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Microstructure–Property Correlations in Industrial Thermal Barrier Coatings

2004; Wiley; Volume: 87; Issue: 7 Linguagem: Inglês

10.1111/j.1151-2916.2004.tb07725.x

1551-2916

Anand A. Kulkarni, A.N. Goland, H. Herman, Andrew J. Allen, Ján Ilavský, Gabrielle G. Long, C. A. Johnson, Jim A. Ruud,

Nuclear Materials and Properties

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.