A survey of fabrication and application of metallic foams (1925-2017)

This review focuses on contemporary metal foams, their fabrication techniques and commercial applications. Different type of foam synthesis techniques like open cell and closed cell foams using solid, liquid, ions or vapor metals are discussed along with their characteristic process parameters. A vast body of research has been established for producing metallic foams for many decades. Space holder methods, sponge replication method, vapor deposition method, hot isostatic pressing as well as powder metallurgy process have been extensively reported in available literature. Techniques like sponge replication have the capability to produce up to 98% porosity with considerable amount of strength. However, metallic foam fabrication of certain metals still poses many challenges, which need to be explored. Metallic foams have enormous industrial applications, like closed cell foams have structural applications, open cell foams can be used for structural as well as biomedical applications. Often open cell metal foams have encountered low fatigue strength that might need alloying as well heat treatment operations for strengthening. Moreover, it is important to understand the physics and techniques of foaming for fabricating a good quality foam, which is also discussed in this article. The focus of the review finally shifts to open cell metallic foams for biomedical applications.