A systematic study of factors affecting the delamination energy release rate and mode mix of a thermal barrier coating attached to a substrate is presented accounting for the influence of thermal gradients combined with rapid hot surface cooling. Transient thermal gradients induce stress gradients through the coating and substrate, which produce overall bending if the substrate is not very thick and if it is not constrained. Due to their influences on the coating stresses, substrate thickness and constraint are important aspects of the mechanics of delamination of coating-substrate systems, which must be considered when laboratory tests are designed and for lifetime assessment under in-service conditions. Temperature gradients in the hot state combined with rapid cooling give rise to a maximum energy release rate for delamination that occurs in the early stage of cooling and that can be considerably larger than the driving force for delamination in the cold state. The rates of cooling that give rise to a large early stage energy release rate are identified.

References

References
1.
Evans
,
A. G.
, and
Hutchinson
,
J. W.
,
2007
, “
The Mechanics of Coating Delamination in Thermal Gradients
,”
Surf. Coat. Technol.
,
201
, pp.
7905
7916
.10.1016/j.surfcoat.2007.03.029
2.
Bunker
,
R. S.
,
2008
, “
The Effects of Manufacturing Tolerances on Gas Turbine Cooling
,”
Proceedings of the 2008 IGTI
,
ASME Turbo Expo: Power for Land Sea and Air
, Berlin, Germany, June 9–13, pp.
1
9
.
3.
Yu
,
H. H.
,
He
,
M. Y.
, and
Hutchinson
,
J. W.
,
2001
, “
Edge Effects in Thin Film Delamination
,”
Acta Mater.
,
49
, pp.
93
107
.10.1016/S1359-6454(00)00293-7
4.
Hutchinson
,
R. G.
, and
Hutchinson
,
J. W.
,
2011
, “
Lifetime Assessment for Thermal Barrier Coatings: Tests for Measuring Mixed Mode Delamination Toughness
,”
J. Am. Ceram. Soc.
,
94
(S
1
), pp.
S85
S95
.10.1111/j.1551-2916.2011.04499.x
5.
Suo
,
Z.
, and
Hutchinson
,
J. W.
,
1990
, “
Interface Crack Between Two Elastic Layers
,”
Int. J. Fract.
,
43
, pp.
1
18
.10.1007/BF00018123
6.
Dickinson
,
G. R.
,
Petorak
,
C.
,
Bowman
,
K.
, and
Trice
,
R. W.
,
2005
, “
Stress Relaxation of Compression Loaded Plasma-Sprayed 7 Wt% Y2O3-ZrO2 Stand-Alone Coatings
,”
J. Am. Ceram. Soc.
,
88
, pp.
2202
2308
.10.1111/j.1551-2916.2005.00407.x
7.
Petorak
,
C.
, and
Trice
,
R. W.
,
2011
, “
Effect of Heat-Treatment on Stress Relaxation Behavior of Plasma-Sprayed 7 Wt% Y2O3-ZrO2 Stand-Alone Coatings
,”
Surf. Coat. Technol.
,
205
, pp.
3218
3225
.10.1016/j.surfcoat.2010.11.040
8.
Lampenscherf
,
S.
,
2010
, private communication.
9.
Mercer
,
C.
,
Faulhaber
,
S.
,
Evans
,
A. G.
, and
Darolia
,
R.
,
2005
, “
A Delamination Mechanism for Thermal Barrier Coatings Subject to Calcium-Magnesium-Alumino-Silicate (CMAS) Infiltration
,”
Acta Mater.
,
53
, pp.
1029
1039
.10.1016/j.actamat.2004.11.028
10.
Kramer
,
S.
,
Yang
,
J.
,
Levi
,
C. G.
, and
Johnson
,
C. A.
,
2006
, “
Thermochemical Interaction of Thermal Barrier Coatings With Molten CaO-MgO-Al2O3-SiO2 (CMAS) Deposits
,”
J. Am. Ceram. Soc.
,
89
, pp.
3167
3175
.10.1111/j.1551-2916.2006.01209.x
11.
Begley
,
M. R.
,
2012
, “
LayerSlayer: An Open Source Code for Analyzing Multilayers
,” (under development).
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