Investigations on the Diffusion of Oxygen in Nickel at 1000°C by SIMS Analysis

Pérusin, Simon; Monceau, Daniel; Andrieu, Éric

doi:10.1149/1.2116787

Cited by 54 publications

(18 citation statements)

References 27 publications

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“…Assuming a particle size of 1 μm, one obtains a value for the surface ion diffusivity equal to D s =6.3×10 −9 cm 2 /s. This is in good agreement (within 30%) with the value D s =10 -8 −10 −9 cm 2 /s measured with solid Ni films at the same temperature (1,000°C) [45]. This confirms the suggestion in [45] that grain boundary diffusion (which is physically very similar to oxygen spillover) is the dominant mechanism of oxygen migration in polycrystalline Ni films.…”

Section: Model Validationsupporting

confidence: 90%

Mathematical modeling of the operation of SOFC Nickel-cermet anodes

Presvytes

Vayenas

2007

Ionics

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A surface diffusion-reaction model is developed and solved to describe the steady-state operation of Nickelcermet anodes in solid oxide fuel cells. The model accounts for the migration (backspillover) and diffusion of oxygen ions from the solid electrolyte onto the nickel surface and the concomitant reaction with the fuel over a finite reaction zone extending from the three-phase boundaries onto the Ni-gas interface. The model is developed for various nickel particle geometries and is compared with existing anode model predictions for flat geometries. The performance of the anode, expressed by an anodic effectiveness factor, is found to depend on two dimensionless numbers, which contain all the operational and structural information of the anode. The model is validated with literature experimental data regarding the dependence of the anode performance on the fuel partial pressure and predicts correctly the observed deviation from linearity of the dependence of cell current on fuel partial pressure.

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Section: Model Validationsupporting

confidence: 90%

Mathematical modeling of the operation of SOFC Nickel-cermet anodes

Presvytes

Vayenas

2007

Ionics

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“…11. Considering that diffusion of oxygen into the surrounding grains is negligible [28,34,35], h can be assumed to be very small. Thus, the predicted threshold values are too low to account for the observed thresholds of ∼ 45 MPa √ m in this work.…”

Section: Crack Growth Mechanisms and Threshold For Time-dependent Growthmentioning

confidence: 99%

Time- and cycle-dependent crack propagation in Haynes 282

Saarimäki

Moverare

Colliander

2016

Materials Science and Engineering: A

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Haynes 282 is a promising superalloy candidate for several high-temperature applications in both aero and land-based gas turbine engines. To study the crack growth behaviour under time-dependent conditions relevant to such applications, a test program was carried out at room temperature up to 700• C with conditions ranging from pure cyclic to sustained tensile loading. At 650• C and high stress intensity factors the crack growth was fully time-dependent for dwell-times of 90 s and longer.At lower stress intensities, the behaviour was mainly controlled by the cyclic loading, even under dwell conditions. The behaviour under dwell-fatigue conditions was well described by a liner superposition model. The main crack growth occurred transgranularly at room temperature and there was a transition in cracking behaviour from cycle dependent transgranular growth to time-dependent intergranular propagation at ∼ 45 MPa √ m for the high temperature tests. No effect of cyclic frequency could be observed at room temperature, and at lower frequencies the crack growth rate increased with temperature.

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“…If PLC suppresses OAIC, it may be because it disturbs one or both aspects: decrease of the local stress level and/or slowing down the embrittlement process. Indeed, on the one hand, several studies have shown that oxygen diffuses in grains boundaries [20] and reduces the cohesion stress of the grain boundaries. On the other hand, these local strain jumps could allow releasing internal intergranular stresses, which may prevent crack initiation.…”

Section: Relation Between Plc Serrations and Rupture Modementioning

confidence: 99%

“…10, plastic strain rate is plotted as a function of the distance to the initial crack tip for two crack propagation rates: 0.2 lm/s and 5 lm/s. The first one is one order of magnitude below the transition rate [17][18][19][20][21], the second one is above. On this plot are also represented the local 3% strain limit (dash points) and the strain rate PLC threshold deduced from Fig.…”

Section: Are There Any Interactions Between Plc Bands and A Crack Tip?mentioning

confidence: 99%