Mechanical strength and electrical conductivity of Ni-YSZ cermets fabricated by viscous processing

Grahl‐Madsen, Laila; Larsen, Peter H.; Bonanos, Nikolaos; Engell, J.; Linderoth, Søren

doi:10.1007/s10853-005-3647-3

Cited by 32 publications

(23 citation statements)

References 6 publications

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“…Grahl-Madsen et al [28] have presented results concerning the influence of redox cycles on the mechanical and electrical properties of 56 wt.-% NiO anode supports. The four point bending tests showed that the mean modulus of rupture before reduction was 20.3 MPa and was only reduced slightly to 17.5 MPa on initial reduction.…”

Section: Effects On Structure and Mechanical/electrical Propertiesmentioning

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: Effects On Structure and Mechanical/electrical Propertiesmentioning

confidence: 99%

“…Fig. 7 Room temperature conductivity as a function of reduction temperature for Ni/YSZ supports [28]. Fig.…”

Section: Effects On Structure and Mechanical/electrical Propertiesmentioning

confidence: 99%

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

2007

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“…Regarding the temperature of reduction, it is believed that there is an increase of the conductivity by raising the temperature [18]. However, once the material has been reduced, subsequent 4 treatment at high temperatures in reducing conditions does not improve conductivity values.…”

Section: Introductionmentioning

confidence: 99%

The influence of the reducing conditions on the final microstructure and performance of nickel-yttria stabilized zirconia cermets

Monzón

Laguna‐Bercero

2016

Electrochimica Acta

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Ni-YSZ (yttria stabilized zirconia) cermets are the most widespread composite materials to be used as SOFC fuel electrodes. These materials are generally fabricated by the reduction of NiO to Ni in a NiO-YSZ composite, where the reducing conditions have a great effect in the final microstructure of the electrode. In the present work, several reducing conditions were explored in order to find the most suitable microstructure for anode-supported microtubular solid oxide fuel cells (SOFCs). Samples were firstly reduced in either pure or diluted H2 (dry or humidified), at temperatures ranging from 400 to 800 °C while their DC conductivity was monitored. The highest conductivity value was measured for the sample reduced in pure humidified hydrogen at 800°C. However, this sample experienced conductivity degradation in comparison with samples reduced under dry conditions. For the studied temperature range, nucleation of nano-porous nickel particles is firstly formed during reduction. However, from our experiments it was concluded that those nanoparticles are not stable with time, at least at temperatures between 600 ºC and 800 ºC. Electrochemical characterization of complete microtubular cells under real wet conditions was also performed under current load, confirming that the microstructure of the Ni-YSZ cermet is still evolving during operation.

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“…In comparison with the well-studied reduction kinetics and mechanics of NiO-YSZ cermets [8][9][10][11][12][13], only limited study has been reported on the microstructural changes in these materials, especially the structural and chemical changes of the interface between NiO and YSZ. However, the interfacial regions can inevitably affect the anode performance as they are active sites for mass transport, diffusion, and segregation.…”

Section: Introductionmentioning

confidence: 99%

Reduction of a NiO thin film deposited by PLD on a single crystal YSZ (111) substrate

et al. 2012

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The NiO/YSZ interface prepared by depositing NiO on a single crystal YSZ (111) substrate has been investigated by transmission electron microscopy. As deposited, a very thin nickel layer ascribing to the nonstoichiometry at the very beginning growth of NiO and an amorphous silica phase resulting from silicon segregation were present at the interface. The orientational relationship of NiO ð111Þ//Ni ð111Þ//YSZ ð111Þ with NiO [110]//Ni [110]//YSZ [110] was observed.

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Mechanical strength and electrical conductivity of Ni-YSZ cermets fabricated by viscous processing

Cited by 32 publications

References 6 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

The influence of the reducing conditions on the final microstructure and performance of nickel-yttria stabilized zirconia cermets

Reduction of a NiO thin film deposited by PLD on a single crystal YSZ (111) substrate

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