A Review of Different Manufacturing Methods of Metallic Foams.

Metallic foam is a popular topic due to its diverse industrial applications and unique combination of properties. Metallic foam is significantly lighter than nonfoam metal materials due to its porous structure, which incorporates a substantial amount of air or voids. This lower density makes metallic foam advantageous in applications in which weight reduction is critical. This makes it ideal for the aerospace, automotive, and construction industries; also, its versatile nature continues to make it an attractive material for various industrial applications such as impact absorbers, heat exchangers, and biomedical and marine engineering. However, the choice between metallic foam and nonfoam metal also depends on other factors like mechanical properties, cost, and specific application requirements. This review describes various fabrication methods of metallic foam that include the liquid metallurgy route which uses liquid or semiliquid metal, the powder metallurgy route uses metal in powder form, metal ion, and the metal vapor route which uses electrolytic deposition method to produce metallic foam. These methods include direct gas injection, adding blowing agents in solid or liquid metals, investment casting, the addition of a space holder in the precursor, metallic ion, vapor deposition on a polymer sponge, and many more. The morphology of metallic foam depends upon the method that is chosen for fabrication, and up to 98% porosity can be achieved by these methods. Additive manufacturing for metallic foam fabrication is an emerging field based on selective laser melting and electron beam melting principles. It has exceptional possibilities for generating complicated 3D shapes and customizing the material characteristics. The main purpose of this review article is to give significant insights into the various production procedures for metallic foams to researchers, engineers, and industry experts, assisting in the selection of acceptable methods depending on individual application needs. This review investigates the manufacturing conditions for metallic foams and finally discusses their advantages, drawbacks, and obstacles in mass production. The findings add to current efforts to expand metallic foam technology and encourage its wider application across diverse sectors, opening the path for future research and development.