Effect of water vapor on thermally-grown alumina scales on Pt-modified and simple aluminide bond coatings

M. J. Lance; K. A. Unocic; J. A. Haynes; B. A. Pint

doi:10.1016/j.surfcoat.2013.06.041

Effect of water vapor on thermally-grown alumina scales on Pt-modified and simple aluminide bond coatings

M. J. Lance, K. A. Unocic, J. A. Haynes, B. A. Pint

Research output: Contribution to journal › Article › peer-review

24 Scopus citations

Abstract

Photo-stimulated luminescence spectroscopy (PSLS), 3D microscopy and focused ion beam cross-sections were used to study the effect of water vapor on the cyclic (1hcycle time) oxidation behavior of simple and Pt-modified aluminide bond coatings on several superalloy substrates at 1125° and 1150°C. By tracking the same region over time, the change in surface roughness with thermal cycling could be attributed to large and small bond coating grains rising and sinking, respectively, with thermal cycling. Oxidation in air with 10% H₂O showed a 0-37% increase in surface roughness compared to oxidation in dry air. Reducing the cycle temperature from 1150° to 1125°C, increased the thermal barrier coating lifetime by >4X but did not prevent bond coating rumpling. Compared to oxidation in dry air, PSLS identified more θ-Al₂O₃ formation on the Pt-modified aluminide bond coatings after 1h at 1125° or 1150°C in air with 10% H₂O but only minor differences in the residual stress after longer cyclic oxidation exposures. Stress histograms produced by PSLS mapping help to elucidate Al₂O₃ scale damage accumulation in each condition but did not clearly identify a mechanism for the effect of water vapor on coating performance.

Original language	English
Pages (from-to)	2-7
Number of pages	6
Journal	Surface and Coatings Technology
Volume	237
DOIs	https://doi.org/10.1016/j.surfcoat.2013.06.041
State	Published - Dec 25 2013

Funding

The authors would like to thank K. M. Cooley, G. Garner, T. Lowe and T. Jordan for assistance with the experimental work at ORNL. Y. Zhang at Tennessee Tech. University provided the Pt plating. B. Nagaraj at General Electric Aircraft Engines provided substrates and coated the specimens with EB-PVD YSZ. K. Murphy at Alcoa Howmet also provided substrates. S. Dryepondt and E. Lara-Curzio provided helpful comments on the manuscript. This research was sponsored by the U.S. Department of Energy, Office of Coal and Power R&D, Office of Fossil Energy , (R. Dennis program manager).

Keywords

Alumina
Bond coating
Oxidation
PSLS
Photo-stimulated luminescence spectroscopy
TBC

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10.1016/j.surfcoat.2013.06.041

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title = "Effect of water vapor on thermally-grown alumina scales on Pt-modified and simple aluminide bond coatings",

abstract = "Photo-stimulated luminescence spectroscopy (PSLS), 3D microscopy and focused ion beam cross-sections were used to study the effect of water vapor on the cyclic (1hcycle time) oxidation behavior of simple and Pt-modified aluminide bond coatings on several superalloy substrates at 1125° and 1150°C. By tracking the same region over time, the change in surface roughness with thermal cycling could be attributed to large and small bond coating grains rising and sinking, respectively, with thermal cycling. Oxidation in air with 10% H2O showed a 0-37% increase in surface roughness compared to oxidation in dry air. Reducing the cycle temperature from 1150° to 1125°C, increased the thermal barrier coating lifetime by >4X but did not prevent bond coating rumpling. Compared to oxidation in dry air, PSLS identified more θ-Al2O3 formation on the Pt-modified aluminide bond coatings after 1h at 1125° or 1150°C in air with 10% H2O but only minor differences in the residual stress after longer cyclic oxidation exposures. Stress histograms produced by PSLS mapping help to elucidate Al2O3 scale damage accumulation in each condition but did not clearly identify a mechanism for the effect of water vapor on coating performance.",

keywords = "Alumina, Bond coating, Oxidation, PSLS, Photo-stimulated luminescence spectroscopy, TBC",

author = "Lance, {M. J.} and Unocic, {K. A.} and Haynes, {J. A.} and Pint, {B. A.}",

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AU - Lance, M. J.

AU - Unocic, K. A.

AU - Haynes, J. A.

AU - Pint, B. A.

PY - 2013/12/25

Y1 - 2013/12/25

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AB - Photo-stimulated luminescence spectroscopy (PSLS), 3D microscopy and focused ion beam cross-sections were used to study the effect of water vapor on the cyclic (1hcycle time) oxidation behavior of simple and Pt-modified aluminide bond coatings on several superalloy substrates at 1125° and 1150°C. By tracking the same region over time, the change in surface roughness with thermal cycling could be attributed to large and small bond coating grains rising and sinking, respectively, with thermal cycling. Oxidation in air with 10% H2O showed a 0-37% increase in surface roughness compared to oxidation in dry air. Reducing the cycle temperature from 1150° to 1125°C, increased the thermal barrier coating lifetime by >4X but did not prevent bond coating rumpling. Compared to oxidation in dry air, PSLS identified more θ-Al2O3 formation on the Pt-modified aluminide bond coatings after 1h at 1125° or 1150°C in air with 10% H2O but only minor differences in the residual stress after longer cyclic oxidation exposures. Stress histograms produced by PSLS mapping help to elucidate Al2O3 scale damage accumulation in each condition but did not clearly identify a mechanism for the effect of water vapor on coating performance.

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KW - Oxidation

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KW - Photo-stimulated luminescence spectroscopy

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ER -

Effect of water vapor on thermally-grown alumina scales on Pt-modified and simple aluminide bond coatings

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