Abstract
To produce metal foam over 95 % porosity, the process using foamed polystyrene sphere as space holder was developed. This process includes the use of low cost metal powder, and the process itself is simple and easy. In this process, slurry of metal powder and water solution of PVA were prepared. The slurry was mixed with foamed polystyrene sphere, and the metal powder was coated on the surface of the sphere. This mixture was molded, frost and kept for 24 hours. The slurry was changed to gel and the defrosted mixture preserves the molded shape. The precursor obtained by this process was desiccated and sintered. All binder and polystyrene were decomposed prior to the sintering step, and thus the high porosity metal foam was obtained. Using stainless powders, the metal foams having the porosity ranging from 90 to 97 % were produced. Pore size could be controlled by changing the size of the sphere used. Productable size of the foam was limited by powder size and the size of sphere. Using this process, the production cost of high porosity metal foam could be decreased and large size steel foam are expected to be produced with a reasonable cost.
