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Nondestructive cell evaluation techniques in SOFC stack manufacturing

 
: Wunderlich, Christian

:
Postprint urn:nbn:de:0011-n-3937868 (1.4 MByte PDF)
MD5 Fingerprint: 975a174fe436b7e49c8eb31ffa2910fa
Copyright Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.
Erstellt am: 3.6.2016


Meyendorf, N.G. ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Smart Materials and Nondestructive Evaluation for Energy Systems 2016 : 21-23 March 2016, Las Vegas, Nevada, United States
Bellingham, WA: SPIE, 2016 (SPIE Proceedings 9806)
ISBN: 978-1-5106-0047-8
Art. 980602
Conference "Smart Materials and Nondestructive Evaluation for Energy Systems" <2, 2016, Las Vegas/Nev.>
Englisch
Konferenzbeitrag, Elektronische Publikation
Fraunhofer IKTS ()
manufacturing; inspection; Ceramics; Strength; Lasers; optical coherence tomography; Oxides; Laser-Speckle-Photometry; Speckle

Abstract
Independent from the specifics of the application, a cost efficient manufacturing of solid oxide fuel cells (SOFC), its electrolyte membranes and other stack components, leading to reliable long-life stacks is the key for the commercial viability of this fuel cell technology. Tensile andshear stresses are most critical for ceramic components and especially for thin electrolyte membranes as used in SOFC cells. Although stack developers try to reduce tensile stresses acting on the electrolyte by either matching CTE of interconnects and electrolytes or by putting SOFC cells under some pressure – at least during transient operation of SOFC stacks ceramic cells will experience some tensile stresses. Electrolytes are required to have a high Weibull characteristic fracture strength. Practical experiences in stack manufacturing have shown that statistical fracture strength data generated by tests of electrolyte samples give limited information on electrolyte or cell quality. In addition, the cutting process of SOFC electrolytes has a major influence on crack initiation. Typically, any single crack in one the 30 to 80 cells in series connection will lead to a premature stack failure drastically reducing stack service life. Thus, for statistical reasons only 100% defect free SOFC cells must be assembled in stacks. This underlines the need for an automated inspection. So far, only manual processes of visual or mechanical electrolyte inspection are established. Fraunhofer IKTS has qualified the method of optical coherence tomography for an automated high throughput inspection. Alternatives like laser speckle photometry and acoustical methods are still under investigation.

: http://publica.fraunhofer.de/dokumente/N-393786.html