Tungsten wire, cathode heater and vibration service lamp filament

Abstract

A tungsten wire containing 1 to 10% by mass of rhenium has a point which indicates a 2% elongation within a quadrangle formed by joining points with straight lines, where the values of x and y are point (20, 75), point (20, 87), point (90, 75), and point (90, 58), in this order, wherein the wire diameter of the aforementioned tungsten wire is represented by x μm, and the elongation of the tungsten wire is 2% after electrically heating with an electrical current which is a ratio of y % to the fusion current (FC) at the wire diameter x μm, and wherein a semi-logarithmic system of coordinates is expressed by a horizontal axis using a logarithmic scale of the aforementioned wire diameter x and a vertical axis using a normal scale of ratio y to the fusion current. According to the above-described configuration, a tungsten wire having a great elongation even under conditions of high temperature can be provided, and the tungsten wire can exhibit an excellent durability when used as component material for constituting cathode heaters and so forth, and the tungsten wire can be manufactured efficiently.

1 . A method of manufacturing a tungsten wire containing 1 to 10% by mass of rhenium and having a wire diameter of 20-90 μm, the method comprising the steps of:
 heating and rolling a tungsten sintered body containing 1 to 10% by mass of rhenium, wherein said rolling process utilizes a process rate of 40 to 75% for a rolling process with one heating process;   performing a recrystallization heat treatment;   heating and swaging the rolled sintered body after the recrystallization heat treatment;   heating and wire drawing the swaged sintered body; and   performing a strain removal heat treatment of said tungsten wire at a temperature of 1200 to 2300° C. at a time when a diameter of the tungsten wire formed by the swaging process or the wire drawing process is 100 μm or less;   said tungsten wire having a point which indicates a 2% elongation within a quadrangle formed by joining points with straight lines, where values of x and y are point (20, 75), point (20, 87), point (90, 75), and point (90, 58), in this order, wherein the wire diameter of said tungsten wire is represented by x μm, and the elongation of the tungsten wire is 2% after electrically heating with an electric current which is a ratio of y % to a fusion current (FC) at said wire diameter x μm, and wherein a semi-logarithmic system of coordinates is expressed by a horizontal axis using a logarithmic scale of said wire diameter x and a vertical axis using a normal scale of ratio y to said fusion current.   
   
   
       2 . The method as claimed in  claim 1 , wherein the tungsten sintered body further contains 40 to 100 ppm of potassium. 
   
   
       3 . The method as claimed in  claim 1 , wherein the tungsten wire is capable of use at a temperature above 1000° C. 
   
   
       4 . The method as claimed in  claim 1 , wherein the tungsten wire is capable of use at a temperature above 2500° C. 
   
   
       5 . A method of manufacturing a tungsten wire containing 1 to 10% by mass of rhenium and having a wire diameter of 20-90 μm, the method comprising the steps of:
 heating and rolling a tungsten sintered body containing 1 to 10% by mass of rhenium, wherein said rolling process utilizes a process rate of 40 to 75% for a rolling process with one heating process;   performing a recrystallization heat treatment;   heating and swaging the rolled sintered body after the recrystallization heat treatment;   heating and wire drawing the swaged sintered body; and   performing a strain removal heat treatment of said tungsten wire at a temperature of 1200 to 2300° C. at a time when a diameter of the tungsten wire formed by the swaging process or the wire drawing process is 100 μm or less;   said tungsten wire having a point which indicates a 5% elongation within a quadrangle formed by joining points with straight lines, where values of x and y are point (20, 73), point (20, 83), point (90, 72), and point (90, 56), in this order, wherein the wire diameter of said tungsten wire is represented by x μm, and the elongation of the tungsten wire is 5% after electrically heating with an electric current which is a ratio of y % to a fusion current (FC) at said wire diameter x μm, and wherein a semi-logarithmic system of coordinates is expressed by a horizontal axis using a logarithmic scale of said wire diameter x and a vertical axis using a normal scale of ratio y to said fusion current.   
   
   
       6 . The method as claimed in  claim 5 , wherein the tungsten sintered body further contains 40 to 100 ppm of potassium. 
   
   
       7 . The method as claimed in  claim 5 , wherein the tungsten wire is capable of use at a temperature above 1000° C. 
   
   
       8 . The method as claimed in  claim 5 , wherein the tungsten wire is capable of use at a temperature above 2500° C. 
   
   
       9 . A method of manufacturing a tungsten wire containing more than 10% by mass but 30% by mass or less of rhenium and having a wire diameter of 20-90 μm, the method comprising the steps of:
 heating and rolling a tungsten sintered body containing 10 to 30% by mass of rhenium, wherein said rolling process utilizes a process rate of 40 to 75% for a rolling process with one heating process;   performing a recrystallization heat treatment;   heating and swaging the rolled sintered body after the recrystallization heat treatment;   heating and wire drawing the swaged sintered body; and   performing a strain removal heat treatment of said tungsten wire at a temperature of 1200 to 2300° C. at a time when a diameter of the tungsten wire formed by the swaging process or the wire drawing process is 100 μm or less;   said tungsten wire having a point which indicates a 2% elongation within a quadrangle formed by joining points with straight lines, where values of x and y are point (20, 55), point (20, 63), point (90, 51), and point (90, 39), in this order, wherein the wire diameter of said tungsten wire is represented by x μm, and the elongation of the tungsten wire is 2% after electrically heating with an electric current which is a ratio of y % to a fusion current (FC) in said wire diameter x μm, and wherein a semi-logarithmic system of coordinates is expressed by a horizontal axis using a logarithmic scale of said wire diameter x and a vertical axis using a normal scale of ratio y to said fusion current.   
   
   
       10 . The method as claimed in  claim 9 , wherein the tungsten sintered body further contains 40 to 100 ppm of potassium. 
   
   
       11 . The method as claimed in  claim 9 , wherein the tungsten wire is capable of use at a temperature above 1000° C. 
   
   
       12 . The method as claimed in  claim 9 , wherein the tungsten wire is capable of use at a temperature above 2500° C. 
   
   
       13 . A method of manufacturing a tungsten wire containing more than 10% by mass but 30% by mass or less of rhenium and having a wire diameter of 20-90 μm, the method comprising the steps of:
 heating and rolling a tungsten sintered body containing 10 to 30% by mass of rhenium, wherein said rolling process utilizes a process rate of 40 to 75% for a rolling process with one heating process;   performing a recrystallization heat treatment;   heating and swaging the rolled sintered body after the recrystallization heat treatment;   heating and wire drawing the swaged sintered body; and   performing a strain removal heat treatment of said tungsten wire at a temperature of 1200 to 2300° C. at a time when a diameter of the tungsten wire formed by the swaging process or the wire drawing process is 100 μm or less;   said tungsten wire having a point which indicates a 5% elongation within a quadrangle formed by joining points with straight lines, where values of x and y are point (20, 53), point (20, 60), point (90, 48), and point (90, 37), in that order, wherein the wire diameter of said tungsten wire is represented by x μm, and the elongation of the tungsten wire is 5% after electrically heating with an electrical current which is a ratio of y % to a fusion current (FC) at said wire diameter x μm, and wherein a semi-logarithmic system of coordinates is expressed by a horizontal axis using a logarithmic scale of said wire diameter x and a vertical axis using a normal scale of ratio y to said fusion current.   
   
   
       14 . The method as claimed in  claim 13 , wherein the tungsten sintered body further contains 40 to 100 ppm of potassium. 
   
   
       15 . The method as claimed in  claim 13 , wherein the tungsten wire is capable of use at a temperature above 1000° C. 
   
   
       16 . The method as claimed in  claim 13 , wherein the tungsten wire is capable of use at a temperature above 2500° C.