Especially, composites of aluminium metal foams are of high potential for lightweight applications in automotive, aerospace and general engineering because of their excellent ratio of low weight and high stiffness. To fulfill the industrial need for these new materials as soon as possible, a new integrated manufacturing process concept has been developed and studied at our institute. The new “easyFoam-process” concept consists of four basic steps: production of semi-finished parts via the powder metallurgical route, forming of the foamable semi-finished part into a near net shape by extrusion or any standard aluminium-forming process, coating of the surface by thermal spraying and foaming by inductive heating. Thus it’s feasible to provide a fast, continuous and efficient production of metal foam composites with highly reproducible properties, resulting in eminent advantages over current techniques for foam sandwich production in terms of degree of anisotropy, statistical spread in foam properties and production economy. This process is also the only one being able to produce a graded pore structure in symmetrical parts of PM-aluminium foams. The thermally sprayed coatings serve simultaneously as mould and as future multifunctional coating. In this paper, some results of our first study in coating the foamable Al-tubes and inductive heating the coated parts are presented.

Various methods of making metallic foams and sponges have been studied, although the materials have not yet been put to commercial use. For foams produced using powder metallurgy, this is largely due to the poor surface quality and limited wear resistance. With thermal spray coatings, however, the foams can be upgraded to lightweight composites with defined surfaces, high wear resistance, and significantly increased strength. In this paper, commercial aluminum foams with closed cells and a closed foaming skin are coated with metal and ceramic layers by means of electric arc and plasma spraying. The coated foams are characterized based on their microstructure and the results of uniaxial compression testing. Paper includes a German-language abstract.

Scientist and engineers show an increasing interest in metal foams. Recent activities are not only limited to the different techniques which already exist to produce and characterise metal foams, but also focus on further steps that these fairly new materials have to pass before entering mass production. Metal foams do not possess a high strength; to increase their mechanical properties and to improve the surface finish, thermally sprayed coatings can be applied. A metal foam is mainly characterised by its alloy composition, its density and the size and shape of the cells and pores. The quality of the coating depends on the coating material, the chosen process, the preparation of the surface, spraying parameters and the adhesion of the coating. The main focus of this paper is to reveal the necessary requirements to realise a sound composite made of a thermally sprayed coating onto metal foam. Basic investigations are carried out and during a later stage of the project parameters are to be identified which allow to describe the properties of the new composite material. The priority within this project will be on aluminium foams.