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@PHDTHESIS{Wolf:890451,
author = {Wolf, Markus},
title = {{E}ntwicklung von {S}chutzschichten für nicht-oxidische
{F}aserverbundwerkstoffe},
volume = {528},
school = {Universität Bochum},
type = {Dr.},
address = {Jülich},
publisher = {Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag},
reportid = {FZJ-2021-00967},
isbn = {978-3-95806-524-6},
series = {Schriften des Forschungszentrums Jülich. Reihe Energie
$\&$ Umwelt / Energy $\&$ Environment},
pages = {VI, 150, 2 S.},
year = {2021},
note = {Universität Bochum, Diss., 2020},
abstract = {The non-oxide ceramic matrix composites (CMCs), which
exhibit good mechanical high-temperature properties and low
density, represent a promising alternative to the
temperature-limited metallic materials. However, a problem
with these CMCs is their high susceptibility to corrosion in
an atmosphere containing water vapor at temperatures above
1200°C. In order to protect the material from the influence
of corrosive media, various protective coating systems
(environmental barrier coatings, EBCs) are applied to the
CMC. The aim of the work described here is to develop a
coating system that protects the base material from
corrosive atmospheres in cooperation with an industrial
partner. The focus of the present work is on the manufacture
and optimization of EBCs for the protection of silicon
carbide-based CMCs. In a first step, different material
candidates have been investigated for their thermal,
thermomechanical, and mechanical properties to evaluate an
optimal EBC candidate. In particular, the corrosion
resistance against calcium-magnesium-aluminum-silicates
(CMAS) has been considered. Subsequently, the best evaluated
materials Yb$_{2}$Si$_{2}$O$_{7}$ and a mixture of
Yb$_{2}$Si$_{2}$O$_{7}$ and Yb$_{2}$SiO$_{5}$ were applied
to the CMC using different thermal spray processes. These
two materials show a high corrosion protection against CMAS
and coefficients of thermal expansion adapted to the CMC.
Below the top layers of these two materials, the CMC is
additionally coated with a silicon bond coat to create a
complete EBC layer system. By varying the process
parameters, it was possible to design the top layers in such
a way that they were very dense, crackfree and crystalline
at the same time. The layers developed with the different
processes were subjected to evaluate the thermal shock
resistance during thermal cycling and compared to each
other. In addition to the material study and the
optimization of layer deposition, the surface of the bond
coat was structured with a laser to increase the adhesion of
the top layer to the bond coat. In this way, the lifetime of
the coatings was further increased. The effect of this
structuring has been verified by means of an adapted test of
interfacial toughness. It turned out that the interfacial
toughness could be increased by 70\% by means of the added
structure. However, it was also found that the test
methodology needs to be optimized, since the observed crack
did not continuously follow the interface to be tested. In a
final test series, the deposition of a
Silicon-Yb$_{2}$Si$_{2}$O$_{7}$ layer system was transferred
from flat substrates to a 3D substrate in the form of a
turbine blade edge.},
cin = {IEK-1},
cid = {I:(DE-Juel1)IEK-1-20101013},
pnm = {124 - Hochtemperaturtechnologien (POF4-124)},
pid = {G:(DE-HGF)POF4-124},
typ = {PUB:(DE-HGF)3 / PUB:(DE-HGF)11},
url = {https://juser.fz-juelich.de/record/890451},
}