Mechanical Characterization of Solid Oxide Fuel Cells and Sealants

List of related publications and presentations 
Part of the results presented in this thesis has already been published and submitted in the 
following articles and the following conferences: 
1. J. Wei, G. Pećanac, J. Malzbender, Review of mechanical characterization methods for 
ceramics used in energy technologies, Ceramics International, 40 (2014) 15371-15380. 
2. J. Wei, G. Pećanac, J. Malzbender, Mechanical behavior of silver reinforced glass–ceramic 
sealants for solid oxide fuel cells, Ceramics International, 41 (2015) 15122-15127. 
3. G. Pećanac, J. Wei, J. Malzbender, Fracture toughness of SOFC anode substrates determined 
by a double-torsion technique, Journal of Power Sources, 327 (2016) 629-637. 
4. T. Osipova, J. Wei, G. Pećanac, J. Malzbender, Room and elevated temperature shear strength 
of sealants for solid oxide fuel cells, Ceramics International, 42 (2016) 12932-12936. 
5. J. Wei, G. Pećanac, et al., Proc. 12th Euro SOFC & SOE Forum, Luzern, B1309, 2016 
6. J. Wei, G. Pećanac, et al., Proc. 12th Euro. SOFC & SOE Forum, Luzern, B0609, 2016. 
7. J. Wei, G. Pećanac, et al., Oral presentation: Mechanical characterization of the SOFC failure-
relevant ceramic components, 14th Conference of the European Ceramic Society, Spain, 2015
8. J. Wei, G. Pećanac, J. Malzbender, Poster: Thermo-mechanical properties of SOFC sealants 
and cells, 39th Int. Conf & Expo on Advanced Ceramics & Composites (ICACC 2015), 
Daytona, US. 
9. J. Wei, G. Pećanac, J. Malzbender, Poster: Mechanical properties of sealants and cells, 12th 
Euro SOFC & SOE Forum, Luzern, A1413, 201

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I 
Content 
1. Introduction ............................................................................................................................. 1 
2. Scope of the work .................................................................................................................... 4 
3. Literature review ...................................................................................................................... 6 
3.1. 
Production of cells ............................................................................................................ 6 
3.2. 
Anode materials................................................................................................................ 8 
3.2.1. 
Working principle ..................................................................................................... 8 
3.2.2. 
Anode failures ......................................................................................................... 11 
3.3. 
Sealants........................................................................................................................... 13 
3.3.1. 
State of sealants for SOFC application ................................................................... 13 
3.3.2. 
Reinforcement of glass-ceramic sealants ................................................................ 17 
3.3.3. 
Failure of sealants in SOFC stacks ......................................................................... 19 
3.4. 
Mechanical characteristics ............................................................................................. 20 
3.4.1. 
Elastic behavior ....................................................................................................... 21 
3.4.2. 
Fracture strength ..................................................................................................... 25 
3.4.3. 
Fracture toughness .................................................................................................. 29 
3.4.4. 
Creep ....................................................................................................................... 32 
3.4.5. 
Mechanical properties of anode-relevant materials ................................................ 40 
3.4.6. 
Mechanical properties of sealants ........................................................................... 49 
4. Experimental .......................................................................................................................... 54 
4.1. 
Materials ......................................................................................................................... 54 
4.1.1. 
Anode substrate materials ....................................................................................... 54 
4.1.2. 
Sealant materials ..................................................................................................... 56 
4.2. 
Microstructural characterization .................................................................................... 59 
4.2.1. 
Microscopy ............................................................................................................. 59 
4.2.2 
X-ray diffraction ..................................................................................................... 60 
4.3. 
Mechanical characterization ........................................................................................... 60 
4.3.1. 
Fracture toughness .................................................................................................. 60 
4.3.2. 
Creep behavior ........................................................................................................ 63 

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II 
4.3.3. 
Finite element simulation ........................................................................................ 67 
4.3.4. 
Bending strength ..................................................................................................... 68 
4.3.5. 
Torsion strength (shear strength) ............................................................................ 71 
5. Results and discussion ........................................................................................................... 73 
5.1. 
Anode material ............................................................................................................... 73 
5.1.1. 
Microstructure ......................................................................................................... 73 
5.1.2. 
Fracture toughness by double torsion test ............................................................... 76 
5.1.3. 
Creep behavior ........................................................................................................ 89 
5.2. 
Sealant materials .......................................................................................................... 105 
5.2.1. 
Microstructure and XRD analysis ......................................................................... 105 
5.2.2. 
Bending fracture stress .......................................................................................... 112 
5.2.3. 
Annealing effects .................................................................................................. 117 
5.2.4. 
Complementary 3-point-bending tests on 7.5 B(Ba) and 10 B(Sr) bar specimens120 
5.2.5. 
Shear strength........................................................................................................ 121 
6. Conclusions ......................................................................................................................... 127 
7. References ........................................................................................................................... 131 
Acknowledgement ...................................................................................................................... 142 
Appendix ..................................................................................................................................... 143 
List of figures .............................................................................................................................. 146 
List of tables ................................................................................................................................ 150 

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Introduction 
1