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 methods for making such foams are presented and discussed. Some techniques start from specially prepared molten metals with adjusted viscosities. Such melts can be foamed by injecting gases or by adding gas-releasing blowing agents which cause the formation of bubbles during their in-situ decomposition. Another method is to prepare supersaturated metal-gas systems under high pressure 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 various foaming processes, the foam-stabilizing mechanisms, and some known problems with the various methods are addressed in this article. In addition, some possible applications for metallic foams are presented.