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Mora-García, A.G. and Alvarado-Orozco, L.M. and Mondragón Rodríguez, G.C. and García-Herrera, J.E. and Cácerez-Díaz, L.A. and Konitzer, D.G. and Trágaga-Martínez, L.G. and Schulz, U. and Muñoz-Saldaña, J. (2013) FAILURE ANALYSIS OF PRE-OXIDIZED ReneN5/ β-(Ni,Pt)Al/7YSZ EB-PVD THERMAL BARRIER COATINGS. XXII International Materials Research Congress, 11.-15. Aug. 2013, Cancún Mexiko.

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Nowadays Pt-modified nickel aluminides, (Ni,Pt)Al, are highly used as alumina-forming alloys in the aerospace industry. These alloys have been studied to improve the lifetime of the thermal barrier coating systems (TBCs) when they are exposed to thermal-cyclic tests [1-3]. The use of (Ni,Pt)Al alloy as bond coat (BC) is to provide oxidation protection of the Ni-base superalloy (SA) used as a substrate of hot-section turbine blades. BCs act as an aluminum reservoir that leads to the formation of a thermally grown oxide (TGO). The TGO improves the adherence between the metal and a ceramic top coat (TC), which provides thermal insulation during the operation of these components. The aim of the present study is to evaluate the effect of the pre-oxidation treatments before TC deposition on the thermal-cyclic life of ReneN5/(Ni,Pt)Al/7YSZ TBCs. The effect of different oxygen partial pressures (pO2= 2.1x10-1, 1.05x10-1, 1x10-5 and 1x10-9 atm) pre-oxidation treatments were evaluated and compared to regular TBCs after EB-PVD TC deposition in “as-coated” conditions. A post-mortem analysis of the samples was also carried out after 1 h thermal-cyclic testing at 1100ºC to study the intrinsic mechanisms associated to the failure. Samples pre-oxidized with a combination of Argon-Gettered atmosphere (pO2=1x10-9 atm) showed the highest performance in average (1550 cycles to failure). For all the different pre-oxidation conditions, the failure occurred majority along the TC/TGO interface. Mapping of grain orientation determined by EBSD combined with nanoindentation tests were carried out to evaluate anisotropic effects and structural characterization with their mechanical properties after thermal-cyclic tests. Efforts are currently being done to link the failure of the samples to the microstructural characteristics. For instance a continuous layer of martensitic phase, L10, along the bond coat has been observed after failure for the thermal-cyclic tested samples. The reversible L10↔β phase transformation and the reaction β γ' are the main phenomena that take place during thermal cycling and results from the BC aluminum depletion due to TGO formation and its diffusion to the SA [4-6]. Moreover, cracks have been identified in the L10/γ' grains interface. Finally, it must be pointed out that the non-pre-oxidized TBCs have shown a mixed zone in the TGO, which consists on a region where zirconia particles are dispersed in the TGO matrix [7]. References [1] A.G. Evans, et.al., Progress in Materials Science 46 (2001) 505 - 553. [2] V.K. Tolpygo and D.R. Clarke, Surface & Coatings Technology 200 (2005) 1276 - 1281. [3] U. Schulz, et.al., Surface & Coatings Technology 203 (2008) 160 - 170. [4] M.W. Chen, et.al., Acta Materialia (2003), 4279 - 4294. [5] J.L. Smialek and R. Giballa; Metallurgical transactions A (1983), 2143 - 2161. [6] B. Gleeson, W. Wang, S. Hayashi, D.J. Sordelet; Mater Sci Forum 2004. [7] M.J. Stiger, et.al; Metallurgical and Materials Transitions A (2007) Vol.38A 848 - 857.

Item URL in elib:https://elib.dlr.de/84683/
Document Type:Conference or Workshop Item (Speech)
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Mora-García, A.G.Cinvestav, Unidad Querétaro, MéxicoUNSPECIFIED
Alvarado-Orozco, L.M.University of PittsburghUNSPECIFIED
Mondragón Rodríguez, G.C.guillermo.mondragon-rodriguez (at) dlr.deUNSPECIFIED
García-Herrera, J.E.Cinvestav, Unidad Querétaro, MéxicoUNSPECIFIED
Cácerez-Díaz, L.A.Cinvestav, Unidad Querétaro, MéxicoUNSPECIFIED
Konitzer, D.G.General Electric CincinnatiUNSPECIFIED
Trágaga-Martínez, L.G.Cinvestav, Unidad Querétaro, MéxicoUNSPECIFIED
Schulz, U.uwe.schulz (at) dlr.deUNSPECIFIED
Muñoz-Saldaña, J.Cinvestav, Unidad Querétaro, MéxicoUNSPECIFIED
Date:13 August 2013
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:No
Keywords:TBCs, pre-oxidation, thermal-cyclic testing, (Ni,Pt)Al BC, martensitic transformation, TGO.
Event Title:XXII International Materials Research Congress
Event Location:Cancún Mexiko
Event Type:international Conference
Event Dates:11.-15. Aug. 2013
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:Propulsion Systems (old)
DLR - Research area:Aeronautics
DLR - Program:L ER - Engine Research
DLR - Research theme (Project):L - Turbine Technologies (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > High Temperature and Functional Coatings
Deposited By: Mondragon Rodriguez, Guillermo Cesar
Deposited On:16 Oct 2013 09:51
Last Modified:08 May 2014 23:25

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