Composite metal foam and method of preparation thereof

Abstract

The present invention is directed to composite metal foams comprising hollow metallic spheres and a solid metal matrix. The composite metal foams show high strength, particularly in comparison to previous metal foams, while maintaining a favorable strength to density ratio. The composite metal foams can be prepared by various techniques, such as powder metallurgy and casting.

1 . An energy absorption panel comprising a plurality of layers of different material, at least one layer including a composite metal foam comprising a plurality of hollow metallic spheres arranged with an interstitial space between the spheres, the interstitial space being filled with a solid metal matrix. 
     
     
         2 . The panel of  claim 1 , wherein the hollow metallic spheres are defined by one or more of the following:
 an average diameter of about 0.5 mm to about 20 mm;   an average wall thickness that is about 1% to about 15% of the average sphere diameter;   an average wall porosity of less than about 12%.   
     
     
         3 - 4 . (canceled) 
     
     
         5 . The panel of  claim 1 , wherein the composite metal foam layer is defined by one or more of the following:
 a strength, evaluated as the plateau stress, of at least 35 MPa;   a density of less than about 4 g/cm 3 ;   an energy absorption of at least about 20 MJ/m 3 .   
     
     
         6 - 7 . (canceled) 
     
     
         8 . The panel of  claim 1 , wherein the hollow metallic spheres and the solid metal matrix are formed of the same metal or metal alloy, or wherein the hollow metallic spheres and the solid metal matrix are formed of different metals or metal alloys. 
     
     
         9 . (canceled) 
     
     
         10 . The panel of  claim 1 , wherein one or more of the following conditions are met:
 the hollow metallic spheres comprise a metal or metal alloy selected from the group consisting of iron, iron alloy, steel, aluminum, aluminum alloy, chromium, titanium, cobalt, lead, nickel, manganese, molybdenum, copper, and combinations thereof;   the solid metal matrix comprises a metal or metal alloy selected from the group consisting of iron, iron alloy, steel, aluminum, aluminum alloy, chromium, titanium, cobalt, lead, nickel, manganese, molybdenum, copper, and combinations thereof;   the solid metal matrix is a sintered mass of metal particles.   
     
     
         11 - 12 . (canceled) 
     
     
         13 . The panel of  claim 10 , wherein solid metal matrix is a sintered mass of a mixture of metal powders formed of a first metal powder having a first average particle size and at least a second metal powder having a second, different average particle size, and wherein the particle sizes are about 1 μm to about 200 μm. 
     
     
         14 . (canceled) 
     
     
         15 . The panel of  claim 1 , further comprising one or both of a ceramic layer and a cloth layer. 
     
     
         16 . (canceled) 
     
     
         17 . The panel of  claim 15 , wherein the cloth is formed of fibers of a natural material or is formed of fibers of a synthetic material. 
     
     
         18 . (canceled) 
     
     
         19 . The panel of  claim 17 , wherein the synthetic material is an aramid. 
     
     
         20 . The panel of  claim 1 , further comprising a layer including an open cell foam. 
     
     
         21 . The panel of  claim 20 , further comprising a radiation shielding material. 
     
     
         22 . The panel of  claim 21 , wherein one or both of the following conditions are met:
 the radiation shielding material comprises a material effective against radiation selected from the group consisting of neutron radiation, cosmic radiation, x-ray radiation, gamma radiation, and combinations thereof;   the open-cell foam is at least partially filled with secondary media.   
     
     
         23 . (canceled) 
     
     
         24 . The panel of  claim 22 , wherein one or more of the following conditions are met:
 the secondary media includes a radiation shielding material;   the secondary media comprises a material selected from the group consisting of water, waxes, polymers, and combinations thereof;   the open-cell foam is at least partially filled with the secondary media combined with a radiation shielding material;   the panel further comprises one or more layers of a non-foam material;   the composite metal foam layer is separated from the open cell foam layer by a non-foam layer.   
     
     
         25 - 27 . (canceled) 
     
     
         28 . The panel of  claim 24 , wherein the non-foam material is selected from the group consisting of metals, natural polymers, synthetic polymers, and combinations thereof. 
     
     
         29 . (canceled) 
     
     
         30 . A personal protection article comprising the energy absorption panel of  claim 1 . 
     
     
         31 . The personal protection article of  claim 30 , wherein the personal protection article is defined by one or both of the following:
 the article is selected from the group consisting of headgear, body armor, and footwear;   the energy absorption panel comprises a layer including the composite metal foam sandwiched between a ceramic layer and a cloth layer or polymer layer.   
     
     
         32 . (canceled) 
     
     
         33 . The personal protection article of  claim 31 , wherein the cloth is formed of fibers of a natural material, or wherein the cloth is formed of fibers of a synthetic material. 
     
     
         34 . (canceled) 
     
     
         35 . The personal protection article of  claim 33 , wherein the synthetic material is an aramid. 
     
     
         36 . The personal protection article of  claim 30 , wherein the article is defined by one or both of the following:
 exhibits sufficient energy absorption such that the energy of a projectile traveling at a velocity of about 200 m/s is completely absorbed by the article without full penetration of the projectile through the article;   absorbs an impact energy of about 2,000 Joules or greater.   
     
     
         37 . (canceled) 
     
     
         38 . An armored vehicle comprising the energy absorption panel of  claim 1 . 
     
     
         39 . The armored vehicle of  claim 38 , wherein the energy absorption panel comprises the composite metal foam layer and a ceramic layer. 
     
     
         40 - 81 . (canceled)