JPH09231939A - High melting point metal electrode, its manufacture, and electrode for discharge lamp using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tungsten electrode, its manufacture, and an electrode for a discharge lamp which is useful for significantly improving anode life by improving conventional tungsten material. SOLUTION: A high melting point metal electrode made of molybdenum, tungsten, its alloy, and the like is provided with a rhenium tungsten portion 6 made of the tungsten to which a rhenium element is added in the range of 1% to 25% in a weight ratio by powder metallurgy method at least at one portion. The high melting point electrode is used as a tungsten anode 5 in an electrode for a discharge lamp, and the rhenium tungsten portion 6 is formed at an electron plunge portion of the tungsten anode 5.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a refractory metal electrode such as a tungsten electrode, and more particularly to a refractory metal electrode used in a discharge lamp or the like.

[0002]

2. Description of the Related Art Generally, tungsten manufactured by powder metallurgy is used as an electrode material for an anode of an electrode of a discharge lamp or the like. This is because high heat resistance and discharge characteristics are required for the anode of the discharge electrode (hereinafter simply referred to as "anode"), and up to now no alternative material has been discovered.

As a method for producing metal tungsten for electrodes, generally, refining or reducing is performed based on ore or an intermediate product to produce powdered tungsten, which is then hardened by a powder metallurgy method and transferred to a compacted one. After forming into an electrode by performing plastic working such as cutting, cutting, etc., it is heat-treated at 1600 ℃ to 2400 ℃ in vacuum to remove the residual gas components inside, and is used by being incorporated inside a discharge lamp or the like. It

[0004]

However, the electrode for a discharge lamp manufactured based on the tungsten material manufactured by the conventional method is used as a discharge lamp due to the blackening phenomenon of the glass surface inside the discharge lamp relatively early. Will bring a lifetime. More specifically, the blackening phenomenon will be explained. In this discharge lamp, when a voltage is applied to each electrode, a discharge occurs from the cathode toward the anode, and this discharge excites the internal gas to function as a discharge lamp. At this time, in the electrode part, the electrons emitted from the cathode rush into the anode with high energy. The anode into which the electrons have entered is partially heated to a high temperature of 2000 ° C. or higher due to the kinetic energy of the electrons and Joule heat. However, it is generally known that in this high temperature state, the tungsten of the anode causes rearrangement behavior of crystal grains. At this time, in the case of general tungsten, an impurity element accumulation phenomenon occurs at the grain boundary, resulting in a difference in electron density between the crystal grain and the grain boundary.
In particular, at the grain boundary, the melting point is lowered due to the accumulation of the above-mentioned elements and the temperature is raised due to the increase in electron density, so that the evaporation and diffusion of the components remarkably occur.

Further, in recent years, with the increase in size and output of the device, the anode is required to have further discharge characteristics and life.

[0006] Therefore, the technical problem of the present invention is to meet these requirements, by refining a conventionally used tungsten material, a refractory metal electrode useful for greatly improving the life of the anode, a method for producing the same, And to provide an electrode for a discharge lamp using the same.

[0007]

According to the present invention, at least a part is provided with a rhenium tungsten part made of tungsten to which a rhenium element is added in a weight ratio of 0.1% to 25%. A high melting point metal electrode is obtained.

Further, according to the present invention, in the refractory metal electrode, there can be obtained a refractory metal electrode in which the rhenium tungsten portion is bonded to a refractory metal.

Further, according to the present invention, any one of the refractory metal electrodes is used as an anode, and the rhenium tungsten portion is formed in an electron rush portion of the anode. Is obtained.

Further, according to the present invention, there is provided an electrode for a discharge lamp characterized in that the electrode for a discharge lamp and a cathode made of a refractory metal are sealed in a sealed tube so as to face each other with a sealed gas. can get.

Further, according to the present invention, a rhenium tungsten part made of tungsten in which a rhenium element is added to a refractory metal in a weight ratio of 0.1% to 25% is formed at least in part. A method for manufacturing a refractory metal electrode is obtained.

Further, according to the present invention, in the method for producing a refractory metal electrode, the rhenium tungsten portion is formed on the refractory metal by pressing, clad, or CVD method. A manufacturing method is obtained.

In the present invention, the refractory metal is preferably molybdenum, tungsten, or an alloy thereof.

In the present invention, the tungsten electrode used as the anode of the discharge lamp has a weight ratio of 0.1 to tungsten.
% -25% rhenium-added tungsten electrode is processed into a predetermined shape, and then heat treatment is performed in a vacuum to remove the residual gas components inside, and then the discharge lamp By using it as an anode, it is possible to greatly improve the life due to the blackening phenomenon.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an outline of a discharge lamp according to an embodiment of the present invention. Referring to FIG. 1, the discharge lamp comprises a tungsten alloy cathode 3 having a diameter larger than that of the electrode support 2 provided at the tip of the first electrode support 2 and a tungsten electrode provided at the tip of the second electrode support 4. And a tungsten anode 5. The tungsten anode 5 and the tungsten alloy cathode 3 are sealed opposite to each other in a quartz sealing tube 8 filled with a sealing gas 7. The above is the same configuration as the conventional technique.

In the discharge lamp according to the embodiment of the present invention, the rhenium-tungsten portion 6 is provided at the tip of the tungsten anode 5.
Are formed. It is formed by bonding rhenium tungsten (Re-W) to tungsten by a press or the like. Rhenium tungsten part 6
Is a tungsten electrode to which rhenium is added in the range of 0.1 to 25%. Here, the rhenium tungsten portion may be formed in a portion where electrons enter, for example, an end surface and a surface portion on the electrode support side facing the cathode.

The tungsten electrode is used as an anode of a discharge lamp after being subjected to heat treatment in a vacuum for removing residual gas components inside after adding rhenium. When this tungsten electrode is used as the anode of a discharge lamp, the strengthening phenomenon by the additive element occurs in the grain boundary of tungsten in the usage situation, and the electron density of the grain boundary is increased due to the preferential bonding of the impurity element and the additive element. Do not focus. Therefore, it is possible to remarkably prevent the blackening phenomenon on the inner surface of the glass caused by the evaporation of the anode, which is the life of the discharge lamp. Further, the same effect can be obtained by bonding Re-W only to the portion of the tungsten anode tip where electrons enter, or by forming a Re-W layer by using a technique such as CVD.

Specific examples of the discharge lamp according to the embodiment of the present invention will be described below.

(Specific Example 1) 3% by weight ratio to tungsten
In order to remove the residual gas components inside by performing sintering, forging, and cutting using general tungsten powder to which the rhenium element has been added, as shown in FIG. 2000 heat treatment in vacuum
It was carried out at a temperature of ℃, and a tungsten electrode containing rhenium element was manufactured. This tungsten electrode was used as an anode in a discharge lamp and an experiment was conducted on its blackening, and the blackening status was compared with that of a pure tungsten electrode of general purity with no rhenium added. The result of the experiment is shown in FIG. As a result of testing and comparing the tungsten electrode anode having a general purity and the anode according to the embodiment of the present invention under the same conditions, it was found that, when the blackening degree of the tungsten electrode having a general purity after 2500 hours was 100, The blackening degree of the tungsten electrode according to the embodiment of the present invention after the lapse of time was 51, which was an improvement.

(Specific Example 2) FIG. 3 shows the results of Specific Example 1 after 2000 Hr of an anode made of a tungsten electrode prepared by the same method as above, while changing the addition amount of rhenium. The comparison was made assuming that the blackening degree was 100 when a general tungsten electrode of 2500 Hr was used as an anode.

From the results of this experiment, it was revealed that the addition of rhenium in the range of 0.1% to 25% improves the life of the tungsten electrode due to the blackening of the anode.

(Example 3) After 3% Re-W and W were bonded together by a press, an electrode manufactured by the same method as in Example 1 was compared with 3% Re-W in Example 2 to find that the degree of blackening was Is 1
7, and almost the same result as the tungsten electrode according to the second specific example was obtained.

[0024]

As described above, according to the present invention,
It is possible to provide a tungsten electrode capable of improving the shortening of the life of the discharge lamp caused by the blackening phenomenon caused by evaporation of the anode metal of the discharge lamp.

Further, according to the present invention, general tungsten processing equipment can be used as it is, so that industrialization is very easy.

Further, according to the present invention, the tungsten electrode can be manufactured at a relatively low cost without using a large amount of expensive rhenium by making only the electron rush portion of the anode Re-W.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a discharge lamp according to an embodiment of the present invention.

FIG. 2 is a diagram showing changes in blackening of the discharge electrodes of the discharge lamp according to the embodiment of the present invention.

FIG. 3 is a diagram showing the degree of blackening of the discharge electrode of the discharge lamp according to the embodiment of the present invention after 2000 hours.

[Explanation of symbols]

 1 Discharge Lamp 2 Electrode Support 3 Tungsten Alloy Cathode 4 Electrode Support 5 Tungsten Anode 6 Rhenium Tungsten Part 7 Filled Gas 8 Quartz Filled Tube

Claims (6)

[Claims] 1. A refractory metal electrode comprising at least a part of a rhenium tungsten part made of tungsten to which a rhenium element is added in a weight ratio of 0.1% to 25%. 2. The refractory metal electrode according to claim 1, wherein the rhenium tungsten portion is bonded to a refractory metal. 3. A discharge lamp electrode, wherein the refractory metal electrode according to claim 1 or 2 is used as an anode, and the rhenium tungsten portion is formed in an electron rush portion of the anode. 4. An electrode for a discharge lamp, characterized in that the electrode for a discharge lamp according to claim 3 and a cathode made of a refractory metal are sealed in a sealed tube so as to face each other and filled with a sealed gas. 5. The weight ratio of the refractory metal is 0.1% to 25%.
A method of manufacturing a refractory metal electrode, comprising forming a rhenium-tungsten part made of tungsten to which a rhenium element is added in at least part of the above range. 6. The method for manufacturing a refractory metal electrode according to claim 5, wherein the rhenium tungsten portion is formed on the refractory metal by pressing, clad, or CVD method. .