Iron powder composition

Abstract

A powder composition for warm compaction comprising an iron-based powder and a lubricant powder consisting essentially of an amide described by the following formula D—C m —B—A—B—C m —D wherein D is —H, COR, CNHR, wherein R is a straight or branched aliphatic or aromatic group including 2-21 C atoms; C is the group —NH(CH) n CO—; B is amino or carbonyl; A is alkylene having 4-16 C atoms optionally including up to 4 O atoms m is an integer 1-10 and n is an integer 5-11.

1 . A powder composition for warm compaction comprising an iron-based powder and a lubricant powder, said lubricant consisting essentially of an amide represented by the following formula  
       D—C m —B—A—B—C m —D  
       wherein 
 D is —H, COR, CNHR, wherein R is a straight or branched aliphatic or aromatic group including 2-21 C atoms  
 C is the group —NH(CH) n CO— 
 B is amino or carbonyl  
 A is alkylen having 4-16 C atoms optionally including up to 4 O atoms  
 m is an integer 1-10  
 n is an integer 5-11.  
 
     
     
         2 . A powder composition according to  claim 1  wherein D is COR, wherein R is an aliphatic group 16-20 C atoms, C is —NH(CH) n CO— wherein n is 5 or 11; B is amino; A is alkylen having 6-14 C atoms optionally including up to 3 O atoms, and m is an integer 2-5.  
     
     
         3 . A powder composition according to any one of the claims  1 - 2  wherein wherein the lubricant consists of a compound selected from the group consisting of 
 CH 3 (CH 2 ) 16 CO—[HN(CH 2 ) 11 CO] 2 —HN(CH 2 ) 12 NH—[OC(CH 2 ) 11 NH] 2 —OC(CH 2 ) 16 CH 3    
 CH 3 (CH 2 ) 16 CO—[HN(CH 2 ) 11 CO] 2 —HN(CH 2 ) 12 NH—[OC(CH 2 ) 11 NH] 3 —OC(CH 2 ) 16 CH 3    
 CH 3 (CH 2 ) 16 CO—[HN(CH 2 ) 11 CO] 3 —HN(CH 2 ) 12 NH—[OC(CH 2 ) 11 NH] 3 —OCCH 2 ) 16 CH 3    
 CH 3 (CH 2 ) 16 CO—[HN(CH 2 ) 11 CO] 3 —HN(CH 2 ) 12 NH—[OC(CH 2 ) 11 NH] 4 —OC(CH 2 ) 16 CH 3    
 CH 3 (CH 2 ) 16 CO—[HN(CH 2 ) 11 CO] 4 —HN(CH 2 ) 12 NH—[OC(CH 2 ) 11 NH] 4 —OC(CH 2 ) 16 CH 3    
 CH 3 (CH 2 ) 16 CO—[HN(CH 2 ) 11 CO] 4 —HN(CH 2 ) 12 N—[OC(CH 2 ) 11 NH] 5 —OC(CH 2 ) 16 CH 3    
 CH 3 (CH 2 ) 16 CO—[HN(CH 2 ) 11 CO] 5 —HN(CH 2 ) 12 NH—[OC(CH 2 ) 11 NH] 5 —OC(CH 2 ) 16 CH 3    
 
     
     
         4 . A powder composition according to any one of the claims  1 - 3 , wherein said amide has a molecular weight of 1500 to 3000 and is present in said composition in an amount of less than 1% by weight.  
     
     
         5 . A powder composition according to any one of the claims  1 - 4 , wherein the lubricant powder is provided in a concentration 0.2 to 0.8% by weight of the composition.  
     
     
         6 . A powder composition according to any one of the claims  1 - 5 , which additionally contains one or more additives selected from the group consisting of binders, processing aids, and hard phases.  
     
     
         7 . A powder composition according to any one of the claims  1 - 6 , wherein said iron-based powder is compressible, and at least 80% by weight of said lubricant powder is made up of said amide oligomer.  
     
     
         8 . A powder composition according to any one of the claims  1 - 6 , wherein said composition is essentially free from ethylenebisstearamide.  
     
     
         9 . A powder composition according to any one of the claims  1 - 8 , characterized in that said iron-based powder has a carbon content of at most 0.04% by weight.  
     
     
         10 . A method for producing sintered products comprising: 
 (a) mixing an iron-based powder with a lubricant powder as defined in the previous claims;    (b) preheating the metal-powder composition,    (c) compacting the metal-powder composition in a preheated tool, and optionally    (d) sintering the compacted metal-powder composition at a temperature above 1050° C. to form a sintered product.