KR101202160B1 - Cladding material for discharge electrode, process for producing the same and discharge electrode - Google Patents

Abstract

Provided are a clad material having excellent deep drawing molding for a cup-shaped discharge electrode, a method of manufacturing the same, and the like.

The cladding material of the present invention has a base layer 1 formed of pure Ni or a Ni base alloy containing Ni as a main component, and a surface layer 2 formed of pure Nb having an oxygen content of 550 ppm or less. The surface layer 2 is diffusion bonded directly to the base layer 1 or through a NiNb intermetallic compound layer of 8.0 mu m or less. Preferably, the base layer 1 and the surface layer 2 are diffusion-bonded by continuous annealing in an Ar gas atmosphere having a dew point of −40 ° C. or lower. By this continuous annealing, it is possible to efficiently diffusion-bond the base layer 1 and the surface layer 2 with high efficiency while easily suppressing the amount of oxygen in the surface layer 2 below 550 ppm.

Discharge electrode, intermetallic compound layer

Description

Clad material for discharge electrode, manufacturing method thereof and discharge electrode {CLADDING MATERIAL FOR DISCHARGE ELECTRODE, PROCESS FOR PRODUCING THE SAME AND DISCHARGE ELECTRODE}

The present invention relates to, for example, a discharge electrode of a fluorescent discharge tube used as a backlight of a liquid crystal display device and an electrode material thereof.

A small fluorescent discharge tube is used as a backlight for a liquid crystal display device. In such a fluorescent discharge tube, as shown in Fig. 3, a fluorescent film (not shown) is formed on an inner wall surface, and a discharge gas (rare gas such as argon gas) is formed therein. And a discharge electrode 52 constituting a glass tube 51 filled with mercury vapor and a pair of cold cathodes provided at both ends of the glass tube 51. The discharge electrode 52 has a pipe part 53 having one end opened, and a cup shape (the bottom of which the other end of the pipe part 53 is closed in the end plate part 54). In the shape of a barrel). One end of the axial support conductor 55 sealed through the end of the glass tube 51 is welded to the end plate portion 54, and the support conductor 55 is welded. The lead wire 57 is connected to the other end of The support conductor 55 is generally formed of W (tungsten) and is typically laser welded to the discharge electrode 52.

The discharge electrode 52 is conventionally formed of pure Ni. The size of the discharge electrode 52 is for a small fluorescent discharge tube such as a backlight, which is about 1.5 mm in inner diameter, about 5 mm in total length, and a pipe part ( 53) is about 0.1mm thick. Such a discharge electrode is normally integrally formed by deep drawing a pure Ni thin plate having the same thickness as that of the tube portion.

As described above, the discharge electrode for the fluorescent discharge tube is formed of pure Ni, which is good in formability and stable in material, but has a problem in that lamp life is relatively short. In other words, when the fluorescent discharge tube is turned on, ions or the like collide with the electrodes to release atoms from the electrode metal (sputtering). The electrode metal is consumed by such sputtering, and the atoms of the released electrode metal combine with mercury encapsulated in the glass tube, thereby consuming mercury vapor in the glass tube. Conventionally, Ni forming the electrode metal has a problem in that the lifetime of the discharge tube tends to decrease because the amount of atomic emission during sputtering is large, that is, the sputtering ratio is high and the consumption of mercury is large.

For this reason, in recent years, as described in Japanese Patent Application Laid-Open No. 2002-110085 (Patent Document 1), it has been attempted to form a discharge electrode of Nb (niob) having a low factor. However, Nb is expensive compared with Ni. In addition, Nb is high melting | fusing point (2793 degreeC), and it is necessary to weld at high temperature at the time of welding with the support conductor of W (melting point 3653 degreeC) which is the same high melting point metal. For this reason, a firm oxide film is easily formed in a welded part. When the discharge electrode welded with the supporting conductor is sealed in the glass tube while the oxide film is attached, the oxide film decomposes during discharge to generate oxygen. This oxygen reacts with the fluorescent film on the inner surface of the tube to deteriorate the fluorescent film. For this reason, the process of removing the oxide film formed in the electrode surface after welding of a support conductor is needed.

By the way, in recent years, as described in Paragraph 0024 of Japanese Patent Laid-Open No. 2002-289138 (Patent Document 2) and International Publication WO2005 / 048285 (Patent Document 3), a discharge electrode is formed in two layers inside and outside. Therefore, attempts have been made to form the outer layer with Ni and the inner layer substantially contributing to the discharge with Nb. In Patent Document 3, a base layer metal sheet formed of Ni and a surface layer metal sheet formed of Nb are press-bonded as a method of manufacturing a discharge electrode having a two-layer structure, and the pressure-contacting material is diffused and annealed ( (Iii) A blank material is taken from the clad material, and deep drawing is carried out in a cup shape.

Patent Document 1: Japanese Patent Publication No. 2002-110085

Patent Document 2: Japanese Patent Application Laid-Open No. 2002-289138

Patent Document 3: International Publication WO2005 / 048285

When manufacturing the clad material, it is necessary to diffuse-anneal the base layer and the surface layer of the pressure-sensitive adhesive material, but since Nb is a material which is very easily oxidized, the pressure-contacting material is usually vacuum Batch-annealed in a heating furnace. That is, the pressure contact member is charged into a vacuum heating furnace, the furnace is vacuumed, and then the temperature is raised to a predetermined temperature and maintained at that temperature. In this case, since the heating atmosphere is vacuum, even if the temperature rise rate is slow and the holding time at the target annealing temperature is shortened, in the process of reaching the target annealing temperature or cooling from the target annealing temperature, the temperature is reduced to 800. The time of exposure to a high temperature range of more than a degreeC becomes long. For this reason, the NiNb intermetallic compound produced between the base layer and the surface layer inevitably grows. When the NiNb intermetallic layer is thin, there is no problem in the bonding between the two layers, but if the intermetallic layer becomes thick to some extent, cracks occur during deep drawing, and the surface layer cannot follow the deformation of the base layer during molding. There is a concern that cracks occur on the surface.

On the other hand, in the case of diffusion annealing the pressure-contacting material using a continuous annealing furnace, the temperature rise to the target annealing temperature and the temperature drop after annealing are accelerated, and excessive growth of the NiNb intermetallic compound layer can be suppressed. In this case, it is necessary to make the atmosphere inside the furnace practically an Ar gas atmosphere. However, according to the experiment of the inventors, in normal Ar gas atmosphere (about dew point -20 degreeC), a crack may enter into an Nb layer at the time of deep drawing molding, and especially when a molding condition becomes severe, a crack will become remarkable. It was found to occur. In addition, nitrogen gas and hydrogen gas cannot be used as the heating atmosphere gas. This is because nitrogen forms nitride with Nb, and hydrogen is easily absorbed by Nb, and both of them embrittle the Nb layer and deteriorate formability.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide a clad material having excellent deep drawing property to a cup-shaped discharge electrode, a method for manufacturing the same, and a discharge electrode molded from the clad material.

(MEANS FOR SOLVING THE PROBLEMS)

The cladding material for a discharge electrode of the present invention has a base layer formed of pure Ni or a Ni-based alloy containing Ni as a main component, and a surface layer formed of pure Nb, wherein the surface layer does not pass through the NiNb intermetallic compound layer or NiNb. The oxygen content in the net Nb forming the surface layer by diffusion bonding to the base layer through the intermetallic compound layer is 550 ppm or less, and the layer thickness of the NiNb intermetallic compound layer is 8.0 μm or less.

According to such a cladding material, since the surface layer is formed of pure Nb having an oxygen content of 550 ppm or less, it is excellent in ductility. In addition, since the surface layer is diffusion-bonded directly to the base layer or through a NiNb intermetallic compound layer of 8.0 μm or less, where cracks are less likely to occur, the adhesion between the base layer and the surface layer is excellent. This excellent bonding property and the ductility excellent in the surface layer match each other, and the clad material is excellent in deep drawing property.

Preferably, the base layer and the surface layer are diffusely annealed by continuous annealing in an Ar gas atmosphere at -40 ° C or lower. By this continuous annealing, the base layer and the surface layer can be efficiently diffusion-bonded while easily suppressing the amount of oxygen absorbed into the surface layer to 550 ppm or less, which is excellent in the productivity of the clad material.

In addition, the base layer alone or in combination with Nb, Ta contains 1.0mass% or more, 12.0mass% or less, preferably formed of a Ni-based alloy composed of the balance Ni and unavoidable impurities. By adding a predetermined amount of Nb and Ta to Ni, corrosion resistance to mercury vapor can be improved and durability of the discharge electrode can be improved.

Moreover, it is preferable that the said surface layer shall be 20 micrometers or more and 100 micrometers or less in thickness.

By setting the thickness of the surface layer to 20 µm or more and 100 µm or less, it is possible to ensure a lifetime equivalent to that of a discharge electrode formed entirely of pure Nb by using a small amount of Nb. For this reason, the material cost of a clad material can be reduced and it is economical.

Moreover, it is preferable to make thickness of surface layer into 70% or less with respect to the thickness of the sum total of the said base layer and surface layer. By setting the thickness of the surface layer in this manner, the base layer can act as a backup layer of the surface layer when forming the cup-shaped discharge electrode. As a result, it is possible to prevent the formation of irregularities due to the ludus band in the surface layer formed of Nb having a high yield point elongation, and to secure good press formability. If the thickness of the surface layer exceeds 70% of the total thickness, even if the base layer is provided as a backup layer, it is difficult to suppress the occurrence of the irregularities, and the press formability is rather deteriorated. For this reason, the thickness of the surface layer is preferably 70% or less, more preferably 60% or less with respect to the total thickness.

In addition, the discharge electrode of the present invention is a discharge electrode in which one end of the tube part is released, and the other end of the tube part is closed, and the tube part and the end plate part are integrally manufactured by press molding. The electrode is molded by the cladding material, and the inner layers of the pipe portion and the end plate portion are formed by the surface layer of the cladding material. Since such a discharge electrode is molded using the said clad material which is excellent in deep drawing forming, since the useless Nb amount which is excellent in productivity and does not contribute to discharge is saved, material cost can be reduced. Moreover, since the base layer formed by pure Ni etc. exists in the outer side of a end plate part, weldability with a support conductor is also favorable.

In addition, in the method for producing a cladding material for a discharge electrode of the present invention, the base metal sheet formed of pure Ni or a Ni-based alloy containing Ni as a main component and the surface metal sheet formed of pure Nb are overlapped and pressed to form a base layer and a surface layer. The pressure contact process for manufacturing the pressure contact material and the pressure contact material is maintained at an annealing temperature range of 800 to 1100 ° C. for 15 seconds or more and 120 seconds or less in an Ar gas atmosphere at a dew point of −40 ° C. or lower, thereby maintaining the base layer and the surface layer. It has a diffusion annealing process of diffusion bonding.

According to this manufacturing method, despite the diffusion bonding of the base layer and the surface layer of the pressure-sensitive adhesive material by using the continuous annealing furnace, the oxygen content of the surface layer of the clad material can be easily reduced to 550 ppm or less, and NiNb generated between the surface layer and the base layer. The thickness of the intermetallic compound layer can be suppressed to 8.0 μm or less. For this reason, the clad material excellent in deep drawing property can be manufactured easily, and it is excellent in productivity.

With respect to this manufacturing method, the base layer may be formed of a Ni base alloy containing 1.0 mass% or more and 12.0 mass% or less in total of one kind or two kinds of Nb and Ta, and the balance Ni and unavoidable impurities. Further, a finish rolling step of adjusting the thickness of the clad material by performing finish rolling on the diffusion-annealed clad material can be provided.

(Best Mode for Carrying Out the Invention)

1 shows a cross-sectional view of a clad material for a discharge electrode according to an embodiment of the present invention, which is a base layer 1 formed of pure Ni or a Ni base alloy containing Ni as a main component, and a surface layer 2 formed of pure Nb. ), The surface layer (2) is roll pressed on the base layer (1), and further diffusion bonded. The surface layer 2 is diffusion-bonded to the base layer 1 through a very thin NiNb intermetallic compound layer of 8.0 μm or less, but the NiNb intermetallic compound layer is not shown in FIG. 1. About this intermetallic compound layer, description of the manufacturing method of the clad material mentioned later is demonstrated.

Pure Ni and Ni base alloys (hereinafter, collectively referred to as "Ni base metals") forming the base layer 1 are excellent in oxidation resistance, excellent in cold workability, and also in deep drawing properties. Good. The Ni-based alloy has a Ni content of 80 mass% or more, more preferably 85 mass% or more, and the amount of 1 in an alloy element (eg, Nb, Mo, W, Ta, V, Ti) dissolved in Ni It is preferable that it contains a species or more and consists of remainder Ni and an unavoidable impurity. Among the above Ni-based alloys, Nb and Ta are contained alone or in combination with 1.0 to 12.0 mass%, more preferably a Ni-Nb alloy, a Ni-Ta alloy, and a Ni-Nb-Ta alloy composed of residual Ni and unavoidable impurities. . Nb and Ta do not deteriorate moldability when the amount is added at this level, and have an effect of improving the corrosion resistance to mercury vapor, thereby improving durability of the electrode. Moreover, the Ni-W alloy which contains 2.0-10 mass% of W, and remainder becomes substantially Ni is also more preferable. W, like Nb and Ta, can improve the corrosion resistance to mercury vapor. W may be added in combination with Nb and / or Ta in the above-described content range, but in this case, the amount of W is preferably limited to 6.0% or less.

Although the said surface layer 2 is formed of pure Nb, it is more preferable that there are few gases, such as oxygen, hydrogen, and nitrogen, which are easy to be absorbed (solidified) by Nb. As will be described later, the clad material is industrially produced by polymerizing and pressing a metal sheet, which is a material of each layer, and then pressing the obtained pressure contact material in an Ar gas atmosphere, but in this case, the water contained in the Ar gas Oxygen generated by decomposition at this high temperature may be absorbed by Nb. When oxygen is absorbed and the amount of oxygen in the Nb exceeds 550 ppm, the ductility of the Nb is markedly deteriorated, thereby degrading the deep drawing formability of the clad material. For this reason, in this invention, the oxygen concentration in the net Nb which forms a surface layer stops at 550 ppm or less, Preferably it is 400 ppm or less. In addition, since pure Nb is manufactured by the vacuum dissolution method, the oxygen content in the produced pure Nb is about 200 ppm or less.

Although the thickness of the said surface layer 2 is about 20 micrometers from the consumption form of a discharge electrode, it should be about 20-100 micrometers, Preferably it is about 40-80 micrometers in consideration of a balance with safety and the thickness of the whole clad material. On the other hand, the thickness of the entire cladding material is about 0.1 mm to 0.2 mm to secure deep drawing formability. Although the thickness of the said base layer 1 is suitably set in order to ensure the whole thickness in consideration of the thickness of the said surface layer 2, about 20-50 micrometers is enough from a viewpoint of ensuring the weldability of a support electrode. In addition, in order to act as a backing layer for preventing deformation of the surface layer 2 and to ensure good press formability during deep drawing, the thickness of the surface layer 2 is the surface layer 2 and the base layer 1. Is 70% or less of the total thickness (total thickness of the cladding material), preferably 60% or less.

FIG. 2 shows a cup-shaped discharge electrode formed by deep drawing using the cladding material. The discharge electrode has a tube portion 11, one end of which is released, and a end plate portion 12 that closes the other end thereof, and the end plate portion 12 is integrally formed together with the tube portion 11. It is becoming. The inner layer of the discharge electrode is formed of the surface layer 2 of the cladding material. When used as a discharge electrode, since the discharge is mainly consumed by the bottom inner surface of the discharge electrode, by forming the discharge electrode intermediate layer as the surface layer 2, the discharge characteristics equivalent to those of the Nb-only discharge electrode and the service life of the fluorescent discharge tube It is possible to reduce the amount of Nb used while ensuring. In addition, the presence of the base layer 1 facilitates welding with the supporting conductor.

The cup-shaped discharge electrode is deep drawn by press molding using a disk-shaped blank material punched out of the clad material as a molding material. When punching the blank material, for example, a part of the blank material may be connected to the outer circumference of the clad material via a connection part, and after the deep drawing molding of the plurality of cup-shaped discharge electrodes, the discharge electrode may be separated from the connection part.

Here, the manufacturing method of the said clad material is demonstrated. First, the Nb sheet (surface metal sheet) serving as the basis of the surface layer 2 is polymerized to the Ni base metal sheet (base metal sheet) serving as the base of the base layer 1, and roll-welded. That is, the polymeric material which superposed | polymerized the Ni sheet | seat and Nb sheet | seat is crimped | bonded through a pair of rolls. This press welding can be performed by cold. The reduction ratio in roll pressure welding may be about 50 to 70% normally. This manufacturing process is called a pressure welding process. By this press welding process, the press contact material with which the base layer and the surface layer were press-contacted can be obtained.

Next, the pressure-contacting material is diffusely annealed at a temperature of about 800 to 1100 ° C, preferably at 900 to 1050 ° C. This manufacturing process is called a "diffusion annealing process." If it is less than 800 degreeC, diffusion will hardly occur, and if it exceeds 1100 degreeC, diffusion will become remarkable, The NiNb intermetallic compound layer produced | generated at the interface of the base material and surface layer of a pressure bonding material will grow in a short time, and the thickness will exceed 8 micrometers. The thick NiNb intermetallic layer, such as more than 8 µm, is very brittle and easily cracked, thereby degrading the formability of the clad material. It is preferable that the thickness of the said NiNb intermetallic compound layer shall be 6.5 micrometers or less. As for time to hold | maintain in said temperature range of 800-1100 degreeC, about 15 to 120 second is preferable. If it is less than about 15 seconds, when the target annealing temperature is about 800 DEG C, the diffusion will be insufficient and the bonding strength will decrease, resulting in deterioration of the formability of the clad material. On the other hand, if it exceeds 120 seconds, when the target annealing temperature is about 1100 DEG C, the diffusion becomes excessive, the intermetallic compound grows remarkably, the bonding strength decreases, and there is a possibility that the formability deteriorates. Preferable target annealing temperature is about 900-1050 degreeC.

As an annealing method that can easily satisfy the diffusion annealing condition, continuous annealing in which the heating atmosphere is an Ar gas atmosphere is recommended. The continuous annealing is performed using a continuous annealing furnace. In the continuous annealing furnace, the Ar gas is supplied into the tunnel furnace so as to have a positive pressure (pressure about 0.0005 to 0.001 MPa higher than the atmospheric pressure), so that the desired temperature distribution can be obtained along the longitudinal direction of the furnace. Controlled. By supplying the material to be treated (for example, strip-shaped pressure-contacting material) to the continuous annealing furnace and conveying it at a predetermined conveying speed in the longitudinal direction of the furnace, the predetermined temperature is based on the conveying speed and the pre-formed temperature distribution. Holding time can be given to a to-be-processed material.

In the case of performing the continuous annealing, in the present invention, the dew point of the Ar gas to be supplied is set to -40 ° C or lower, preferably -45 ° C or lower. When the dew point exceeds -40 DEG C, the moisture contained in Ar gas increases, and this moisture decomposes under high temperature annealing temperature, so that oxygen generated is absorbed into Nb. For this reason, the ductility of surface layer deteriorates and the moldability of a clad material falls. The dew point can hold the oxygen concentration in the surface layer of the clad material at 550 ppm or less by reducing the holding time in the temperature range of 800 to 1100 ° C in the Ar gas atmosphere below -40 ° C, thereby suppressing the ductility deterioration of the surface layer. You can do it.

The diffusion annealing of the pressure contact member may be performed under vacuum. Above all, in order to make the amount of oxygen in the net Nb forming the surface layer 2 550 ppm or less, it is preferable to select a heating and cooling method that satisfies the annealing conditions. The following vacuum heating method is mentioned as an example. Using a vacuum chamber provided with a heating device in the chamber, the object to be processed is stored in the vacuum chamber, and the inside of the chamber is vacuumed, and the object is quickly heated and maintained at a predetermined temperature by the heating device. At the time of cooling, heating is stopped and Ar gas is introduced into the vacuum chamber to cool rapidly. When the diffusion annealing is performed under vacuum, almost no NiNb intermetallic compound layer is formed between the base layer 1 and the surface layer 2, and the surface layer 2 can be diffusion bonded directly to the base layer 1.

The clad material after diffusion annealing can be cold rolled as needed. As a result, the plate thickness of the clad material can be adjusted. After finishing rolling, in order to soften the material, annealing may be performed under the same conditions as the diffusion annealing as necessary. The clad material manufactured as described above is slit to an appropriate width as necessary, and further, the blank material is punched out of the slit strip material, and the blank material is provided for press molding.

Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not interpreted limitedly by these Examples.

BRIEF DESCRIPTION OF THE DRAWINGS The principal part sectional drawing of the clad material for discharge electrodes which concerns on embodiment of this invention is shown.

2 is a longitudinal cross-sectional view of a discharge electrode for a fluorescent discharge tube according to the embodiment of the present invention.

3 is a longitudinal sectional view of an essential part of a fluorescent discharge tube having a discharge electrode for a conventional fluorescent discharge tube.

(Explanation of Symbols)

1 base layer 2 surface layer

11 pipe 12 end plate

Samples of various clad materials in which the surface layer formed of pure Nb was diffusion-bonded under various conditions on the base layer formed of pure Ni were produced by the following method. Pure Ni sheet (30mm in width, 100mm in length, 0.5mm in thickness) as the base of the base layer and pure Nb sheet (30mm in width, 100mm in length and 0.15mm in thickness) as the basis of the surface layer are prepared, polymerized and cold roll-welded. And the pressure contact sheet of thickness 0.28mm was obtained. The press contact sheet was subjected to diffusion annealing under various conditions shown in Table 1 through a continuous annealing furnace of an Ar gas atmosphere, and then cold rolled to each obtained clad material, so that the thickness of each clad material was 0.15 mm (0.114 mm, the thickness of the substrate). Surface layer thickness (0.036 mm)). In addition, about some of the pressure welding sheets, the sheet was annealed under the conditions shown in Table 1 in a vacuum furnace, and cold rolling was applied to the obtained clad material so as to have the above thickness.

A sample of each clad material produced as described above was embedded in a resin, and the obtained resin block was polished so that the cross section of the embedded clad material was exposed to the surface. And about the sample of each clad material, the average thickness of the NiNb intermetallic compound layer produced | generated between the base layer of the clad material and the surface layer was measured using the electron microscope (1000-3500 times magnification). Moreover, the analysis piece was extract | collected from each clad material, and oxygen content was measured with the oxygen nitrogen analyzer (model number EMGA-520, product made by Horiba, Ltd.). Since the amount of oxygen in the base layer was about 1 to 2 ppm and a trace amount, the measured amount of oxygen was defined as the amount of oxygen in the surface layer. These measurement results are shown in Table 1 together.

Next, using the cladding materials described above, as illustrated in FIG. 2, the cup-shaped discharge electrodes having an outer diameter of 1.1 mm, an inner diameter of 0.9 mm, and a pipe length of 4 mm were subjected to drawing processing in 10 steps without performing intermediate annealing. Deep drawing was performed, and the crack generation state of the cup-shaped discharge electrode after molding was visually observed. The results are shown in Table 1 together. Since the base material of the clad material is excellent in malleability, the clad material of any sample could be formed until the final process without cracking in the outer layer of the cup-shaped discharge electrode corresponding to the base material of the clad material. On the other hand, in the clad material, as shown by the molding result of Table 1, there existed a crack in the inner layer of the cup-shaped discharge electrode corresponding to the surface layer of the clad material. This crack is presumed that at the time of molding, the surface layer of the clad material failed to follow the deformation of the base layer.

From Table 1, in the cladding material of the invention example, since the average thickness of the NiNb intermetallic compound layer was only 6.5 micrometers or less, and the oxygen content of the surface layer was also 380 ppm or less, the outstanding deep drawing formability was obtained. In contrast, the dew point of Ar gas was -35 ° C or higher. In the cladding materials of 4 and 5, the amount of oxygen in the surface layer was excessively 700 ppm or more, the ductility of the surface layer was deteriorated, and cracks occurred in the surface layer. In addition, sample No. annealed in a vacuum furnace. In the cladding material of 3, the time required to be maintained at 800 ° C or higher was inevitably long, and the deep drawing property was deteriorated because the intermetallic compound layer grew excessively.

[Table 1]

According to the present invention, it is possible to provide a clad material having excellent deep drawing molding for a cup-shaped discharge electrode, a manufacturing method thereof, and the like.

Claims (10)

delete A base layer formed of pure Ni or a Ni base alloy, a surface layer formed of a NiNb intermetallic compound layer and pure Nb, The surface layer is diffusion-bonded to the base layer through the NiNb intermetallic compound layer, the oxygen content in the net Nb forming the surface layer is 550 ppm or less, and the discharge thickness of the NiNb intermetallic layer layer is 8.0 μm or less. Dragon clad material. 3. The method of claim 2, The base layer and the surface layer, the clad material for a discharge electrode, which is diffusion-bonded by continuous annealing in an Ar gas atmosphere having a dew point of −40 ° C. or less. 3. The method of claim 2, The base layer comprises at least 1.0 mass%, not more than 12.0 mass% of one kind or two kinds of Nb and Ta, and the remainder is formed of a Ni base alloy composed of Ni and inevitable impurities. The method according to any one of claims 2 to 4, The said cladding material is 20 micrometers or more and 100 micrometers or less in thickness, and is 70% or less of the cladding materials for discharge electrodes with respect to the thickness of the sum total of the said base layer and surface layer. As a discharge electrode having a pipe part of which one end is released and a end plate part which closes the other end of the pipe part, the pipe part and the end plate part are integrally manufactured by press molding. A discharge electrode, wherein said discharge electrode is molded by the clad material as described in any one of Claims 2-4, and the inner layer of the said pipe part and the end plate part was formed by the surface layer of the clad material. Press-bonding process for polymerizing and pressing the base metal sheet formed of pure Ni or Ni-based alloy and the surface metal sheet formed of pure Nb to form a press contact material in which the base layer and the surface layer are press-bonded. Diffusion annealing in which the pressure-contacting material and the pressure-contacting material are kept at least 15 seconds and not more than 120 seconds in an annealing temperature range of 800 to 1100 ° C. in an Ar gas atmosphere having a dew point of −40 ° C. or lower, and diffusion bonding the base layer and the surface layer. A method for producing a cladding material for a discharge electrode, which has a step. The method of claim 7, wherein The base metal sheet includes a clad for the discharge electrode, which comprises 1.0 mass% or more and 12.0 mass% or less in total of one kind or two kinds of Nb and Ta, and the balance is made of Ni base alloy composed of Ni and inevitable impurities. Method of making ash. 9. The method according to claim 7 or 8, A method of manufacturing a clad material for discharge electrode, comprising a finish rolling step of performing finish rolling on the diffusion-annealed clad material to adjust the thickness of the clad material. As a discharge electrode having a pipe part of which one end is released and a end plate part which closes the other end of the pipe part, the pipe part and the end plate part are integrally manufactured by press molding. A discharge electrode, wherein the discharge electrode is molded by the clad material according to claim 5, and the inner layers of the pipe part and the end plate part are formed by the surface layer of the clad material.

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