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TY  - THES
AU  - Li, Xinfang
TI  - Entwicklung glasbasierter Dichtungsmaterialien für das Fügen von Sauerstofftransportmembranen
PB  - Rheinisch-Westfälische Technische Hochschule Aachen
VL  - Dissertation
CY  - Aachen
M1  - RWTH-2022-10883
SP  - 1 Online-Ressource : Illustrationen, Diagramme
PY  - 2022
N1  - Veröffentlicht auf dem Publikationsserver der RWTH Aachen University 2023. - Überarbeitete Auflage mit Korrektur von Abbildungen verfügbar
N1  - Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2022
AB  - In this thesis, different glass-based sealants were developed for joining oxygen transport membranes (OTM) to obtain matching the coefficient of thermal expansion (CTE) with membrane and support metals. The crystallization behavior of the BaO–CaO–SiO2–B2O3 system glass (H) and BaO–SrO–SiO2–B2O3 system glasses (BS) will be discussed. In addition, the glass-forming stability of glass matrices, filler type and amount effect on CTE, chemical compatibility, mechanical strength, shrinking behavior, viscous flow property, joining behavior, thermal cycling and long-term thermal stability were analyzed for various glass-based sealants. The feasibility of the fast joining process was also investigated to economize the energy costs of the heating process. SrTi0.75Fe0.25O3-δ (STF25) was used as an OTM, and the sealing partners were ferritic steel Aluchrom, pre-oxidized Aluchrom and Crofer22APU.BaO–CaO–SiO2–B2O3 system glass H matrix was first investigated with respect to its glass-forming tendency, crystallization and CTE. The crystalline behavior of glass H as the sealant matrix was investigated and predicted by experimental X-ray diffraction (XRD) analysis and the simulation using the thermodynamic package FactSage. Glass H exhibits a relatively low CTE (9.6 × 10-6 K-1) compared to STF25 and Aluchrom. Nine different filler materials were added to glass H in various amount for improving the CTE of glass-based composite sealants. Dilatometric tests were carried out to observe the influence of filler on thermal expansion. The viscous flow behavior of the composite sealant was investigated by hot stage microscopy (HSM) to determine the optimal joining temperature. The joining behavior of glass-based sealants for different thermal joining processes were analyzed via helium leakage testing, X-ray computed tomography (CT) inspection, scanning electron microscopy (SEM) analysis on cross-sections of the joints. The joints showed low helium leak rates smaller than 10-9 mbar·l·s-1 and good adherence of the glass sealants to the support metals and STF25. The mechanical shear strengths of sealants were measured by torsion testing on hourglass-shaped samples. A higher shear stress up to 62.2 MPa was found on composite joint which 40 wt.
LB  - PUB:(DE-HGF)11
DO  - DOI:10.18154/RWTH-2022-10883
UR  - https://publications.rwth-aachen.de/record/856444
ER  -