Method and composition for making a wire

Abstract

A method for producing wires, such as welding or hardfacing wires, made of superalloys and other metals. In a disclosed embodiment, the method includes forming a green-state wire from a feedstock comprising a metal powder and a binder, such as by extruding the feedstock through a die orifice, and sintering the wire to effect consolidation and densification of the wire.

1 . A method for making a wire comprising: 
 forming a green-state wire from a feedstock comprising a metal powder and a binder; and    sintering the green-state wire.    
   
   
       2 . The method of  claim 1 , wherein the metal powder comprises a nickel-based superalloy.  
   
   
       3 . The method of  claim 1 , wherein the binder comprises a plasticizer, a strengthener, a compatibilizer for the plasticizer and strengthener, and a surfactant.  
   
   
       4 . The method of  claim 1 , wherein, prior to sintering, the green-state wire is debound by placing the wire in a bath of at least one solvent.  
   
   
       5 . The method of  claim 4 , wherein the solvent comprises trichloroethylene.  
   
   
       6 . The method of  claim 5 , wherein the trichloroethylene is at a temperature of about 155° F. and the green-state wire is placed in the bath of trichloroethylene for about 30 to 90 minutes.  
   
   
       7 . The method of  claim 1 , wherein forming the green-state wire comprises extruding the feedstock to form the green-state wire.  
   
   
       8 . The method of  claim 7 , wherein extruding the feedstock comprises: 
 heating the feedstock to a temperature sufficient to melt the binder and form an extrudable paste; and    extruding the paste to form the green-state weld wire.    
   
   
       9 . The method of  claim 8 , wherein the feedstock is heated to a temperature of about from 300° F. to 500° F. to form the paste.  
   
   
       10 . The method of  claim 1 , wherein forming the green-state wire comprises rolling the feedstock to form the green-state wire.  
   
   
       11 . The method of  claim 1 , wherein forming the green-state wire comprises pressing the feedstock to form the green-state wire.  
   
   
       12 . The method of  claim 1 , wherein forming the green-state wire comprises injection molding the feedstock to form the green-state wire.  
   
   
       13 . The method of  claim 1 , wherein forming the green-state wire comprises compression molding the feedstock to form the green-state wire.  
   
   
       14 . The method of  claim 1 , wherein forming the green-state wire comprises transfer molding the feedstock to form the green-state wire.  
   
   
       15 . The method of  claim 1 , wherein forming the green-state wire comprises plunger molding the feedstock to form the green-state wire.  
   
   
       16 . The method of  claim 1 , wherein the green-state wire is placed in a mold to maintain its shape during sintering.  
   
   
       17 . The method of  claim 1 , wherein the feedstock is formed by mixing the metal powder and the binder, heating the metal powder and the binder to a temperature of about from 300° F. to 400° F. to form a paste, solidifying the paste, and fractionating the solidified paste to form a plurality of feedstock particles.  
   
   
       18 . The method of  claim 17 , wherein forming the green-state wire comprises heating the feedstock particles to a temperature sufficient to cause the binder to melt and form an extrudable paste, and extruding the paste to form the green-state wire.  
   
   
       19 . The method of  claim 7 , wherein extruding the feedstock comprises injection molding the feedstock through a die.  
   
   
       20 . The method of  claim 1 , comprising sintering the unsintered wire to densify the wire to at least about 90% of the theoretical density of the metal.  
   
   
       21 . The method of  claim 1 , wherein the sintered wire has a diameter of about 0.015 to 0.100 inch.  
   
   
       22 . The method of  claim 1 , wherein the sintering is carried out at a temperature of about 2200° F. or greater for at least 4 hours.  
   
   
       23 . The method of  claim 1 , wherein the sintering is carried out in an atmosphere containing an inert gas.  
   
   
       24 . The method of  claim 1 , wherein a continuous spool of wire is formed from the sintered wire.  
   
   
       25 . The method of  claim 1 , wherein the wire is a welding wire or a hardfacing wire.  
   
   
       26 . The method of  claim 1 , wherein the metal powder is selected from the group comprising a nickel-based superalloy, a titanium-based superalloy, a cobalt-based superalloy, and an iron-based superalloy.  
   
   
       27 . The method of  claim 3 , wherein the binder comprises wax, polypropylene, styrene-buta-diene, and stearic acid.  
   
   
       28 . The method of  claim 1 , wherein the metal powder comprises a hardfacing alloy.  
   
   
       29 . A method for making a wire comprising: 
 extruding a feedstock comprising a metal powder and a binder through a die to form an unsintered wire; and    sintering the unsintered wire.    
   
   
       30 . The method of  claim 29 , wherein the wire is a welding wire or a hardfacing wire.  
   
   
       31 . The method of  claim 29 , further comprising immersing the unsintered wire in a solvent to extract a portion of the binder from the wire.  
   
   
       32 . The method of  claim 29 , wherein the metal powder is selected from the group comprising a nickel-based superalloy, a titanium-based superalloy, a cobalt-based superalloy, and an iron-based superalloy.  
   
   
       33 . The method of  claim 32 , wherein the metal powder is a nickel-based superalloy and contains metals selected from the group consisting of tungsten, molybdenum, cobalt and tantalum.  
   
   
       34 . The method of  claim 33 , wherein the metal powder comprises René® 142.  
   
   
       35 . The method of  claim 29 , wherein the binder comprises a plasticizer, a strengthener, a compatibilizer for the plasticizer and strengthener, and a surfactant.  
   
   
       36 . The method of  claim 35 , wherein the binder comprises wax, polypropylene, styrene-buta-diene, and stearic acid.  
   
   
       37 . The method of  claim 36 , wherein the binder has a composition comprising in weight percent about 45% to 55% plasticizer, about 45% to 55% strengthener, about 3% to 6% compatibilizer, and about 0.25% to 0.5% surfactant.  
   
   
       38 . The method of  claim 29 , wherein, prior to extruding the feedstock, the feedstock is formed by mixing the metal powder and the binder to form a mixture and heating the mixture to a temperature sufficient to melt the binder and form an extrudable paste.  
   
   
       39 . The method of  claim 29 , comprising sintering the unsintered wire to densify the wire to at least about 95% of the theoretical density of the metal.  
   
   
       40 . The method of  claim 29 , wherein the extruded wire is placed in a groove of a tray to maintain the shape of the wire during sintering.  
   
   
       41 . A method for making a welding or hardfacing wire comprising: 
 forming a feedstock by mixing a metal powder and a binder, and heating the mixture to a temperature sufficient to cause the binder to melt, wherein the metal powder is selected from the group comprising a nickel-based superalloy, a titanium-based superalloy, a cobalt-based superalloy, and an iron-based superalloy, and the binder comprises wax, polypropylene, styrene-buta-diene, and stearic acid;    extruding the feedstock to form an unsintered wire;    placing the unsintered wire in a groove of a tray;    debinding the unsintered wire by immersing the tray and the wire in a bath of trichloroethylene; and    sintering the unsintered wire.    
   
   
       42 . A composition for making a wire comprising: 
 at least one metal powder; and    a binder comprising wax, polypropylene, styrene-buta-diene, and stearic acid.    
   
   
       43 . The composition of  claim 42 , wherein the at least one metal powder is selected from the group comprising a nickel-based superalloy, a titanium-based superalloy, a cobalt-based superalloy, and an iron-based superalloy.  
   
   
       44 . The composition of  claim 43 , wherein the metal powder comprises René® 142.  
   
   
       45 . The composition of  claim 43 , wherein the metal powder comprises René® 195.  
   
   
       46 . The composition of  claim 42 , wherein the metal powder comprises a stainless steel.  
   
   
       47 . The composition of  claim 42 , wherein the metal powder comprises a hardfacing alloy.