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Fatigue cracks in a thermal barrier coating system on a super alloy in multiaxial thermomechanical testing

Bartsch, Marion and Baufeld, Bernd and Dalkilic, Serdar and Chernova, Liudmila and Heinzelmann, Michael (2007) Fatigue cracks in a thermal barrier coating system on a super alloy in multiaxial thermomechanical testing. International Journal of Fatigue, 30 (2), pp. 211-218. Elsevier. doi: 10.1016/j.ijfatigue.2007.01.037.

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Official URL: http://www.sciencedirect.com


Thermal barrier coatings (TBC) are applied on cooled gas turbine components. Between the heated and cooled surfaces a thermal gradient develops, resulting for constraint components in high multiaxial stresses, which may exceed stresses due to mechanical loading. In order to investigate the damage behaviour of TBC systems under close to reality conditions, thermal mechanical fatigue tests with controlled thermal gradients (TGMF-tests) were performed on coated tubular specimens. The specimen substrate was made from directionally solidified nickel base superalloy IN100 DS, and the coating system comprised a NiCoCrAlY bond coat and a ceramic top coat from partially stabilized zirconia. The stress distribution over the specimen wall, which was generated in the course of one TGMF cycle, has been analysed by linear elastic Finite Element calculations. In TGMF testing specific damages occurred underneath the adherent ceramic top coat, evolving into fatigue cracks, which propagated primarily in the metallic bond coat parallel to the surface. In length sections the crack shape in this stage resembles a ‘smiley’. During further cycling the crack path deviated to the interface between BC and top coat, enhancing spallation. The ‘smiley’-crack patterns, which only occurred in TGMF but not in isothermal low cycle fatigue or thermal fatigue, are discussed with respect to the cyclic local stress distribution.

Item URL in elib:https://elib.dlr.de/49408/
Document Type:Article
Title:Fatigue cracks in a thermal barrier coating system on a super alloy in multiaxial thermomechanical testing
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Baufeld, BerndKatholieke Universiteit Leuven, BelgiumUNSPECIFIEDUNSPECIFIED
Dalkilic, SerdarAnadolu University, Eskishir, TurkeyUNSPECIFIEDUNSPECIFIED
Heinzelmann, MichaelFachhochschule Bonn-Rhein-SiegUNSPECIFIEDUNSPECIFIED
Date:March 2007
Journal or Publication Title:International Journal of Fatigue
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:pp. 211-218
Keywords:Gas turbines; Thermomechanical fatigue/cycling; Crack formation; Fatigue crack growth; Stress analysis
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Aeronautics
HGF - Program Themes:L VU - Air Traffic and Environment (old)
DLR - Research area:Aeronautics
DLR - Program:L VU - Air Traffic and Environment
DLR - Research theme (Project):L - Low-Emission Air Traffic (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research
Deposited By: Bartsch, Dr.-Ing. Marion
Deposited On:16 Nov 2007
Last Modified:27 Apr 2009 13:58

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