Delamination toughness of electron beam physical vapor deposition (EB-PVD) Y2O3–ZrO2 thermal barrier coatings by the pushout method: Effect of thermal cycling temperature

2008 ◽  
Vol 23 (9) ◽  
pp. 2382-2392 ◽  
Author(s):  
M. Tanaka ◽  
Y.F. Liu ◽  
S.S. Kim ◽  
Y. Kagawa
Keyword(s):  
Electron Beam ◽  
Thermal Cycling ◽  
Bond Coat ◽  
Physical Vapor Deposition ◽  
Thermally Grown Oxide ◽  
Test Method ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
Delamination Toughness ◽  
Cycling Temperature

A pushout test method was used to quantify effect of thermal cycling temperatures on the delamination toughness of an electron beam physical vapor deposited thermal barrier coating (EB-PVD TBC). The delamination toughness, Γi, was related to the maximum thermal cycling temperature, Th, equal to 1000, 1025, 1050, and 1100 °C. The measured delamination toughness varied from 9 to 95 J/m2. At Th = 1000 °C, Γi attained a maximum value, larger than that of the as-deposited sample and decreasing with increased Th. During the thermal cycling tests, the thermally grown oxide (TGO) was formed between the TBC and the bond coat deposited onto the superalloy substrate. Inside the TGO layer, mixture of Al2O3 and ZrO2 oxides was observed close to the TBC side with nearly pure Al2O3 phases close to the bond-coat side. During the pushout test, delamination occurred at the interface of the mixture and pure Al2O3 layer with an exception for Th = 1100 °C specimens where delamination also occurred at the interface between the TGO and bond-coat layers. The effect of thermal cycling temperatures on the delamination toughness is discussed in terms of the microstructural change and delamination behavior.

Influence of Processing on Microstructure and Performance of Electron Beam Physical Vapor Deposition (EB-PVD) Thermal Barrier Coatings

2002 ◽  
Vol 124 (2) ◽  
pp. 229-234 ◽  
Author(s):  
U. Schulz ◽  
K. Fritscher ◽  
C. Leyens ◽  
M. Peters
Keyword(s):  
Electron Beam ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Processing Parameters ◽  
Columnar Structure ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
And Performance ◽  
Microstructure And Performance

The paper addresses the effect of processing parameters on microstructure and lifetime of electron beam physical vapor deposition, partially yttria-stabilized zirconia (EB-PVD PYSZ) coatings deposited onto NiCoCrAlY-coated Ni-base superalloys. In particular, the formation of a thermally grown oxide layer, an equi-axed zone, and various columnar arrangements of the highly textured PYSZ layers are discussed with respect to processing conditions. Three different microstructures were cyclically tested at 1100°C. The intermediate columnar structure was superior with respect to cyclic life times to a fine and to a coarse columnar structure which was mainly attributed to differences in the elastic properties. The effect of PYSZ microstructure on hot corrosion behavior of the thermal barrier coating (TBC) system at 950°C is briefly discussed.

A Comparative Study of Two-Layer NiAl Bond Coat TBC and its Failure Mechanism

2007 ◽  
Vol 336-338 ◽  
pp. 1770-1772
Author(s):  
He Fei Li ◽  
Zhao Hui Zhou ◽  
Hesnawi A ◽  
Kuo Jiang ◽  
Sheng Kai Gong
Keyword(s):  
Electron Beam ◽  
Comparative Study ◽  
Thermal Cycling ◽  
Failure Mechanism ◽  
Thermal Barrier Coatings ◽  
Vapor Deposition ◽  
Bond Coat ◽  
Physical Vapor Deposition ◽  
Thermal Barrier ◽  
Barrier Coatings

Thermal barrier coatings with one-layered/ two-layered NiAl bond coat were produced by electron beam physical vapor deposition (EB-PVD). Compared to the TBC with one-layered bond coat, the TBC with two-layered bond coat improved the thermal cycling resistance significantly. The failure mechanism of the two-layer NiAl bond coat TBC was investigated in this paper.

TGO Formation with NiCoCrAlYTa Bond Coat Deposition Using APS and HVOF Method

2015 ◽  
Vol 1125 ◽  
pp. 18-22 ◽  
Author(s):  
S. Mohd Zulkifli ◽  
Muhammad Azizi Mat Yajid ◽  
Mohd Hasbullah Idris ◽  
M. Daroonparvar ◽  
Halimaton Hamdan
Keyword(s):  
Bond Coat ◽  
Oxidation Process ◽  
Thermally Grown Oxide ◽  
Inconel 625 ◽  
Thermal Barrier ◽  
Air Plasma Spray ◽  
Air Plasma ◽  
Continuous Layer ◽  
Barrier Coating ◽  
Coating Failure

Formation of thin and continuous layer of thermally grown oxide (TGO) in thermal barrier coating (TBC) are essential in order to avoid coating failure for high temperature applications. As-sprayed high velocity oxy-fuel (HVOF) bond coat can provide more uniform TGO layer in TBC system and much less oxide compare to air plasma spray (APS). In this paper, both APS and HVOF method are used to deposit NiCoCrAlYTa bond coat on Inconel 625 substrate followed by topcoat, YSZ deposition. Pre-oxidation process was done in normal oxygen furnace at 1000°C for 12 to 24 hours to study the characteristic of TGO formation via these two different methods. From the result obtained, it shows that HVOF method provide better TGO formation as compared to APS.

R&D Status and Needs for Improved EB-PVD Thermal Barrier Coating Performance

2000 ◽  
Vol 645 ◽  
Author(s):  
C. Leyens ◽  
U. Schulz ◽  
M. Bartsch ◽  
M. Peters
Keyword(s):  
Thermal Barrier Coating ◽  
Bond Coat ◽  
Gas Turbines ◽  
Systems Approach ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Factors Affecting ◽  
Performance Improvements ◽  
Barrier Coating ◽  
Temperature Capability

ABSTRACTThe key issues for thermal barrier coating development are high temperature capability and durability under thermal cyclic conditions as experienced in the hot section of gas turbines. Due to the complexity of the system and the interaction of the constituents, performance improvements require a systems approach. However, there are issues closely related to the ceramic top coating and the bond coat, respectively. Reduced thermal conductivity, sintering, and stresses within the ceramic coating are addressed in the paper as well as factors affecting failure of the TBC by spallation. The latter is primarily governed by the formation and growth of the thermally grown oxide scale and therefore related to the bond coat. A strategy for lifetime assessment of TBCs is discussed.

Oxidation Behavior of Thermal Barrier Coatings on Copper Substrates

2010 ◽  
Vol 66 ◽  
pp. 74-79
Author(s):  
Jana Schloesser ◽  
Martin Bäker ◽  
Joachim Rösler ◽  
Robert Pulz
Keyword(s):  
Thermal Cycling ◽  
Thermal Barrier Coatings ◽  
Bond Coat ◽  
Thermal Protection ◽  
Rocket Engine ◽  
Copper Substrate ◽  
Thermally Grown Oxide ◽  
Substrate Material ◽  
Thermal Barrier ◽  
Barrier Coatings

In rocket engine combustion chambers, the cooling channels experience extremely high temperatures and environmental attack. Thermal protection can be provided by Thermal Barrier Coatings. Due to the need of good heat conduction, the inner combustion liner is made of copper. The performance of a standard coating system for nickel based substrates is investigated on copper substrates. Thermal cycling experiments are performed on the coated samples. Due to temperature limitations of the copper substrate material, no thermally grown oxide forms at the interface of the thermal barrier coating and the bond coat. Delamination of the coatings occurs at the interface between the substrate and the bond coat due to oxide formation of the copper at uncoated edges. In real service a totally dense coating can probably not be assured which is the reason why this failure mode is of importance. Different parameters are used for thermal cycling to understand the underlying mechanisms of delamination. Furthermore, laser heating experiments account for the high thermal gradient in real service. Pilot tests which led to a delamination of the coating at the substrate interface were performed successfully.

Shear Strength of a Thermal Barrier Coating Parallel to the Bond Coat

1998 ◽  
Vol 120 (1) ◽  
pp. 26-32 ◽  
Author(s):  
T. A. Cruse ◽  
R. C. Dommarco ◽  
P. C. Basti´as
Keyword(s):  
Shear Strength ◽  
Thermal Barrier Coating ◽  
Bond Coat ◽  
Low Cycle Fatigue ◽  
High Stress ◽  
Test Method ◽  
Thermal Barrier ◽  
Cycle Fatigue ◽  
Air Plasma ◽  
Barrier Coating

The static and low cycle fatigue strength of an air plasma sprayed (APS) partially stabilized zirconia thermal barrier coating (TBC) is experimentally evaluated. The shear testing utilized the Iosipescu shear test arrangement. Testing was performed parallel to the TBC-substrate interface. The TBC testing required an innovative use of steel extensions with the TBC bonded between the steel extensions to form the standard losipescu specimen shape. The test method appears to have been successful. Fracture of the TBC was initiated in shear, although unconstrained specimen fractures propagated at the TBC-bond coat interface. The use of side grooves on the TBC was successful in keeping the failure in the gage section and did not appear to affect the shear strength values that were measured. Low cycle fatigue failures were obtained at high stress levels approaching the ultimate strength of the TBC. The static and fatigue strengths do not appear to be markedly different from tensile properties for comparable TBC material.

Development of a Thermal Barrier Coating Life Model

2003 ◽  
Author(s):  
K. Chan ◽  
S. Cheruvu ◽  
R. Viswanathan
Keyword(s):  
Gas Turbine ◽  
Bond Coat ◽  
Thermally Grown Oxide ◽  
Experimental Program ◽  
Thermal Barrier ◽  
Barrier Coating ◽  
Life Model ◽  
Useful Life ◽  
Plasma Sprayed ◽  
Kinetics Of

Thermal barrier coatings (TBCs) are widely used on the first stage turbine buckets and vanes of land-based (F and G class) gas turbine machines. These coatings normally fail by spallation due to delamination of the ceramic layer along the vicinity of the thermally grown oxide (TGO)/TBC interface. The failure processes involve several mechanisms including oxidation of the bond coat, thermomechanical fatigue, sintering, and spallation of the TBC. This paper describes the development of an analytical tool for predicting the useful life of TBCs for land-based gas turbine applications. The analytical model, called TBCLIFE, has been developed to treat bond coat oxidation, sintering and spallation of the TBC, as well as effects of coating thickness and substrate curvature on TBC spallation. In addition, a parallel experimental program has also been initiated to evaluate the durability of a plasma-sprayed TBC under isothermal and thermal cycling exposures. These results will be used to determine the kinetics of TGO scale growth and the material constants for the TBC life model. The TBC life model will be applied to predicting TBC life as a function of cycle time and the results will be presented as coating life diagrams. The utility of a coating life diagram for estimating the remaining life of TBC will be illustrated and discussed.

Effect of Temperature-Dependent Properties on Cyclic Plasticity of Bond Coat in Thermal Barrier Systems

2013 ◽  
Vol 535-536 ◽  
pp. 193-196
Author(s):  
Luo Chuan Su ◽  
Jian Guo Li ◽  
Wei Xu Zhang ◽  
Tie Jun Wang
Keyword(s):  
Bond Coat ◽  
Thermally Grown Oxide ◽  
Cyclic Plasticity ◽  
Effect Of Temperature ◽  
Thermal Barrier ◽  
Temperature Dependent ◽  
Barrier Coating ◽  
Thermal Growth ◽  
Key Factor ◽  
Temperature Dependent Properties

The accumulation of cyclic plasticity in bond coat (BC) is a key factor controlling the displacement instability of the thermally grown oxide (TGO) in thermal barrier systems. The cyclic plasticity is affected by the component material properties, which vary observably with the service temperature. A numerical model with the behavior of creep and thermal growth in TGO under thermal cycling is used to explore the effect of temperature-dependent properties on cyclic plasticity in BC. The influence of temperature-dependent Young's modulus of thermal barrier coating (TBC), TGO, BC and substrate, thermal expansion coefficient of TBC, BC and substrate, and the yield strength of BC on cyclic plasticity in BC is discussed respectively.

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