Capacitor-grade lead wires with increased tensile strength and hardness

Abstract

A capacitor-grade wire made from powder metallurgy containing at least niobium and silicon, wherein the niobium is the highest weight percent metal present in the niobium wire. The wire having a controlled tensile strength at finish diameter exceeds the strength of capacitor-grade wire formed by ingot metallurgy. Also, the powder metallurgy wire hardness exceeds capacitor-grade wire formed from ingot metallurgy with electrical leakage meeting the specifications normally applied to capacitor grade tantalum, niobium or niobium-zirconium lead wire at sinter temperatures of about 1150° C. and above.

1 - 9 . (canceled)  
     
     
         10 . A capacitor grade wire prepared by a process comprising: 
 (a) forming a low oxygen niobium powder by hydriding a niobium ingot or a niobium bar and grinding or milling the ingot or the bar, and thereby making a powder having a Fisher Average Particle Diameter particle size range of less than about 150 microns;    (b) (i) the niobium powder, and 
 (ii) deoxidating the dehydrided niobium powder, 
 thereby forming a low oxygen niobium powder;  
 
   (c) blending the low oxygen niobium powder with a silicon additive powder, and compacting the powder blend of low oxygen niobium poser and silicon additive powder by cold isotactic pressing to form a bar;    (d) thermomechanically processing the bar into a rod; and    (e) subjecting the rod to the following sequential steps, 
 (i) annealing at a temperature of about 2500° F. for 1.5 hours,  
 (ii) rolling to a diameter of about 0.440 inches,  
 (iii) annealing at a temperature of about 2500° F. for 1.5 hours,  
 (iv) reducing to a diameter of about 0.1 inches, and  
 (v) drawing to a wire having a diameter of at least about 0.005 inches,  
   thereby forming said capacitor grade wire,    wherein said capacitor grade wire has a tensile strength exceeding the tensile strength of capacitor-grade niobium wire and niobium-zirconium alloys derived directly from ingot metallurgy.    
     
     
         11 . The capacitor grade wire of  claim 10 , wherein the silicon is added in an amount that is less than about 600 ppm.  
     
     
         12 . The capacitor grade wire of  claim 10 , wherein the silicon is added in an amount ranging from about 150 to about 300 ppm.  
     
     
         13 - 15 . (canceled)  
     
     
         16 . The capacitor grade wire of  claim 10 , wherein the wire further comprises a metal component selected from the group consisting of tantalum, zirconium, titanium, and combinations thereof.  
     
     
         17 . The capacitor grade wire of  claim 10 , wherein the niobium powder has an oxygen level that is below about 400 ppm.  
     
     
         18 . (canceled)  
     
     
         19 . The capacitor grade wire of  claim 10  wherein the niobium powder has an oxygen level of less than 200 ppm.