Mechanisms of Degradation and Failure in a Plasma-Deposited Thermal Barrier Coating

Demasi-Marcin, Jeanine T.; Sheffler, K. D.; Bose, Sudhangshu

doi:10.1115/1.2906198

Cited by 131 publications

(27 citation statements)

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“…Thus, it is of great importance to understand their failure mechanisms. Even though a substantial amount of research has been performed to understand the failure of TBC systems, [2][3][4][5][6][7][8] the exact failure mechanisms are still not clear due to the contribution of many factors in their failures. The fact that the type and fabrication procedures of the bond coats, as well as the TBCs, result in different failure behaviors complicates the understanding of TBC failures even more.…”

Section: Introductionmentioning

confidence: 99%

Failure characteristics during cyclic oxidation of yttria stabilized zirconia thermal barrier coatings deposited via electron beam physical vapor deposition on platinum aluminide and on NiCoCrAlY bond coats with processing modifications for improved performances

Yanar

Pettit

Meier

2006

Metall Mater Trans A

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In this study, the cyclic oxidation lives of the current state-of-the-art thermal barrier coating (TBC) systems (heavy grit-blasted Pt aluminide and NiCoCrAlY bond coats with EBPVD TBCs) were investigated first, followed by TBC systems that were modified based on the results obtained on the failure of the state-of-the-art TBC systems. The specimens were subjected to cyclic oxidation testing, mostly at 1100°C, in a bottom-loading furnace in laboratory air. Optical and scanning electron microscopy techniques were used to characterize the as-processed and failed specimens. The state-of-the-art TBC systems with NiCoCrAlY bond coats failed as the result of defects that were identified as TBC defects, transient oxides, surface defects, and reactive element-rich oxide protrusions. On the other hand, the failures of the state-of-the-art TBC systems with Pt aluminide bond coats were due to deformation of the bond coat by a mechanism known as ratcheting. The stored strain energy in the thermally grown oxide (TGO) was also a factor that contributed to the failure of both systems. Most of the modifications performed on the state-of-the-art TBC systems improved their lives to some extent. In the case of NiCoCrAlY systems, elimination or at least minimization of the identified defects was responsible for the improvements, whereas the prevention of the ratcheting type of failure was the main reason for the improvement in lives in the case of Pt aluminide systems. On the other hand, other issues, such as slower growth of the TGO as well as improved TGO/bond coat interfacial toughnesses with some of the modifications, were observed to be contributing factors in the improved lives. Based on the observations on the failure of both the state-of-the-art as well as the modified TBC systems, the surface condition of the bond coats and the morphology of the TBCs close to the TGO were found to have a first-order effect on the failure of TBC systems. The characteristics of the TGO, such as composition, growth rate, and adherence both to the bond coat and the TBC, as well as the characteristics of the bond coats were also observed to have an effect on the failures. Recommendations for future work that should be pursued to better define the conditions necessary for optimized TBC performances are given.

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Section: Introductionmentioning

confidence: 99%

Failure characteristics during cyclic oxidation of yttria stabilized zirconia thermal barrier coatings deposited via electron beam physical vapor deposition on platinum aluminide and on NiCoCrAlY bond coats with processing modifications for improved performances

Yanar

Pettit

Meier

2006

Metall Mater Trans A

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“…nificantly lower than the 1.5-1.9W/mK reported for the EB-PVD coating [29]. The APS coating therefore provides superior thermal protection.…”

Section: Effect Of Coating Processmentioning

confidence: 72%

“…The failure mechanism of TBCs is strongly dependent on coating process [29,30] from another point of view. Prolonged exposure to a high temperature oxidizing environment may lead to coating failure.…”

Section: Failure Of Tbcsmentioning

confidence: 99%

The Potential for the Improvement of High Performance Thermal Barrier Coatings

Okazaki

2003

Journal of the Society of Materials Science, Japan

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“…[1,2] These coatings allow increased operating temperature of the engine and therefore enhanced efficiency, increased durability, and extended life of metallic components subjected to high temperatures and high stresses. [3,4] Also achieved are reduced cooling requirements to metallic components at the high operating temperature. These YSZ topcoats are deposited using atmospheric plasma spray (APS) or electron beam-physical vapor deposition (EB-PVD) processes, each producing distinctively different microstructures.…”

Section: Introductionmentioning

confidence: 99%

Microstructural characterization of electron beam-physical vapor deposition thermal barrier coatings through high-resolution computed microtomography

Kulkarni

Herman

DeCarlo

et al. 2004

Metall Mater Trans A

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Thermal barrier coatings (TBCs), deposited using the electron beam-physical vapor deposition (EB-PVD) process, comprise a unique architecture of porosity capable of bridging the technological gap between insulation/life extension and prime reliance. The TBC microstructures consist of columnar structure, nucleated via vapor condensation, along with a high degree of intercolumnar porosity, thus providing enhanced stress relief on thermomechanical loading and also accommodating misfit stresses resulting from CTE mismatch. In this article, we report the characterization of these coatings using high-resolution synchrotron-based X-ray computed microtomography (XMT) at 1.3-m resolution. Experiments focused on quantitative characterization/visualization of imperfections in these coatings and on the relative changes in microstructural features upon isothermal annealing. The influence of time/temperature of exposure was investigated and the results were correlated with elastic modulus.

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Mechanisms of Degradation and Failure in a Plasma-Deposited Thermal Barrier Coating

Cited by 131 publications

References 0 publications

Failure characteristics during cyclic oxidation of yttria stabilized zirconia thermal barrier coatings deposited via electron beam physical vapor deposition on platinum aluminide and on NiCoCrAlY bond coats with processing modifications for improved performances

Failure characteristics during cyclic oxidation of yttria stabilized zirconia thermal barrier coatings deposited via electron beam physical vapor deposition on platinum aluminide and on NiCoCrAlY bond coats with processing modifications for improved performances

The Potential for the Improvement of High Performance Thermal Barrier Coatings

Microstructural characterization of electron beam-physical vapor deposition thermal barrier coatings through high-resolution computed microtomography

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