Influence of isothermal and cyclic oxidation on the apparent interfacial toughness in thermal barrier coating systems

Liu, Y.; Vidal, Vanessa; Roux, Sabine Le; Blas, F.; Ansart, Florence; Lours, Philippe

doi:10.1016/j.jeurceramsoc.2015.07.018

Cited by 19 publications

(7 citation statements)

References 20 publications

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“…5). It can be noticed that the values of the interfacial toughness for all conditions are significantly lower in the case of APS TBC than for EB-PVD as reported in [8] suggesting a lower resistance to crack initiation and propagation for APS systems.…”

Section: Resultsmentioning

confidence: 62%

“…It was also confirmed that the position of the straight line is independent of the aging temperature and holding time. Both conditions justify to gather all values on a same master curve [8]. As well, crack curves (lna) versus (lnP) giving the evolution of the load-induced crack length for the various oxidation conditions tested are superimposed to the graph.…”

Section: Resultsmentioning

confidence: 99%

“…In sol-gel TBC, defects occur within the YSZ (Yttria-Stabilized Zirconia) layer as well as at the bond coat/TGO interface or even within the TGO itself [6]. Meanwhile, the EB-PVD (Electron Beam Physical Vapor Deposition) TBC delaminates mainly between the bond coat/TGO interface for TGO layers thicker than circa 3 μm and at the TGO/top coat interface for thinner TGO [8], In this paper, a complete TBC system has been developed including not only the top coat but also the bond coat both deposited using the APS (Atmospheric Plasma Spraying) method. In some cases and for the purpose of comparison, an additional step of surface modification, namely Supersonic Fine Particles Bombarding (usually SiO 2 particles) (SFPB) has been implemented on bond coat prior to the final deposition of the top coat.…”

Section: Introductionmentioning

confidence: 99%

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Influence of isothermal aging conditions on APS TBC's interfacial fracture toughness

Liu

Lours

et al. 2017

Surface and Coatings Technology

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Interfacial toughness is an important factor to address thermal barrier coating's (TBC) durability. In this paper, a promising method, based on interfacial indentation, is used to analyze apparent interfacial toughness of TBC deposited by Atmospheric Plasma Spray (APS). The specimens made by APS were treated using different oxidation holding times and temperatures, namely 1050°C-100 h, 1100°C-100 h, 1050°C-300 h and 1100°C-300 h, respectively. The morphology of the interface between the TBC and the underlying bond coat was analyzed by Scanning Electron Microscopy (SEM). Results have shown that the fracture toughness of the interface between the bond coat and the top coat decreased as the oxidation conditions become more severe that is the temperature and/or to a lesser extent the exposure time is increased. Simultaneously, the thickness of the thermally grown oxide (TGO) generated on top of the aluminum reservoir bond coat increases as well. The TGO is a "double layer" oxide successively composed of a first scale of Al 2 O 3 close to the bond coat and a second scale of CoCrNiO close to top coat. In addition, it was also found that the possible thermally activated spallation of APS TBC's system occurs in the zone of the TGO layer, especially within the CoCrNiO oxide scale. Consequently damage of APS systems is shown to initiate at the interface through complex mechanism of delamination in relation with both the toughness and the microstructure of the interface. In order to inhibit the growth of the detrimental CoCrNiO oxide and in turn favors the development of a dense and stable alumina scale, a Supersonic Fine Particles Bombarding (SFPB) method was used to optimize the quality of APS coating.

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Section: Resultsmentioning

confidence: 62%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of isothermal aging conditions on APS TBC's interfacial fracture toughness

Liu

Lours

et al. 2017

Surface and Coatings Technology

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“…Interfacial indentation tests [37][38][39], push-out tests [40], scratch tests [41], etc., have already been evaluated with regard to their efficiency in delivering relevant interfacial toughness data. The current challenge is to ensure that the laboratory tests proposed produce similar effects to those found in service.…”

Section: Mechanical Tests For Interfacial Toughness Determinationmentioning

confidence: 99%

Development of bending tests for near shear mode interfacial toughness measurement of EB-PVD thermal barrier coatings

Vaunois

Poulain

Kanouté

et al. 2017

Engineering Fracture Mechanics

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“…The TGO layer significantly reduces the adhesion toughness between the TC and the BC [3,4]. In addition, the large mismatch of coefficients of thermal expansion (CTEs) between the TGO and the BC results in a large compressive residual stress in the TGO layer during cooling.…”

mentioning

confidence: 99%

A new spallation mechanism of thermal barrier coatings and a generalized mechanical model

Yuan

Harvey

Thomson

et al. 2019

Composite Structures

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Multilayer thermal barrier coating (TBC) systems typically consist of three layers of materials: A thermal barrier top coat (TC), a thermally-grown oxide (TGO), and a bond coat (BC) in addition to the substrate. Local strain energy concentrations, called 'pockets of energy concentration (PECs)' in this work, often occur around the interface between the TGO and the BC. They have various causes, including local phase changes, and non-uniform creep and plastic relaxation. It is discovered that both PECs and buckling drive the spallation of a TBC in a new spallation mechanism. A PEC-based mechanical model is developed that describes, explains and predicts how blisters nucleate in a TBC under constant biaxial compressive residual stress, steadily and then unsteadily grow, and finally spall off. Two conditions are established for the occurrence of TBC spallation, which depend on the compressive residual strain energy density in the TC and the TGO, and the interface fracture toughness. Experimental validation of the model was performed using aircraft jet engine turbine blades with electron beam physical vapor deposition (EBPVD) TBCs. The predictions from the developed PEC-based mechanical model for the radii of spallation in the TBC are in a good agreement with experiment results.

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Influence of isothermal and cyclic oxidation on the apparent interfacial toughness in thermal barrier coating systems

Cited by 19 publications

References 20 publications

Influence of isothermal aging conditions on APS TBC's interfacial fracture toughness

Influence of isothermal aging conditions on APS TBC's interfacial fracture toughness

Development of bending tests for near shear mode interfacial toughness measurement of EB-PVD thermal barrier coatings

A new spallation mechanism of thermal barrier coatings and a generalized mechanical model

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