Surface Modified Metallic Particulate In Sintered Products

Abstract

Disclosed are interfacially modified metal particulate composite materials for use in powder metallurgy sintered products and processes.

We claim: 
     
         1 - 27 . (canceled) 
     
     
         28 . An article consisting essentially of:
 (i) a metal particulate having a surface and a particle size of 1 to 300 microns; and   (ii) a metallic coating on the particle surface comprising a non-volatile residue derived from an organo metallic coating of about 0.1 to 2 wt. % of an interfacial modifier; wherein each particle surface is bonded to at least one adjacent particle surface with a bond that comprises at least one element from each particle and at least one non-volatile residue element derived from the interfacial modifier, and wherein the article is substantially free of volatile organic material and has a packing density greater than 70%.   
     
     
         29 . The article of  claim 28  wherein the non-volatile residue comprises titanium, boron, aluminum, silicon, strontium, neodymium, yttrium, zirconium or mixtures thereof. 
     
     
         30 . The article of  claim 28  wherein the metal particulate is ferrous metal or ferrous alloy. 
     
     
         31 . The article of  claim 30  wherein the ferrous alloy is stainless steel. 
     
     
         32 . The article of  claim 28  wherein the metal particulate is a copper metal, a nickel metal, a tungsten metal, a molybdenum metal or an alloy thereof. 
     
     
         33 . The article of  claim 28  that is substantially free of an internal void space flaw. 
     
     
         34 . The article of  claim 28  wherein the metal particulate has an excluded volume of about 5 to 22 vol. % 
     
     
         35 . The article of  claim 28  wherein the metal particulate comprises at least two different metals. 
     
     
         36 . The article of  claim 35  wherein the metal particulate is a blend of two particulates each having a different particle size and the ratio of diameters is 2:1 to 7:1. 
     
     
         37 . The article of  claim 35  wherein the metal particulate is a blend of three particulates each having a different particle size and the ratio of diameters is 49:7:1. 
     
     
         38 . The article of  claim 29  wherein the non-volatile residue has a thickness of about 1-500 Å. 
     
     
         39 . An article formed by powder metallurgy consisting essentially of:
 (i) a steel particulate including a particle having a surface and a particle size of 1 to 300 microns; and   (ii) a titanium or zirconium metallic coating on the particle surface comprising a non-volatile residue derived from an organo metallic coating of about 0.1 to 2 wt. % of an interfacial modifier; and wherein each particle is bonded to at least one adjacent particle with a bond that comprises at least one element from each particle and at least one non-volatile residue element derived from the interfacial modifier, and wherein the article is substantially free of volatile organic material and has a packing density greater than 70%.   
     
     
         40 . The article of  claim 39  wherein the article is substantially free of an internal void space. 
     
     
         41 . The article of  claim 39  wherein the particulate is a blend of two steel particulates. 
     
     
         42 . The article of  claim 39  wherein the interfacial modifier coating has a thickness of about 1-500 Å. 
     
     
         43 . A process for forming a final shaped article made by melt molding manufacture comprising:
 (i) combining a metal particulate having a D 50  particle size of about 2 to 500 microns and about 0.1 to 2 wt. % of an organo metallic interfacial modifier to form a coated particulate into a composite;   (ii) forming the composite into a green article using a heated mold;   (iii) heating the green article to a temperature less than about 200° C.; and   (iv) sintering the green article in a non-oxidizing atmosphere at a temperature less than the melting temperature of the particulate to form the final shaped article.   
     
     
         44 . The process of  claim 43  wherein step (ii) comprises forming the composite into a green article using a heated injection mold. 
     
     
         45 . The process of  claim 43  wherein step (ii) comprises forming the composite into a green article using a heated compression mold. 
     
     
         46 . The process of  claim 43  wherein the non-oxidizing atmosphere is a reducing atmosphere.