Microstructure–Property Correlations in Industrial Thermal Barrier Coatings |
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Authors: | Anand A Kulkarni Allen Goland Herbert Herman rew J Allen Jan Ilavsky Gabrielle G Long Curtis A Johnson Jim A Ruud |
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Affiliation: | Department of Materials Science and Engineering, State University of New York, Stony Brook, New York 11794;National Institute of Standards and Technology, Gaithersburg, Maryland 20899;General Electric Corporate Research Division, Schenectady, New York 12309 |
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Abstract: | This paper describes the results from multidisciplinary characterization/scattering techniques used for the quantitative characterization of industrial thermal barrier coating (TBC) systems used in advanced gas turbines. While past requirements for TBCs primarily addressed the function of insulation/life extension of the metallic components, new demands necessitate a requirement for spallation resistance/strain tolerance, i.e., prime reliance, on the part of the TBC. In an extensive effort to incorporate these TBCs, a design-of-experiment approach was undertaken to develop tailored coating properties by processing under varied conditions. Efforts focusing on achieving durable/high-performance coatings led to dense vertically cracked (DVC) TBCs, exhibiting quasi-columnar microstructures approximating electron-beam physical-vapor-deposited (EB-PVD) coatings. Quantitative representation of the microstructural features in these vastly different coatings is obtained, in terms of porosity, opening dimensions, orientation, morphologies, and pore size distribution, by means of small-angle neutron scattering (SANS) and ultra-small-angle X-ray scattering (USAXS) studies. Such comprehensive characterization, coupled with elastic modulus and thermal conductivity measurements of the coatings, help establish relationships between microstructure and properties in a systematic manner. |
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Keywords: | coatings X-ray methods scattering |
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