Process for producing a lightweight molded part and molded part made of metal foam

Abstract

A process for producing a lightweight molded part, comprising introducing a gas into a particle-containing, molten metal to produce a metal foam having voids with a monomodal distribution of their dimensions, introducing the metal foam into a casting die and compressing it therein essentially under all-round pressure; and the molded part made by this process.

1 . A lightweight molded part made by a process comprising (a) introducing a gas into a particle-containing, molten metal to produce a metal foam having voids therein, said voids having a monomodal distribution of their dimensions, (b) at least partially introducing the metal foam into a casting die and compressing it therein under essentially all-round pressure, and (c) allowing the liquid phase to solidify.  
   
   
       2 . A lightweight molded part made of metal foam and comprising a metal matrix which encloses voids, wherein particles are embedded in the metal matrix and the voids show a monomodal distribution of the dimensions thereof.  
   
   
       3 . The lightweight molded part of  claim 2 , wherein a proportionate maximum longitudinal extension of the voids ranges from 1 to 30 mm.  
   
   
       4 . The lightweight molded part of  claim 3 , wherein said voids are at least one of essentially spherical and essentially ellipsoid.  
   
   
       5 . The lightweight molded part of  claim 2 , wherein boundary walls of the metal matrix enclosing the voids at least partially have planar areas.  
   
   
       6 . The lightweight molded part of  claim 4 , wherein boundary walls of the metal matrix enclosing the voids at least partially have planar areas.  
   
   
       7 . The lightweight molded part of  claim 5 , wherein a ratio of maximum longitudinal extensions of two different voids for at least 20 pairs on the average is lower than 45.  
   
   
       8 . The lightweight molded part of  claim 7 , wherein said ratio is lower than 30.  
   
   
       9 . The lightweight molded part of  claim 7 , wherein said ratio is lower than 15.  
   
   
       10 . The lightweight molded part of  claim 7 , wherein said ratio is lower than 5.  
   
   
       11 . The lightweight molded part of  claim 4 , wherein adjacent voids are completely separated from each other by the metal matrix.  
   
   
       12 . The lightweight molded part of  claim 5 , wherein said particles are evenly distributed in the metal matrix.  
   
   
       13 . The lightweight molded part of  claim 12 , wherein said particles have a size of 1 to 50 μm.  
   
   
       14 . The lightweight molded part of  claim 13 , wherein said particles have a size of 3 to 20 μm.  
   
   
       15 . The lightweight molded part of  claim 13 , wherein a volume fraction of the particles in the metal ranges from 10 vol % to 50 vol %.  
   
   
       16 . The lightweight molded part of  claim 2 , wherein a volume fraction of the particles in the metal ranges from 15 vol % to 30 vol %.  
   
   
       17 . The lightweight molded part of  claim 2 , wherein the particles comprise particles of SiC, Al 2 O 3 , intermetallic phases and mixtures thereof.  
   
   
       18 . The lightweight molded part of  claim 14 , wherein the particles comprise particles of Al 2 O 3 .  
   
   
       19 . The lightweight molded part of  claim 17 , wherein the metal comprises a light metal.  
   
   
       20 . The lightweight molded part of  claim 15 , wherein the metal comprises at least one of aluminum and an aluminum alloy.  
   
   
       21 . The lightweight molded part of  claim 2 , wherein the metal comprises aluminum.  
   
   
       22 . The lightweight molded part of  claim 3 , wherein the metal foam has a density of less than 1.05 g/cm 3 .  
   
   
       23 . The lightweight molded part of  claim 8 , wherein the metal foam has a density of less than 0.7 g/cm 3 .  
   
   
       24 . The lightweight molded part of  claim 2 , wherein the metal foam has a density of less than 0.3 g/cm 3 .  
   
   
       25 . The lightweight molded part of  claim 2 , wherein boundary walls of metal matrix enclosing the voids at least partially have planar areas, wherein a proportionate maximum longitudinal extension of the voids ranges from 1 to 30 mm, wherein a ratio of maximum longitudinal extensions of two different voids for at least 20 pairs on the average is lower than 15, wherein the metal comprises aluminum, wherein the particles comprise particles of Al 2 O 3  and have a size of 3 to 20 μm, wherein a volume fraction of the particles in the metal ranges from 15 vol % to 30 vol %, and wherein the metal foam has a density of less than 0.3 g/cm 3 .