Composite electrode for a plasma arc torch

Abstract

A plasma arc torch that includes a torch body having a nozzle mounted relative to a composite electrode in the body to define a plasma chamber. The torch body includes a plasma flow path for directing a plasma gas to the plasma chamber in which a plasma arc is formed. The nozzle includes a hollow, body portion and a substantially solid, head portion defining an exit orifice. The composite electrode can be made of a metallic material (e.g., silver) with high thermal conductivity in the forward portion electrode body adjacent the emitting surface, and the aft portion of the electrode body is made of a second low cost, metallic material with good thermal and electrical conductivity. This composite electrode configuration produces an electrode with reduced electrode wear or pitting comparable to a silver electrode, for a price comparable to that of a copper electrode.

1 - 50 . (cancelled)  
   
   
       51 . A composite electrode for use in a torch comprising: 
 a forward portion comprising a first material; and    an aft portion directly welded to the forward portion and comprising a second material different from the first material.    
   
   
       52 . The composite electrode of  claim 51  further comprising an emissive insert in direct contact with the forward portion.  
   
   
       53 . The composite electrode of  claim 52 , wherein an entire length of the emissive insert is in direct contact with the forward portion.  
   
   
       54 . The composite electrode of  claim 52 , wherein the forward portion is directly cooled by a coolant.  
   
   
       55 . The composite electrode of  claim 54 , wherein the emissive insert is directly cooled by a coolant.  
   
   
       56 . The composite electrode of  claim 51 , wherein the first material and the second material have a heat transfer property, the value of the heat transfer property for the first material being greater than that of the second material.  
   
   
       57 . The composite electrode of  claim 51 , wherein the forward portion comprises silver and the aft portion comprises copper.  
   
   
       58 . The composite electrode of  claim 57 , wherein the forward portion comprises a silver alloy.  
   
   
       59 . An electrode for use in a torch comprising: 
 a composite electrode body defining a recess, the composite electrode body including a forward portion comprising a first material in direct contact with an aft portion comprising a second material; and    an emissive insert disposed within the composite electrode body, wherein the insert is directly cooled by a coolant within the recess.    
   
   
       60 . The electrode of  claim 59 , wherein the first material of the composite electrode body has a first heat transfer property and the second material of the composite electrode body has a second heat transfer property, the first heat transfer property being greater than the second heat transfer property.  
   
   
       61 . The electrode of  claim 59 , wherein the first material comprises silver and the second material comprises copper.  
   
   
       62 . The electrode of  claim 61 , wherein the first material comprises a silver alloy.  
   
   
       63 . The electrode of  claim 61 , wherein the forward portion comprising the first material is directly cooled by a coolant within the recess.