The hot gas path components of gas turbines have to withstand to severe conditions in terms of high temperature oxidation, hot corrosion, and creep-fatigue phenomena. The evaluation of components residual life is an important matter for gas turbines producers and the estimation of service temperatures is a key tool for this evaluation. The most diffused methods to estimate service temperatures of gas turbines blades and vanes in Ni based superalloys are related to the microstructural evolution of the dispersed intermetallic phase γ′, Ni3Al. The aim of this work has been the determination of a tool to estimate service temperature on the basis of the microstructural evolutions of a NiCoCrAlY+Re coating. In order to obtain a deep characterization of the coating after exposure at different durations and temperatures, an extensive experimental test program has been planned. Samples of Ni based superalloys, covered by the investigated coating, have been aged in chamber furnaces in the temperature range 700 °C–1000 °C with durations up to 20,000 h. The microstructure of this coating is characterized by β phase, NiAl, which is the Al reservoir, embedded in the matrix, that is constituted by γ′ phase at low temperature and by γ phase over 900 °C. Moreover, electron back scattered diffraction and X-ray diffraction measurements on samples have revealed three classes of secondary phases: the first one has been identified as σ-Cr2Re3, the second one as Cr carbide-Cr23C6 and the third one as α-Cr. σ phase is very abundant at the lower temperatures while it disappears after long exposures at temperatures higher than 900 °C. The σ phase composition is different at different temperatures and the Re content in particular increases with the temperature. Starting from the σ phase composition determined at different temperatures, a tool has been constructed that relates the service temperature to the Re content in the same phase. The new tool has been applied to the analyses of different components. The results of the new method have been compared to those ones obtained with the method based on γ′ features, developed in the past through huge experimental campaigns. The agreement between the two methods is generally good, they can be used in a complementary way due to the fact that the γ′ one seems to be more suitable for high temperature ranges (T > 900 °C) where it gives a reliable estimation, while the σ method is more suitable in the temperature range 700 °C–900 °C.

References

References
1.
Reed
,
R. C.
,
2006
,
The Superalloys, Fundamentals and Applications
,
Cambridge University Press
,
Cambridge
, UK, pp.
33
216
.
2.
Mughrabi
,
H.
,
2009
, “
Microstructural Aspects of High Temperature Deformation of Monocrystalline Nickel Base Superalloys: Some Open Problems
,”
Mater. Sci. Technol.
,
25
(
2
), pp.
191
204
.10.1179/174328408X361436
3.
Baldan
,
A.
,
2002
, “
Review: Progress in Ostwald Ripening Theories and Their Applications to γ′-Precipitates in Nickel-Base Superalloy: Part II—Ni-Base Superalloys
,”
J. Mater. Sci.
,
37
, pp.
2379
2405
.10.1023/A:1015408116016
4.
Roy
,
I.
,
Balikci
,
E.
,
Ibekwe
,
S.
, and
Raman
,
A.
,
2005
, “
Precipitate Growth Activation Energy Requirements in the Duplex Size γ′ Distribution in the Superalloy IN738LC
,”
J. Mater. Sci.
,
40
, pp.
6207
6215
.10.1007/s10853-005-3154-6
5.
Balikci
,
E.
and
Raman
,
A.
,
2008
, “
The Relationship Between Activation Energy and Precipitate Size for Precipitate Agglomeration
,”
J. Mater. Sci.
,
43
, pp.
927
932
.10.1007/s10853-007-2206-5
6.
Mammoliti
,
F.
,
Mastromatteo
,
F.
,
Giannozzi
,
M.
,
Iozzelli
,
F.
, and
Lucci
,
D.
,
2004
, “
The Coarsening Kinetic of γ′ Particle in Nickel-Based Superalloys During Aging at High Temperature
,”
ASME
Paper No. GT2006-90137.10.1115/GT2006-90137
7.
Moshtaghin
,
S.
, and
Asgari
,
S.
,
2003
, “
Growth Kinetics of γ′ Phase Precipitates in Superalloy IN738LC During Long Term Aging
,”
Mater. Des.
,
24
, pp.
325
330
.10.1016/S0261-3069(03)00061-X
8.
Stevens
,
R. A.
, and
Flewitt
,
P.E.J.
,
1979
, “
The Effect of γ′ Precipitate Coarsening During Isothermal Aging and Creep of Nickel-Base Superalloy IN738
,”
Mater. Sci. Eng.
,
37
, pp.
237
247
.10.1016/0025-5416(79)90157-5
9.
Aurrecoechea
,
J.
, and
Brentnall
,
W.
,
1990
, “
Operating Temperature Estimation and Life Assessment of Turbine Blade Airfoils
,”
Gas Turbine Aeroengine Congress and Exposition, Brussels
,
Belgium
, Belgium, June 11–14, ASME Paper No. 90-GT-23.
10.
Vacchieri
,
E.
,
Bonadei
,
A.
,
Delogu
,
G.
,
Cordano
,
E.
,
Corcoruto
,
S.
, and
Poggio
,
E.
,
2008
, “
Operating Temperature Estimation Based on Microstructure Evolution of Ni-Base Superalloys for GT Blades/Vanes
,”
The Future of Gas Turbine Technology 4th International Conference
,
Brussels, Belgium
, October 15–16.
11.
Poggio
,
E.
,
Corcoruto
,
S.
, and
Vacchieri
,
E.
,
2009
, “
Microstructural Degradation of a Cast Ni-Based Superalloy After Creep, LCF, and TMF Tests
,”
ECCC Creep Conference
,
Zurich
, April 21–23.
12.
Krukovskii
,
P. G.
, and
Tadlya
,
K. A.
,
2007
, “
Method for Estimation of the Average Local Working Temperature and the Residual Resource of Metal Coatings of Gas Turbine Blades
,”
J. Eng. Phys. Thermophys.
,
80
(
3
), pp.
440
447
.10.1007/s10891-007-0058-0
13.
Krukovsky
,
P.
,
Kolarik
,
V.
,
Tadlya
,
K.
,
Rybnikov
,
A.
,
Kryukov
,
I.
,
Mojaiskaya
,
N.
, and
Juez-Lorenzo
,
M.
,
2004
, “Lifetime Prediction for MCrAlY Coatings by Means of Inverse Problem Solution (IPS),”
Surf. Coat. Technol.
,
177–178
, pp.
32
36
.10.1016/j.surfcoat.2003.06.002
14.
Achar
,
D.R.G.
,
Munoz-Arroyo
,
R.
,
Singheiser
,
L.
, and
Quadakkers
,
W. J.
,
2004
, “
Modelling of Phase Equilibria in MCrAlY Coating Systems
,”
Surf. Coat. Technol.
,
187
, pp.
272
283
.10.1016/j.surfcoat.2004.02.018
15.
Ellison
,
K. A.
,
Daleo
,
J. A.
, and
Hussain
,
K.
,
2004
A New Method of Metal Temperature Estimation for Service-Run Blades and Vanes
,”
10th International Symposium on Superalloys
, Champion, PA, September 19–23, pp.
759
768
, http://www.tms.org/superalloys/10.7449/2004/Superalloys_2004_759_768.pdf
16.
Dahl
,
K. V.
, and
Hald
,
J.
,
2006
, “
Estimation of Metal Temperature of MCrAlY Coated IN738 Components Based on Interdiffusion Behaviour
,”
Energy Mater.
,
1
, pp.
106
115
.10.1179/174892306X99723
17.
Czech
,
N.
,
Schmitz
,
W. F.
, and
Stamm
,
W.
,
1995
, “
Microstructural Analysis of the Role of Rhenium in Advanced MCrAlY Coatings
,”
Surf. Coat. Technol.
,
76-77
, pp.
28
33
.10.1016/0257-8972(95)02546-4
18.
Beele
,
W.
,
Czech
,
N.
,
Quadakkers
,
W. J.
, and
Stamm
,
W.
,
1997
, “
Long-Term Oxidation Tests on a Re-Containing MCrAlY Coating
,”
Surf. Coat. Technol.
,
94–95
, pp.
41
45
.10.1016/S0257-8972(97)00473-
19.
Täck
,
U.
,
2004
, “
The Influence of Cobalt and Rhenium on the Behaviour of MCrAlY Coatings
,” Ph.D. thesis, Tech. Univ. Frieberg, Germany.
20.
Toscano
,
J.
,
Gil
,
A.
,
Hüttel
,
T.
,
Wessel
,
E.
,
Naumenko
,
D.
,
Singheiser
,
L.
, and
Quadakkers
,
W. J.
,
2007
, “
Temperature Dependence of Phase Relationships in Different Types of MCrAlY-Coatings
,”
Surf. Coat. Technol.
,
202
, pp.
603
607
.10.1016/j.surfcoat.2007.06.044
21.
Huang
,
L.
,
Sun
,
X. F.
,
Guan
,
H. R.
, and
Hu
,
Z. Q.
,
2006
, “
Improvement of the Oxidation Resistance of NiCrAlY Coatings by the Addition of Rhenium
,”
Surf. Coat. Technol.
,
201
, pp.
1421
1425
.10.1016/j.surfcoat.2006.02.009
22.
Liu
,
Xu
,
Huang
,
L.
,
Bao
,
Z. B.
,
Wei
,
H.
,
Sun
,
X. F.
,
Guan
,
H. R.
, and
Hu
,
Z. Q.
,
2009
, “
Oxidation Behavior of Graded NiCrAlYRe Coatings at 900, 1000, and 1100 °C
,”
Oxid. Met.
,
71
, pp.
125
142
.10.1007/s11085-008-9131-0
23.
Phillips
,
M. A.
, and
Gleeson
,
B.
,
1998
, “
Beneficial Effects of Rhenium Additions on the Cyclic-Oxidation Resistance of β-NiAl + α-Cr Alloys
,”
Oxid. Met.
,
50
(
5/6
), pp.
399
429
.10.1023/A:1018804824847
24.
Czech
,
N.
,
Schmitz
,
W. F.
, and
Stamm
,
W.
,
1994
, “
Improvement of MCrAlY Coatings by Addition of Rhenium
,”
Surf. Coat. Technol.
,
68–69
, pp.
17
21
.10.1016/0257-8972(94)90131-7
25.
Barbareschi
,
E.
,
Bonadei
,
A.
,
Costa
,
A.
,
Guarnone
,
P.
, and
Vacchieri
,
E.
, 2010, “
Assessment of a Residual Life Evaluation Tool for Gas Turbine Blades and Vanes Based on Microstructural Evolution of a NiCoCrAlY+Re Coating
,” 9th Liege Conference: Materials for Advanced Power Engineering Liège, Belgium, September 27–29.
26.
Costa
,
A.
,
Bonadei
,
A.
,
Vacchieri
,
E.
,
Cirilli
,
F.
,
Di Donato
,
A.
, and
Tassa
,
O.
, “
Thermodynamic and Diffusive Model for NiCoCrAlY+Re Coatings Applied on Gas Turbine Hot Gas Path Components
,” 25th International Conference on Surface Modification Technologies (SMT25), Trollhattan, Sweden, June 20–22.
27.
Baufeld
,
B.
, and
Schmucker
,
M.
,
2005
,
Microstructural Evolution of a NiCoCrAlY Coating on an IN100 Substrate
,”
Surf. Coat. Technol.
,
199
, pp.
49
56
.10.1016/j.surfcoat.2004.06.014
28.
Yang
,
Y.-M.
,
Liao
,
H.
, and
Coddet
,
C.
,
2002
, “
Simulation and Application of a HVOF Process for MCrAlY Thermal Spraying
,”
J. Therm. Spray Technol.
,
11
(
1
), pp.
36
43
.10.1361/105996302770348952
29.
Zhao
,
L.
,
Parco
,
M.
, and
Lugscheider
,
E.
, “
High Velocity Oxy-Fuel Thermal Spraying of a NiCoCrAlY Alloy
,”
Surf. Coat. Technol.
,
179
, pp.
272
278
.10.1016/S0257-8972(03)00818-1
30.
Lugscheider
,
E.
,
Herbst
,
C.
, and
Zhao
,
L.
, “
Parameter Studies on High-Velocity Oxy-Fuel Spraying of MCrAlY Coatings
,”
Surf. Coat. Technol.
,
108–109
, pp.
16
23
.10.1016/S0257-8972(98)00630-6
31.
Brandl
,
W.
,
Toma
,
D.
,
Kruger
,
J.
,
Grabke
,
H. J.
, and
Matthaus
,
G.
,
1997
, “
The Oxidation Behaviour of HVOF Thermal-Sprayed MCrAlY Coatings
,”
Surf. Coat. Technol.
,
93–95
, pp.
21
26
.10.1016/S0257-8972(97)00470-2
32.
Saeidi
,
S.
,
Voisey
,
K. T.
, and
McCartney
,
D. G.
,
2009
, “
The Effect of Heat Treatment on the Oxidation Behavior of HVOF and VPS CoNiCrAlY Coatings
,”
J. Therm. Spray Technol.
,
18
(
2
), pp.
209
216
.10.1007/s11666-009-9311-8
33.
Brandl
,
W.
,
Toma
,
D.
, and
Grabke
,
H. J.
,
1998
, “
The Characteristics of Alumina Scales Formed on HVOF-Sprayed MCrAlY Coatings
,”
Surf. Coat. Technol.
,
108–109
, pp.
10
15
.10.1016/S0257-8972(98)00613-6
You do not currently have access to this content.