Vibration Damping of Thermal Barrier Coatings Containing Ductile Metallic Layers

This paper explores the vibration damping properties of thermal barrier coatings (TBCs) containing thin plastically deformable metallic layers embedded in an elastic ceramic matrix. We develop an elastic–plastic dynamical model to study how work hardening, yield strain, and elastic modulus of the metal affect the macroscopic damping behavior of the coating. Finite element (FE) simulations validate the model and are used to estimate the damping capacity under axial and flexural vibration conditions. The model also provides an explanation for the widely observed nonlinear variation of the loss factor with strain in plasma-spayed TBCs. Furthermore, it facilitates the identification of multilayer configurations that maximize energy dissipation.

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Vibration damping of superalloys and thermal barrier coatings at high-temperatures

Materials Science and Engineering A ◽

10.1016/j.msea.2007.02.047 ◽

2007 ◽

Vol 466 (1-2) ◽

pp. 256-264 ◽

Cited By ~ 19

Author(s):

Giuliano Gregori ◽

Lí Lì ◽

John A. Nychka ◽

David R. Clarke

Keyword(s):

Thermal Barrier Coatings ◽

High Temperatures ◽

Vibration Damping ◽

Thermal Barrier ◽

Barrier Coatings

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Parametric Studies of Nonlinear Damping Behavior of APS Thermal Barrier Coatings Based on Cohesive Interface Model

Volume 7: Structures and Dynamics, Parts A and B ◽

10.1115/gt2012-69343 ◽

2012 ◽

Author(s):

Yong Chen ◽

Wei Dong

Keyword(s):

Thermal Barrier Coatings ◽

Turbine Blades ◽

Ceramic Coatings ◽

Nonlinear Damping ◽

Contact Friction ◽

Thermal Barrier ◽

Interface Model ◽

Damping Properties ◽

Barrier Coatings ◽

Cohesive Interface

Thermal barrier coatings (TBCs) could reduce the temperature of the turbine blades and allow them working at higher temperatures, which leads to higher durability and reliability of turbine blades, and improves engine performance and fuel efficiency. Recent researches shown that thermal barrier coatings have very good damping properties, which means it could also improve the high cycle fatigue (HCF) life of the turbine blades. Previous studies found that damping of air plasma spray (APS) thermal barrier coatings exhibit non-linearities (amplitude-dependent) due to its microstructures, which consists of several layers of splats with inter- and intra-microstructural micro-cracks. The main purpose of this paper is on the application of a bilinear cohesive interface model to simulate the microstructural features, the damage process and the contact friction between the interfaces of microstructural faults in APS ceramic topcoat. A representative volume element (RVE) model which coupled with the cohesive interface model is built and parametric relations, in terms of interface strength and stiffness, vibration amplitude and vibration cycles, are computed in this paper for understanding the effect of interfacial degradation, de-bonding, sliding, and contact friction between the interfaces of microstructural faults on the nonlinear damping properties. The calculation results could provide a fundamental understanding of the mechanisms responsible for the observed nonlinear energy dissipation and damping properties in APS ceramic coatings.

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Characterization of thermal barrier coatings formed by electon-beam physical vapor deposition (EB-PVD)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015410x ◽

1989 ◽

Vol 47 ◽

pp. 426-427

Author(s):

Ozer Unal

Keyword(s):

Thermal Barrier Coatings ◽

Physical Vapor Deposition ◽

Ceramic Coating ◽

High Vacuum ◽

Ceramic Coatings ◽

High Energy ◽

Thermal Barrier ◽

Protective Oxide ◽

Barrier Coatings ◽

Energy Beam

Interest in ceramics as thermal barrier coatings for hot components of turbine engines has increased rapidly over the last decade. The primary reason for this is the significant reduction in heat load and increased chemical inertness against corrosive species with the ceramic coating materials. Among other candidates, partially-stabilized zirconia is the focus of attention mainly because ot its low thermal conductivity and high thermal expansion coefficient.The coatings were made by Garrett Turbine Engine Company. Ni-base super-alloy was used as the substrate and later a bond-coating with high Al activity was formed over it. The ceramic coatings, with a thickness of about 50 μm, were formed by EB-PVD in a high-vacuum chamber by heating the target material (ZrO2-20 w/0 Y2O3) above its evaporation temperaturef >3500 °C) with a high-energy beam and condensing the resulting vapor onto a rotating heated substrate. A heat treatment in an oxidizing environment was performed later on to form a protective oxide layer to improve the adhesion between the ceramic coating and substrate. Bulk samples were studied by utilizing a Scintag diffractometer and a JEOL JXA-840 SEM; examinations of cross-sectional thin-films of the interface region were performed in a Philips CM 30 TEM operating at 300 kV and for chemical analysis a KEVEX X-ray spectrometer (EDS) was used.

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