Metal foams—high temperature colloids

Babcsán, Norbert; Leitlmeier, D.; Banhart, John

doi:10.1016/j.colsurfa.2004.12.030

Cited by 71 publications

(35 citation statements)

References 23 publications

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“…The cell rapture occurred at cell wall thicknesses below 50 lm. A cell wall rupture time below 33 ms was further found in the external foaming of a 20 vol% SiC (10 lm) particle-added Al melt by argon gas blowing [10,11], proving again a fast cell wall rupture in a few milliseconds.…”

Section: Discussionmentioning

confidence: 99%

“…The compaction process breaks the oxide layer skin. These thin oxide films are converted to broken oxide filaments with a size between 4 and 100 nm and an average of 20 nm [10].…”

Section: Discussionmentioning

confidence: 99%

“…Contrary to TiB 2 addition, SiC p addition of 3 and 10 wt.% was shown to improve the foam stability of Al powder compacts [8,9]. Babcsan et al [10,11] analyzed the stability of Al metal foaming processes ex situ and in situ. In foams of 13 lm SiC particles, the particles were observed to segregate to the cell wall surfaces, while in foams of 70 lm SiC particles, only small amount of particles were observed on the cell wall surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Foaming behavior of Ti6Al4V particle-added aluminum powder compacts

2009

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The foaming behavior of 5 wt.% Ti6Al4V (Ti64) particle (30-200 lm)-added Al powder compacts was investigated in order to assess the particle-addition effects on the foaming behavior. Al compacts without particle addition were also prepared with the same method and foamed. The expansions of Ti64 particle-added compacts were measured to be relatively low at small particle sizes and increased with increasing particle size. At highest particle size range (160-200 lm), particle-added compacts showed expansion behavior similar to that of Al compacts without particle addition, but with lower expansion values. Expansions studies on 30-45 lm size Ti64-added compacts with varying weight percentages showed that the expansion behavior of the compacts became very similar to that of Al compact when the particle content was lower than 2 wt.%. However, Ti64 addition reduced the extent of drainage. Ti64 particles and TiAl 3 particles formed during foaming increased the apparent viscosity of the liquid foam and hence reduced the flow of liquid metal from cell walls to plateau borders. The reduced foamability in the compacts with the smaller size Ti64 addition was attributed to the relatively high viscosities, due to the higher cumulative surface area of the particles and higher rate of TiAl 3 formation between liquid Al and Ti64 particles.

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Section: Discussionmentioning

confidence: 99%

“…The compaction process breaks the oxide layer skin. These thin oxide films are converted to broken oxide filaments with a size between 4 and 100 nm and an average of 20 nm [10].…”

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Foaming behavior of Ti6Al4V particle-added aluminum powder compacts

2009

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“…1,2) The number of imperfections, such as missing and buckled cell walls, has decreased resulting in stiffer and stronger foams (see Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Fracture Behavior of Metal Foam Made of Recycled MMC by the Melt Route

et al. 2006

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Metal foam was made from recycled MMC precursor by the melt route. The original starting material was an Al-9Si alloy containing 20 vol% of SiC particles (10 mm), which are used to stabilize the foam during the foaming process. The starting material has been used to make foam parts from which the residue was recycled and refoamed. During the (re)foaming process Fe is present in the melt. During solidification of the foam, -AlSiFe plates are formed with the surplus of Si and Al present in the alloy. These plates run through the entire thickness of the cell wall (40-50 mm) and their length ranges between 50 and 200 mm. During in-situ tensile tests fracture initiates in the -AlFeSi plates and propagates through other -AlFeSi plates leading to brittle fracture of the cell walls.

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“…The interface concentration after solidification goes up to 32%, compatible with values given in the literature. 5,15 Interestingly, the solidified state shows a more pronounced correlation than the second stage of the liquid. A part of this correlation increase can be ascribed to rearrangements before solidification, but part of it might be caused by the pushing of particles to the L / G interfaces by the solidification front.…”

mentioning

confidence: 99%

Why are metal foams stable?

Haibel

Rack

Banhart

2006

Applied Physics Letters

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Although metal foams are becoming accepted engineering materials, the reason for their stability in the liquid state is still under dispute. Liquid metal foams contain solid constituents which according to the existing models stabilize foam films by either modifying the curvature of the liquid/gas ͑L / G͒ interfaces, or by forming particle bridges across metallic films and transmitting repulsive "disjoining" forces mechanically. Using high-resolution synchrotron tomography and a quantitative three-dimensional image analysis the authors show that there is little evidence for such curvature changes or particle bridges. The authors conclude that the main stabilizing action must be due to interactions between neighboring particles attached to L / G interfaces.

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Metal foams—high temperature colloids

Cited by 71 publications

References 23 publications

Foaming behavior of Ti6Al4V particle-added aluminum powder compacts

Foaming behavior of Ti6Al4V particle-added aluminum powder compacts

Fracture Behavior of Metal Foam Made of Recycled MMC by the Melt Route

Why are metal foams stable?

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