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Aging behavior of reactive air brazed seals for SOFC

 
: Pönicke, Andreas; Schilm, Jochen; Kusnezoff, Mihails; Michaelis, Alexander

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Fulltext urn:nbn:de:0011-n-3236758 (923 KByte PDF)
MD5 Fingerprint: b5153659e3ed1cd7b0ba13ce0857a9f6
Created on: 27.1.2015


Kusnezoff, Mihails (Scientific Advisory Committee) ; European Fuel Cell Forum -EFCF-:
11th European SOFC & SOE Forum 2014. Proceedings and additional information. CD-ROM : 1 - 4 July 2014, Kultur und Kongresszentrum Luzern, Lucerne, Switzerland
Luzern-Adligenswil: European Fuel Cell Forum, 2014
ISBN: 978-3-905592-16-0
Paper A1409, 12 pp.
European Solid Oxide Fuel Cell Forum (SOFC) <11, 2014, Luzern>
International Solid Oxide Fuel Cell and Electrolyser Conference <2014, Luzern>
English
Conference Paper, Electronic Publication
Fraunhofer IKTS ()
SOFC system; Brennstoffzellensystem

Abstract
The mechanical integrity of solid oxide fuel cells (SOFC) and the long-term stability underoperating conditions are basic requirements for a reliable operation of SOFC stacks. In this respect the use of metallic brazes as sealing material is considered to have advantages incomparison to the widely used brittle glasses or glass ceramics. In this study the mechanical properties of reactive air brazed YSZ-steel joints and their long-term stability at high temperatures in air and dual atmospheres are investigated. Silver-based braze compositions like Ag-4CuO are used for reactive air brazing of gas tightness samples. During aging in air at 850°C for 800 h the thickness of the interfacial oxide layers increases with time, while the bending strength decreases. Microstructural analysis reveals the formation of voids within the brazing zone and the development of multilayered reactionlayers. In contrast, the aging in dual atmospheres at 850°C causes strong degradation andthe total loss of gas tightness. However, the addition of small amounts of TiH2 to the brazecompositions enhances the dual atmosphere tolerance of the reactive air brazed seals.

: http://publica.fraunhofer.de/documents/N-323675.html