Preparation of High Porosity Metal Foams

Metal foams with porosities greater than 90 pct were prepared by a novel powder metallurgy route using a polymeric vehicle. Coarse titanium powder and fine carbonyl iron powder were tested. The powders were blended with each component of a two-part polyol-isocyanate foaming system, and the resulting suspensions were mixed and allowed to expand. Although the resulting polymer-metal foam was closed cell, particles were not retained in the windows. Upon pyrolysis to remove the resin, the windows opened and the final sintered metal foam was reticulated. Such foams present very low sintered density and are correspondingly weak after sintering but offer a fine reticulated structure with cell diameters in the region of 100 to 200 µm. They may have applications in the areas of catalysis, biomaterials, and composites.