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Detailed Program
Paper Number : AD-I03
Time Frame : 15:50~16:15
Presentation Date : Thurseday, 27, November
Session Name : Advanced Coating for Gas Turbines
Session Chair 1# : Yoonsuk Oh
Session Chair 2# : Shunkichi Ueno
Effects of Feedstock Species in Top Coat on Thermal Durability of Thermal Barrier Coatings in Cyclic Thermal Exposure
Sang-Won MYOUNG
Changwon National University
Thermal durability and failure mechanisms of thermal barrier coatings (TBCs) are closely related with its microstructure. Therefore, the effects of feedstock species in a top coat on the thermal durability and/or fracture behavior of TBCs were investigated through thermal fatigue tests. Two kinds of feedstock with different purity in 8YSZ were employed for the top coat, which were prepared by air plasma spray (APS) process [1-2]. The bond coat was formed by high velocity oxygen fuel (HVOF) process using Ni based intermatellic powder. The microstructural evolution and mechanical properties of the designed TBCs were investigated through thermal fatigue tests. The cyclic furnace thermal fatigue (CFTF) tests were performed at 1100 and 1300 ¡ÆC with a temperature difference of 150 ¡ÆC between the surface and bottom of TBC sample till 872 cycles in the specially designed furnace. The flame thermal fatigue (FTF) tests were also performed at a surface temperature of 1100¡ÆC for a dwell time of 5 min till 872 cycles. The TBC with a high purity showed a better thermal durability than that with a relatively low purity at both temperatures in the CFTF, and the microstructure of TBC after the CFTF was more dramatically changed than that after the FTF, showing a relatively thick TGO layer. The influences of feedstock species on microstructural evolution and interfacial stability was discussed, based on the microstructure observation and comparison before and after cyclic thermal exposure tests.

References:

[1] Y.H. Sohn, E.Y. Lee, B.A. Nagaraj, R.R. Biederman and R.D. Sisson Jr, Surf. Coat. Technol 132 (2001) p. 146
[2] K. Richardt, K. Bobzin, D. Sporer, T. Schläfer, P. Fiala, Surf. Coat. Technol 17 (2008) p. 612
Acknowledgements :