Accelerated creep of Ni-YSZ anodes during reduction

Henrik Lund Frandsen, Fabio Greco, De Wei Ni, Declan Curran, Peter Vang Hendriksen

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review


To evaluate the reliability of solid oxide fuel cell (SOFC) stacks during operation the stress field must be known at all times. This is influenced by external loads, the operating conditions, the particular design of the stack components and their mechanical properties and finally by the thermomechanical history of the stack (e.g. sintering temperature, time at temperature etc.). During operation the stress state will depend on time as stresses are relaxed by creep processes. Creep has mainly been studied at operating conditions, where the Ni-YSZ anode is in the reduced state and YSZ is the main load-carrying component. In this work we report on a new creep-reduction phenomenon observed to take place during the reduction process itself, where stresses are relaxed at a rate much faster (~×104) than during operation where the anode is in fully reduced state. Furthermore, samples exposed to a very small tensile stress (0.004 MPa) were observed to expand during reduction, which is in contrast with reports in literature [Ref].The “accelerated” creep has a tremendous impact on the stress field in an operating SOFC stack. Creep experiments, where carried out on NiO-YSZ anode support structures loaded in three point bending or uniaxial tension and the deformations recorded during the reduction process. The fast creep is observed only during the reduction, but due to the extremely high rate this will effectively relax all the residual compressive stresses in the electrolyte at the reduction temperature. Therefore this phenomenon has to be considered both in the production of stacks and in the simulation of the stress field in an SOFC stack.
Original languageEnglish
Title of host publicationProceedings of 11th European SOFC and SOE Forum 2014
PublisherEuropean Fuel Cell Forum
Publication date2014
ChapterChapter 14 - Session B11
ISBN (Print)978-3-905592-16-0
Publication statusPublished - 2014
EventEuropean fuel cell 2014 - 11th European SOFC and SOE Forum 2014 - Lucerne, Switzerland
Duration: 1 Jul 20144 Jul 2014


ConferenceEuropean fuel cell 2014 - 11th European SOFC and SOE Forum 2014


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