Metal Foaming Investigated by X-ray Radioscopy

García‐Moreno, Francisco; Mukherjee, M.; Jiménez, Catalina; Rack, Alexander; Banhart, John

doi:10.3390/met2010010

Cited by 42 publications

(27 citation statements)

References 30 publications

(45 reference statements)

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“…The expansion of the foam was found to be accompanied by bubble wall rupture leading to bubble coalescence, occurring in short time periods of about 55 ms in bubble walls, which had thinned down to about 50 μm. Further improvements to mean time estimates of coalescence and cell wall rupture were made using fast synchrotron X‐ray radioscopy with a recording speed of 1 05 000 fps with a frame interval of 9.5 μs . These estimations show coalescence of two bubbles was completed in a very short span of 475 μs wherein the time for film rupture was estimated to be 380 μs.…”

Section: Introductionmentioning

confidence: 99%

Bubble Size Distribution in Foaming of Liquid Aluminum and the Role of Coarsening and Coalescence

2017

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Evolution of bubble size distribution in liquid aluminum foam prepared by dissociation of TiH 2 particles is studied by rapidly cooling samples during foam expansion and carrying out metallographic analysis of the solidified foam. Further, diameters of bubbles growing directly on TiH 2 particles are calculated to arrive at volume expansion and bubble size distribution. The cells in the solidified foam are orders of magnitude coarser and fewer than those predicted by the "pure growth" based model at all stages of foam expansion. If bubble coarsening was accounted for, the calculated bubble sizes are less than, but the same order of magnitude as the experimentally observed cell sizes. The remaining discrepancy of cell size (and population) can be explained based on bubble coalescence, strongly supported by observations on early stages of foaming.

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Section: Introductionmentioning

confidence: 99%

Bubble Size Distribution in Foaming of Liquid Aluminum and the Role of Coarsening and Coalescence

2017

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“…% TiH 2 at a temperature of 640°C) captured with an acquisition rate of 105; 000 images∕s (9.5 μs temporal sampling/ 6 μs exposure time, 8 m propagation distance, 18.1 μm effective pixel size, approximately 4.2 mm × 3.0 mm FOV)[24]. Times given refer to the first frame.…”

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confidence: 99%

Hierarchical radioscopy using polychromatic and partially coherent hard synchrotron radiation

et al. 2013

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Pushing synchrotron x-ray radiography to increasingly higher image-acquisition rates (currently up to 100,000 fps) while maintaining spatial resolutions in the micrometer range implies drastically reduced fields of view. As a consequence, either imaging a small subregion of the sample with high spatial resolution or only the complete specimen with moderate resolution is applicable. We introduce a concept to overcome this limitation by making use of a semi-transparent x-ray detector positioned close to the investigated sample. The hard x-rays that pass through the sample either create an image on the first detector or keep on propagating until they are captured by a second x-ray detector located further downstream. In this way, a process can be imaged simultaneously in a hierarchical manner within a single exposure and a projection of the complete object with moderate resolution as well as a subregion with high resolution are obtained. As a proof-of-concept experiment, image sequences of an evolving liquid-metal foam are shown, employing frame rates of 1000 images/s (1.2 μm pixel size) and 15,000 images/s (18.1 μm pixel size) for the first and second detector, respectively.

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“…[1][2][3][4][5] On the other hand in situ X-ray radioscopy was demonstrated to be a powerful tool for the study of foam evolution. [6][7][8][9][10] The combination of X-ray radioscopy and microgravity conditions offers a unique environment for fundamental studies.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2014

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Complex liquid structures such as metallic foams were produced in a furnace that allowed in situ X-ray monitoring of the evolution of the structure and distribution of the liquid in the foam. The experiments were carried out during parabolic flights which provided varying levels of gravity. The evolution of the characteristic liquid fraction profiles due to gravity induced drainage was measured and analysed in terms of the foam drainage equation, obtaining viscosity and surface tension by fitting solutions of the equation to the experimental data. The surface tension of the melt in the foam was decreased up to 40%. Effective viscosities of up to 139 times the viscosity of a pure bulk melt were observed. These effects could be attributed to the smaller influence of solid particles dispersed in the melt and the larger influence of the complex foam structure.

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Metal Foaming Investigated by X-ray Radioscopy

Cited by 42 publications

References 30 publications

Bubble Size Distribution in Foaming of Liquid Aluminum and the Role of Coarsening and Coalescence

Bubble Size Distribution in Foaming of Liquid Aluminum and the Role of Coarsening and Coalescence

Hierarchical radioscopy using polychromatic and partially coherent hard synchrotron radiation

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

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