JPH03283255A - High-pressure discharge lamp - Google Patents

Abstract

PURPOSE:To obtain an electrode with a stable arc by forming a base metal member dispersed with a rare earth oxide as emitters in a tungsten-rhenium alloy containing the specific wt.% of rhenium by a heat-treating means so that the average grain size is set to W<=0.1mm in a specific region in the vertical direction to the axis. CONSTITUTION:In a base metal member 1 dispersed with a rare earth oxide as emitters in a tungsten-rhenium alloy containing rhenium 1-27wt.%, most of emitters are fed to proceed straightly to the tip of the base metal member 1 along grain boundaries 3 of crystal grains 2 formed longitudinally with the average grain size 0.1mm or below in the vertical direction to the axial direction of the crystal structure within at least 10% of the region in the vertical direction to the center axis to the axis. Emission is satisfactory, and an arc is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a small xenon lamp, a water-cooled xenon lamp with an output of 30 KW, and a high-pressure discharge lamp used in a high-pressure mercury lamp, etc.

[Prior Art] Conventionally, electrodes made of tungsten containing yttrium oxide or lanthanum oxide have been used as electrodes for high-pressure discharge lamps (Utility Model Application No. 63-9762), as already proposed by the same applicant as the present application. There are electrodes made of tungsten containing cerium oxide and thorium oxide (see Japanese Utility Model Application No. 63-9763).

[Invention or problem to be solved] Tungsten containing rare earth oxides such as lanthanum oxide and yttrium oxide, which has been conventionally used as an electrode material, was originally developed as an electrode rod for welding and is used in high-pressure discharge lamps. The problem is that the crystal structure is not suitable for use as electrodes.

That is, in a high-pressure discharge lamp, for example, when used as a cathode, a high current density of about 3000 A/crrf flows through the cathode, and in addition, the stability of the arc between the electrodes is maintained. There are some challenges that must be met.

Therefore, in order to withstand the high temperatures caused by the flow of high-density current and maintain the stability of the arc, it is important to have good electron-emitting properties (emissions).
The issue is how to arrange the crystal structure of the rare earth oxide (emitter) so that it is constantly and smoothly supplied from the inside to the tip of the electrode.

There are also electrodes made of tungsten containing thorium oxide as an emitter, but thorium oxide is a radioactive substance, and tungsten containing thorium oxide requires careful handling, has high operating temperatures, and suffers from severe wear and tear. .

Furthermore, since the recrystallization temperature of conventional tungsten containing thorium oxide is 2000° C. or lower, recrystallization is likely to occur, and as a result, there is a problem that emitter supply cannot be carried out smoothly.

This invention has been made to solve these problems, and is a high-pressure discharge lamp having an electrode that is easy to handle, can withstand high temperatures, and can smoothly supply the emitter to stabilize the arc. The purpose is to provide

[Means for Solving the Problems] In order to achieve the above object, the high pressure discharge lamp of the present invention includes a base material in which a rare earth oxide is dispersed as an emitter in a tungsten-rhenium alloy containing 1 to 27% by weight of rhenium. In addition to processing the metal member into a planar or spherical shape suitable for supporting the tip or arc, heat treatment is used to reduce the area within at least 10% of the central axis of the base metal member in the direction perpendicular to the axis. In the area, the member is provided as an electrode with an average particle diameter W≦0° in a direction perpendicular to the axial direction of the crystal structure of the member, and one layer is formed. It is constructed to have a pressure of 1 atm or more.

[Function] By having the above structure, the crystal structure of the electrode is stabilized, recrystallization is prevented until the temperature rises, and the grain boundaries are stabilized, so that the emitter supply is performed smoothly and the arc becomes stable.

Also, when a lamp is made, there is hydrogen gas that remains as an impurity inside the lamp, but since rhenium has a weak adsorption ability for hydrogen gas compared to tungsten, it absorbs the hydrogen gas adsorbed on the electrodes when starting the lamp. It is less likely to be emitted and cause poor lighting, and therefore lighting performance is improved.

Furthermore, tungsten containing rhenium is
It has a lower work function than one that does not contain rhenium, and the lower the work function, the lower the operating temperature.Therefore, for the same current, the electrode temperature can be lowered, resulting in less wear and tear on the electrode.

[Example Figure 1 is a diagram shown to explain the crystal structure inside an electrode according to an example of the present invention in comparison with a conventional one.
is a base metal member that is an electrode.

2 is a crystal particle existing inside this base metal member l, 3
denotes the grain boundary formed between the crystal grains 2, and 4.5 denotes the side surface and tip of the base metal member 1, respectively.

In conventional electrodes, the emitter diffuses to the side surface 4 around the base metal member 1 and then travels along the surface of the base metal member l to the tip 5, which tends to cause the arc to become unstable.

However, in the base metal member 1 shown in FIG. 1, most of the emitters within at least 10% of the area from the central axis in the direction perpendicular to the axis are composed of average grains in the direction perpendicular to the axis of the crystal structure. The arc is supplied straight to the tip of the base metal member 1 through the grain boundaries 3 of vertically formed crystal grains 2 with a diameter of 0.1 m or less, resulting in good emission and stable arc.

FIG. 2 is a state diagram of metals and alloys of tank stainless rhenium alloy, which is described in, for example, "Metal Data Hook" published by Maruzen Co., Ltd. on January 30, 1984. In the figure,
The area below the solid line is a solid state, and the area above the dotted line is a liquid state.

As is clear from Figure 2, when rhenium has a high content exceeding 27%, its melting point is low and must be avoided as it creates another crystal layer. It is expensive and therefore not used in large quantities.

In this way, when a tungsten-rhenium alloy with a low melting point is used as an electrode, the electrode is likely to be worn out.

On the other hand, when the rhenium content is 27% or less, it is in a completely alloyed state (solid phase) at a temperature of 3000°C or lower.

The actual operating temperature of a high-pressure discharge lamp when lit is 2500.
Since the temperature does not reach 3000° C., the rhenium content should be 27% or less to be able to withstand this temperature. As is clear from FIG. 2, stable supply of the alloy emitter is carried out smoothly, and the stability of the arc is maintained.

Furthermore, as mentioned above, rhenium has a weak hydrogen adsorption property compared to tungsten, so rhenium is less likely to cause lighting failures, and its low work function lowers the operating temperature, reducing electrode wear and tear. Few.

Crystal grains having this structure require an area (6 in the figure) within at least 10% of the central axis of the base metal member 1 in a direction perpendicular to the axis.

This is because the region of the tip 5 has a diameter within 10% of the electrode diameter, and the emitter is supplied to this region from inside the electrode directly through the grain boundary, so the direction perpendicular to the axis from the central axis of the electrode This can be said because the area within at least 10% of the area is important for supplying the emitter to the tip of the electrode.

With this structure, most of the emitter has a width of 0 or 0.
．． It passes through the grain boundaries 3 of the M-product number 2, which are formed in a vertically elongated manner, and is smoothly supplied to the electrode tip 5, resulting in good emission and stable arcing.

Although CEO2 was used as the rare earth oxide of the present invention,
There is no particular limitation to this.

5. Does the content change depending on the type of discharge lamp?
If it is more than 0% by weight, it will be difficult to process the sintered body, and if it is more than 0.1
If the amount is less than 0.1 to 5.0% by weight, it will not be effective as an emitter, so if the electrode formed in this way is used in a 150W xenon lamp, the arc will be stable even if it is lit for 100 hours. was.

[Effects of the Invention] As explained above, the recrystallization temperature of conventional W/Th02 is low, so recrystallization tends to occur and there is a problem in supplying the emitter, but in the electrode of the present invention, the particle crystals are elongated. ,and,
The crystal structure is stabilized and recrystallization is inhibited when the temperature rises, and the grain boundaries are stabilized, so that the emitter is smoothly supplied and the arc is stabilized.

Furthermore, by incorporating rhenium into tungsten, lighting performance is improved due to weak adsorption of hydrogen, and wear of the electrodes is reduced because the electrode temperature is lowered for work-related reasons.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the crystal structure inside an electrode according to an embodiment of the present invention in comparison with a conventional one.
The figure is a phase diagram of metals and alloys of tungsten-rhenium alloy. In the figure, l two-substrate metal member 2: crystal grain: grain boundary 4, side tip

Claims (1)

[Scope of Claims] A base metal member made of a tungsten-rhenium alloy containing 1 to 27% by weight of rhenium with a rare earth oxide dispersed therein as an emitter, the tip of which has a planar or spherical shape suitable for supporting an arc. In a region within at least 10% from the central axis of the base metal member in the direction perpendicular to the axis, the average particle diameter W in the direction perpendicular to the axis of the crystal structure of the base metal member is reduced by the heat treatment means. ≦0.
A high-pressure discharge lamp, comprising the member formed to have a thickness of 1 mm as an electrode, and further configured such that discharge gas or steam is at 1 atm or more during lighting.