Metal foams. Structures and processing routes

Metal foams are cellular materials generally considered to be new. However, the first production techniques for these materials were introduced almost a century ago. This impression of novelty is induced by the fairly recent mastery of manufacturing processes, which today enable us to offer foams whose morphological characteristics are relatively well controlled. This mastery makes it possible to manufacture products whose service properties are predictable and repeatable, which is essential when using a material.

The morphological characteristics of foams determine the functions they can perform and their properties of use. As a result, depending on the intended application, a particular structure may have to be chosen. But this structure is closely linked to the process by which it is created. As the process itself has its own limitations and conditions of use, it is the choice of the process/structure pairing that must be made.

This article focuses on the link between metal foam manufacturing processes and the structures of these materials. After a first section detailing the vocabulary specific to metallic foams, a description of the processes used to manufacture these materials is proposed. The processes are grouped according to the physical principles involved. The key elements in mastering these processes are discussed.