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.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application is a Divisional of U.S. application Ser. No. 10 / 491,793, filed Apr. 6, 2004, which is based upon PCT National Stage Application No. PCT / JP2002 / 10474 filed Oct. 9, 2002, and claims the benefit of priority from prior Japanese Patent Application No. 2001-311533, filed Oct. 9, 2001, and the entire contents of each of these applications are incorporated herein by reference.TECHNICAL FIELD[0002]The present invention relates to tungsten wire, and in particular relates to a tungsten wire and a cathode heater with extensive elongation under conditions of high temperature, capable of exhibiting excellent shock resistance and durability (longevity) when used as a component of a vibration service lamp filament or a cathode heater.BACKGROUND ART[0003]In general, various tungsten wires have been widely used as components for discharge electrodes, contact elements, high temperature structural elements, filament material for use i...

AI Technical Summary

Benefits of technology

[0014]The inventors of the present invention have discovered that tungsten wire having high elongation properties even in an environment using high temperatures can be efficiently manufactured by means of adding the process of rolling at a high process rate of 40 to 75% after providing one heating treatment to swaging process of a tungsten sintered compact, and by precisely controlling the heating temperature when performing electrical heating treatment of a predetermined wire diameter, i.e. the ratio of the heating current value to the fusion current (FC), and thus have completed the present invention.

Problems solved by technology

However, when used under conditions of high temperatures above 1000° C. such as with cathode heaters, or when applied to uses which include a heat treatment process of over 2500° C. during the manufacturing process, there was the problem of easily decreased durability and longevity of the products in use because the strength and elongation would decrease.

However, thin wires made from Re—W alloy manufactured using conventional manufacturing processes had the difficulties of losing its elongation when heat treated at 2500° C. or higher, or the elongation gradually decreasing as a cathode heater was used for long periods of time, and problems occurred where the heater elements were damaged by minor impact or vibration in the cathode heater and longevity was decreased.

Therefore, in order to process the fixed tungsten thin wire raw material from a tungsten sintered compact, it is necessary to perform numerous repetitions of heat treatment and swaging processing as illustrated in FIG. 2, and while the manufacturing cost of tungsten wire increases due to the increasingly complicated manufacturing process of repetition of heating and swaging, strain (distortion) accumulates and the hardening effects do not work, so that only tungsten wire having a low tensile strength could be obtained.

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