Surface-Roughness Induced Residual Stresses in Thermal Barrier Coatings: Computer Simulations

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Adherence of plasma-sprayed thermal barrier coatings (TBC'S} is strongly dependent on mechanical interlocking at the interface between the ceramic coating and the underlying metallic bond coat. Typically, a rough bond-coat surface topology is required to achieve adequate mechanical bonding. However, the resultant interfacial asperities modify the residual stresses that develop in the coating system due to thermal expansion differences, and other misfit strains, and generate stresses that can induce progressive fracture and eventual spallation of the ceramic coating. For a flat interface the principal residual stress is parallel to the interface as the stress normal to the interface is zero. ... continued below

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7 Pages

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Becher, P.F.; Carter, C.; Fuller, E.R., Jr.; Hsueh, C.H. & Langer, S.A. October 26, 1998.

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Adherence of plasma-sprayed thermal barrier coatings (TBC'S} is strongly dependent on mechanical interlocking at the interface between the ceramic coating and the underlying metallic bond coat. Typically, a rough bond-coat surface topology is required to achieve adequate mechanical bonding. However, the resultant interfacial asperities modify the residual stresses that develop in the coating system due to thermal expansion differences, and other misfit strains, and generate stresses that can induce progressive fracture and eventual spallation of the ceramic coating. For a flat interface the principal residual stress is parallel to the interface as the stress normal to the interface is zero. However, the residual stress normal to the interface becomes non-zero, when the interface has the required interlocking morphology. In the present study, an actual microstructure of a plasma-sprayed TBC system was numerically simulated and analyzed with a recently developed, object-oriented finite element analysis program, OOF, to give an estimate of the localized residual stresses in a TBC system. Additionally, model TBC rnicrostructures were examined to evaluate the manner in which the topology of interfacial asperities influences residual stresses. Results are present for several scenarios of modifying interfacial roughness.

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7 Pages

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  • 5th International Symposium on Functionally Graded Materials (FGM '98), Dresden, Germany, October 26-29, 1998

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  • Other: DE00001741
  • Report No.: ORNL/CP-99990
  • Grant Number: AC05-96OR22464
  • Office of Scientific & Technical Information Report Number: 1741
  • Archival Resource Key: ark:/67531/metadc669253

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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  • October 26, 1998

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  • June 29, 2015, 9:42 p.m.

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  • Nov. 4, 2015, 2:34 p.m.

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Becher, P.F.; Carter, C.; Fuller, E.R., Jr.; Hsueh, C.H. & Langer, S.A. Surface-Roughness Induced Residual Stresses in Thermal Barrier Coatings: Computer Simulations, article, October 26, 1998; United States. (digital.library.unt.edu/ark:/67531/metadc669253/: accessed January 20, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.