allowed temperature of the superalloy employed. Therefore, the thermal durability and lifetime performance of thermal barrier coating (TBC) system applied to the high-temperature components of gas turbines should be enhanced, and various microstructures have been proposed, such as dense vertical cracked TBC, gradient coating, high porosity coating, and thick thickness coating, etc [1-3]. In this study, the microstructure of TBC was controlled in the top and bond coats to propose the layered TBC and its influence on the thermal durability was investigated through cyclic thermal exposure tests. The results included the number of cycle to failure and a phenomenological description of failure with microstructure species. Several properties for the single and layered TBCs, such as hardness, toughness, damage tolerance, and thermal durability, were determined and compared. The microstructure in TBCs was well controlled, showing layered structure either in the top coat or in the bond coat. Mechanical properties were also well corresponded to the microstructure design in TBCs. The layered TBC showed a better thermal durability than the common TBC (single layered TBC) in cyclic thermal exposure, without or less degradation in properties. Especially, the TBC with the layered structure enhanced the thermal durability, indicating that the structural effectiveness is one of important factors for improving the thermal durability. These observations allows us to design a certain microstructure in TBC to propose an efficient coating to ensure the thermal durability and mechanical properties in the cyclic thermal exposure environments.
References:
[1] N. P. Padture, M. Gell, and E. H. Jordan, Science 296 (2002) p. 280-
[2] G. Bertrand, P. Bertrand, P. Roy, C. Rio and R. Mevrel, Surf. Coat. Technol 202 (2008) p. 1994
[3] S.W. Myoung, S.S. Lee, H.S. Kim, M.S. Kim, Y.G. Jung, S.I. Jung, T.K. Woo and U. Paik, Surf.
Coat. Technol 215 (2013) p. 46 |
| Acknowledgements : |
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