Distribution & Access For Publication Downloads News About Us Contact Us
Paper Titles
Hydrogen Detection in Buried Layers of Thermal Barrier Coatings
p.177
Aluminide Coating Formation on Internal Passages of GTD-111 Superalloy by Slurry Technique
p.185
Enigmatic Moisture Effects on Al2O3 Scale and TBC Adhesion
p.191
Phase Field Modeling of Interdiffusion Microstructure in Ni-Cr-Al Diffusion Couples
p.199
Degradation of Yttria Stabilized Zirconia Thermal Barrier Coatings by Molten CMAS (CaO-MgO-Al2O3-SiO2) Deposits
p.207
Characterization of TBC Systems with NiPtAl or NiCoCrAlYTa Bond Coatings after Thermal Cycling at 1100°C: A Comparative Study of Failure Mechanisms
p.213
Depth Distribution of Residual Stress in Graded (Ti, Al) N Coating and Fatigue Properties of Coated Stainless Steel
p.223
Solid Reactions between Enamel and O-Phase Ti-Al-Nb Intermetallics at 800 °C
p.233
Compositional Factors Affecting the Oxidation Behavior of Pt-Modified γ-Ni+γ’-Ni3Al-Based Alloys and Coatings
p.239

Degradation of Yttria Stabilized Zirconia Thermal Barrier Coatings by Molten CMAS (CaO-MgO-Al2O3-SiO2) Deposits

Article Preview

Abstract:

In advanced gas turbine engines that operate in a dust-laden environment causing ingestion of siliceous debris into engines, thermal barrier coatings (TBCs) are highly susceptible to degradation by molten CMAS (calcium-magnesium alumino silicate) deposits. In this study, the degradation mechanisms other than the commonly reported thermomechanical damage are investigated with an emphasis on the thermochemical aspects of molten CMAS induced degradation of TBCs. Free-standing yttria stabilized zirconia (8YSZ) TBC specimens in contact with a model CMAS composition were subjected to isothermal heat treatment in air at temperatures ranging from 1200°C to 1350°C. Phase transformations and microstructural development were examined by using x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Starting at 1250°C, the molten CMAS readily infiltrated and dissolved the YSZ coating followed by reprecipitation of zirconia with a different morphology and composition that depends on the local melt chemistry. Significant amount of Y2O3 depleted monoclinic ZrO2 phase evolved from CMAS melt that dissolved ť-ZrO2 was evident. Thus the mechanism of dissolution and reprecipitation due to molten CMAS damage resulted in destabilization of the YSZ with disruptive phase transformation (t’  f + m).

You might also be interested in these eBooks
High Temperature Corrosion and Protection of Materials 7 View Preview

Info:

Periodical:

Materials Science Forum (Volumes 595-598)

Pages:

207-212

DOI:

https://doi.org/10.4028/www.scientific.net/MSF.595-598.207

Citation:

Cite this paper

Online since:

September 2008

Authors:

Prabhakar Mohan, Biao Yuan, Travis Patterson, Vimal Desai, Yong Ho Sohn

Keywords:

CMAS, Degradation, Thermal Barrier Coating (TBC), Yttria Stabilized Zirconia (YSZ)

Export:

RIS, BibTeX

Price:

Permissions:

Request Permissions

References

[1] R. A. Miller, J. Am. Ceram. Soc., Vol. 67.

Google Scholar

[8] (1984), p.517.

Google Scholar

[2] N. P. Padture, M. Gell, and E. H. Jordan, Science, Vol. 296, (2002), p.280.

Google Scholar

[3] A. G. Evans, D. R. Mumm, J. W. Hutchinson, G. H. Meier, and F. S. Pettit, Prog. Mater. Sci., Vol. 46, (2001), p.505.

Google Scholar

[4] M.P. Borom, C.A. Johnson and L.A. Peluso, Surf. Coat. Technol., Vol. 86-87 (1996), p.116.

Google Scholar

[5] J. J. Kim, M. G. Dunn, A. J. Baran, D. P. Wade, and E. L. Tremba, ASME Trans. J. Eng. Gas Turbines Power, Vol. 115.

Google Scholar

[7] (1993), p.641.

Google Scholar

[6] D. J. de Wet, R. Taylor, and F. H. Stott, J. Phys. IV, 3 [C9] (1993), p.655.

Google Scholar

[7] K.M. Grant, S. Kramer, J.P.A. Lofvander, and C.G. Levi, Surf. Coat. Technol., Vol. 202, (2007), 653.

Google Scholar

[8] C. Mercer, S. Faulhaber, A.G. Evans and R. Darolia, Acta Mater., Vol. 53.

Google Scholar

[4] (2005), p.1029.

Google Scholar

[9] X. Chen, Surf. Coat. Technol., Vol. 200, (2006), p.3418.

Google Scholar

[10] S. Kramer, J. Yang and C.G. Levi, J. Am. Ceram. Soc., Vol. 89.

Google Scholar

[10] (2006), p.3167.

Google Scholar

[11] A. J. Burns, R. Subramanian , B. W. Kempshall, and Y. H. Sohn, Surf. Coat. Technol., Vol. 177 -178, (2004), p.89.

Google Scholar

[12] R. Stevens, An Introduction to Zirconia, Magnesium Elektron Ltd., Twickenham, UK, 1983, p., 7.

Google Scholar

Scientific.Net is a registered brand of Trans Tech Publications Ltd
© 2024 by Trans Tech Publications Ltd. All Rights Reserved