Manufacturing routes for metallic foams

The study of metallic foams has become attractive to researchers interested in both scientific and industrial applications. In this paper various meth ods for making such foams are presented and discussed. Some techniques star t from specially prepared molten metals with adjusted viscosities. Such mel ts can be foamed by injecting gases or by adding gas-releasing blowing agen ts which cause the formation of bubbles during their in-situ decomposition. Another method is to prepare supersaturated metal-gas systems under high p ressure and initiate bubble formation by pressure and temperature control. Finally, metallic foams can be made by mixing metal. powders with a blowing agent, compacting the mix, and then forming the compact by melting. The va rious foaming processes, the foam-stabilizing mechanisms, and some known pr oblems with the various methods are addressed in this article. In addition, some possible applications for metallic foams are presented.