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Investigation of CMAS Resistance of Sacrificial Suspension Sprayed Alumina Topcoats on EB-PVD 7YSZ Layers

Mikulla, Christoph and Naraparaju, Ravisankar and Schulz, Uwe and Toma, Filofteia-Laura and Barbosa, Maria and Leyens, Christoph (2019) Investigation of CMAS Resistance of Sacrificial Suspension Sprayed Alumina Topcoats on EB-PVD 7YSZ Layers. Journal of Thermal Spray Technology. Springer. DOI: 10.1007/s11666-019-00951-4 ISSN 1059-9630

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Official URL: https://link.springer.com/article/10.1007%2Fs11666-019-00951-4

Abstract

Molten calcium-magnesium-aluminum-silicate (CMAS) mineral particles cause significant degradation of thermal barrier coatings (TBCs) in aero-engines. One approach to protect the TBC coating against the CMAS attack is the application of a sacrificial coating on top of the TBC coating. In this work, Al2O3 coatings were deposited on EB-PVD 7YSZ layers using suspension plasma spraying (SPS) and suspension high velocity oxy-fuel spraying (SHVOF), in order to produce sacrificial topcoats with two different microstructures and porosity levels. The coating systems were tested under CMAS attack with one natural volcanic ash and two artificial CMAS powders by conducting infiltration tests at 1250 °C in the time intervals between 5 min and 10 h. It was found that the porosity and morphology of suspension sprayed alumina topcoats, the chemical composition of the deposits and the infiltration conditions strongly influence the CMAS infiltration, reaction kinetics and formation of the reaction products. While the porous SPS coatings offer limited resistance against CMAS infiltration, the dense SHVOF coatings show promising CMAS sealing behavior. Among the formed reaction products, only (Fe, Mg) Al spinel acted as an efficient barrier against CMAS infiltration. However, the formation of uniform spinel layers strongly depends on the pore morphology of the sacrificial coating and the CMAS chemistry.

Item URL in elib:https://elib.dlr.de/130457/
Document Type:Article
Title:Investigation of CMAS Resistance of Sacrificial Suspension Sprayed Alumina Topcoats on EB-PVD 7YSZ Layers
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Mikulla, ChristophChristoph.Mikulla (at) dlr.deUNSPECIFIED
Naraparaju, RavisankarRavisankar.Naraparaju (at) dlr.deUNSPECIFIED
Schulz, UweUwe.Schulz (at) dlr.dehttps://orcid.org/0000-0003-0362-8103
Toma, Filofteia-LauraFraunhofer-Institut für Werkstoff und Strahltechnik IWSUNSPECIFIED
Barbosa, MariaFraunhofer-Institut für Werkstoff und Strahltechnik IWSUNSPECIFIED
Leyens, ChristophTU DresdenUNSPECIFIED
Date:11 November 2019
Journal or Publication Title:Journal of Thermal Spray Technology
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
DOI :10.1007/s11666-019-00951-4
Editors:
EditorsEmail
Vardelle, ArmelleUniversité de Limoges/ENSIL, France
Publisher:Springer
ISSN:1059-9630
Status:Published
Keywords:7YSZ, Al2O3, CMAS, EB-PVD, sacrificial coating, suspension spraying, thermal barrier coatings, Wärmedämmschichten
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
Location: Köln-Porz
Institutes and Institutions:Institute of Materials Research > High Temperature and Functional Coatings
Deposited By: Mikulla, Christoph
Deposited On:15 Nov 2019 12:54
Last Modified:24 Jan 2020 11:11

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