Non-destructive measurement of top coat thickness in TBC systems by 3D optical topometry

Moskal, G.; Swadźba, Radosław; Witala, B.

doi:10.1080/10589759.2014.984297

Cited by 3 publications

(5 citation statements)

References 28 publications

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“…[1,3,4], which makes the performance of TBCs unsatisfactory. As a result, the wide application of TBCs has been entitled to advanced nondestructive test (NDT) techniques for evaluation and failure detection during service [5][6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Nondestructive Interface Morphology Characterization of Thermal Barrier Coatings Using Terahertz Time-Domain Spectroscopy

Wang

Huang

et al. 2019

Coatings

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In this work, a terahertz time-domain spectroscopy (THz-TDS) system was used to measure the thickness of thermal barrier coatings (TBCs) and characterize the interface morphology of TBCs after erosion. Reflection mode, with an angle of incidence of 0, was used for inspection before and after erosion. The refractive index, thickness, and internal structure evolution tendency of the yttria-stabilized zirconia (YSZ) top coat were estimated under consideration of the interaction between the pulsed THz waves and the TBCs. The surface roughness of the top coat surface was considered for the errors analysis in the refractive index and thickness measurement. To reduce the errors introduced by the refractive index change after erosion, two mathematical models were built to assess the thickness loss. Then, the thickness loss was compared with results estimated by the micrometer inspection method. Finally, the basic erosion sample profile with Ra roughness was obtained, and the broadening of THz pulses were suggested as a possible measure for the top coat porosity change, showing that THz waves can be a novel online non-destructive and non-contact evaluation method that can be widely utilized to evaluate the integrity of TBCs applied to gas turbine blades.

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Section: Introductionmentioning

confidence: 99%

Nondestructive Interface Morphology Characterization of Thermal Barrier Coatings Using Terahertz Time-Domain Spectroscopy

Wang

Huang

et al. 2019

Coatings

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“…The overall coating thickness was below 160 µm. The coating thickness was controlled by 3D optical scanning and comparing the geometry of the uncoated and coated component [27]. For metallographic specimens, it was measured with Scanning Electron Microscopy (SEM).…”

Section: Coatingsmentioning

confidence: 99%

“…With 3D scanning systems, it is possible to measure the geometry of the uncoated and coated component. After comparing these two datasets numerically, coating thickness can be calculated and visualized [27]. For used blades, the results of their inspection determine the possibility of their reuse.…”

Section: Introductionmentioning

confidence: 99%

Health and Durability of Protective and Thermal Barrier Coatings Monitored in Service by Visual Inspection

et al. 2022

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Protective and Thermal Barrier Coatings (TBC) applied on gas-turbine blades gradually degrade due to oxidation, aluminum depletion and impacts of environmental particles. Among various non-destructive coating testing methods (NDT), visual inspection can be undertaken regularly in service, but it provides little quantitative information, and only surface defects can be detected. This work aims at in-service monitoring of turbine blades with multilayer coatings applied by atmospheric plasma spraying (APS) in a few variants. They were validated during a series of accelerated mission tests of a retired military turbofan engine in a test cell together with five other technologies. The fifty-hour rainbow test focused on assessing coating durability. Between engine runs, 12 borescope inspections were conducted to monitor the health of the blades. Finally, the blades were disassembled and examined using computed tomography (CT) and metallographic methods. Throughout the testing, 31 newly-coated blades (66%) withstood the tests, producing results comparable to the reference blades. However, 16 blades suffered intolerable failures observed as increased roughness, gradual loss of the topcoat, spallation and minor foreign object damage. Visual inspection results were generally in agreement with subsequent laboratory tests.

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“…on TBCs causes erosion and delamination, thus reducing the overall functionality and strength of the TBCs. , Consequently, various advanced nondestructive test (NDT) methods for TBC evaluation and failure detection during service are commonly used in TBC applications. , Among such NDT methods, characterization techniques such as ultrasonic waves testing, eddy current testing, X-ray imaging, and rare-earth luminescence examination are particularly significant . Some NDT technologies can also measure TBC thickness and monitor their condition. , …”

Section: Tbc Characterizationmentioning

confidence: 99%

“…94 Some NDT technologies can also measure TBC thickness and monitor their condition. 95,96 However, these characterization methods have their downsides; for example, in evaluating complex coating components, the eddy current test signal is vulnerable when nonmetallic materials are involved, as it requires the lift-off operation step, which creates large noise in the signal. 97 The ultrasound acoustic waves are significantly limited by the edge effects of the coatings, and the constraints imposed by liquid coolants make this technique unpopular.…”

Section: Tbc Characterizationmentioning

confidence: 99%

Thermal Barrier Coatings Overview: Design, Manufacturing, and Applications in High-Temperature Industries

Mondal

Nuñez

Myer

et al. 2021

Ind. Eng. Chem. Res.

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Today's competitive world economy is creating an indispensable demand for increased efficiency of engineering components that operate in harsh environments (i.e., very high-temperature, corrosive, or neutron irradiation environments), for applications in the energy, automotive, aerospace, electronics, and power industries. Increased research is being done on thermal barrier coatings (TBCs) for protecting such components, since the versatility of manufacturing techniques and the scale of deployment result in increased life, economics, performance, and durability. This review focuses on the advances that led to using TBCs for component life extension and, more recently, as an integral part of advanced component design for high-temperature and other types of harsh environments, such as those found in nuclear-related applications. Factors that led to state-of-the-art advanced coating-fabrication techniques [e.g., electron-beam physical vapor deposition (EB-PVD), plasma spray deposition, and electrophoretically deposited TBCs, as well as functionally graded material (FGM) manufacturing] have also been emphasized in current coating R&D. This review explores the current state of TBCs, i.e., the latest advances regarding their fabrication and performance, associated challenges, and recommendations for their future use in aerospace, nuclear, high-temperature, or otherwise harsh environments.

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Non-destructive measurement of top coat thickness in TBC systems by 3D optical topometry

Cited by 3 publications

References 28 publications

Nondestructive Interface Morphology Characterization of Thermal Barrier Coatings Using Terahertz Time-Domain Spectroscopy

Nondestructive Interface Morphology Characterization of Thermal Barrier Coatings Using Terahertz Time-Domain Spectroscopy

Health and Durability of Protective and Thermal Barrier Coatings Monitored in Service by Visual Inspection

Thermal Barrier Coatings Overview: Design, Manufacturing, and Applications in High-Temperature Industries

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