Alternative starting materials for the metal foam production process
Presentation held at 7th International Conference on Porous Metals and Metallic Foams, MetFoam 2011, September 18-21 2011, BEXCO, Busan, Korea
Alternative Einsatzstoffe für den Herstellungsprozess metallischer Schäume
Alternative starting materials for the metal foam production process The aim of current investigations of the Fraunhofer Institute for Machine Tools and Forming Technology IWU focuses at one of the most critical points about metal foam: The price! Alternative starting materials for the metal foam production have been investigated during a publicly funded project in close cooperation with industrial partners. A technology for the substitution of the starting powders has been developed allowing a cost effective production on an industrial scale. Metal chips for instance from milling and turning production processes have been fractured down to a grain size suitable for the substitution of metal powder in the powder metallurgical route of metal foam production. In addition to the large impact onto the resource material reduction and directly connected the energy savings, the use of recycling materials will open a new horizon for the application of metal foams caused by the new price structure. The technical requirements for the fracturing process of metal chips have been realized in a specially designed and built prototype device called Chip-Breaker. Its functionality has been proven in several tests. Another way for cost reduction is the substitution of the currently used very expensive blowing agent (TiH2). As the decomposition of the new blowing (CaCO3) agent releases carbon-dioxide instead of hydrogen the danger of explosion has been reduced to a minimum. As usual the material mixture of metal and blowing agent has been compacted by extrusion pressing, portioned in a mold and heat treated for the final foaming step. The results show differences in foaming structure but no significant loss in foamability. The combination of both substitutes aluminum chips and alternative blowing agent can reduce the costs of the metal foam to a third of the current stage. That way, new application markets such as architecture, ship building and art work show major interest leading metal foam to a new industrial stage.