FG Struktur und Eigenschaften von Materialien

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Recent Submissions
Der Schäumprozess von Aluminiumlegierungen: Tomoskopische Untersuchung der Gasnukleation

Kamm, Paul Hans (2018)

Die Verbesserung der Struktur metallischer Schäume und damit ihrer Eigenschaften bedarf eines tieferen Verständnisses der während des Schäumens und der späteren Degradation ablaufenden Mechanismen. Um diesen dynamischen Prozess in seiner dreidimensionalen Komplexität und zeitlichen Veränderung zu erfassen wurde in dieser Arbeit das Verfahren der zeitaufgelösten Tomographie (Tomoskopie: Ein Kuns...

Suitability of various complex hydrides for foaming aluminum alloys

Kamm, Paul H. ; García-Moreno, Francisco ; Jiménez, Catalina ; Banhart, John (2013)

Some hydrides that could replace TiH2 as the hitherto most suitable blowing agent for foaming aluminum alloys were investigated. Hydrides taken from the group MBH4 (M = Li, Na, K) and LiAlH4 were selected since these have not been studied in the past although their decomposition characteristics appear to be suitable. Foamable precursors of alloy AlSi8Mg4 were manufactured by pressing blends of ...

Slow crystallisation of a monodisperse foam stabilised against coarsening

Meagher, Aaron J. ; Whyte, David ; Banhart, John ; Hutzler, Stefan ; Weaire, Denis ; García-Moreno, Francisco (2015)

The evolution of a three-dimensional monodisperse foam was investigated using X-ray tomography over the course of seven days. The coarsening of the sample was inhibited through the use of perfluorohexane gas. The internal configuration of bubbles is seen to change markedly, evolving from a disordered arrangement towards a more ordered state. We chart this ordering process through the use of the...

Radiographic and tomographic investigation of water transport in operating polymer electrolyte membrane fuel cells

Alrwashdeh, Saad Sabe' (2017)

Fuel cells are foreseen to play a leading role in many future sustainable energy strategies as they allow for environmental friendly and locally pollutant-free energy conversion systems. One of the most important and prevalent types is the polymer electrolyte membrane fuel cell (PEMFC). One of the key issues of the PEM fuel cell is the water management since efficiency, cell performance and...

X-ray radiographic and tomographic investigations of cycled lithium ion batteries

Sun, Fu (2017)

Lithium ion batteries (LIBs) have become the predominant power supplies in portable electronic devices such as cell phones, laptops and tablets. They are regarded as promising candidates to power future electric vehicles and to store the intermittent and fluctuating energy harvested from solar and wind sources. Unfortunately, the current LIB technology fails to meet the growing energy demand re...

Particle-stabilised foams: structure and aging

Stocco, Antonio ; Garcia-Moreno, Francisco ; Manke, Ingo ; Banhart, John ; Langevin, Dominique (2011)

We show that aqueous foams stabilised by nanoparticles can be easily imaged using an X-ray laboratory source. We have used hydrophobically modified silica nanoparticles that confer to the foam a remarkable stability. The X-ray tomography observations were compared with the information obtained using a multiple light scattering technique. Both techniques confirm that provided the concentration o...

Kinetics of coalescence in liquid aluminium foams

Garcia-Moreno, Francisco ; Solorzano, E. ; Banhart, Jon (2011)

The cell wall rupture kinetics for a collection of AlSi9 foam samples kept at a constant temperature over the melting point for a long time period (700 s) has been characterized by in situ X-ray radioscopy. The images obtained have been computed by using image analysis algorithms allowing the identification of the cell wall ruptures in the molten state. The time evolution, the spatial distribut...

The rupture of a single liquid aluminium alloy film

Heim, K. ; Garcia-Moreno, F. ; Kumar, G. S. Vinod ; Rack, A. ; Banhart, J. (2014)

The present study is based on the idea of understanding the rupture of films in metal foams by studying free standing metallic films as a model system. Liquid dynamics, the velocity of the rupturing material as well as the behaviour of ceramic particles inside the melt were analysed optically ex situ and by synchrotron X-ray radiography in situ. It was found that the resistance of films to rupt...

On the structural integrity and electrochemical activity of a 0.5Li(2)MnO(3)center dot 0.5LiCoO(2) cathode material for lithium-ion batteries

Rana, Jatinkumar ; Klöpsch, Richard ; Li, Jie ; Scherb, Tobias ; Schumacher, Gerhard ; Winter, Martin ; Banhart, John (2014)

Structural changes in a 0.5Li2MnO3·0.5LiCoO2cathode material were investigated by X-ray absorption spectroscopy. It is observed that both Li2MnO3and LiCoO2components of the material exist as separate domains, however, with some exchange of transition metal (TM) ions in their slab layers. A large irreversible capacity observed during activation of the material in the 1stcycle can be attributed t...