Analysis of liquid metal foams through X-ray radioscopy and microgravity experiments

García‐Moreno, Francisco; Tobin, Steven T.; Mukherjee, M.; Jiménez, Catalina; Solórzano, E.; Kumar, G. S. Vinod; Hutzler, Stefan; Banhart, John

doi:10.1039/c4sm00467a

Cited by 21 publications

(14 citation statements)

References 41 publications

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“…Two mechanisms have been discussed as possible triggers for bubble coalescence: first, for metal foams blown with an agent such as TiH 2 , expansion coalescence induced by growth has been postulated 7 as during foam expansion films might eventually be stretched to beyond the limit of stability. Moreover, it has been suspected that drainage induces drainage coalescence, as it removes liquid from aqueous 22 and metallic films 32 .…”

Section: Discussionmentioning

confidence: 99%

Using X-ray tomoscopy to explore the dynamics of foaming metal

et al. 2019

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The complex flow of liquid metal in evolving metallic foams is still poorly understood due to difficulties in studying hot and opaque systems. We apply X-ray tomoscopy –the continuous acquisition of tomographic (3D) images– to clarify key dynamic phenomena in liquid aluminium foam such as nucleation and growth, bubble rearrangements, liquid retraction, coalescence and the rupture of films. Each phenomenon takes place on a typical timescale which we cover by obtaining 208 full tomograms per second over a period of up to one minute. An additional data processing algorithm provides information on the 1 ms scale. Here we show that bubble coalescence is not only caused by gravity-induced drainage, as experiments under weightlessness show, and by stresses caused by foam growth, but also by local pressure peaks caused by the blowing agent. Moreover, details of foam expansion and phenomena such as rupture cascades and film thinning before rupture are quantified. These findings allow us to propose a way to obtain foams with smaller and more equally sized bubbles.

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Section: Discussionmentioning

confidence: 99%

Using X-ray tomoscopy to explore the dynamics of foaming metal

et al. 2019

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“…The previously induced drainage due to gravity disappeared. This effect could be observed especially after gravity transition from 1.8 to 0 g. The flow back of liquid during the transition from 0 g to 1.8 g enabled calculation of the effective viscosity and surface tension of the liquid foams for the first time [34].…”

Section: Parabolic Flight Experiments: Othermentioning

confidence: 97%

Overview of In Situ X-Ray Studies of Light Alloy Solidification in Microgravity

Browne

García‐Moreno

Nguyen-Thi

et al. 2017

The Minerals, Metals &Amp; Materials Series

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Gravity has significant effects on alloy solidification, primarily due to thermosolutal convection and solid phase buoyancy. Since 2004, the European Space Agency has been supporting investigation of these effects by promoting in situ X-ray monitoring of the solidification of aluminium alloys on microgravity platforms, on earth, and in periodically varying g conditions. The first microgravity experimentinvestigating foaming of liquid metalswas performed on board a sounding rocket, in 2008. In 2012 the first ever X-raymonitored solidification of a fully dense metallic alloy in space was achieved: the focus was columnar solidification of an Al-Cu alloy. This was followed in 2015 by a similar experiment, investigating equiaxed solidification. Ground reference experiments were completed in all cases. In addition, experiments have been performed on board parabolic flightswhere the effects of varying gravity have been studied. We review here the technical and scientific progress to date, and outline future perspectives.

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“…It is based on the attenuation of X-rays by the liquid phase and has been employed for both aqueous and liquid metal foams [82,83]. Since the X-rays are not scattered by the foamed liquid, the difference in emitted and detected intensity is directly related to the total amount of liquid which the Xrays have traversed.…”

Section: Experimental Techniquesmentioning

confidence: 99%

Structure and energy of liquid foams

Drenckhan

Hutzler

2015

Advances in Colloid and Interface Science

139

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a b s t r a c t a r t i c l e i n f oWe present an overview of recent advances in the understanding of foam structure and energy and their dependence on liquid volume fraction. We consider liquid foams in equilibrium for which the relevant energy is surface energy. Measurements of osmotic pressure can be used to determine this as a function of liquid fraction in good agreement with results from computer simulations. This approach is particularly useful in the description of foams with high liquid content, so-called wet foams. For such foams X-ray tomography proves to be an important technique in analysing order and disorder. Much of the discussion in this article is also relevant to bi-liquid foams, i.e. emulsions, and to solid foams, provided that the solidification preserves the structure of the initially liquid foam template.

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Analysis of liquid metal foams through X-ray radioscopy and microgravity experiments

Cited by 21 publications

References 41 publications

Using X-ray tomoscopy to explore the dynamics of foaming metal

Using X-ray tomoscopy to explore the dynamics of foaming metal

Overview of In Situ X-Ray Studies of Light Alloy Solidification in Microgravity

Structure and energy of liquid foams

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