Regular Metal Foams produced by Expandable Polystyrene Technology

A new process for the production of a regular metal foam using polystyrene foaming technology has been developed. This technique includes a spray coating process of polystyrene spheres with a metal powder slurry. Filled in a mould the cavity between green spheres is eliminated by expansion of the polystyrene core and all green spheres transform into a polyhedron shaped structure. The subsequent heat treatment includes the debinding and sintering. Various metals and alloys can be applied for this technology. The new regular metal foams are characterised by high homogeneity, whereas all cells are similar polyhedron with a homogeneous wall thickness in a very close tolerance. A low structural density down to 0.3 g/cm³ (for steel) can be achieved. This new structures have a very high stiffness per weight ratio. The paper presents details of the technology and estimations of the mechanical properties of the cellular structure.