Nondestructive Measurement of Porosity in Thermal Barrier Coatings

Rogé, B.; Fahr, A.; Giguère, J. S. R.; McRae, K. I.

doi:10.1361/105996303772082279

Cited by 44 publications

(13 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For example, the ultrasound waves are limited to the existence of edge effects and the requirement of a liquid couplant [7,11,12]. The eddy current test signal is susceptible, and the measurement of non-metallic materials was not suitable for the evaluation of complex components as it requires the lift-off operation step, which generates large noise [13][14][15][16]. The rare earth luminescence method needs extra doping of rare earth elements and cannot be used to characterize the morphology quantitatively [6,17,18].…”

Section: Introductionmentioning

confidence: 99%

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

Wang

Huang

et al. 2019

Coatings

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionmentioning

confidence: 99%

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

Wang

Huang

et al. 2019

Coatings

View full text Add to dashboard Cite

show abstract

“…Changes in electrical and dielectric properties of electrically conductive materials can be used to detect changes in capacitance due to porosity or other defects (Rogé et al, 2003;Du et al, 2013). Direct current resistivity technique appears to be capable of not only detecting cracks but also measuring hardness and density.…”

Section: Electromagnetic and Eddy Current Techniquesmentioning

confidence: 99%

Powder-based additive manufacturing - a review of types of defects, generation mechanisms, detection, property evaluation and metrology

Taheri

Shoaib

Koester³

et al. 2017

IJASMM

View full text Add to dashboard Cite

Powder-based additive manufacturing (AM) technologies have been evaluated for use in different fields of application (aerospace, medical, etc.). Ideally, AM parts should be at least equivalent, or preferably better quality than conventionally produced parts. Manufacturing defects and their effects on the quality and performance of AM parts are a currently a major concern. It is essential to understand the defect types, their generation mechanisms, and the detection methodologies for mechanical properties evaluation and quality control. We consider the various types of microstructural features or defects, their generation mechanisms, their effect on bulk properties and the capability of existing characterisation methodologies for powder based AM parts in this work. Methods of in-situ non-destructive evaluation and the influence of defects on mechanical properties and design considerations are also reviewed. Together, these provide a framework to understand the relevant machine and material parameters, optimise the process and production, and select appropriate characterisation methods.Abstract: Powder-based additive manufacturing (AM) technologies have been evaluated for use in different fields of application (aerospace, medical, etc.). Ideally, AM parts should be at least equivalent, or preferably better quality than conventionally produced parts. Manufacturing defects and their effects on the quality and performance of AM parts are a currently a major concern. It is essential to understand the defect types, their generation mechanisms, and the detection methodologies for mechanical properties evaluation and quality control. We consider the various types of microstructural features or defects, their generation mechanisms, their effect on bulk properties and the capability of existing characterisation methodologies for powder based AM parts in this work. Methods of in-situ non-destructive evaluation and the influence of defects on mechanical properties and design considerations are also reviewed. Together, these provide a framework to understand the relevant machine and material parameters, optimise the process and production, and select appropriate characterisation methods.Reference to this paper should be made as follows: Taheri, H., Shoaib, M.R.M., Koester, L., Bigelow, T.A., Collins, P.C. and Bond, L.J. (2017) 'Powder-based additive manufacturing -a review of types of defects, generation mechanisms, detection, property evaluation and metrology', Int. Institute of Aviation Technology conducting research on UAVs and designing and printing 3D parts for UAVs. His research interest areas include engineering mechanics, additive manufacturing and non-destructive testing.Lucas W. Koester received his PhD from the University of Nebraska at Lincoln studying wave propagation and scattering in polycrystalline media. His current and past research interests include wave propagation in polycrystalline media, defect scattering, and modelling with emphasis on additive manufacturing processes and materials.Powder-based additive...

show abstract

“…Figure 5(b) shows the change in capacitance and the corresponding relative permittivity at each segment with and without CMAS infiltration. Here, the relative permittivity, ε , was calculated from the obtained capacitance, C, using a parallel-plate condenser model (Rogé et al, 2003):…”

Section: Capacitance Of the Cmas Damaged Ceramic Top Coat Specimenmentioning

confidence: 99%

Non-destructive detection of CMAS damage on thermal barrier coatings using AC impedance technique

Hayashi

Yamagishi

Okazaki

2016

Mechanical Engineering Journal

View full text Add to dashboard Cite

Thermal barrier coatings (TBCs) on high temperature components in gas turbine engines are in some cases damaged by calcium-magnesium-alumino-silicates (CMAS) resulting from the ingestion of siliceous minerals at high temperatures exceeding 1200°C. An attempt to develop a non-destructive detection technique of CMAS damage on TBCs was carried out through an AC impedance technique in this work. The CMAS-affected TBC specimens were prepared by simulating the CMAS damage in laboratory, employing a synthetic CMAS product. The change in electric capacitance was measured by using an LCR meter. It was found that the capacitance of the ceramic top coat showed higher value at CMAS infiltrated areas, compared with that at the non-infiltrated ones. While the capacitance increased with increasing infiltration depth, the change in capacitance of the TBC specimen decreased when the CMAS enhanced the delamination damage of TBC top coat. Some discussion was made on the changes in capacitance using a simple condenser model, so that the present electric technique is applied to the CMAS damage detection and evaluation.

show abstract

Nondestructive Measurement of Porosity in Thermal Barrier Coatings

Cited by 44 publications

References 13 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

Powder-based additive manufacturing - a review of types of defects, generation mechanisms, detection, property evaluation and metrology

Non-destructive detection of CMAS damage on thermal barrier coatings using AC impedance technique

Contact Info

Product

Resources

About