Production of metallic foams from ceramic foam precursors

A process has been developed for obtaining closed cell metallic foams using a ceramic foam precursor. In this approach, the major constituent of the ceramic foam precursor is iron oxide (Fe2O3); which is mixed with various foaming/setting additives. The mixture sets rapidly at room temperature to stabilize the foam generated by hydrogen release. The oxide foam is then reduced in a nonflammable hydrogen/inert gas mixture to obtain a metallic foam with a cell diameter of 0.5-2 mm. Iron foams with a relative density of 0.23 were tested in compression and yielded an average compressive strength of similar to 34 MPa. The compressive stress-strain curves obtained were typical of cellular metals. The normalized strengths of the metal foams obtained in the present study compare very favorably with that of steel foams produced by other techniques.