Endogenous Particle Stabilization During Magnesium Integral Foam Production

Körner, Carolin; Hirschmann, Markus; Bräutigam, V.; Singer, Robert F.

doi:10.1002/adem.200405147

Cited by 55 publications

(26 citation statements)

References 4 publications

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“…If, however, a critical cell wall thickness exists, below which a film ruptures, the number of bubbles will reduce and the mean pore diameter D will grow more quickly. One can show that: D∝ 3 q À1 À 1 p for coalescence-free growth, [71] D∝ 6d crit (q -1 -1) growth with rupture at d crit, [23] where the second eq. has been slighly modified by the author.…”

Section: Phenomenology Of Drainage and Coalescencementioning

confidence: 99%

Metal Foams: Production and Stability

2006

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Liquid metal foam can be generated by creating gas inside a liquid or semi‐liquid metallic melt which has been pre‐treated in a suitable way. Such foams are self‐supporting disordered structures in complete analogy to aqueous foams. The stabilisation mechanism of metallic foams is still not fully understood. In order to facilitate discussion of foam stabilisation the various methods for making such foams are classified with respect to the mode of gas generation and the type of melt used for foaming. Metal foams can be produced by gas injection from an external source or by in‐situ nucleation of gas bubbles in the melt for which various possibilities are known. Melts amenable to foaming range from almost pure molten alloys to melts to which particles have been added, formed by in‐situ reactions or which have been already present in the solid precursor prior to melting. Some of the available experimental evidence for the action of stabilising particles in metallic foams is presented. It is found that although stabilisation seems to be based on the presence of a solid constituent in all the foaming processes, the mechanisms might vary. At present the nature of stabilisation is not yet fully understood and many questions remain open.

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Section: Phenomenology Of Drainage and Coalescencementioning

confidence: 99%

Metal Foams: Production and Stability

2006

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“…In the case of integral foam moulding endogenous stabilization 7) was identified as the primary mechanism. Foam evolution takes place during solidification.…”

Section: Cell Morphologymentioning

confidence: 99%

“…3) Compared to polymers, the development of metal integral foam moulding is just at the beginning. [4][5][6][7][8][9][10][11] The time delay of four decades between commercialization of polymer integral foam moulding and the current onset of investigations with respect to metals can hardly be explained. Nevertheless, we suppose that there is huge economical potential for metal integral foam moulding.…”

Section: Introductionmentioning

confidence: 99%

Integral Foam Moulding of Light Metals

Körner¹,

Hirschmann²,

Wiehler³

2006

Mater. Trans.

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Integral foam moulding (IFM) is an economical way to produce castings with integrated cellular structure, i.e. a solid skin and a foamed core. IFM has been known for polymers for more than four decades and is well established in industrial production. Polymer integral foam parts are accepted as a material system with own properties which simplifies designs, reduces production costs and weight, and increases stiffness and overall strength. On the other hand, integral foam moulding for metals is a new field of research. The development of metal based integral foam moulding processes at WTM moves along analogous paths as that of polymers by transferring and adapting successful moulding technologies for polymer integral foam to metals. Two moulding techniques for metal integral foam are presented, a low and a high pressure process. In the low pressure process, the molten metal charged with blowing agent is injected into a permanent steel mould without completely filling it. In this case, the mould gets eventually filled by foam expansion.In the high pressure process foaming is initiated by expansion of the mould cavity after it has been filled completely with the mixture of the metal melt and the blowing agent. The moulded parts are characterized with respect to their cellular structure, density profile and pore size distribution. Mechanical properties such as stiffness and damping behaviour are discussed.

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“…Hydrides have the advantage that no oxide remnant is left behind after decomposition, thus avoiding weakening of the metallic matrix. Besides TiH 2 , other hydrides of a single element have been evaluated experimentally, including ZrH 2 , 12 HfH 2 , LiH, LaH 3 , MgH 2 , 13 and CaH 2 , 14 but none of these showed advantage over TiH 2 . In this study, we include complex hydrides, which contain a metal and boron, namely MBH 4 (M 5 Li, Na, K), and LiAlH 4 .…”

Section: Introductionmentioning

confidence: 99%

Suitability of various complex hydrides for foaming aluminum alloys

et al. 2013

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Some hydrides that could replace TiH 2 as the hitherto most suitable blowing agent for foaming aluminum alloys were investigated. Hydrides taken from the group MBH 4 (M 5 Li, Na, K) and LiAlH 4 were selected since these have not been studied in the past although their decomposition characteristics appear to be suitable. Foamable precursors of alloy AlSi8Mg4 were manufactured by pressing blends of metal and blowing agent powders. Powders, precursors and precursor filings were studied by mass spectrometry to obtain the hydrogen desorption profile. Foaming experiments were conducted with simultaneous x-ray radiographic monitoring. Two Li-containing blowing agents were found to perform well and can be considered alternatives to TiH 2 .

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Endogenous Particle Stabilization During Magnesium Integral Foam Production

Cited by 55 publications

References 4 publications

Metal Foams: Production and Stability

Metal Foams: Production and Stability

Integral Foam Moulding of Light Metals

Suitability of various complex hydrides for foaming aluminum alloys

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