On the stabilization mechanisms in liquid metallic foams

Abstract

Metal foams are porous structures made up of conventional metals such as aluminium. Their advantageous density to stiffness ratio leads to a variety of applications especially in automotive industry, where they have gained interest as material used in shock absorbers and light weight construction parts.

Solid metal foams are usually produced by solidification of a liquid metallic foam. The latter is generated by the introduction of gas into a melt analogous to aqueous foams. Depending on the parameters of the production process, porous structures with relative densities down to 10% of the original metal can be achieved. However, while the mechanisms leading to stable aqueous foams are quite well understood, this is not the case for metallic foams. In contrast for example to soap foams, no surface active or polar substances are present in liquid metals. It is merely known empirically that solid particles have a major influence on the stability of a liquid metallic foam.

In this paper we present experimental observations showing that the stability and structure of metallic foams produced via a melt route are predominantly governed by interface rather than drainage effects. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)