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Estimation of CMAS Infiltration depth in EB-PVD TBCs: A new constraint model supported with experimental approach.

Naraparaju, Ravisankar and Gomez Chavez, Juan J and Niemeyer, Philipp David and Hess, Kai Uwe and Song, Wenjia and Dingwell, D.B and Lokachari, Siddharth and Ramana, C.V. and Schulz, Uwe (2019) Estimation of CMAS Infiltration depth in EB-PVD TBCs: A new constraint model supported with experimental approach. Journal of the European Ceramic Society, 39, pp. 2936-2945. Elsevier. DOI: 10.1016/j.jeurceramsoc.2019.02.040 ISSN 0955-2219

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Abstract

Two standard 7YSZ coatings were deposited by EB-PVD techniques and tested against CMAS infiltration at short time intervals (up to 8 min.) at 1250˚C in air. They exhibited different microstructures, i.e. porosities and microstructural features. Two species of CMAS with different compositions were used and their viscosities were determined using the concentric cylinder method and their contact angles were measured using high temperature heating microscopy. The theoretical viscosities, which were calculated using a statistical model based on the chemical composition of the melts, differed from the measured values of the viscosities by one order of magnitude. A large variation in the contact angles within a very short range of temperature (1243-1266°C) was observed as well. The porosity and surface area measurements were performed on both EB-PVD microstructures using the nitrogen physisorption method. Additionally, the produced coatings exhibited porosities of 14.5 and 29.5 percent and the infiltration experiments have shown that the more porous coating provides higher infiltration resistance. The effect of porosity on CMAS infiltration kinetics was investigated and the results elucidate that the porosity network plays a more preeminent role than the amount of porosity. The experimental infiltration results have been compared with calculated infiltration data using a novel mathematical approach proposed in previous studies in which the permeability of the coatings is assessed with two contrasting methods termed “concentric pipe” and “open pipe” models. The infiltration was calculated by incorporating the experimentally determined properties such as contact angle, viscosity and porosity. A fitting parameter has been derived from the equations for the geometry factor for both microstructures. The calculated and experimental results are in good agreement with the concentric pipe model supporting the validity of this CMAS infiltration model.

Item URL in elib:https://elib.dlr.de/130379/
Document Type:Article
Title:Estimation of CMAS Infiltration depth in EB-PVD TBCs: A new constraint model supported with experimental approach.
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Naraparaju, RavisankarRavisankar.Naraparaju (at) dlr.deUNSPECIFIED
Gomez Chavez, Juan Jjjgomez2 (at) miners.utep.eduUNSPECIFIED
Niemeyer, Philipp DavidPhilipp.Niemeyer (at) dlr.dehttps://orcid.org/0000-0002-4386-2589
Hess, Kai UweUNSPECIFIEDUNSPECIFIED
Song, WenjiaUNSPECIFIEDUNSPECIFIED
Dingwell, D.Bludwig maximilians universität münchen, earth & environmental sciences, germanyUNSPECIFIED
Lokachari, SiddharthUNSPECIFIEDUNSPECIFIED
Ramana, C.V.rvchintalapalle (at) utep.eduUNSPECIFIED
Schulz, UweUwe.Schulz (at) dlr.dehttps://orcid.org/0000-0003-0362-8103
Date:26 February 2019
Journal or Publication Title:Journal of the European Ceramic Society
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:39
DOI :10.1016/j.jeurceramsoc.2019.02.040
Page Range:pp. 2936-2945
Publisher:Elsevier
ISSN:0955-2219
Status:Published
Keywords:CMAS, EB-PVD, Infiltration kinetics, 7YSZ
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
Institute of Materials Research > Aerogels and Aerogel Composites
Deposited By: Naraparaju, Dr Ravisankar
Deposited On:11 Nov 2019 18:17
Last Modified:11 Nov 2019 18:17

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