Book/Dissertation / PhD Thesis

FZJ-2024-06139

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Abscheidung kolumnarer Wärmedämmschichten mittels Suspensionsplasmaspritzen (SPS) und Plasma Spray – Physical Vapor Deposition (PS-PVD) Prozesse

Joeris, J. (Corresponding author)

2024
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-752-3

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Please use a persistent id in citations: doi:10.34734/FZJ-2024-06139

Abstract: In this work, columnar thermal barrier coatings are prepared by suspension plasma spraying (SPS) and plasma spray-physical vapor deposition (PS-PVD) process. For industrial applications, increasing the lifetime of the coatings is an important aim. For this purpose, the thermal expansion coefficient of metal and ceramic is equalized by introducing an oxide dispersion strengthened (ODS) layer, which can reduce the radial stresses in the thermal barrier coating. Furthermore, the service life is extended by pre-oxidation of the bond coat with formation of an aluminum oxide layer. At the beginning of the work, the material and process parameters for the coating processes are evaluated. The objective is to produce columnar microstructures that have a high column density. In the SPS process, the microstructure is significantly affected by the feed rate of the suspension. Too high feeding rates increases the porosity of the coating strongly and significantly reduce the deposition efficiency. Columnar structures are then difficult to produce. To deposit columnar structures, the atomization of the suspension and the melting of the agglomerated particles must be optimized. This is achieved by optimizing the plasma gas composition and quantity. For the SPS process, a high column density is achieved when as.sprayed bondcoats with a high number of roughness peaks are used, whereas polished surfaces are required for the PS-PVD process. The evaluated parameters are then used to coat cylinders and thermal cycle samples of IN738 and CMSX-4. Thermal cycling samples are used to investigate the thermal shock resistance of the thermal barrier coatings. In addition to the microstructure of the topcoat, the composition of the bondcoats has an impact on their durability. By using ODS layers, the lifetime of the thermal barrier coating (TBC) can be improved. Promising results can be achieved by pre-oxidation of the bondcoats. By heat-treating the bondcoats before coating the topcoat, a thermally grown oxide (TGO) layer is formed, which makes it possible to increase the lifetime of SPS coatings significantly. This makes it possible for the first time to produce single-layer SPS coatings that have comparable lifetimes to other coating processes. The present work was carried out within the framework of the Collaborative Research Center SFB/Transregio 103 "From the atom to the turbine blade".

Note: Dissertation, Bochum University, 2023

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Contributing Institute(s):

1. Werkstoffsynthese und Herstellungsverfahren (IEK-1)

Research Program(s):

1. 1241 - Gas turbines (POF4-124) (POF4-124)

Appears in the scientific report 2024

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