Stabilisation of aluminium foams and films by the joint action of dispersed particles and oxide films

Heim, K.; Vinodkumar, G. S.; García‐Moreno, Francisco; Rack, Alexander; Banhart, John

doi:10.1016/j.actamat.2015.07.064

Cited by 49 publications

(36 citation statements)

References 42 publications

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“…Clogging of thickener has also been reported for the Melt route [13]. However, bridge formation of thickener attributed to oxide film is thought to be the main stabilization mechanism in Melt route [12]. For Semi-solid route, since the size of thickener is large, clogging is possible to occur below the thinnest part of film and it is assumed that film is not required to be thin for the clogging to occur.…”

Section: Suppression Of Drainage By Clogging Of Primary Crystalsmentioning

confidence: 99%

“…al. approximated the cross-sectional shape of the pulled-up film as a rectangle [12]. Then, the film will start to curve as the drainage progresses.…”

Section: Suppression Of Drainage By Thickeningmentioning

confidence: 99%

“…Moreover, in the Melt route, Heim et al expressed that some thickener particles are covered by oxide skin of cell wall and interact and builds bridge with other particles resulting to prevent drainage [12]. This is thought to be the stabilization mechanism of cell wall in the Melt route.…”

Section: Introductionmentioning

confidence: 99%

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Stabilization Mechanism of Semi-Solid Film Simulating the Cell Wall during Fabrication of Aluminum Foam

Kubo

Kaya

Osaka

et al. 2020

Metals

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Semi-solid route is a fabrication method of aluminum foam where the melt is thickened by primary crystals. In this study, semi-solid aluminum alloy films were made to observe and evaluate the stabilization mechanism of cell walls in Semi-solid route. Each film was held at different solid fractions and holding times. In lower solid fractions, as the holding time increases, the remaining melt in the films lessens and this could be explained by Poiseuille flow. However, the decreasing tendency of the remaining melt in the films lessens as the solid fraction increases. Moreover, when the solid fraction is high, decreasing tendency was not observed. These are because at a certain moment, clogging of primary crystals occurs under the thinnest part of the film and drainage is largely suppressed. Moreover, clogging is occurring in solid fraction of 20–45% under the thinnest part of the film. Moreover, the time to occur clogging becomes earlier as the solid fraction increases.

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Section: Suppression Of Drainage By Clogging Of Primary Crystalsmentioning

confidence: 99%

“…al. approximated the cross-sectional shape of the pulled-up film as a rectangle [12]. Then, the film will start to curve as the drainage progresses.…”

Section: Suppression Of Drainage By Thickeningmentioning

confidence: 99%

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Stabilization Mechanism of Semi-Solid Film Simulating the Cell Wall during Fabrication of Aluminum Foam

Kubo

Kaya

Osaka

et al. 2020

Metals

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“…Two different cannulas (from Robert Helwig GmbH, Berlin, Germany) with a conical tip made of stainless steel with an outlet of 500 µm or 200 µm outer (d o ) and 200 µm or 90 µm inner diameter (d i ), respectively, are used, thus ensuring small bubble sizes [17]. A detailed description of the setup and procedure can be found elsewhere [3]. The temperature of the melt (680 °C) and the overpressure in the cannulas (300 mbar) are kept constant.…”

Section: General Set-upmentioning

confidence: 99%

“…Especially metal foams created from the liquid by directly injecting gas into a melt through an orifice and forming bubbles therein can be produced in a cost efficient way [2]. Thereby, the cell size can be controlled by the gas flow rate, the orifice diameter and other parameters [3,4]. However, only alloys containing ceramic particles, so-called metal matrix composites (MMCs), can be used to create a stable foam [5,6].…”

Section: Introductionmentioning

confidence: 99%

Stability of various particle-stabilised aluminium alloys foams made by gas injection

et al. 2017

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Aluminium alloy foams are created by injecting air into liquid alloys containing non-metallic particles. In addition to an alloy containing the usual SiC particles, other types of metal/particle composites are studied, which are created by in-situ reactions in the melts: two fluoride salts react and form TiB 2 particles, Ca addition or addition of CuO and SiO 2 gives rise to the formation of various oxides and spinel particles. Injecting air into the molten composites through two different steel cannulas leads to the formation of first bubbles and then foam.The entire process is monitored in-situ by X-ray radioscopy. The goal is not only to understand how and what kind of particles stabilise gas injected foams better, but also to reduce the fraction of added particles, which could improve mechanical properties, solve recycling issues and reduce production costs. All the observed composites are shown to have the potential to be processed to metallic foam. Melts containing TiB 2 particles are found to perform as well as those containing SiC even at lower volume fractions. Oxidation of alloy melts promoted by Ca addition gives rise to melts that exhibit good foamability. Melts oxidised by CuO and SiO 2 addition show partial stability. Mg is found to be a required alloying element to create stable foams. Smaller bubbles can be produced using smaller injector needle openings. By reducing bubble size and using new variants of in-situ generated particles, more stable foams can be achieved with a lower number density of stabilising particles.

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X‐ray Tomography and Tomoscopy on Metals: A Review

et al. 2023

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X‐ray tomography is a versatile tool in materials research and engineering since it allows for a non‐destructive and three‐dimensional mapping of the constituents of a heterogeneous material as long as they differ in their interactions with X‐rays. Recent developments of the technique have brought down the time needed for the acquisition of a single tomogram by many orders of magnitude compared to what was needed 25 years ago. Nowadays, up to 1000 full tomograms can be recorded in a second, which enables real‐time studies of changes in samples caused by reactions or by applied processing operations. The term tomoscopy has been coined for such sequences of 3D images. We review the application of X‐ray tomography and tomoscopy on metals and describe each step required and the associated challenges. A selection of representative investigations is presented with a focus on time‐resolved phenomena in metals and alloys ranging from mechanical deformation, solidification to metals processing processes such as welding and additive manufacturing. Finally likely future developments are discussed.

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Stabilisation of aluminium foams and films by the joint action of dispersed particles and oxide films

Cited by 49 publications

References 42 publications

Stabilization Mechanism of Semi-Solid Film Simulating the Cell Wall during Fabrication of Aluminum Foam

Stabilization Mechanism of Semi-Solid Film Simulating the Cell Wall during Fabrication of Aluminum Foam

Stability of various particle-stabilised aluminium alloys foams made by gas injection

X‐ray Tomography and Tomoscopy on Metals: A Review

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