Short metal fibers

Abstract

The present invention relates to short metal fibers. A set of short metal fibers, with an equivalent diameter ranging from 1 to 150 μm, comprises entangled and curved fibers. At least 10 % of the short metal fibers are entangled, whereas the length of the curved fibers is distributed according to a gamma-distribution, having an average length preferably between 10 and 2000 μm.

1 . A method to provide a set of short metal fibers, comprising the steps of: 
 individualizing the metal fibers by a carding operation;    providing the set of short metal fibers by cutting or entangling and sieving the set of short metal fibers.    
   
   
       2 . A method to provide a set of short metal fibers as in  claim 1 , wherein said providing the set of short metal fibers by cutting or entangling and sieving the set of short metal fibers is done using a comminuting machine.  
   
   
       3 . A method to provide a set of short metal fibers as in  claim 1 , said fibers having an equivalent diameter D in the range of 1 to 150 μm, characterized in that said set of short metal fibers comprises curved fibers and entangled fibers, said curved fibers having an average length Lc in the range of 10 to 2000 μm.  
   
   
       4 . A method to provide a set of short metal fibers as in  claim 3 , said entangled fibers having an average length Le, said Le being more than 5 times said Lc.  
   
   
       5 . A method to provide a set of short metal fibers as in  claim 3 , wherein the lengths of said curved fibers are distributed according to a gamma-distribution.  
   
   
       6 . A method to provide a set of short metal fibers as in  claim 1 , wherein at least 10% of said short metal fibers are entangled fibers.  
   
   
       7 . A method to provide a set of short metal fibers as in  claim 1 , L being the average length of said set of short metal fibers, D being an equivalent diameter, L/D being larger than 5.  
   
   
       8 . A method to provide a set of short metal fibers as in  claim 3 , wherein Lc/D is larger than 5.  
   
   
       9 . A method to provide a set of short metal fibers as in  claim 1 , wherein said short metal fibers are stainless steel fibers.  
   
   
       10 . A method to provide a set of short metal fibers as in  claim 1 , wherein said set of short metal fibers have an apparent density between 10 and 40%.  
   
   
       11 . A method to provide a set of short metal fibers as in  claim 3 , wherein said curved fibers have a major axis, said major axis having a direction, said direction changing more than 90° for at least 40% of said curved fibers.  
   
   
       12 . A method to provide a set of short metal fibers as in  claim 2 , said fibers having an equivalent diameter D in the range of 1 to 150 μm, characterized in that said set of short metal fibers comprises curved fibers and entangled fibers, said curved fibers having an average length Lc in the range of 10 to 2000 μm.  
   
   
       13 . A method to provide a set of short metal fibers as in  claim 2 , comprising entangled fibers having an average length Le, said Le being more than 5 times Lc, wherein Lc is an average length of curved fibers.  
   
   
       14 . A method to provide a set of short metal fibers as in  claim 2 , wherein lengths of curved fibers are distributed according to a gamma-distribution.  
   
   
       15 . A method to provide a set of short metal fibers as in  claim 2 , wherein at least 10% of said short metal fibers are entangled fibers.  
   
   
       16 . A method to provide a set of short metal fibers as in  claim 2 , L being the average length of said set of short metal fibers, D being an equivalent diameter, UD being larger than 5.  
   
   
       17 . A method to provide a set of short metal fibers as in  claim 13 , wherein Lc/D is larger than 5, wherein D is an equivalent diameter.  
   
   
       18 . A method to provide a set of short metal fibers as in  claim 2 , wherein said short metal fibers are stainless steel fibers.  
   
   
       19 . A method to provide a set of short metal fibers as in  claim 2 , wherein said set of short metal fibers have an apparent density between 10 and 40%.  
   
   
       20 . A method to provide a set of short metal fibers as in  claim 2 , comprising curved fibers having a major axis, said major axis having a direction, said direction changing more than 90° for at least 40% of said curved fibers.  
   
   
       21 . A method of manufacturing a sintered product, said method comprising the steps of 
 providing a set of short metal fibers as in  claim 1;     pouring said set of short metal fibers into a three-dimensional mould or on an essentially plane surface;    sintering said set of short metal fibers to form a sintered product.    
   
   
       22 . A method according to  claim 21 , wherein said method further comprises the step of pressing said short metal fibers together before performing said sintering step.  
   
   
       23 . A method according to  claim 21 , wherein said product has a porosity of more than 60%.  
   
   
       24 . A method according to  claim 21 , wherein said product has an absolute filter rating between 0.5 and 20 μm.  
   
   
       25 . A method according to  claim 21 , wherein an absolute filter rating of said sintered product is between ⅓ and ½ of the equivalent diameter of said short metal fibers.  
   
   
       26 . A method of manufacturing a sintered product, said method comprising the steps of 
 providing a set of short metal fibers as in  claim 2;     pouring said set of short metal fibers into a three-dimensional mould or on an essentially plane surface;    sintering said set of short metal fibers to form a sintered product.    
   
   
       27 . A method according to  claim 26 , wherein said method further comprises the step of pressing said short metal fibers together before performing said sintering step.  
   
   
       28 . A method according to  claim 26 , wherein said product has a porosity of more than 60%.  
   
   
       29 . A method according to  claim 26 , wherein said product has an absolute filter rating between 0.5 and 20 μm.  
   
   
       30 . A method according to  claim 26 , wherein an absolute filter rating of said sintered product is between ⅓ and ½ of the equivalent diameter of said short metal fibers.