Mechanical behaviour of yttria- and ferric oxide-doped zirconia at different temperatures

Gogotsi, G. A.

doi:10.1016/s0272-8842(97)00060-6

Cited by 14 publications

(4 citation statements)

References 18 publications

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“…Substituting elastic property values from Table 5, and assuming anode, electrolyte and cathode each have a thickness of 10 lm then an oxidation strain of 1% gives an energy release rate of 8.2 J m -2 . Thus this indicates that an [44] N/A 18 (m p =24%) [46] 105 (m p =40%) [46] oxidation strain of this magnitude can just be tolerated without delamination. This result shows that this configuration is expected to be more resistant to redox cycling than the others.…”

Section: Inert Substrate-supported Configurationmentioning

confidence: 95%

“…Substituting some typical values for the mechanical properties from Table 5 [43][44][45][46][47], an oxidation strain of 1% gives an extremely high electrolyte tensile stress of 2.2 GPa and a correspondingly small critical electrolyte thickness of only 0.074 lm. Therefore, this problem cannot be solved by reducing the electrolyte thickness, because such a thin, and at the same time dense, electrolyte is not technically feasible.…”

Section: Anode-supported Configurationmentioning

confidence: 99%

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Redox Cycling of Ni‐Based Solid Oxide Fuel Cell Anodes: A Review

2007

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The published literature relating to damage to SOFCs caused by redox cycling of Ni‐based anodes is reviewed. The review covers the kinetics of Ni oxidation and NiO reduction (as single phases and as constituents of composites with yttria‐stabilised zirconia, YSZ), the dimensional changes associated with redox cycling and the effect of this on the mechanical integrity and electrical performance of cells and stacks. A critical parameter is the expansion strain that is caused by oxidation. Several studies report that the first complete oxidation of a Ni/YSZ composite causes a linear expansion of the order of 1%, but the actual values vary substantially between different investigations. The oxidation strain is the result of microstructural irreversibility during the redox process and leads to strain accumulation over several redox cycles. This can cause mechanical disruption to an anode, anode support or other cell components attached to the anode.A simplified mechanical model of the stress and damage that are likely to be caused by anode expansion is proposed and applied to anode‐supported, electrolyte‐supported and inert substrate‐supported cell configurations. This allows the maximum oxidation strain to avoid damage in each configuration to be estimated.

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Section: Inert Substrate-supported Configurationmentioning

confidence: 95%

Section: Anode-supported Configurationmentioning

confidence: 99%

Redox Cycling of Ni‐Based Solid Oxide Fuel Cell Anodes: A Review

2007

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“…where E is Young's modulus and n is Poisson's ratio. The total strain is e tot ~et ze e (3) and must be equal for all the components in the planar structure.…”

Section: Stresses At Uniform Temperaturementioning

confidence: 99%

“…The authors then discuss the issues determining the thermomechanical stresses in different classes of planar SOFC and the key thermomechanical properties of the relevant materials [ Table 1 (Refs. [1][2][3][4][5][6]]. The three generic planar SOFC configurations considered are: electrolyte supported, anode supported and inert substrate supported SOFCs; and these are illustrated schematically in Fig.…”

Section: Introductionmentioning

confidence: 99%

Residual stress and thermal cycling of planar solid oxide fuel cells

Atkinson¹,

Sun²

2007

Materials Science and Technology

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The published literature relating to damage to planar solid oxide fuel cells caused by thermally induced stresses and thermal cycling is reviewed. This covers reported studies of thermal cycling performance and stresses induced by temperature gradients and differences in thermal expansion coefficients in typical planar SOFC configurations, namely electrolyte supported; anode supported and inert substrate supported cells. Generally good agreement is found between electrolyte residual stresses measured by X-ray diffraction or cell curvature and stresses calculated from simple thermo-elastic analysis. Finite element modelling of temperature distributions in cells and stacks in steady state operation are well advanced and capable of being extended to compute stress distributions. Failure criteria are then discussed for laminated cell structures based on critical energy release rate fracture mechanics models developed originally for coatings. However, in most cases the data required to apply the models quantitatively (such as elastic moduli of actual laminated material and fracture energies of materials and interfaces) are not available. Where data are available there are inconsistencies that require resolution. Seals are critical components in many planar solid oxide fuel cell configurations, but again there are discrepancies in experimental mechanical properties and the role of internal stresses in their fracture. In addition, there is as yet no firm evidence that thermal cycling damage involves any true materials fatigue process. Effect of thermal cycling on SOFC integrityTaniguchi et al. 7 investigated the thermal cycling performance of electrolyte supported planar SOFCs

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Mechanical stability

Atkinson

Marquis

2010

Handbook of Fuel Cells

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This article summarizes the approach to assessing the mechanical stability of solid oxide fuel cell (SOFC) ceramic materials and cell structures. The sources of stress are reviewed and their potential relaxation by creep is discussed together with the approach that is taken to calculate the complex stress distributions that arise in a working SOFCs. The alternative approaches to failure of brittle ceramics based on critical stress (strength) and fracture mechanics are described and illustrated using examples of stability of thin layers and probability of delayed fracture of an electrolyte. The critical stress approach is then illustrated in a more complicated example of a repeat‐unit channel in an anode‐supported SOFCs. The methodology illustrates how the cumulative probability of failure of the unit can be estimated as it passes through manufacture, initial commissioning, and representative duty cycles.

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Mechanical behaviour of yttria- and ferric oxide-doped zirconia at different temperatures

Cited by 14 publications

References 18 publications

Redox Cycling of Ni‐Based Solid Oxide Fuel Cell Anodes: A Review

Redox Cycling of Ni‐Based Solid Oxide Fuel Cell Anodes: A Review

Residual stress and thermal cycling of planar solid oxide fuel cells

Mechanical stability

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