Journal Article

PreJuSER-10212

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Thermal-gradient testing of thermal barrier coatings under simultaneous attack by molten glassy deposits and its mitigation

Drexler, J. M. ; Aygun, A. ; Li, D. ; Vaßen, R.FZJ* ; Steinke, T.FZJ* ; Padture, N. P.

2010
Elsevier Science Amsterdam [u.a.]

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Please use a persistent id in citations: doi:10.1016/j.surfcoat.2010.02.026

Abstract: Degradation of thermal barrier coatings (TBCs) in gas-turbine engines by molten calcium-magnesium-aluminosilicate (CMAS) glassy deposits is becoming a pressing issue, as engines are required to operate under increasingly harsh conditions. While new approaches for mitigating CMAS attack of TBCs are starting to emerge, there is a need for appropriate tests for evaluating the efficacy of those approaches. To that end, we present here a new thermal-cycling test for the evaluation of TBC performance, where a thermal gradient is applied across the TBC. with simultaneous injection of CMAS. The conditions simulated in this new test are closer to actual conditions in an engine, as compared to the conventional furnace test without thermal gradient. This new test is applied to a TBC with a new composition designed for mitigating CMAS attack, where the mitigation mechanisms are observed to be similar to those found in the conventional furnace test. However, based on a previously established mechanics model it is shown here that thermal-gradient cyclic testing is essential for evaluating thermomechanical performance of TBCs under attack by CMAS, and that the use of just the conventional furnace test can lead to the underestimation of the TBC performance. (C) 2010 Elsevier B.V. All rights reserved.

Keyword(s): J ; Thermal barrier coating (auto) ; Thermal-gradient cyclic testing (auto) ; Glass deposits (auto) ; Failure mechanics (auto)

Note: The authors thank Mr. L Flower (Haynes), Dr. R. Kowalik (NavAir), Dr. B. Nagaraj (GE Aviation), and Dr. X. Ma (lnframat Corp.) for their help with this project. The authors also thank Profs. A. Evans (UCSB) and J. Hutchinson (Harvard) for fruitful discussions and their help with the E-H model. The suggestions by Prof. C. Levi (UCSB) on producing a feasible CMAS source are gratefully acknowledged. The authors also thank Dr. D. Mack (Julich) for discussion and support during the thermal-cycling experiments, and Mrs. N. Adels (Julich) for performing the burner rig tests. The research at the Ohio State University was supported by a grant from the U.S. Office of Naval Research (award no. N00014-08-1-0458) monitored by Dr. D. Shifler. Additional support was provided by the U.S. Department of Energy (award no. DE-NT0006552).

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Contributing Institute(s):

1. Werkstoffsynthese und Herstellungsverfahren (IEF-1)

Research Program(s):

1. Rationelle Energieumwandlung (P12)

Appears in the scientific report 2010

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