Phase-field simulations of multi-component solidification and coarsening based on thermodynamic datasets
Phase-field simulations of multi-component solidification and coarsening based on thermodynamic datasets

Author: Schulz, Sebastian

Publisher: KIT Scientific Publishing

Published: 2017-02-22

Total Pages: 246

ISBN-13: 3731506181

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The utilization of thermodynamic and mobility data plays a major role in phase-field modeling. This work discusses different formulations for the thermodynamic quantities of a grand potential model along with practices to determine parameters from datasets. The framework is used to study solidification of Al-Si-Mg for a variation of composition, diffusivities and surface energy anisotropies. To verify the simulations, they are compared with solidification theories.

Phase-field Simulations of Multi-component Solidification and Coarsening Based on Thermodynamic Datasets
Phase-field Simulations of Multi-component Solidification and Coarsening Based on Thermodynamic Datasets

Author: Sebastian Schulz

Publisher:

Published: 2020-10-09

Total Pages: 234

ISBN-13: 9781013281273

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The utilization of thermodynamic and mobility data plays a major role in phase-field modeling. This work discusses different formulations for the thermodynamic quantities of a grand potential model along with practices to determine parameters from datasets. The framework is used to study solidification of Al-Si-Mg for a variation of composition, diffusivities and surface energy anisotropies. To verify the simulations, they are compared with solidification theories. This work was published by Saint Philip Street Press pursuant to a Creative Commons license permitting commercial use. All rights not granted by the work's license are retained by the author or authors.

Phase-field Modeling of Phase Changes and Mechanical Stresses in Electrode Particles of Secondary Batteries
Phase-field Modeling of Phase Changes and Mechanical Stresses in Electrode Particles of Secondary Batteries

Author: Zhang, Tao

Publisher: KIT Scientific Publishing

Published: 2021-09-27

Total Pages: 224

ISBN-13: 3731510022

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Most storage materials exhibit phase changes, which cause stresses and, thus, lead to damage of the electrode particles. In this work, a phase-field model for the cathode material NaxFePO4 of Na-ion batteries is studied to understand phase changes and stress evolution. Furthermore, we study the particle size and SOC dependent miscibility gap of the nanoscale insertion materials. Finally, we introduce the nonlocal species concentration theory, and show how the nonlocality influences the results.

Development of NbN based Kinetic Inductance Detectors on sapphire and diamond substrates for fusion plasma polarimetric diagnostics
Development of NbN based Kinetic Inductance Detectors on sapphire and diamond substrates for fusion plasma polarimetric diagnostics

Author: Mazzocchi, Francesco

Publisher: KIT Scientific Publishing

Published: 2022-07-01

Total Pages: 212

ISBN-13: 3731511819

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This work aimed at designing, studying and producing the first prototypes of KIDs tailored for fusion plasma polarimetric diagnostics. Diamond was considered for the first time as substrate material for low-temperature superconducting detectors given its unmatched optical, radiation hardness and thermal qualities, properties necessary for working environments potentially saturated with radiation. This work represents a first step toward the optimization and final application of this technology.

Dynamic Model-based Analysis of Oxygen Reduction Reaction in Gas Diffusion Electrodes
Dynamic Model-based Analysis of Oxygen Reduction Reaction in Gas Diffusion Electrodes

Author: Röhe, Maximilian

Publisher: KIT Scientific Publishing

Published: 2024-01-09

Total Pages: 178

ISBN-13: 3731512343

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In this work, the first simulation model of oxygen depolarized cathodes (ODC), which are silver catalyst-based gas diffusion electrodes, is presented that considers the phase equilibrium of the gas-liquid interface and structure-related inhomogeneities in electrolyte distribution. By means of the model it has been identified that mass transport of water and ions in the liquid phase is a crucial factor for electrode performance and how it is influenced by the electrode structure.

Consequences of hydroxyl generation by the silica/water reaction - Part II: Global and local Swelling - Part III: Damage and Young's Modulus
Consequences of hydroxyl generation by the silica/water reaction - Part II: Global and local Swelling - Part III: Damage and Young's Modulus

Author: Fett, Theo

Publisher: KIT Scientific Publishing

Published: 2022-07-11

Total Pages: 226

ISBN-13: 3731511592

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Water diffusing into silica surfaces gives rise for several effects on diffusion behaviour and mechanical properties. In a preceding booklet, we focused on diffusion and fiber strengths and deformations which were obtained by water soaking under external loading. In the present booklet we deal with results and interpretations of strength increase in the absence of applied stresses.

Consequences of hydroxyl generation by the silica/water reaction - Part I: Diffusion and Swelling
Consequences of hydroxyl generation by the silica/water reaction - Part I: Diffusion and Swelling

Author: Fett, Theo

Publisher: KIT Scientific Publishing

Published: 2022-07-11

Total Pages: 226

ISBN-13: 3731511487

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Water diffusing into silica surfaces gives rise for several effectson diffusion behaviour and mechanical properties. Water added to silica glass increases its specific volume so that the silica expands near the surface. Mechanical boundary conditions give rise for compressive “swelling stresses”. This fact provides a tool for the interpretation of many experimental observations from literature.

On the Electro-Chemo-Mechanical Coupling in Solid State Batteries and its Impact on Morphological Interface Stability
On the Electro-Chemo-Mechanical Coupling in Solid State Batteries and its Impact on Morphological Interface Stability

Author: Ganser, Markus

Publisher: KIT Scientific Publishing

Published: 2021-03-09

Total Pages: 272

ISBN-13: 3731510472

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Solid state batteries with a lithium metal electrode are considered the next generation of high energy battery technology. Unfortunately, lithium metal is prone to harmful protrusion or dendrite growth which causes dangerous cell failure. Within this work the problem of protrusion growth is tackled by deriving a novel electro-chemo-mechanical theory tailored for binary solid state batteries which is then used to discuss the impact of mechanics on interface stability by numerical studies.

Characterisation and Modelling of Continuous-Discontinuous Sheet Moulding Compound Composites for Structural Applications
Characterisation and Modelling of Continuous-Discontinuous Sheet Moulding Compound Composites for Structural Applications

Author: Trauth, Anna

Publisher: KIT Scientific Publishing

Published: 2020-12-11

Total Pages: 468

ISBN-13: 3731509504

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The main objective of this work is to significantly deepen the understanding of the material and the structural behaviour of continuous-discontinuous SMC composites, following a holistic approach to investigate microscopic aspects, macroscopic mechanical behaviour as well as failure evolution at the coupon, structure and component level. In addition, criteria to evaluate the effect of hybridisation are introduced and modelling approaches are presented and discussed.