Thermal barrier coatings (TBCs) provide thermal insulation to high-temperature superalloys. Residual stresses develop in TBCs during cool-down from processing temperatures due to the thermal expansion mismatch between the different layers (substrate, bond coat, and the ceramic TBC). These residual stresses can initiate microcracks at the bond coat/TBC interface which can lead to debonding at the bond coat/TBC interface. Elasticity-based modeling was used to determine the transient stresses in the TBC, bond coat, and the superalloy substrate with specific attention to the interfaces. For the steady-state case, finite element modeling was undertaken as well. Closed-form elasticity solutions correlated well with the finite element results for the steady-state case. The highest residual stresses occurred at the interface between the bond coat and the TBC. An important result of this investigation was that the TBC/bond coat interface was under biaxial stress field. An important result was that the residual stresses developed in the substrate are higher for the case of partly cooled specimen compared to the fully cooled specimen which can be rationalized due to the presence of higher temperature gradients at earlier times during cool-down from processing temperature.

Issue Section:
Technical Papers
Topics:
Residual stresses, Thermal barrier coatings, Transients (Dynamics), Elasticity, Finite element analysis, Modeling, Steady state, Stress, Superalloys, Temperature, Ceramics, High temperature, Microcracks, Temperature gradient, Thermal expansion, Thermal insulation
1.
Boley, B. A., and Weiner, J. H., 1960, Theory of Thermal Stress, John Wiley and Sons, New York.
2.
Chang
G. C.
, and
Phucharoen
W.
,
Miller
R. A.
,
1987
, “
Finite Element Thermal Stress Solutions for Thermal Barrier Coatings
,”
Surface and Coatings Technology
, Vol.
32
, pp.
307
–
325
.
3.
Chung
B. T. F.
,
Kermani
M. M.
,
Braun
M. J.
,
Padovan
J.
, and
Hendricks
R. C.
,
1985
, “
Heat Transfer in Thermal Barrier Coated Rods with Circumferential and Radial Temperature Gradients
,”
ASME Journal of Engineering for Gas Turbines and Power
, Vol.
107
, pp.
135
–
141
.
4.
Drake
J. T.
,
Williamson
R. L.
, and
Rabin
B. H.
,
1993
, “
Finite Element Analysis of Thermal Residual Stresses at Graded Ceramic-Metal Interfaces, Part II: Interface optimization for residual stress reduction
,”
J. Appl. Phys.
, Vol.
74
, pp.
1321
–
1326
.
5.
Hasselman, D. P. H., and Heller, R. A., 1980, Thermal Stresses in Severe Environments, Plenum Press, New York.
6.
Holmes, J. W., McCliutock, F. A., O’Hara, K. S., and Conners, M. E., 1988, “Thermal Fatigue Testing of Coated Monocrystalline Superalloys,” Low Cycle Fatigue, ASTM STP 942, pp. 672–691.
7.
Hwaki, T., 1986, “Transient Thermal Stresses in Fully and Partly Cooled Circular Rings,” Exp. Mechs., pp. 163–168.
8.
Kardomateas
G. A.
,
1989
, “
Transient Thermal Stresses in Cylindrically Orthotropic Composite Tubes
,”
ASME JOURNAL OF APPLIED MECHANICS
, Vol.
56
, pp.
411
–
417
.
9.
Kardomateas
G. A.
,
1990
, “
The Initial Phase of Transient Thermal Stresses due to General Boundary Thermal Loads in Orthotropic Hollow Cylinders
,”
ASME JOURNAL OF APPLIED MECHANICS
, Vol.
57
, pp.
719
–
724
.
10.
Kardomateas
G. A.
, and
Chung
C. B.
,
1994
, “
Boundary Layer Transient Hygroscopic Stresses in Orthotropic Thick Shells Under External Pressure
,”
ASME JOURNAL OF APPLIED MECHANICS
, Vol.
61
, pp.
161
–
168
.
11.
Kokini
K.
, and
Homack
T. R.
,
1988
, “
Transient Thermal Load Effects on Coatings Bonded to Cylindrical Substrates and Containing Circumferential Cracks
,”
ASME Journal of Engineering Materials and Technology
, Vol.
110
, pp.
35
–
40
.
12.
Manson, S. S., 1966, Thermal Stress and Low-Cycle Fatigue, McGraw-Hill, New York.
13.
Mikata
Y.
, and
Taya
M.
,
1985
, “
Stress Field in a Coated Continuous Fiber Composite Subjected to Thermo-Mechanical Loadings
,”
J. of Cump. Mat.
, Vol.
19
, pp.
554
–
578
.
14.
Ozisik, M. N., 1968, Boundary Value Problems of Heat Conduction, Dover, New York.
15.
Padovan
J.
,
Dougherty
D.
,
Hendricks
B.
,
Bratun
M. J.
, and
Chung
B. T. F.
,
1984
, “
High Temperature Thermomechanical Analysis of Ceramic Coatings
,”
J. of Thermal Stresses
, Vol.
7
, pp.
51
–
74
.
16.
Padovan
J.
,
Dougherty
D.
, and
Hendricks
B.
,
1986
, “
Inelastic High-Temperature Thermomechanical Response of Ceramic Coated Gas Turbine Seals
,”
J. of Thermal Stresses
, Vol.
9
, pp.
31
–
43
.
17.
Padovan
J.
,
Padovan
P.
, and
Xiaru
Y.
,
1986
, “
Analysis of Thermomechanical Oxidation Fields in Thermal Barrier Coatings
,”
J. of Thermal Stresses
, Vol.
9
, pp.
251
–
277
.
18.
Takeuchi
Y. R.
, and
Kokini
K.
,
1994
, “
Thermal Fracture of Multilayer Ceramic Thermal Barrier Coatings
,”
ASME Journal of Engineering for Gas Turbines and Power
, Vol.
116
, pp.
266
–
271
.
19.
Timoshenko, S. P., and Goodier, J. N., 1971, Theory of Elasticity McGraw-Hill, New York.
20.
Tittle
C. W.
,
1965
, “
Boundary-Value Problems in Composite Media: Quasi-Orthogonal Functions
,”
J. of App. Phy.
, Vol.
36
, pp.
1486
–
1488
.
21.
Tittle, C. W., and Robenson, V. L., 1965, “Analytical Solution of Conduction Problems in Composite Media,” ASME paper 65-WA-HT-52.
22.
Williamson
R. L.
,
Rabin
B. H.
, and
Drake
J. T.
,
1993
, “
Finite Element Analysis of Thermal Residual Stresses at Graded Ceramic-Metal Interfaces, Part I: Model Description and Geometrical Effects
,”
J. Appl. Phys.
, Vol.
74
, pp.
1310
–
1320
.
23.
Wright, P. K., 1995, private communication, General Electric Aircraft Engines, Evendale, OH.
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