Method for production of metal foam or metal-composite bodies

Abstract

A method for the production of foamable or foamed metal pellets, parts and panels. The method comprises the steps of: i) providing a mixture of a metal alloy powder with a foaming agent powder, ii) pre-compacting the mixture of step i); iii) heating the pre-compacted mixture of step ii) to a temperature below a decomposition temperature of the foaming and at which permanent bonding of the particles occurs v) hot compacting the body for producing a compacted body made of a metal matrix embedding the foaming agent; and vi) reducing the compacted body into metal fragments and thereby obtaining dense foamable metal chips. A method for the production of a foam metal using a closed volume metal shell is also disclosed. The method comprises the steps of: a) providing metal pieces and reducing said metal pieces into smaller metal particles; b) mixing the metal particles with an additive having a decomposition temperature that is greater than a solidus temperature of said metal particles; c) pouring the mixture of step b) into a closed volume metal shell having a given thickness and providing the metal shell with at least one passage for gases to escape; d) reducing the thickness of the metal shell by applying pressure; e) heating the metal shell to a temperature above said solidus temperature of the metal particles and below said decomposition temperature of the additive, and immediately applying pressure on the metal shell sufficient to compress the metal particles and to create micro shear conditions between the metal particles so as to obtain a dense metal product.

1 - 32 . (canceled) 
   
   
       33 . A method for the production of a metal product comprising the steps of:
 introducing a mixture comprising metal particles and an additive having a decomposition temperature that is greater than a solidus temperature of said metal particles into a closed volume metal shell having a given thickness and providing the metal shell with at least one passage for gases to escape;   increasing the density of the metal shell with metal particles and additive by applying pressure; and   heating the metal shell to a temperature above a temperature equal to said solidus temperature minus 50-60 degrees Celsius and below said decomposition temperature of the additive, and immediately applying pressure on the metal shell sufficient to compress the metal particles and to create micro shear conditions between the metal particles so as to obtain a dense metal product.   
   
   
       34 . The method of  claim 33 , further comprising pre-compacting the mixture before increasing the density of the metal shell with metal particles and additive. 
   
   
       35 . The method of  claim 34 , wherein pre-compacting of the mixture is performed by vibration. 
   
   
       36 . The method of  claim 33 , wherein the pressure is applied to said metal shell by hot rolling the metal shell. 
   
   
       37 . The method of  claim 36 , wherein the hot rolling is performed with a compression force sufficient for obtaining a 95-100% dense metal product. 
   
   
       38 . The method of  claim 33 , wherein the closed volume metal shell comprises two continuous longitudinal main surfaces with side edges, and is deformable in a cross direction. 
   
   
       39 . The method of  claim 38 , wherein the continuous surfaces are at least partially closed at their side edges, said partial closing being made by a process selected from the group consisting of welding, bending, clamping and bonding. 
   
   
       40 . The method of  claim 38 , wherein the hot rolling is performed by at least one roll moving along one of said surfaces of the shell. 
   
   
       41 . The method of  claim 33 , wherein the closed volume metal shell is obtained by providing a flat pan with a lid; and wherein the mixture is introduced into the pan and closing the lid of the pan leaving said at least one passage. 
   
   
       42 . The method of  claim 33 , wherein increasing the density of the metal shell comprises cold rolling the metal shell. 
   
   
       43 . The method of  claim 33 , wherein the metal particles comprises recycled aluminium scraps. 
   
   
       44 . The method of  claim 33 , wherein the metal particles are metal chips, a powder of finely dispersed metal particles, agglomerated powders, particles, or mixtures thereof. 
   
   
       45 . The method of  claim 33 , wherein the additive comprises a foaming agent that decomposes into gas at a temperature greater than said decomposition temperature. 
   
   
       46 . The method of  claim 45 , wherein the dense metal product obtained consists essentially in a dense foamable metal product comprising said metal particles and said foaming agent. 
   
   
       47 . The method of  claim 45 , wherein the dense metal product obtained is a sandwich structure metal product comprising a dense foamable metal core comprising metal particles and said foaming agent; and two metal facings. 
   
   
       48 . The method of  claim 47 , wherein said metal facings are made of said metal shell. 
   
   
       49 . The method of  claim 47 , wherein said product comprises metallic bonds between said core and said facings. 
   
   
       50 . The method of  claim 45 , wherein the foaming agent is chosen from TiH 2 , CaCO 3 , and a mixture thereof. 
   
   
       51 . The method of  claim 45 , further comprising the step of heating the dense metal product to a temperature greater than the decomposition temperature of the foaming agent, for obtaining a foam metal product. 
   
   
       52 . The method of  claim 51 , wherein the foam metal product obtained consists essentially in a porous metal product comprising said metal particles. 
   
   
       53 . The method of  claim 51 , wherein the foam metal product obtained is a sandwich structure metal product comprising a porous metal core comprising metal particles; and two metal facings. 
   
   
       54 . The method of  claim 53 , wherein said metal facings are made of said metal shell. 
   
   
       55 . The method of  claim 54 , wherein said product comprises metallic bonds between said core and said facings. 
   
   
       56 . A dense foamable metal product obtained by a method as defined in  claim 45 . 
   
   
       57 . A dense foamable metal product obtained by a method as defined in  claim 47 . 
   
   
       58 . A dense foamable metal product obtained by a method as defined in  claim 48 . 
   
   
       59 . A foam metal product obtained by a method as defined in  claim 52 . 
   
   
       60 . A foam metal product obtained by a method as defined in  claim 53 . 
   
   
       61 . A sandwich structure metal product comprising a dense foamable core comprising metal particles and a foaming agent; and two metal facings, said product being characterized in that it comprises metallic bonds between said core and said facings. 
   
   
       62 . A sandwich structure metal product comprising a porous metal core; and two metal facings, said product being characterized in that it comprises metallic bonds between said core and said facings.