Interface Oxidation Process of 8wt.%Y2O3-ZrO2/CoNiCrAlY Thermal Barrier Coating under Variation of Temperature

正行, 荒井; 宇一, 岩田

doi:10.1299/kikaia.69.800

Cited by 3 publications

(2 citation statements)

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“…TGO formation changes layered structure from dual to triple. However, it is known [13] that TGO is formed at exposure temperature higher than 1073[K]. Thus, in cyclic test case of 673[K] and 873[K], coating stress generation mechanism associated with holding period at maximum temperature is still supported by swelling deformation of the ceramic coating.…”

Section: Cyclic Heating-cooling Test With Dwelling Timementioning

confidence: 99%

Coating Stresses in Thermal Barrier Coatings by an In-Situ Curvature Monitoring Technique

Arai

2008

JMMP

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In this paper, coating stresses in thermal barrier coating (TBC) changing with cyclic heating -cooling are measured with a curvature measurement device developed in this study. The coating system chosen in this study is a dual-layered structure, and it consists of a partially stabilized zirconia (PSZ) as the ceramic coating layer and CoNiCrAlY as the metal-bond coating layer. The specimen used here is a strip-plate shape with thin thickness (600µm) extracted chemically from carbon steel coated by a thermal spraying process. A cyclic heating-cooling test and a cyclic heating-cooling test with a dwelling time at the maximum temperature are conducted for the strip-plate specimen. Deflection and coating stresses are measured continuously under these cyclic tests, and thermal deformation mechanisms generating the deflection and coating stresses are discussed based on primitive knowledge using an elementary beam theory.

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Section: Cyclic Heating-cooling Test With Dwelling Timementioning

confidence: 99%

Coating Stresses in Thermal Barrier Coatings by an In-Situ Curvature Monitoring Technique

Arai

2008

JMMP

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“…For instance, Evans et al [2] comprehensively reviewed TGO formation mechanisms based upon thermodynamics and inner stress during thermal cycling test using dissimilar elastic model with the periodic oscillation of amplitude A and wave length L. They strongly supported TGO rumpling phenomenon [3] for explanation of TBC delamination mechanism using stress analysis of the elastic model. Arai et al [4], [5] showed TGO growth rate rule that was identified from the cross-sectional observation of the TBC sample exposed at constant temperature and cyclic changed temperature. Similar studies can find out other references [6], [7].…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Numerical Simulation on Thermally Grown Oxide and Internal Stress Evolutions in Thermal Barrier Coatings

Nakajima

Katori

Arai³

et al. 2019

KEM

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TBCs (Thermal Barrier Coatings) is deposited on gas turbine blades to protect the substrate from a combustion gas flow. One of the serious problems occurred in gas turbine is TBC delamination which is caused by startup, steady and stop operation in service. TBC delamination results from subjecting to both cyclic thermal stress and evolution of internal stress due to thermally grown oxide (TGO). In this study, the finite element code which can simulate thermal and internal stress fields generated in TBC was developed. The developed code involves the follows: inelastic constitutive equation for ceramic coating, bilinear-type constitutive equation for bond coating and Chaboche-type inelastic constitutive equation for the substrate, and mass transfer equation in consideration of oxygen diffusion and chemical reaction with aluminum. Thermal cycling simulation was conducted using the developed code. It was confirmed that maximum stress and its location in the ceramic coating/bond coating interface were matched with the associated experimental results.

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Study on Electromotive Force Generated in Thermal Barrier Coatings at High-Temperature

Arai

2017

J. Soc. Mat. Sci., Japan

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The purpose of this study is to propose the principle for detecting the damage of TBC deposited onto the gas turbine blade based upon the electromotive force generated between TBC surface and substrate at a high temperature. The electromotive force of TBC can be easily monitored at an elevated temperature. It was found that the exposure temperature generating the electromotive force was approximately 800K, which corresponds to ductile-brittle-transition temperature of the bond coating materials CoNiCrAlY in TBC system. Thus, there is a possibility to distinguish the damage patterns of the crack as piercing to the substrate and the crack as leading to delamination of top coat by detecting the electromotive force. As a future work, it is necessary to develop a high reliable technology to connect a conductor on the actual gas turbine blade surface to detect the electromotive force and relate between the generated electromotive force and TBC delamination life.Key words: Gas turbine blade, Thermal barrier coating, Damage detection, Delamination, Cracking, Electromotive force, High-temperature exposure, High-temperature tensile test

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Interface Oxidation Process of 8wt.%Y2O3-ZrO2/CoNiCrAlY Thermal Barrier Coating under Variation of Temperature

Cited by 3 publications

References 0 publications

Coating Stresses in Thermal Barrier Coatings by an In-Situ Curvature Monitoring Technique

Coating Stresses in Thermal Barrier Coatings by an In-Situ Curvature Monitoring Technique

Comprehensive Numerical Simulation on Thermally Grown Oxide and Internal Stress Evolutions in Thermal Barrier Coatings

Study on Electromotive Force Generated in Thermal Barrier Coatings at High-Temperature

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