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Determination of the Structure and Chemistry of Thermally Grown Oxides in Thermal Barrier Coatings

Published online by Cambridge University Press:  02 July 2020

M.R. Brickey  and
J.L. Lee
M.R. Brickey
Affiliation:
School of Materials Engineering, Purdue University, West Lafayette, IN47907-1289, USA
J.L. Lee
Affiliation:
School of Materials Engineering, Purdue University, West Lafayette, IN47907-1289, USA
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Extract

Thermal barrier coatings (TBCs) insulate gas turbine hot section components from the hot (∽1200 - 1450°C) combustion gas exhaust stream. An airline company can save millions of dollars per year by using TBCs to protect vital engine components and to improve fuel efficiency. TBCs typically consist of an 8 wt.% yttria-partially-stabilized zirconia (YPSZ) ceramic topcoat deposited on a platinum-nickel-aluminide (Pt-Ni-Al) bondcoat covering a nickel-based superalloy substrate. Thermal exposure during YPSZ electron beam-physical vapor deposition (EB-PVD) and engine operation promotes the formation of a thermally grown oxide (TGO) between the Pt-Ni-Al and the YPSZ layers. Stresses can develop at the Pt-Ni-Al/TGO and TGO/YPSZ interfaces due to TGO growth and thermal expansion coefficient mismatch. These stresses eventually cause spallation of the YPSZ, leaving the metallic substrate vulnerable to high temperature degradation since exhaust temperatures are often higher than the melting temperature of most nickel-based superalloys (∽1200 - 1450°C).

Type
Oxidation/Corrosion
Information
Microscopy and Microanalysis , Volume 5 , Issue S2: Proceedings: Microscopy & Microanalysis '99, Microscopy Society of America 57th Annual Meeting, Microbeam Analysis Society 33rd Annual Meeting, Portland, Oregon August 1-5, 1999 , August 1999 , pp. 854 - 855
Copyright
Copyright © Microscopy Society of America

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References

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6. We wish to acknowledge Wortman, D.J. and Rigney, J.D. of General Electric Aircraft Engines for providing the TBC specimens andVasiliev, A.L. of Purdue University for helpful discussions.Google Scholar