Composite electro-spark electrode and methods of its use

Abstract

Composite electro-spark electrodes, along with methods of their use in an electro-spark deposition process, are provided. The composite electro-spark electrode can include an electrode tip that is mechanically and electrically attached to a shank. The shank comprises a resistive material, and the electrode tip comprises a metal, with the metal of the electrode tip being less electrically resistive than the resistive material of the shank. Additionally, the metal of the electrode tip can be more thermally conductive than the resistive material of the shank.

What is claimed is: 
     
         1 . A composite electro-spark electrode, comprising:
 a shank comprising a resistive material; and   an electrode tip comprising a metal, wherein the electrode tip is mechanically and electrically attached to the shank, and wherein the metal of the electrode tip is less electrically resistive than the resistive material of the shank.   
     
     
         2 . The composite electro-spark electrode of  claim 1 , wherein the metal of the electrode tip is more thermally conductive than the resistive material of the shank. 
     
     
         3 . The composite electro-spark electrode of  claim 2 , wherein the metal of the electrode tip has a thermal conductivity of about 1.3 W/cmK to about 1.8 W/cmK, and wherein the resistive material has a thermal conductivity of about 0.07 W/cmK to about 1 W/cmK. 
     
     
         4 . The composite electro-spark electrode of  claim 1 , wherein the metal of the electrode tip comprises molybdenum, tungsten, magnesium, rhodium, iridium, or alloys thereof. 
     
     
         5 . The composite electro-spark electrode of  claim 1 , wherein the metal of the electrode tip is selected from the group consisting of molybdenum and tungsten. 
     
     
         6 . The composite electro-spark electrode of  claim 1 , wherein the metal of the electrode tip has an electrical resistance of about 5.3×10 −8  ohm meters at 295 K to about 4.3×10 −8  ohm meters at 295 K, and wherein the resistive material has an electrical resistance of about 139.0 ohm meters at 295 K×10 −8  to about 5.8×10 −8  ohm meters at 295 K. 
     
     
         7 . The composite electro-spark electrode of  claim 1 , wherein the resistive material comprises a resistive metal. 
     
     
         8 . The composite electro-spark electrode of  claim 7 , wherein the resistive metal comprises titanium, nickel, cobalt, iron, manganese, zirconium, chromium, or an alloy thereof. 
     
     
         9 . The composite electro-spark electrode of  claim 7 , wherein the resistive metal is selected from the group consisting of titanium, nickel, cobalt, iron, manganese, zirconium, and chromium. 
     
     
         10 . The composite electro-spark electrode of  claim 1 , wherein the metal of the electrode tip comprises molybdenum. 
     
     
         11 . The composite electro-spark electrode of  claim 10 , wherein the resistive material of the shank comprises titanium. 
     
     
         12 . The composite electro-spark electrode of  claim 1 , wherein the electrode tip is welded to an end of the shank. 
     
     
         13 . The composite electro-spark electrode of  claim 1 , wherein the electrode tip is brazed to an end of the shank. 
     
     
         14 . The composite electro-spark electrode of  claim 1 , wherein the electrode tip includes a tapered end that defines a point, wherein the tapered end is positioned at an opposite end of the electrode tip from the shank. 
     
     
         15 . The composite electro-spark electrode of  claim 1 , wherein the electrode tip defines a diameter, and wherein the shank defines a shank diameter that is greater than the diameter of the electrode tip. 
     
     
         16 . A composite electro-spark electrode, comprising:
 a shank consisting of a resistive metal; and   an electrode tip consisting of a metal that is different than the resistive metal of the shank, wherein the electrode tip is mechanically and electrically attached to the shank, and wherein the metal of the electrode tip is less electrically resistive than the resistive material of the shank.   
     
     
         17 . The composite electro-spark electrode of  claim 16 , wherein the metal of the electrode tip is selected from the group consisting of molybdenum and tungsten, and wherein the shank resistive metal consists of titanium. 
     
     
         18 . The composite electro-spark electrode of  claim 16 , wherein the metal of the electrode tip is more thermally conductive than the resistive material of the shank. 
     
     
         19 . The composite electro-spark electrode of  claim 16 , wherein the metal of the electrode tip has an electrical resistance of about 5.3×10 −8  ohm meters at 295 K to about 4.3×10 −8  ohm meters at 295 K, and wherein the resistive material of the shank has an electrical resistance of about 139.0×10 −8  ohm meters at 295 K to about 5.8×10 −8  ohm meters at 295 K. 
     
     
         20 . The composite electro-spark electrode of  claim 16 , wherein the electrode tip defines a diameter, and wherein the shank defines a shank diameter that is greater than the diameter of the electrode tip.