Assessment of ex-service parts is important for the power generation industry. It gives us the opportunity to correlate part conditions to specific operating conditions like fuel used, local atmospheric conditions, operating regime, and temperature load. For assessment of thermal barrier coatings, one of the most valuable pieces of information is the local thermal condition. A method has been developed in Alstom, allowing determination of a thermal barrier coating average surface temperature after engine operation. It is based on the analysis of the phase composition of the thermal barrier coating by the acquisition of an X-ray diffraction spectrum of the coating surface, and its analysis using Rietveld refinement. The method has been validated by comparing its outcome to thermal models and base metal temperature mapping data. It is used for assessment of combustor and turbine coatings with various purposes: Determination of remnant coating life, building of lifing models, or determination of the coating degradation mechanisms under some specific operating conditions. Examples will be presented showing applications of this method.

References

References
1.
Chamberlain
,
J. R.
,
1991
, “
Temperature Indicating Paint and Method of Preparing a Specimen with the Same
,” United State Patent No. US5008136B, p.
4
.
2.
Bossmann
,
H.-P.
,
Bachegowda
,
S.
, and
Schnell
,
A.
,
2010
, “
Manufacturing Optimization for Bondcoat/Thermal Barrier Coating Systems
,”
ASME J. Eng. Gas Turbines Power
,
132
(
2
), p.
022101
.10.1115/1.3155398
3.
Bossmann
,
H.-P.
,
Witz
,
G.
, and
Baumann
,
R.
,
2011
, “
Development of Reliable Thermal Barrier Coatings for High-Loaded Turbine and Combustor Parts
,”
VGB PowerTech
,
10
, pp.
50
54
.
4.
Young
,
R. A.
,
1993
, “
Introduction to the Rietveld Method
,”
The Rietveld Method
(International Union of Crystallography Monographs on Crystallography 5)
,
R. A.
Young
, ed.,
Oxford University Press, Oxford
, UK, pp.
1
38
.
5.
Larson
,
A. C.
, and
Von Dreele
,
R. B.
,
2000
, “
General Structure Analysis System (GSAS)
,” LAUR 86-748, Los Alamos National Laboratory, Los Alamos, NM.
6.
Toby
,
B. H.
,
2001
, “
EXPGUI, a Graphical User Interface for GSAS
,”
J. Appl. Crystallogr.
,
34
, pp.
210
213
.10.1107/S0021889801002242
7.
Scott
,
H. G.
,
1975
, “
Phase Relationships in the Zirconia–Yttria System
,”
J. Mater. Sci.
,
10
, pp.
1527
1535
.10.1007/BF01031853
8.
Miller
,
R. A.
,
Smialek
,
J. L.
, and
Garlick
,
R. G.
,
1981
, “
Phase Stability in Plasma-Sprayed, Partially Stabilized Zirconia–Yttria
,”
Science and Technology of Zirconia
, Vol. 1,
A. H.
Heuer
and
L. W.
Hobbs
, eds.,
American Ceramic Society
,
Columbus
, OH, pp.
241
253
.
9.
Ilavsky
,
J.
,
Stalick
,
J. K.
, and
Wallace
,
J.
,
2001
, “
Thermal Spray Yttria-Stabilized Zirconia Phase Changes During Annealing
,”
J. Thermal Spray Technol.
,
10
(
3
), pp.
497
501
.10.1361/105996301770349277
10.
Brandon
,
J. R.
, and
Taylor
,
R.
,
1991
, “
Phase Stability of Zirconia-Based Thermal Barrier Coatings Part I, Zirconia–Yttria Alloys
,”
Surface Coating Technol.
,
46
, pp.
75
90
.10.1016/0257-8972(91)90151-L
11.
Schulz
,
U.
,
2000
, “
Phase Transformation in EB-PVD Yttria Partially Stabilized Zirconia Thermal Barrier Coatings During Annealing
,”
J. Am. Ceram. Soc.
,
83
(
4
), pp.
904
910
.10.1111/j.1151-2916.2000.tb01292.x
12.
Azzopardi
,
A.
,
Mévrel
,
R.
,
Saint-Ramond
,
B.
,
Olson
,
E.
, and
Stiller
,
K.
,
2004
, “
Influence of Aging on Structure and Thermal Conductivity of Y-PSZ and Y–FSZ EB–PVD Coatings
,”
Surface Coating Technol.
,
177–178
, pp.
131
139
.10.1016/j.surfcoat.2003.08.073
13.
Krogstad
,
J. A.
,
Krämer
,
S.
,
Lipkin
,
D. M.
,
Johnson
,
C. A.
,
Mitchell
,
D. R. G.
,
Cairney
,
J. M.
, and
Levi
,
C. G.
,
2011
, “
Phase Stability of t′-Zirconia-Based Thermal Barrier Coatings: Mechanistic Insights
,”
J. Am. Ceram. Soc.
,
94
(
S1
), pp.
S168
S177
.10.1111/j.1551-2916.2011.04531.x
14.
Ilavsky
,
J.
, and
Stalick
,
J. K.
,
2000
, “
Phase Composition and its Changes During Annealing of Plasma-Sprayed YSZ
,”
Surface Coating Technol.
,
127
, pp.
120
129
.10.1016/S0257-8972(00)00562-4
15.
Heal
,
G. R.
,
2002
, “
Thermogravimetry and Derivative Thermogravimetry
,”
Principles of Thermal Analysis and Calorimetry
,
P. J.
Haines
, ed.,
RSC Paperbacks
,
Cambridge
, UK, pp.
42
50
.
16.
Witz
,
G.
,
Shklover
,
V.
,
Steurer
,
W.
,
Bachegowda
,
S.
, and
Bossmann
,
H.-P.
,
2007
, “
Phase Evolution in Yttria-Stabilized Zirconia Thermal Barrier Coatings Studied by Rietveld Refinement of X-Ray Powder Diffraction Patterns
,”
J. Am. Ceram. Soc.
,
90
(
9
), pp.
2935
2940
.10.1111/j.1551-2916.2007.01785.x
17.
Borom
,
M. P.
,
Johnson
,
C. A.
, and
Peluso
,
L. A.
,
1996
, “
Role of Environmental Deposits and Operating Surface Temperature in Spallation of Air Plasma Sprayed Thermal Barrier Coatings
,”
Surface Coatings Technol.
,
86–87
, pp.
116
126
.10.1016/S0257-8972(96)02994-5
18.
Mercer
,
C.
,
Faulhaber
,
S.
,
Evans
,
A. G.
, and
Darolia
,
R.
,
1995
, “
A Delamination Mechanism for Thermal Barrier Boatings Subject to Calcium–Magnesium–Alumino-Silicate (CMAS) Infiltration
,”
Acta Mater.
,
53
, pp.
1029
1039
.10.1016/j.actamat.2004.11.028
19.
Krämer
,
S.
,
Yang
,
J.
,
Levi
,
C. G.
,
Johnson
,
C. A.
,
2006
, “
Thermochemical Interaction of Thermal Barrier Coatings with Molten CaO–MgO–Al2O3–SiO2 (CMAS) Deposits
,”
J. Am. Ceram. Soc.
,
89
(
10
), pp.
3167
3175
.10.1111/j.1551-2916.2006.01209.x
20.
Hamilton
,
J. C.
, and
Nacelberg
,
A. S.
,
1984
, “
In Situ Raman Spectroscopic Study of Yttria-Stabilized Zirconia Attack by Molten Sodium Vanadate
,”
J. Am. Ceram. Soc.
,
67
(
10
), pp.
686
690
.10.1111/j.1151-2916.1984.tb19683.x
21.
Bol'shakov
,
K. A.
, and
Fedorov
,
P. I.
,
1956
, “
Study of Sodium Sulfate-Cobalt Sulfate, and Sodium Sulfate-Nickel Sulfate Systems
,”
Zh. Obshchei Khimii
,
26
(
2
), pp.
348
350
.
You do not currently have access to this content.