A life prediction method for combustion turbine blade coatings has been developed by modeling coating degradation mechanisms including oxidation, spallation, and aluminum loss due to inward diffusion. Using this model, the influence of cycle time on coating life is predicted for GTD-111 coated with an MCrAlY, PtAl, or aluminide coating. The results are used to construct a coating life diagram that depicts failure and safe regions for the coating in a log-log Plot of number of startup cycles versus cycle time. The regime where failure by oxidation, spallation, and inward diffusion dominates is identified and delineated from that dominated by oxidation and inward diffusion only. A procedure for predicting the remaining life of a coating is developed. The utility of the coating life diagram for predicting the failure and useful life of MCrAlY, aluminide, or PtAl coatings on the GTD-111 substrate is illustrated and compared against experimental data.

Issue Section:
Gas Turbines: Manufacturing Materials and Metallurgy
Topics:
Coatings, Combustion, Turbine blades, Cycles, Diffusion (Physics), Failure, Oxidation, Spallation (Nuclear physics), Modeling, Aluminum, Service life (Equipment)
1.
Chan
K. S.
,
1997
, “
A Mechanics-Based Treatment of Cyclic Oxidation
,”
Met. Mat. Transactions A
, Vol.
28A
, pp.
411
–
422
.
2.
Chan, K. S., Cheruvu, N. S., and Leverant, G. R., 1997, “Coating Life Prediction Under Cyclic Oxidation Conditions,” ASME Paper No. 97-GT-389.
3.
Cheruvu, N. S., Chan, K. S., and Leverant, G. R., 1998, “Cyclic Oxidation Behavior of Aluminide, Platinum Modified Aluminide, and MCrAlY Coatings on GTD-111,” presented at the 1998 ASME TURBO EXPO, June 2–5, 1998, Stockholm, Sweden.
4.
Kirkaldy
J. S.
,
1970
, “
Isothermal Diffusion in Multi Component Systems
,”
Adv. In Mat. Research
, H. Herman, ed., Vol.
4
, Interscience, New York, pp.
55
–
100
.
5.
Lee
E. Y.
,
Charter
D. M.
,
Biederman
R. R.
, and
Sisson
R. D.
,
1987
, “
Modeling the Microstructural Evolution and Degradation of M-Cr-Al-Y Coatings During High Temperature Oxidation
,”
Surface and Coatings, Technology
, Vol.
32
, pp.
19
–
39
.
6.
Lowell
C. E.
,
Barrett
C. A.
,
Palmer
R. W.
,
Auping
J. V.
, and
Probst
H. B.
,
1991
, “
COSP: A Computer Model of Cyclic Oxidation
,”
Oxidation of Metals
, Vol.
36
, No.
1/2
, pp.
81
–
112
.
7.
Nesbitt, J. A., 1984, “Overlay Coating Degradation by Simultaneous Oxidation and Coating/Substrate Interdiffusion,” NASA TM 83738, NASA-Lewis Research Center, Cleveland, OH.
8.
Nesbitt, J. A., 1989, “Diffusional Aspects of the High-Temperature Oxidation of Protective Coatings,” Diffusion Analysis & Applications, A. D. Romig, Jr., and M. A. Dayananda, eds., TMS, Warrendale, PA, pp. 307–324.
9.
Nesbitt
J. A.
,
1989
, “
Predicting Minimum Aluminum Concentrations for Protective Scale Formation on Ni-base Alloys
,”
Journal of Electrochemical Society
, Vol.
136
, pp.
1518
–
1527
.
10.
Nesbitt, J. A., and Barrett, C. A., 1993, “Predicting the Oxidation-Limited Lifetime of β NiAl,” Structural Intermetallics, R. Darolia, J. J. Lewandowski, C. T., Liu, P. L. Martin, D. B. Miracle, and M. V. Nathal, eds., TMS, Warrendale, PA, pp. 601–609.
11.
Nesbitt
J. A.
, and
Heckel
R. W.
,
1984
, “
Modeling Degradation and Failure of Ni-Cr-Al Overlay Coatings
,”
Thin Solid Films
, Vol.
119
, pp.
281
–
290
.
12.
Probst
H. B.
, and
Lowell
C. E.
,
1988
, “
Computer Simulation of Cyclic Oxidation
,”
Journal of Metals
, Vol.
40
, No.
10
, pp.
18
–
21
.
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