Erhöhung und Charakterisierung der Festigkeit von Metallschäumen für lasttragende Anwendungen durch thermisch gespritzte Verbundstrukturen

Maurer, Matthias; Lugscheider, E.

doi:10.1002/1521-4052(200006)31:6<523::aid-mawe523>3.0.co;2-#

Cited by 1 publication

(2 citation statements)

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“…The foam will eventually rise and fill the column. Another possibility is to start from a foamed part and to coat it with aluminium by thermal spraying [8]. This way a dense outer skin can be prepared.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Real-time X-ray Investigation of Aluminum Foam Sandwich Production

Banhart¹,

Stanzick

Helfen

et al. 2001

Adv. Eng. Mater.

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Cellular metals can be produced by various methods. [1±3] Among these, foaming methods are especially attractive because they allow for manufacturing fairly inexpensive closed-cell materials with promising mechanical properties. By ªfoamingº one usually means releasing gas in a liquid, ensuring that the gas bubbles do not escape, and finally stabilizing the resulting liquid foam by cooling. A manufacturing method for producing closed-cell metal foams from metal powders was developed some years ago. [4±6] The process consists of mixing powdered metal with a powdered blowing agent and compacting the mix to a dense semi-finished product (called ªfoamable precursor materialº) by hot pressing, extrusion, powder rolling, or some other method. In a final step, the precursor material is foamed by heating it up to its melting point. This softens the metal and simultaneously forces the blowing agent to decompose and release gas, thus forming bubbles in the semi-molten metal and creating a highly porous structure. For aluminum alloys, titanium hydride (TiH 2 ) is the preferred blowing agent. TiH 2 releases hydrogen gas at only 400 C, but the main decomposition takes place at 550±600 C. The content of TiH 2 in the alloy is usually 0.5 wt.-%, corresponding to a total released hydrogen volume of about 20 times the initial volume of the precursor material. [6] For structural applications one often uses foam in conjunction with conventional dense metal structures such as sheets, columns, or more complex shaped hollow metal structures. This allows mechanical properties to be optimized for a given loading situation [7] and encloses the metal foam inside a closed and dense structure, which is advantageous (e.g., from the viewpoint of corrosion protection). Such composites containing aluminum foam produced by the method just described can be made in various ways. The most obvious and straightforward way is by adhesive bonding of pre-fabricated aluminum foams and flat face sheets. However, this approach has certain disadvantages and is not feasible in all cases. An alternative and preferable way is to create composites during foaming. Foam-filled columns can be made by inserting foamable precursor material inside a column and heating up column and foam simultaneously. The foam will eventually rise and fill the column. Another possibility is to start from a foamed part and coat it with aluminum by thermal spraying. [8] In this way a dense outer skin can be prepared. Yet another way is to use the foam as a core for diecasting. [9,10] Sandwich panels can be manufactured in a very elegant way by roll-cladding face sheets to a sheet of foamable precursor material, creating the desired shape in an optional working step, and finally foaming the entire composite. [11,12] Foaming will create a highly porous core structure without melting the face sheets if the melting points of the foam and the face sheets are different and process parameters are chosen appropriately.Metal foams have been characterized thoroughly with respect to their morp...

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Section: Introductionmentioning

confidence: 99%

“…Another possibility is to start from a foamed part and coat it with aluminum by thermal spraying. [8] In this way a dense outer skin can be prepared. Yet another way is to use the foam as a core for diecasting.…”

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confidence: 99%