Methods for solventless bonding of metallurgical compositions

Abstract

The present invention is directed to methods of preparing a bonded metallurgical powder composition comprising melting a binding agent and blending the melted binding agent with a metallurgical powder mixture, in the substantial absence of solvent, for a time sufficient to form the bonded metallurgical powder composition. Bonded metallurgical powder compositions prepared using these methods are also described, as well as compacted powder metallurgical parts prepared using them.

What is claimed: 
     
         1 . A method of preparing a bonded metallurgical powder composition comprising:
 melting a binding agent, in the substantial absence of solvent;   and   blending the melted binding agent with a metallurgical powder mixture, in the substantial absence of solvent, for a time sufficient to form the bonded metallurgical powder composition.   
     
     
         2 . The method of  claim 1 , wherein the binding agent comprises less than 5% by weight of solvent, based on the weight of the binder. 
     
     
         3 . The method of  claim 1 , wherein the binding agent comprises less than 2% by weight of solvent, based on the weight of the binder. 
     
     
         4 . The method of  claim 1 , wherein the binding agent comprises no added solvent. 
     
     
         5 . The method of  claim 1 , wherein the binding agent is a stearamide, behenic acid, an oleamide, a polyethylene, paraffin wax, an ethylene bisstearamide, a cotton seed wax, or a combination thereof. 
     
     
         6 . The method of  claim 1  wherein the melting step includes heating the binding agent to a temperature above the melting point of the binding agent for a time sufficient to melt the binding agent. 
     
     
         7 . The method of  claim 6 , wherein the binding agent is heated to a temperature of between about 50° C. to about 110° C. 
     
     
         8 . The method of  claim 1 , wherein the binder is polyethylene. 
     
     
         9 . The method of  claim 1 , wherein the metallurgical powder mixture comprises
 at least about 80% by weight, based on the weight of the mixture, of a metal-based powder; and   at least one alloying powder.   
     
     
         10 . The method of  claim 9 , wherein the metallurgical powder mixture comprises at least about 90% by weight of the metal-based powder. 
     
     
         11 . The method of  claim 9 , wherein the metal-based powder is an iron-based powder. 
     
     
         12 . The method of  claim 9 , wherein the metallurgical powder mixture further comprises 0.20% to about 5.0%, by weight of the composition, of alloying powers. 
     
     
         13 . The method of  claim 1 , wherein the bonded metallurgical powder composition comprises about 0.15% to about 2.0%, by weight of the composition, of the binding agent. 
     
     
         14 . The method of  claim 6 , wherein the metallurgical powder mixture is heated to between about 60° C. to about 85° C. 
     
     
         15 . The method of  claim 1  in which, prior to the blending step, the melted binding agent is applied to the metallurgical powder, in the substantial absence of solvent, by spraying the powder with the melted binding agent. 
     
     
         16 . The method of  claim 6 , in which, prior to the blending step, the melted binding agent is applied to the metallurgical powder, in the substantial absence of solvent, by spraying the powder with the melted binding agent. 
     
     
         17 . The method of  claim 16  in which the binding agent contains less than 2% by weight, based on the weight of the binder, of solvent. 
     
     
         18 . A bonded metallurgical powder composition prepared according to the method of  claim 1 . 
     
     
         19 . A compacted powder metallurgical part prepared using the bonded metallurgical powder composition of  claim 6 .