Sub-mm sized bubbles injected into metallic melts

García‐Moreno, Francisco; Siegel, Benjamin M.; Heim, K.; Meagher, A.J.; Banhart, John

doi:10.1016/j.colsurfa.2014.12.038

Cited by 17 publications

(12 citation statements)

References 39 publications

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“…Static gas injection method means the gas injection needle was in static condition during the preparation process for uniform cells [7,11]. In order to reduce the size of bubbles and then improve the mechanical properties of gas injection aluminum foams, some dynamic methods were applied in the gas injector, such as the rotating or reciprocating of the gas injector developed by Cymat [22,26], ultrasonic oscillation used by Aluhab [27], mechanical vibration generated by a stepper motor [28] and the high-speed horizontal oscillation [29]. The mechanical properties of some gas injection aluminum foams have been reported, such as the static gas injection aluminum foam [11,30], Aluhab prepared by ultrasonic oscillation method [31] and aluminum foam prepared by rotating gas injector [32].…”

Section: Introductionmentioning

confidence: 99%

Compressive performance and deformation mechanism of the dynamic gas injection aluminum foams

Wang

Maire

Chen

et al. 2019

Materials Characterization

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The dynamic gas injection method with high-speed horizontal oscillation could reduce the cell size and improve the cell quality of aluminum foams, so it is of interest to study the compressive performance and deformation mechanism of the foams produced with this process. In-situ compression in X-ray tomography was used for this research. Results have shown that the plateau stresses of bulk aluminum foams prepared by the dynamic gas injection method are in the range of 0.3 ~ 11 MPa. When the cell size is reduced to around 1 mm, the plateau stress could reach 22 MPa. In addition, the brittle deformation characteristics of aluminum foams in the quasi-static compression process are obvious. The dynamic gas injection method could greatly improve the mechanical properties of aluminum foams, and aluminum foams prepared by this method have a better compressive performance compared to that prepared by static method even at the same relative density. The uniformity of the cell size and sphericity also affects the mechanical properties. The result of in-situ compression shows that there are two main failure modes for cell walls of aluminum foams: the fracture after buckles of the cell walls and the direct fracture of the cell walls. The aluminum foams prepared by the dynamic gas injection method could have a wide application prospect due to its superior compressive performance.

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Section: Introductionmentioning

confidence: 99%

Compressive performance and deformation mechanism of the dynamic gas injection aluminum foams

Wang

Maire

Chen

et al. 2019

Materials Characterization

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“…For foaming, all composites are remelted in a furnace and processed into foam by air injection. 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].…”

Section: General Set-upmentioning

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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“…[ 30–32 ] García‐Moreno et al attained small bubbles by reducing the equivalent area of gas‐injecting cannulae, optimizing the cannula shapes and applying oscillations to the cannulae. [ 8 ] They also observed that small and uniform bubbles aligned in chains, which implies an initial formation of ordered foam structures. [ 8 ] Wang et al reduced the bubble size by applying high‐speed horizontal oscillations to the gas injection needle and improving the foamable melt, wherein uniform cells can be obtained under specific vibration conditions.…”

Section: Introductionmentioning

confidence: 99%

“…[ 8 ] They also observed that small and uniform bubbles aligned in chains, which implies an initial formation of ordered foam structures. [ 8 ] Wang et al reduced the bubble size by applying high‐speed horizontal oscillations to the gas injection needle and improving the foamable melt, wherein uniform cells can be obtained under specific vibration conditions. [ 9,33 ] Based on this research on small‐cell aluminum foam, it is worthwhile and interesting to further explore whether closed‐cell aluminum foam can achieve an ordered foam structure.…”

Section: Introductionmentioning

confidence: 99%

Short‐Range Ordered Aluminum Foams

et al. 2021

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Ordering the bubbles of closed‐cell aluminum foams can contribute to decorative esthetics and create directional mechanical properties that disordered foams do not have. High‐porosity (>80%) aluminum foams prepared by the traditional static gas injection method usually have large and polyhedral cells, which do not form an ordered stacking. Aluminum foams with relatively uniform and small cells (cell size ≈1.2 mm) have been recently obtained by gas injection through a nozzle rotating at high speed. Herein, the stacking of aluminum foams with different cell sizes and a monodisperse aqueous foam are characterized by X‐ray tomography and compared with an ideal face‐centered cubic (FCC) structure. The aluminum foam featuring the smallest cells has a concentrated distribution of cell coordination number with a peak of 12 and the first peaks of the radial distribution function are found to be consistent with those of the monodisperse aqueous foam and an ideal FCC structure. Furthermore, many aligned bubble chains with more than five bubbles are observed on cross‐sectional images. Therefore, aluminum foam can become short‐range ordered whenever the cell size is uniform enough and reduced to around 1.2 mm. Methods for further improving the order of aluminum foam are discussed.

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Sub-mm sized bubbles injected into metallic melts

Cited by 17 publications

References 39 publications

Compressive performance and deformation mechanism of the dynamic gas injection aluminum foams

Compressive performance and deformation mechanism of the dynamic gas injection aluminum foams

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

Short‐Range Ordered Aluminum Foams

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