JPS60193228A - Impregnated cathode structure - Google Patents

Abstract

PURPOSE:To fixedly weld an inner sleeve and an outer sleeve in a favorable and stable manner, by inserting a joining material consisting of a particular alloy between the inner and outer sleeves. CONSTITUTION:An inner sleeve 3 which is made of Ta, Mo, W or an alloy thereof and joined at one end with a base metallic body consisting of W impregnated with an electronic radiative material and an outer sleeve 4 which is fixedly welded to this one end of the inner sleeve 3 for supporting the same and made of Ni, Fe or an alloy thereof are fixedly welded togethe at the other end of said inner sleeve 3. When they are welded to form the structure, a joining material 11 consisting of a Re. Re-Mo alloy or Re-W alloy is inserted between th inner and outer sleeves 3 and 4 at this welded portion. Since the inserted joining material of Re, Re-Mo alloy or Re-W alloy is easy to alloy, the sleeves can be welded solidly and therefore favorable electronic tube characteristics can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an impregnated cathode structure used in an electron tube.

[Technical background of the invention and its problems]

FIG. 1 shows an example of an impregnated cathode assembly installed in an electron tube, such as a cathode ray tube. (1) is a base metal body,
Made by sintering W, BaO, IJtO, CaO'
It is made into a plate-like body made by melting and impregnating an electron-emitting substance consisting of the following in a reducing atmosphere, and has an outer diameter of 1.5 am.

The thickness is 0.5B. (2) is a cup, Ta or M6
The base metal body (1) is obtained by press-molding a thin plate with a thickness of 0.025 am to form a cap-shaped body consisting of the above-mentioned base metal body (1) so that the electron radioactive substance does not scatter into the inner sleeve (described later) or into the heater. is crowned. (3) is an inner sleeve made of a cylindrical body made of a high melting point metal such as Ta Jp Mo, formed by processing a thin plate with a thickness of 0.025 as, and a base metal with a cup attached to one end. The body is joined. Furthermore, (4) is the outer sleeve, which is made of 4% W-Ni alloy, has a cylindrical body with a larger diameter than the inner sleeve, and has a cut-out portion at one end with slits at three locations on the circumference. (5), this portion contacts the open end of the inner sleeve (3) opposite to the end to which the base metal body is joined, and is resistance welded at a welding point (6). Further, a heater (not shown) is inserted into the inner sleeve (3). A ceramic plate (ceramic plate) is attached to the outer side of the outer sleeve (4) by caulking.

The impregnated cathode structure thus formed has the following drawbacks. In other words, since the inner sleeve is made of a high-melting point metal, it is difficult to weld it easily, resulting in welding defects during manufacturing and the welding part peeling off during life tests. This inconvenience occurs. The reason for this is that the melting point of the steel material used as the welding electrode material is extremely lower than that of the inner sleeve material, so a strong current is passed during welding, causing the welding electrode to melt and making it impossible to completely weld the welded part. be.

When an electron tube equipped with a cathode formed in this manner is operated, the welding of the cathode structure gradually becomes incomplete due to the heat cycle caused by turning the heater on and off, and there is no place for heat to escape through heat conduction. The cathode becomes extremely hotter than the initially set proper operating temperature, resulting in increased thermal evaporation of the electron-emitting material in the base metal, resulting in a shortened lifespan and problems such as leakage between electrodes. occurs, resulting in deterioration of characteristics.

In order to reduce such defects, welding using laser welding results in an extremely good welding condition, at least immediately after welding, but the cathode formed in this way is incorporated into an electron tube and subjected to a heat cycle. This results in the same result as in the case of resistance welding described above. This is thought to be due to the following phenomenon.

In other words, the welded area between the inner sleeve and the outer sleeve forms a molten and solidified area that is mixed and integrated, but a reaction layer between the molten area and the high melting point metal of the inner sleeve is generated near this molten and solidified area, and this reaction layer This is thought to be the result of high-temperature embrittlement. In addition, if T1 is used for the outer sleeve, it is easy to weld with the same material, but since there is a process of caulking a ceramic plate to the outer sleeve, T1 is a brittle material.
a cannot be used. Since it is difficult to weld the sleeves very well, there has been a demand for an impregnated cathode structure for electron tubes that can be well welded to the sleeve, has a long life, and has good characteristics.

[Purpose of the invention]

The present invention has been made in consideration of these points, and an object of the present invention is to provide an impregnated cathode assembly in which an inner sleeve and an actor sleeve are well and firmly welded and fixed to maintain high quality.

[Summary of the invention]

This invention comprises an inner sleeve made of TJI, Mo, W, W, etc., or any alloy thereof, with a base metal body made of W impregnated with an electron radioactive substance bonded to one end. An outer sleeve made of Ni, Fe, or an alloy thereof is fixed by welding at one end to support the inner sleeve, and an outer sleeve made of Ni, Fe, or an alloy thereof is fixed by welding at the other end of the inner sleeve. Between the sleeve and the outer sleeve are Re and Re-Mo alloys.

This is an impregnated cathode structure formed by inserting and welding a bonding material made of Re-W alloy or the like.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In Fig. 2, (1) is the base metal body, (2) is the cup, (
3) is an inner sleeve, (4) is an actor sleeve,
(7) is a ceramic plate, and at the welding part with the outer sleeve at the other end of the inner sleeve opposite to the one end where the base metal body (1) is attached, a bonding material αυ is interposed between both sleeves. It is inserted.

Each component of such a cathode assembly is formed as follows. The base metal body is made of BaOe M! after compression molding W powder and sintering it. oa * Obtained by melting and impregnating an electron radioactive substance made of CaO in a high-temperature reducing atmosphere, and has an outer diameter of 1.5 m11. It is made into a plate-like body with a thickness of 0.5B. The cup is a cap-shaped body having a diameter of about 1.5 wm and a height of 0.5 sn by press-molding a Ta plate with a thickness of 0.025 ms. The inner sleeve is made into a cylindrical body with an outer diameter of 1.5 wit by rolling a Ta plate with a thickness of 0.025111 mm. The outer sleeve is made of rolled 4% W-Ni alloy plate.
Butt welded and cored, outer diameter 311
It is a cylindrical body with a wall thickness of 0.08 am, and one end is provided with three protruding slits in the circumferential direction. The bonding material inserted between the inner sleeve and the outer sleeve has a thickness of 0.03 m and a width of 0.4 mm.
e Use a ribbon.

The inner sleeve is welded and fixed to the actor sleeve at the open end opposite to the joined end of the base metal body as follows.

After wrapping the Re ribbon αυ around the outer periphery near the open end of the inner sleeve (3) made of Ta, the inner Insert the sleeve (3).Next, push uniformly through the slits formed at three locations on the outer sleeve (4) to form the protruding portion α2, and completely seal the protruding portions of the inner sleeve, bonding material ribbon, and actor sleeve. contact with.

The contact portion thus formed is laser welded from the outer sleeve side. For example, the inner sleeve and the actor sleeve are welded by laser irradiation using a pulsed YAG laser with a slot diameter of 0.3 smφ and an energy of 1.6 ginyl/pulse.

When welded in this way, Ni material with a melting point of 1455°C, 29
Melting point force 3 that makes it very easy to alloy with Ta material at 77℃
A 180°C Re ribbon is inserted, and although there is a large difference in melting point, the thickness of the Actor sleeve is larger than that of the inner sleeve and bonding material, and therefore the heat capacity is larger (2 to 5 times). The welding area is very efficient, and the welding area is well welded and a strong joint is obtained.It is a high-quality product that does not cause welding defects even after repeated heat cycles due to the heater being turned on and off. A cathode structure is formed.

In the above description, the inner sleeve is made of Ta, but it is not limited to this, and may be made of Mo, W, Nb, or an alloy thereof. In addition, although Re ribbon was used as the bonding material, Re-Mo alloy, Re-?
Similar excellent effects are obtained when W gold alloy is used as the bonding material. Further, the outer sleeve was formed of 4% W-tooth alloy, but not only this but also %Ni.

It may be formed using Fe or an alloy thereof, and caulking with a ceramic plate is performed well, and it goes without saying that welding can be performed in the same manner as in the above example.

Furthermore, regarding the shapes of the actor sleeve and the inner sleeve, as shown in Figures 3 and 4, the lower part (2) of the inner sleeve CD to be welded to the outer sleeve Q
Actor sleeve G3 to be welded to the inner sleeve (311) may be used by increasing the diameter of the inner sleeve (311) and inserting and welding fixation by inserting a bonding material between both sleeves at the welding part (311).
The cathode assembly may be formed by reducing the diameter of the lower part (32A) of the welding part, inserting a bonding material between both sleeves of the welding part, and fixing by welding.

〔Effect of the invention〕

In the cathode structure of the present invention, at the welded portion of the inner sleeve made of Ta, Mo, W, Nb or an alloy thereof, to which the base metal body made of W is joined, and the actor sleeve made of Nj, RE or an alloy thereof, , a highly alloyed Re between both sleeves.

Because the bonding material made of Re-Mo alloy, Re-W alloy, etc. is inserted, strong welding is possible, and the welds are well bonded without the problems of conventional welds. Incorporated into the electron tube, heat cycle begins,
Even if the tube is replaced, it does not cause welding defects and good electron tube characteristics can be maintained. For example, FIG. 5 is a temperature change diagram of the cathode assembly, which shows the relationship between the heat cycle time and the amount of temperature change of the cathode assembly.
1), and the conventional one is shown in curve (2), which shows that the inventive one hardly causes any abnormal temperature rise over a long period of time and is superior. In other words, it is shown that the welded portion of the present invention maintains a stable and good condition over a long period of time without causing problems such as peeling.

In this way, in the device of the present invention, both sleeves are welded and fixed well, the operating temperature of the cathode does not rise abnormally, and therefore there is no abnormal evaporation of the electron radioactive material from the cathode base, and the gap between the electrodes is reduced. This is an industrially useful impregnated cathode structure that does not cause problems such as leakage, does not deteriorate its life characteristics, and stably provides good characteristics.

The same applies to cathode assemblies using the so-called span set method, in which the cathode assemblies and electron gun are welded while measuring the distance between the first grid and the cathode assemblies using an air microscope, if considered as an outer sleeve that holds the cathode. Good results can be obtained with this method.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional impregnated cathode structure, FIG. 2 is a sectional view of an impregnated cathode structure of the present invention, FIGS. 3 and 4 are sectional views of other embodiments of the present invention, and FIG. The figure is a curve diagram showing the relationship between heat cycle time and temperature change of the cathode assembly. DESCRIPTION OF SYMBOLS 1... Base metal body, 2... Cup, 3... Inner sleeve, 4... Actor sleeve, 7... Ceramic plate, 11... Bonding material, 12... Actor sleeve protruding portion, 21, 31...inner sleeve, 22.32...actor sleeve, 23.33.
...Joining material. Figure 1 Figure 2

Claims (2)

[Claims] (1) A base metal body impregnated with an electron radioactive material and made of W is joined to one end, and an inner sleeve made of Ta, Mo, W, Nb or an alloy thereof is welded to the inner sleeve at one end to form an inner sleeve. A supporting outer sleeve made of Ni or Fe or an alloy thereof, and a ceramic plate caulked to the center of the outer sleeve are provided, and the inner sleeve and the actor sleeve are fixed by welding. The welding part is Re, R between the inner sleeve and the actor sleeve.
An impregnated cathode assembly characterized in that a bonding material made of either an e-Mo alloy or a Re-W alloy is inserted. (2) The impregnated cathode assembly according to claim 1, wherein the outer sleeve has a larger heat capacity than the inner sleeve.