#################################################### # Jules Routbort # requesting 3 days, at minimum=2 days # beamline 34ID-E, Studies of Cr poisoning and void formation in solid oxide fuel cells using x-ray microprobe # instrument 34ID-E microbeam #################################################### # top:/home/www/beamtime-requests/req01102.txt # UNICAT Member Beam Time Request #1102 # created Mon Dec 18 10:01:31 CST 2006 #################################################### apsrun: 2007-01 beamline: 34ID-E collaboration: No collaborator_Paul: ON collaborator_Wenjun: ON contact: routbort@anl.gov days: 3 description: There are two critical problems that have deleterious consequences for the lifetime of a solid-oxide fuel cell. Chromium migrates (mainly vapor phase transport, although some surface diffusion and reaction may also be occurring) from the ferritic stainless steel bipolar plate into the electrodes and results in poisoning of the cathode. The second critical problem is void formation at the cathode/electrolyte interfaces resulting in decreased contact and thus a lower current. Eventually as the voids linkup, they form cracks which can ultimately result in fracture. This second mechanism is believed to be the result of kinetic de-mixing with diffusion of Sr to the cathode and vacancies to the anode. Neither of these problems is effectively understood. Argonne is in the process of submitting a proposal to DOE. An extremely important aspect of the SOFC proposal is an experimental study combined with theory and possible means of mitigation of the Cr poisoning and the void formation. We propose to use an x-ray microprobe technique to study the Cr poisoning effect. The fuel-cell samples, operated at various temperatures, will then be cross-sectioned. The cross-sections consist of an LSM contact paste layer (~30 microns, can vary quit a bit), a 15 to 20 micron LSM cathode layer, a 15-20 micron LSM/YSZ active cathode layer, a 5 micron YSZ electrolyte, a 5 micron Ni/YSZ active cathode and an ~600 micron Ni/YSZ anode support. We plan to use the x-ray microprobe to map the Cr concentration and phase distributions along the cross section of the cathode layers. An x-ray microflorescence method will be used to map the relative Cr concentration distribution along the cross-section, and an x-ray microdiffraction method will be used to map the phase distribution of Cr-compound. Residual stress measurements will be used to measure the temporal lattice expansion that results from vacancy formation and subsequent void formation. equipment_required: N/A. experiment: Studies of Cr poisoning and void formation in solid oxide fuel cells using x-ray microprobe foreign_nationals: hazards: There is no hazard associated with this experiment. instrument: 34ID-E microbeam instrument_other: minimumdays: 2 name: Jules Routbort new_request: ON nonmembers: Michael Krumpelt, CMT Terry Cruse, CMT submit: Submit unacceptable_dates: N/A. z34ID_change_undulator: yes z34ID_details: z34ID_on_axis: yes z34ID_parasitic: yes z34ID_taper: yes #REMOTE_HOST: chen-212-lap.es.anl.gov #REMOTE_ADDR: 146.139.78.35 #CONTENT_LENGTH: 2619 #HTTP_REFERER: http://www.uni.aps.anl.gov/admin/unireq.html #HTTP_USER_AGENT: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322; .NET CLR 2.0.50727)