TY  - THES
AU  - Gatzen, Caren Sophia
TI  - Entwicklung von korrosionsstabilen Schutzschichten für oxidische Faserverbundwerkstoffe
VL  - 471
PB  - Univ. Bochum
VL  - Dissertation
CY  - Jülich
M1  - FZJ-2019-04897
SN  - 978-3-95806-422-5
T2  - Schriften des Forschungszentrums Jülich Reihe Energie & Umwelt / Energy & Environment
SP  - II, 143
PY  - 2019
N1  - Dissertation, Univ. Bochum, 2019
AB  - Due to their high specific strength and high temperature resistance, oxide ceramic matrix composites (CMCs) are promising materials for high-temperature applications, e.g. in gas turbine combustion chambers. However, degradation due to water vapor corrosion at temperatures above 1200 °C is a serious problem. Environmental barrier coatings (EBCs) are required to prevent or minimize these reactions. The focus of this work is the development of EBCs for an alumina-based CMC, especiallythe improvement of the adhesion between coating and CMC. First, different methods of surface structuring of the CMC were investigated. The structuring by laser ablation turned out to be promising and was investigated in detail. Subsequently, YSZ, Gd$_{2}$Zr$_{2}$O$_{7}$, Y$_{2}$O$_{3}$ and YAlO$_{3}$ were selected as potential protective coatings due to their low recession rates and fitting thermal expansion coefficients. Samples of the CMC, with and without laser structuring were coated by plasma spraying. The suitability of these coating systems and their adhesion to the substrate were investigated by tensile adhesion tests and thermal cycling. Two different adhesion mechanisms were found: YSZ- and Gd$_{2}$Zr$_{2}$O$_{7}$- coatings adhere mainly by mechanically interlocking to the substrate.Structuring of the samples before coating could considerably improve the adhesion. Y$_{2}$O$_{3}$- and YAlO$_{3}$- coatings react with the Al$_{2}$O$_{3}$-based substrate to form yttrium alluminates. Due to the formation of this boundary layer, a very good adhesion was achieved, even on unstructured samples. Since the corrosion stability is also important for an EBC, selected samples were used to validate a new corrosion test procedure in which significant corrosion rates can be measured within a short time by using a HVOF torch.
LB  - PUB:(DE-HGF)3 ; PUB:(DE-HGF)11
UR  - https://juser.fz-juelich.de/record/865446
ER  -