Cellular Automaton Simulations of Surface Mass Transport Due to Curvature Gradients: Simulations of Sintering in 3-D.

Bentz, Dale P.; Pimienta, P.J.P.; Garboczi, Edward J.; Carter, W.C.

doi:10.1557/proc-249-413

Cited by 13 publications

(19 citation statements)

References 15 publications

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“…Generally speaking the transition rules used in the literature fall into two categories, based on either cell counting or free energy. The cell counting approach has been used for modeling microstructure changes that are driven only by interface curvature (15,29,32,33), whereas the free energy based approach has been employed in modelling microstructure changes driven by other driving forces, such as stored elastic energy, stored dislocation density and crystallographic orientation mismatch (28,34,35). The advantage of the free energy based approach is that the transition rule can be made scalable to any mesh size and to any combination of interface mobility and energy (34).…”

Section: Introductionmentioning

confidence: 99%

Modeling Microstructure Evolution of Ni Cermet Using a Cellular Automaton Approach

Wang

Atkinson

2014

J. Electrochem. Soc.

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The degradation of SOFC electrodes is often determined by their microstructure changes. It is desirable that the microstructure evolution of electrodes in service can be simulated in 3-D for real materials so that the changes in their electrochemical performance can be predicted.This involves changes in important parameters such as: electronic and ionic conductivities; TPB (triple phase boundary) density and connectivity; and tortuosity of condensed phases and porosity. In this contribution a new cellular automaton (CA) approach to simulating complex microstructure evolution is presented, which is based on free energy reduction by using an interface imbalanced interaction model. The approach is validated first in 2-D examples to reproduce wetting between two solids and grain boundary grooving, which shows the new approach is fully consistent with classical theories. The approach is then applied to simulation of the evolution of a real 3 dimensional microstructure of a Ni-YSZ cermet fuel cell anode. The modelling results show that the microstructure evolution is sensitive to the wettability of Ni on YSZ and that a good wettability is helpful in maintaining a slower coarsening rate and smaller reduction of electrode performance.

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Section: Introductionmentioning

confidence: 99%

Modeling Microstructure Evolution of Ni Cermet Using a Cellular Automaton Approach

Wang

Atkinson

2014

J. Electrochem. Soc.

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“…To address this challenge, Pimienta et al [91] developed a model for simulating sintering evolution due to surface mass transport, driven by curvature differences. By estimating curvature of the surface indirectly from images, and relocating pixels (mass) based on the measured curvature differences, realistic cases of random particle collections in two dimensions were successfully simulated, and the algorithm was later extended to three dimensions [92]. In their approach, analysis begins by replacing an atomically stepped surface with a continuous depiction, represented digitally by pixels.…”

Section: Microstructure Development During Sinteringmentioning

confidence: 99%

Advances in Fluid and Thermal Transport Property Analysis and Design of Sintered Porous Wick Microstructures

Bodla¹,

Weibel²,

Garimella

2013

Journal of Heat Transfer

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Sintered porous structures are ubiquitous as heat transport media for thermal management and other applications. In particular, low-porosity sintered packed beds are used as capillary-wicking and evaporation-enhancement structures in heat pipes. Accurate prediction and analysis of their transport characteristics for different microstructure geometries is important for improved design. Owing to the random nature and geometric complexity of these materials, development of predictive methods has been the subject of extensive prior research. The present work summarizes and builds upon past studies and recent advances in pore-scale modeling of fluid and thermal transport within such heterogeneous media. A brief review of various analytical and numerical models for simplified prediction of transport characteristics such as effective thermal conductivity, permeability, and interfacial heat transfer is presented. More recently, there has been a growing interest in direct numerical simulation of transport in realistic representations of the porous medium geometry; for example, by employing nondestructive 3D imaging techniques such as X-ray microtomography. Future research directions are identified, looking beyond techniques intended for material characterization alone, and focusing on those targeting the reverse engineering of wick structures via modeling of the physical sintering fabrication processes. This approach may eventually be employed to design intricate sintered porous structures with desired properties tailored to specific applications.

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“…By estimating curvature of the surface indirectly from digital images, and relocating pixels (mass) based on the measured curvature differences, realistic cases of random particle collections in two and three dimensions were successfully simulated in Ref. [21]. In this approach, an atomically stepped surface is replaced with a continuous depiction, represented digitally by pixels.…”

Section: Introductionmentioning

confidence: 99%

“…In this work, we employ the cellular automaton-based sintering model originally proposed in [20], and later extended to three dimensions in Ref. [21]. The model is only described briefly here, and readers are referred to Refs.…”

Section: Introductionmentioning

confidence: 99%

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Simulated Microstructural Evolution and Design of Porous Sintered Wicks

Bodla

Garimella

2014

Journal of Heat Transfer

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Porous structures formed by sintering of powders, which involves material-bonding under the application of heat, are commonly employed as capillary wicks in two-phase heat transport devices such as heat pipes. These sintered wicks are often fabricated in an ad hoc manner, and their microstructure is not optimized for fluid and thermal performance. Understanding the role of sintering kinetics-and the resulting microstructural evolution-on wick transport properties is important for fabrication of structures with optimal performance. A cellular automaton model is developed in this work for predicting microstructural evolution during sintering. The model, which determines mass transport during sintering based on curvature gradients in digital images, is first verified against benchmark cases, such as the evolution of a square shape into an areapreserving circle. The model is then employed to predict the sintering dynamics of a sideby-side, two-particle configuration conventionally used for the study of sintering. Results from previously published studies on sintering of cylindrical wires are used for validation. Randomly packed multiparticle configurations are then considered in two and three dimensions. Sintering kinetics are described by the relative change in overall surface area of the compact compared to the initial random packing. The effect of sintering parameters, particle size, and porosity on fundamental transport properties, viz., effective thermal conductivity and permeability, is analyzed. The effective thermal conductivity increases monotonically as either the sintering time or temperature is increased. Permeability is observed to increase with particle size and porosity. As sintering progresses, the slight increase observed in the permeability of the microstructure is attributed to a reduction in the surface area.

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Cellular Automaton Simulations of Surface Mass Transport Due to Curvature Gradients: Simulations of Sintering in 3-D.

Cited by 13 publications

References 15 publications

Modeling Microstructure Evolution of Ni Cermet Using a Cellular Automaton Approach

Modeling Microstructure Evolution of Ni Cermet Using a Cellular Automaton Approach

Advances in Fluid and Thermal Transport Property Analysis and Design of Sintered Porous Wick Microstructures

Simulated Microstructural Evolution and Design of Porous Sintered Wicks

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