Metal-based powder compositions containing silicon carbide as an alloying powder

Abstract

Metallurgical powder compositions are provided that include silicon carbide to enhance the strength, ductility, and machine-ability of the compacted and sintered parts made therefrom. The compositions generally contain a metal powder, such as an iron-based powder, that constitutes the major portion of the composition. A silicon carbide-containing powder is blended with the metal powder, preferably in the form of a silicon carbide powder. Optionally, common alloying powders, lubricants, binding agents, and other powder metallurgy additives can be blended into the metallurgical composition. The metallurgical powder composition is used by compacting it in a die cavity to produce a “green” compact that is then sintered, preferably at relatively high temperatures.

1 - 7 . (cancelled).  
     
     
         8 . A sintered metal part made from a metallurgical powder composition, the composition comprising: 
 at least about 85 percent by weight of a base metallurgical powder comprising nickel-based powder; and    a silicon containing additive powder in an amount sufficient to provide from about 0.035 to about 0.35 percent by weight silicon in the sintered metal part.    
     
     
         9 . The sintered metal part of  claim 8  wherein the silicon containing additive provides from about 0.17 to about 0.35 percent by weight silicon in the sintered metal part.  
     
     
         10 . The sintered metal part of  claim 8  wherein the base metallurgical powder comprises a prealloy of nickel-based powder.  
     
     
         11 . The powder composition of  claim 8  wherein the silicon containing additive powder has a particle size distribution such that it has a d 50  value below about 25 microns.  
     
     
         12 . The sintered metal part of  claim 8 , wherein the silicon containing additive powder has a particle size distribution such that it has a d 50  value below about 25 microns.  
     
     
         13 . A sintered metal part made from a metallurgical powder composition, the composition comprising: 
 at least about 85 percent by weight of a water atomized base metallurgical powder comprising nickel-based powder; and    a silicon containing additive powder in an amount sufficient to provide from about 0.035 to about 0.35 percent by weight silicon in the sintered metal part.    
     
     
         14 . The sintered metal part of  claim 13  wherein the silicon containing additive provides from about 0.17 to about 0.35 percent by weight silicon in the sintered metal part.  
     
     
         15 . The sintered metal part of  claim 13  wherein the base metallurgical powder comprises a prealloy of nickel-based powder.  
     
     
         16 . The sintered metal part of  claim 13  wherein the silicon containing additive powder has a particle size distribution such that it has a d 50  value below about 25 microns.  
     
     
         17 . A sintered metal part made from a metallurgical powder composition comprising: 
 (a) at least about 85 percent by weight of an iron based powder comprising at least 50 percent by weight atomized iron-based powder having an apparent density of between 2.75 and 4.6 g/cm 3 ; and    (b) from about 0.05 to about 2.1 percent by weight silicon, wherein the total carbon content of the powder composition is between about 0.015 and about 0.63 percent by weight.    
     
     
         18 . The sintered metal part of  claim 17  wherein the iron based powder comprises iron and at least one alloying element selected from the group consisting of molybdenum, manganese, magnesium, chromium, silicon, copper, nickel, tin, gold, vanadium, columbium, graphite, phosphorus, aluminum, and sulfur.  
     
     
         19 . The sintered metal part of  claim 17  wherein the iron based powder comprises iron and molybdenum.  
     
     
         20 . The sintered metal part of  claim 19  further comprising manganese, nickel, or combinations thereof.  
     
     
         21 . The sintered metal part of  claim 17  wherein the iron based powder comprises iron and manganese.  
     
     
         22 . The sintered metal part of  claim 21  further comprising nickel.  
     
     
         23 . The sintered metal part of  claim 17  wherein the iron based powder comprises: 
 at least about 85 weight percent iron, and from about 0.25 to about 5 weight percent molybdenum, from about 0.25 to about 5 weight percent manganese, from about 0.25 to about 5 weight percent nickel, or combinations thereof  
 
     
     
         24 . The sintered metal part of  claim 17  wherein the density of the sintered part is at least about 6.76 g/cm 3 .