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Syntactic foams based on metal matrix compounds with integrated micro glass bubbles

Syntaktische Schäume auf der Basis von Metallmatrix-Verbundwerkstoffen mit integrierten Mikroglasblasen
: Weise, J.; Salk, N.; Yezerska, O.; Schmitt, M.

Stephani, G. ; Fraunhofer-Institut für Fertigungstechnik und Angewandte Materialforschung -IFAM-, Dresden:
Cellular metals for structural and functional applications, CELLMET 2008 : Proceedings of the International Symposium on Cellular Metals for Structural and Functional Applications held October 8 - 10, 2008 in Dresden, Germany
Dresden: Fraunhofer IFAM, 2009
International Symposium on Cellular Metals for Structural and Functional Applications (CELLMET) <2, 2008, Dresden>
Fraunhofer IFAM ()
Aluminium; Dichte; Druckfestigkeit; Energieabsorption; Metallmatrix-Verbundwerkstoff; Metallschaum; pulvermetallurgisches Spritzgießen; Stahl

Microporous syntactic metal foams based on compounds of metal matrices and integrated micro glass bubbles present a group of materials with interesting properties. They demonstrate outstanding specific compression strengths, very high specific compression energy absorption capability, are tight against infiltration by fluids even at higher pressures and can be coated using techniques which are more common for compact materials like anodizing, copper- and chromium-plating. Corrosion properties of aluminium and zinc syntactic foams were tested by electrochemical potential measurements, immersion tests and long-time out-door exposure and determined to be close to those of compact alloys. Several approaches have been performed by IFAM for the production of these materials, e.g. by infiltration of sintered glass bubbles preforms with aluminium and zinc alloys using squeeze casting or gas-pressure infiltration of sintered preforms with aluminium. However, for alloys with higher melting temperatures liquid infiltration is not always possible. Therefore, tests have recently been carried out to examine the feasibility of the production of glass bubble syntactic foams with steel matrices by metal powder injection moulding (MIM). Blends of 58 vol% Fe50Ni50 powder mixed in polymers and waxes (binder) and 2, 3, 5 and 7 wt% 3M-S38 glass bubbles were produced and injection moulded into test specimens. After moulding the binder was removed out of the samples and the metallic material was densified around the glass bubbles in a sintering step. Though the sintering process was carried out at temperatures of 1OOO deg C, exceeding by far the softening temperatures of the glass, it was possible to obtain good foam structures with densities of 6.8g/cm(exp3), 6.2g/cm(exp3) and 5.7g/cm(exp3) for syntactic foams with 2, 3 and 5wt% glass bubbles respectively (density of compact material: 8.4g/cm ).