Manufacture, characterisation and application of cellular metals and metalfoams

The possibilities for manufacturing metal foams or other porous metallic st ructures are reviewed. The various manufacturing processes are classified a ccording to the state of matter in which the metal is processed-solid, liqu id, gaseous or ionised. Liquid metal can be foamed directly by injecting ga s or gas-releasing blowing agents, or by producing supersaturated metal-gas solutions. Indirect methods include investment casting, the use of space-h olding filler materials or melting of powder compacts which contain a blowi ng agent. If inert gas is entrapped in powder compacts, a subsequent heat t reatment can produce cellular metals even in the solid state. The same hold s for various sintering methods, metal powder slurry foaming, or extrusion and sintering of polymer/powder mixtures. Finally, electro-deposition or me tal vapour deposition also allow for the production of highly porous metall ic structures. The various ways for characterising the properties of cellul ar metals are reviewed in second section of this paper. Non-destructive as well as destructive methods are described. Finally, the various application fields for cellular metals are discussed. They are divided into structural and functional applications and are treated according to their relevance f or the different industrial sectors. (C) 2001 Elsevier Science Ltd. All rig hts reserved.