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SYNCHROTRON XRD MEASUREMENTS MAPPING INTERNAL STRAINS OF THERMAL BARRIER COATINGS DURING THERMAL GRADIENT MECHANICAL FATIGUE LOADING

Knipe, Kevin and Sofronsky, Stephen and Almer, Jonathan and Meid, Carla and Bartsch, Marion and Manero, Albert and Okasinski, John and Wischek, Janine and Karlsson, Anette M. and Raghavan, Seetha (2014) SYNCHROTRON XRD MEASUREMENTS MAPPING INTERNAL STRAINS OF THERMAL BARRIER COATINGS DURING THERMAL GRADIENT MECHANICAL FATIGUE LOADING. In: ASME Turbo Expo 2014: Turbine Technical Conference and Exposition, Vol. 6, V006T02A011. ASME Publishing, New York. ASME Turbo Expo 2014: Turbine Technical Conference and Exposition, 16.-20. Juni 2014, Düsseldorf. ISBN 978-0-7918-4575-2 ISSN GT2014-26919

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Abstract

An understanding of the high temperature mechanics experienced in Thermal Barrier Coatings (TBC) during cycling conditions would be highly beneficial to extending the lifespan of the coatings. This study will present results obtained using synchrotron x-rays to measure depth resolved strains in the various layers of TBCs under thermal mechanical loading and a superposed thermal gradient. Tubular specimens, coated with Yttria Stabilized Zirconia (YSZ) and an aluminum containing nickel alloy as a bond coat both through Electron Beam - Physical Vapor Deposition (EBPVD), were subjected to external heating and controlled internal cooling generating a thermal gradient across the specimen’s wall. Temperatures at the external surface were in excess of 1000 °C. Throughout high temperature testing, 2-D high-resolution XRD strain measurements are taken at various locations through the entire depth of the coating layers. Across the YSZ a strain gradient was observed showing higher compressive strain at the interface to the bond coat than towards the surface. This behavior can be attributed to the specific microstructure of the EB-PVD-coating, which reveals higher porosity at the outer surface than at the interface to the bond coat, resulting in a lower in plane modulus near the surface. This location at the interface displays the most significant variation due to applied load at room temperature with this effect diminishing at elevated uniform temperatures. During thermal cycling with a thermal gradient and mechanical loading, the bond coat strain moves from a highly tensile state at room temperature to an initially compressive state at high temperature before relaxing to zero during the high temperature hold. The results of these experiments give insight into previously unseen material behavior at high temperature which can be used to develop an increased understanding of various failure modes and their causes.

Item URL in elib:https://elib.dlr.de/91664/
Document Type:Conference or Workshop Item (Speech)
Title:SYNCHROTRON XRD MEASUREMENTS MAPPING INTERNAL STRAINS OF THERMAL BARRIER COATINGS DURING THERMAL GRADIENT MECHANICAL FATIGUE LOADING
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Knipe, KevinUniversity of Central Florida, Orlando, FL, USAUNSPECIFIED
Sofronsky, StephenUniversity of Central Florida, Orlando, FL, USAUNSPECIFIED
Almer, JonathanAdvanced Photon Source, Argonne National Laboratory, Argonne, IllinoisUNSPECIFIED
Meid, Carlacarla.meid (at) dlr.deUNSPECIFIED
Bartsch, Marionmarion.bartsch (at) dlr.deUNSPECIFIED
Manero, AlbertUniversity of Central Florida, Orlando, FL, USAUNSPECIFIED
Okasinski, JohnAdvanced Photon Source, Argonne National Laboratory, Argonne, IllinoisUNSPECIFIED
Wischek, Janinejanine.wischek (at) dlr.deUNSPECIFIED
Karlsson, Anette M.Cleveland State University, Ohio, USAUNSPECIFIED
Raghavan, SeethaUniversity of Central Florida, Orlando, FL, USAUNSPECIFIED
Date:19 June 2014
Journal or Publication Title:ASME Turbo Expo 2014: Turbine Technical Conference and Exposition
Refereed publication:Yes
Open Access:No
In DOAJ:No
In SCOPUS:No
In ISI Web of Science:No
Volume:Vol. 6
Page Range:V006T02A011
Publisher:ASME Publishing, New York
Series Name:ASME Turbo Expo 2014: Turbine Technical Conference and Exposition
ISSN:GT2014-26919
ISBN:978-0-7918-4575-2
Status:Published
Keywords:Fatigue , Thermal barrier coatings , Temperature gradient
Event Title:ASME Turbo Expo 2014: Turbine Technical Conference and Exposition
Event Location:Düsseldorf
Event Type:international Conference
Event Dates:16.-20. Juni 2014
Organizer:ASME - American Society of Mechanical Engineers
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:propulsion systems
DLR - Research area:Aeronautics
DLR - Program:L ER - Engine Research
DLR - Research theme (Project):L - Virtual Engine and Validation methods
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > Experimental and Numerical Methods
Deposited By: Bartsch, Dr.-Ing. Marion
Deposited On:11 Nov 2014 14:51
Last Modified:11 Nov 2014 14:51

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