TY - JOUR A1 - Tötzke, C. A1 - Manke, I. A1 - Gaiselmann, G. A1 - Bohner, J. A1 - Müller, Bernd R. A1 - Kupsch, Andreas A1 - Hentschel, Manfred P. A1 - Schmidt, V. A1 - Banhart, J. A1 - Lehnert, W. T1 - A dedicated compression device for high resolution X-ray tomography of compressed gas diffusion layers JF - Review of scientific instruments N2 - We present an experimental approach to study the three-dimensional microstructure of gas diffusion layer (GDL) materials under realistic compression conditions. A dedicated compression device was designed that allows for synchrotron-tomographic investigation of circular samples under well-defined compression conditions. The tomographic data provide the experimental basis for stochastic modeling of nonwoven GDL materials. A plain compression tool is used to study the fiber courses in the material at different compression stages. Transport relevant geometrical parameters, such as porosity, pore size, and tortuosity distributions, are exemplarily evaluated for a GDL sample in the uncompressed state and for a compression of 30 vol.%. To mimic the geometry of the flow-field, we employed a compression punch with an integrated channel-rib-profile. It turned out that the GDL material is homogeneously compressed under the ribs, however, much less compressed underneath the channel. GDL fibers extend far into the channel volume where they might interfere with the convective gas transport and the removal of liquid water from the cell. KW - PEM fuel cell KW - Gas diffusion layer (GDL) KW - Compression device KW - X-ray tomography KW - Synchrotron KW - Tortuosity PY - 2015 DO - https://doi.org/10.1063/1.4918291 SN - 0034-6748 SN - 1089-7623 VL - 86 IS - 4 SP - 043702-1 EP - 043702-6 PB - American Institute of Physics CY - Melville, NY, USA AN - OPUS4-33081 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Manke, I. A1 - Kardjilov, N. A1 - Schäfer, R. A1 - Hilger, A. A1 - Grothausmann, R. A1 - Strobl, M. A1 - Dawson, M. A1 - Grünzweig, C. A1 - Tötzke, C. A1 - David, C. A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Banhart, J. T1 - Three-dimensional imaging of magnetic domains with neutron grating interferometry JF - Physics procedia N2 - This paper gives a brief overview on3D imaging of magnetic domains with shearing grating neutron tomography. We investigated the three-dimensional distribution of magnetic domain walls in the bulk of a wedge-shaped FeSi single crystal. The width of the magnetic domains wasanalyzed at different locations within the crystal. Magnetic domains close to the tip of the wedge are much smaller than in the bulk. Furthermore, the three-dimensional shape of individual domains wasinvestigated. We discuss prospects and limitations of the applied measurement technique. KW - Neutron imaging KW - Tomography KW - Magnetic domains KW - Grating interferometry KW - Darkfield imaging KW - Shearing gratings KW - Talbot-Lau KW - Three-dimensional data quantification KW - Tomographic reconstruction PY - 2015 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-341919 DO - https://doi.org/10.1016/j.phpro.2015.07.057 SN - 1875-3892 VL - 69 SP - 404 EP - 412 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-34191 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Tötzke, C. A1 - Gaiselmann, G. A1 - Osenberg, M. A1 - Bohner, J. A1 - Arlt, Tobias A1 - Markötter, H. A1 - Hilger, A. A1 - Wieder, F. A1 - Kupsch, Andreas A1 - Müller, Bernd R. A1 - Hentschel, Manfred P. A1 - Banhart, J. A1 - Schmidt, V. A1 - Lehnert, W. A1 - Manke, I. T1 - Three-dimensional study of compressed gas diffusion layers using synchrotron X-ray imaging JF - Journal of power sources N2 - We present a synchrotron X-ray tomographic study on the morphology of carbon fiber-based gas diffusion layer (GDL) material under compression. A dedicated compression device is used to provide well-defined compression conditions. A flat compression punch is employed to study the fiber geometry at different degrees of compression. Transport relevant geometrical parameters such as porosity, pore size and tortuosity distributions are calculated. The geometric properties notably change upon compression which has direct impact on transport conditions for gas and fluid flow. The availability of broad 3D paths, which are most important for the transport of liquid water from the catalyst layer through the GDL, is markedly reduced after compression. In a second experiment, we study the influence of the channel-land-pattern of the flow-field on shape and microstructure of the GDL. A flow-field compression punch is employed to reproduce the inhomogeneous compression conditions found during fuel cell assembly. While homogenously compressed underneath the land the GDL is much less and inhomogeneously compressed under the channel. The GDL material extends far into the channel volume where it can considerably influence gas and fluid flow. Loose fiber endings penetrate deeply into the channel and form obstacles for the discharge of liquid water droplets. KW - Synchrotron X-ray tomography KW - Gas diffusion layer (GDL) KW - Microstructure KW - Water transport path KW - Pore size analysis KW - Geometrical tortuosity PY - 2014 DO - https://doi.org/10.1016/j.jpowsour.2013.12.062 SN - 0378-7753 VL - 253 SP - 123 EP - 131 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-29979 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Arlt, Tobias A1 - Grothausmann, R. A1 - Manke, I. A1 - Markötter, H. A1 - Hilger, A. A1 - Kardjilov, N. A1 - Tötzke, C. A1 - Banhart, J. A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Krüger, P. A1 - Haußmann, J. A1 - Hartnig, C. A1 - Wippermann, K. T1 - Tomografische Methoden für die Brennstoffzellenforschung JF - Materials Testing N2 - Aufgrund des hohen Wirkungsgrades und der vielfältigen Einsatzmöglichkeiten können Brennstoffzellen einen wichtigen Beitrag zur zukünftigen Energieversorgung leisten. Für die Optimierung der Brennstoffzellentechnik ist es erforderlich, die während des Zellbetriebs ablaufenden Prozesse zu verstehen und exakt zu charakterisieren. Ein ausbalanciertes Wassermanagement ist die Grundlage für die optimale Leistungsfähigkeit einer wasserstoffbetriebenen Zelle. Das während des Betriebs entstehende Wasser muss die Membran ausreichend befeuchten, um deren Protonenleitfähigkeit aufrechtzuerhalten. Andererseits behindern zu große Wasseransammlungen in der Zelle die Gaszufuhr durch die porösen Materialien sowie in den Kanälen der Gasverteilerstrukturen. Alterungsphänomene einzelner Zellkomponenten können die Verteilung der Wasseransammlungen und somit das Wassermanagement empfindlich stören und so die Leistungsfähigkeit der Brennstoffzelle herabsetzen. Zur Analyse der Wasserverteilung werden zerstörungsfreie, bildgebende Methoden, wie die Ex-situ-Neutronentomografie und die In-situ-Synchrotronradiografie, eingesetzt. Diese Methoden können während des Brennstoffzellenbetriebs mit weiteren Messverfahren, beispielsweise der ortsaufgelösten Stromdichtemessung, kombiniert werden. Auf diese Weise werden einzelne Komponenten, wie zum Beispiel die Gasdiffusionsschichten, charakterisiert. KW - Computertomographie KW - Elektronentomographie KW - Neutronentomographie KW - Brennstoffzelle KW - Stromdichtemessung KW - Wassermanagement PY - 2013 DO - https://doi.org/10.3139/120.110429 SN - 0025-5300 VL - 55 IS - 3 SP - 207 EP - 213 PB - Hanser CY - München AN - OPUS4-27950 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grothausmann, R. A1 - Zehl, G. A1 - Manke, I. A1 - Fiechter, S. A1 - Bogdanoff, P. A1 - Dorbandt, I. A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Schumacher, G. A1 - Banhart, J. T1 - Dreidimensionale Charakterisierung von Katalysatornanopartikeln JF - International journal of materials research N2 - We present transmission electron microscope (TEM) tomography investigations of ruthenium-based fuel cell catalyst materials as employed in direct methanol fuel cells (DMFC). The digital three-dimensional representation of the samples not only enables detailed studies on number, size, and shape but also on the local orientation of the ruthenium particles to their support and their freely accessible surface area. The shape analysis shows the ruthenium particles deviate significantly from spherical symmetry which increases their surface to volume ratio. The morphological studies help to understand the structure formation mechanisms during the fabrication as well as the high effectiveness of these catalysts in the oxygen reduction reaction at the cathode side of fuel cells. KW - Radiography KW - Tomography KW - Neutrons KW - Polymer electrolyte membrane fuel cell (PEMFC) KW - Fuel cell stack PY - 2012 SN - 1862-5282 VL - 103 IS - 1 SP - 135 EP - 136 PB - Carl Hanser CY - München AN - OPUS4-25976 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Markötter, H. A1 - Manke, I. A1 - Kuhn, R. A1 - Arlt, Tobias A1 - Kardjilov, N. A1 - Hentschel, Manfred P. A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hartnig, C. A1 - Scholta, J. A1 - Banhart, J. T1 - Neutron tomographic investigations of water distributions in polymer electrolyte membrane fuel cell stacks JF - Journal of power sources N2 - Neutron tomography was applied to study the 3D water distribution in full polymer electrolyte membrane fuel cell (PEMFC) stacks. The water distribution after switch-off of the fuel cell was analyzed over a period of 36 h. We found a slowly increasing water amount in the fuel cell, but only few changes within a time period of 5 h, which is about the time necessary for neutron tomography. In this way, the requirement for successful tomography was obtained. It is demonstrated how the quasi in-situ tomography technique enables us to study the water content in individual flow field channels of three-fold stacks. Flow field as well as stack design issues are addressed by this visualization method showing weak points due to a non-uniform water distribution that can be identified by means of neutron imaging. KW - Radiography KW - Tomography KW - Neutron imaging KW - Polymer electrolyte membrane fuel cell (PEMFC) KW - Manifold stack KW - Water management PY - 2012 DO - https://doi.org/10.1016/j.jpowsour.2012.07.043 SN - 0378-7753 VL - 219 SP - 120 EP - 125 PB - Elsevier CY - Amsterdam [u.a.] AN - OPUS4-26317 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grothausmann, R. A1 - Zehl, G. A1 - Manke, I. A1 - Fiechter, S. A1 - Bogdanoff, P. A1 - Dorbandt, I. A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Schumacher, G. A1 - Banhart, J. T1 - Nanometer-Tomographie: kleinste Katalysatorteilchen erblicken - Mit Elektronen und Computern die mobile Brennstoffzelle erforschen JF - Materials and corrosion KW - Electron tomography KW - Polymer electrolyte membrane fuel cell (PEMFC) KW - Reconstruction algorithm KW - DIRECTT PY - 2012 DO - https://doi.org/10.1002/maco.201290007 SN - 0947-5117 SN - 1521-4176 VL - 63 IS - 2 SP - 1 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-26348 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Grothausmann, R. A1 - Zehl, G. A1 - Manke, I. A1 - Fiechter, S. A1 - Bogdanoff, P. A1 - Dorbandt, I. A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Schumacher, G. A1 - Banhart, J. T1 - Quantitative structural assessment of heterogeneous catalysts by electron tomography JF - Journal of the American chemical society N2 - We present transmission electron microscope (TEM) tomography investigations of ruthenium-based fuel cell catalyst materials as employed in direct methanol fuel cells (DMFC). The digital three-dimensional representation of the samples not only enables detailed studies on number, size, and shape but also on the local orientation of the ruthenium particles to their support and their freely accessible surface area. The shape analysis shows the ruthenium particles deviate significantly from spherical symmetry which increases their surface to volume ratio. The morphological studies help to understand the structure formation mechanisms during the fabrication as well as the high effectiveness of these catalysts in the oxygen reduction reaction at the cathode side of fuel cells. KW - Electron tomography KW - Reconstruction algorithm KW - Catalyst KW - Fuel cell PY - 2011 DO - https://doi.org/10.1021/ja2032508 SN - 0002-7863 SN - 1520-5126 VL - 133 IS - 45 SP - 18161 EP - 18171 PB - American Chemical Society CY - Washington, DC AN - OPUS4-24833 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Arlt, Tobias A1 - Grothausmann, R. A1 - Manke, I. A1 - Markötter, H. A1 - Krüger, P. A1 - Haussmann, J. A1 - Hilger, A. A1 - Kardjilov, N. A1 - Hartnig, C. A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Hentschel, Manfred P. A1 - Wippermann, K. A1 - Banhart, J. T1 - Tomografische Methoden für die Brennstoffzellenforschung T2 - DGZfP-Jahrestagung 2011 N2 - Auf Grund des hohen Wirkungsgrades und der vielfältigen Einsatzmöglichkeiten stellen Brennstoffzellen sowie Brennstoffzellenverbünde eine vielversprechende Energiequelle dar. Daher ist es wichtig, die Prozesse während des Betriebs einer Brennstoffzelle exakt charakterisieren zu können, um diese im nächsten Schritt zu optimieren. So ist ein ausbalanciertes Wassermanagement in einer mit Wasserstoff betriebenen Zelle ausschlaggebend für ihre Leistungsfähigkeit. Für eine dauerhafte Leistungsfähigkeit muss das entstehende Wasser die Membran feucht halten, um so die Protonenleitfähigkeit aufrecht zu erhalten. Zu viel Wasser kann jedoch die Gaszufuhr durch die porösen Materialien in Richtung Membran verhindern. Alterungsphänomene der einzelnen Komponenten können dieses sensible Wassermanagement stören und so die Leistungsfähigkeit einer Brennstoffzelle herabsetzen. Zum tieferen Verständnis der Wasserverteilung werden zerstörungsfreie Methoden, wie zum Beispiel die ex situ Neutronentomografie oder die in situ Synchrotronradiografie eingesetzt. Letztere Methode kann während des Brennstoffzellenbetriebs in Kombination mit weiteren Messmethoden, wie der ortsaufgelösten Stromdichtemessung, eingesetzt werden. So können einzelne Brennstoffzellenkomponenten, wie die Gasdiffusionsschichten, charakterisiert werden. T2 - DGZfP-Jahrestagung 2011 CY - Bremen, Germany DA - 30.05.2011 KW - Computer-Tomographie KW - Rekonstruktionsalgorithmen KW - Röntgen-Kanten-Tomographie KW - Neutronen-Tomographie KW - Elektronen-Tomographie PY - 2011 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-250023 SN - 978-3-940283-33-7 IS - DGZfP-BB 127 (P7) SP - 1 EP - 8 PB - Deutsche Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) AN - OPUS4-25002 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Manke, I. A1 - Kardjilov, N. A1 - Schäfer, R. A1 - Hilger, A. A1 - Strobl, M. A1 - Dawson, M. A1 - Grünzweig, C. A1 - Behr, G. A1 - Hentschel, Manfred P. A1 - David, C. A1 - Kupsch, Andreas A1 - Lange, Axel A1 - Banhart, J. T1 - Three-dimensional imaging of magnetic domains JF - Nature communications N2 - Magnetic domains have been the subject of much scientific investigation since their theoretical existence was first postulated by P.-E. Weiss over a century ago. Up to now, the three-dimensional (3D) domain structure of bulk magnets has never been observed owing to the lack of appropriate experimental methods. Domain analysis in bulk matter thus remains one of the most challenging tasks in research on magnetic materials. All current domain observation methods are limited to studying surface domains or thin magnetic films. As the properties of magnetic materials are strongly affected by their domain structure, the development of a technique capable of investigating the shape, size and distribution of individual domains in three dimensions is of great importance. Here, we show that the novel technique of Talbot-Lau neutron tomography with inverted geometry enables direct imaging of the 3D network of magnetic domains within the bulk of FeSi crystals. KW - Computed tomography KW - Reconstruction algorithm KW - Talbot-Lau neutron tomography KW - Magnetic domains PY - 2010 DO - https://doi.org/10.1038/ncomms1125 SN - 2041-1723 SP - 1 EP - 6 PB - Nature Publishing Group CY - London, UK AN - OPUS4-22609 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Manke, I. A1 - Hartnig, C. A1 - Kardjilov, N. A1 - Hilger, A. A1 - Lange, Axel A1 - Kupsch, Andreas A1 - Banhart, J. T1 - Wasserverteilung in PEM-Brennstoffzellen - In-situ-Untersuchung mit Neutronenradiografie und -tomografie JF - MP materials testing N2 - In-situ-Neutronenradiografie wird erfolgreich eingesetzt, um flüssiges Wasser in Niedertemperatur-PEM-Brennstoffzellen während des Betriebs zerstörungsfrei abzubilden und das sogenannte Wassermanagement – eine der größten Herausforderungen der Entwicklung – durch Anpassung der Materialeigenschaften zu optimieren. Dabei werden die besonderen Eigenschaften der Neutronen genutzt, die metallische Bauteile relativ leicht durchdringen, während selbst kleine Wassermengen durch ihre starke Streuung leicht nachweisbar sind. Die relativ langen Messzeiten für die Neutronentomografie werden durch den Betrieb der Zelle im “angehaltenen” Zustand realisierbar, sodass die dreidimensionale Wasserverteilung darstellbar wird. KW - Neutronen-Radiographie KW - Neutronen-Tomographie KW - Tomographische Rekonstruktionsalgorithmen KW - Brennstoffzellen KW - In-Situ-Radiologie PY - 2009 SN - 0025-5300 VL - 51 IS - 4 SP - 219 EP - 226 PB - Hanser CY - München AN - OPUS4-19221 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -