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Understanding the presence of CaSO4 within CMAS and its effect on the infiltration behaviour in EB-PVD 7YSZ

Naraparaju, Ravisankar and Mechnich, Peter and Mondragón Rodríguez, G.C. and Schulz, Uwe (2016) Understanding the presence of CaSO4 within CMAS and its effect on the infiltration behaviour in EB-PVD 7YSZ. Journal of the American Ceramic Society, 99 (4), pp. 1398-1403. Wiley. doi: 10.1111/jace.14077. ISSN 0002-7820.

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Infiltration and deposition of CaSO4 in thermal barrier coatings (TBC) in addition to the CMAS deposits was found in many occasions on real aviation engines. The source and role of CaSO4 on the degradation of TBC is not well understood. CaSO4 containing CMAS was synthesized and a systematic study of its role on the CMAS infiltration behaviour in EB-PVD 7YSZ is presented in this work. Its influence on the melting and crystallisation behaviour of CMAS was studied with the help of differential scanning calorimetry. The decomposition of CaSO4 into CaO and SO3 was observed at 1050 °C in laboratory air under the presence of CMAS using mass spectroscopy and in situ high temperature XRD. The same amount of CaO is brought into the CMAS system by means of adding CaCO3 which will eventually decompose into CaO and CO2 at 700 °C. CMAS infiltration tests were carried out at different temperatures with and without CaSO4/CaCO3 and the results demonstrate that the sulphur has no direct effect on the aggressiveness of the anhydrite containing CMAS with regard to its infiltration behaviour in EB-PVD 7YSZ at high temperatures. The extra amount of calcia added to CMAS that is introduced by the evaporating species is responsible for enhanced infiltration of the deposits into the TBC.

Item URL in elib:https://elib.dlr.de/100184/
Document Type:Article
Title:Understanding the presence of CaSO4 within CMAS and its effect on the infiltration behaviour in EB-PVD 7YSZ
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Naraparaju, Ravisankarravisankar.naraparaju (at) dlr.deUNSPECIFIED
Mondragón Rodríguez, G.C.guillermo.mondragon-rodriguez (at) dlr.deUNSPECIFIED
Journal or Publication Title:Journal of the American Ceramic Society
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In ISI Web of Science:Yes
DOI :10.1111/jace.14077
Page Range:pp. 1398-1403
Keywords:thermal barrier coatings, zirconia: yttria stabilized, infiltration, aluminosilicates, phase transformations
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 - Turbine Technologies (old)
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > High Temperature and Functional Coatings
Institute of Materials Research > Keramische Strukturwerkstoffe
Deposited By: Naraparaju, Dr Ravisankar
Deposited On:30 Nov 2015 12:58
Last Modified:08 Mar 2018 18:45

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