JPS5846550A - Manufacture of oxidized cathode structural body - Google Patents

Abstract

PURPOSE:To obtain a cathode with an excellent electron emission characteristic further with a long life, by combining a process of internal oxidation treatment with a process of decomposition of alkaline earth metal carbonate to oxide. CONSTITUTION:A disc, constituted by a nickel radical alloy contained with magnesium and silicon, is held to one end of a sleeve 53 as a basic metal 52, and then held for 20min in a hydrogen gas stream at 1,000 deg.C thus performed with annealing for purposes of removing work distortion residual in the basic metal 52 and growing a crystal grain. Then grinding work, parallelly running to one diametrical direction of the basic metal disc, and grinding work, rotated about the center shaft of a cathode basic unit as a center, are simultaneously performed to newly generate work distortion to a surface of the cathode basic unit. Then the sleeve is held for 10min in a hydrogen gas stream at 900 deg.C, and then allowed to pass through a process of applying ternary carbonate (Ba, Sr, Ca) CO3 51 of alkaline earth metal, thus an indirectly-heated oxidized cathode structural body is manufactured. This structural body is built in an electron gun of a color cathode-ray tube, and a cathode is heated by a heater 54 while performing exhaust in an ordinary schedule, then a normal process of sealing and the like is carried out after performing decomposition of the ternary carbonate to an oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for producing an oxide cathode assembly suitable for use in cathode assemblies for electron tubes, particularly for cathode ray tubes such as color cathode ray tubes, having a long life and long performance. , the molten gold M constituting the llide cathode structure is mainly composed of nickel (Ml), and the reducing agents are magnesium (Mt), silicon (81), aluminum (M1), and zirconium CZ.
r) lli-M containing I-Tung-Ai-Ten (W)
y, lIi -810Mi -4-81°N1-muj
elii-1,) Ii-muj W, Mi-
An alloy such as W-N7°Mi-Zr is used. A base metal Fi consisting of this alloy C2 is identified at the tip of the cathode sleeve, and on this base metal is barium (B).

Strontium (sr) *Alkaline earth metal carbonates such as calcium (0,) (Ba, 8r+ ca) cog
After this carbonate is incorporated into a color television picture tube, etc., it is heated to a predetermined temperature in a vacuum.

and C2, an alkaline earth metal oxide (Ba I B
r+ Oa) OI: Decomposed. Among these alkaline earth metal oxides, BaO contributes most to electron emission.

This BaO oxide diffuses into the base metal during the operation of the oxide cathode. M4 Zr
It is reduced at the boundary between the base metal and the oxide by the reducing agent of wW. For example, when Mt is used as the reducing agent, free B4, which causes electron emission, is formed from reaction I of the following formula.

Ba0(s) + MIt(in Ni) → B'(1n
Bad) ”MyO(@)---(1) Therefore, in such a metal cathode, as mentioned above, the reaction between the reducing agent and the oxide, which is an electron emitting substance, is caused by the reaction between the base metal and the oxide. Because it proceeds at the interface, whether we like it or not, a compound layer is formed between the two that is bonded to the intermediate layer.

Recently, there has been a growing demand for ultra-interlocking, high definition, and high brightness for television receivers, and higher performance oxide cathodes are desired. 1 that meets these requirements
Two approaches have been considered, such as thinning the base metal and increasing the amount of reducing agent added. There was a limit to the reaction with the J cathode.

However, as a result of several detailed studies on acidic L compounds @ polar pores, the present inventors found (1) the dissociation reaction of acid wheels from electron-emitting substances and the location of the reaction between this oxygen and the reducing agent ( site) can be separated, and furthermore, (11
) It has been found that a control layer for the diffusion of # element and reducing agent can be formed between both reaction sites.

Based on the above findings≦2, the present inventors created a skin oxide cathode structure using a base metal having a cross-sectional structure as shown in Figure #11 or Figure 2, and assembled it into a cathode ray tube as an electron gun. We conducted extensive emission life tests and obtained good results.

In Figure 1C2, (b) is an electron-emitting substance, (the chest is the base metal, and (El is the oxide particle of the reducing agent.
1; The distribution state of the oxide particles of the reducing agent shown is observed by optical microscopy and IPMA. In the region where the oxide particles (to) are present in the cathode substrate (b), all the reducing agent is the oxide particles asj, forming a practically non-reducing agent region. l! having such a cross-sectional structure! For example, the 11-pole substrate is manufactured as follows [7
In other words, a thin plate made of M1-based alloy containing a trace amount of reducing agent (
For example, Rhinoceros 150. am) at 1000°C in an air stream of a mixed gas of CO and 003 (partial pressure ratio 1:20).
This is a method in which internal oxidation treatment is performed by holding the material for 1 hour to obtain a desired cross-sectional structure, which is then punched out into a disk and used as a base metal.

It has been found that in the oxide cathode structure having the structure shown in FIG. 1, the oxidation reaction of the M2C agent occurs inside the cathode substrate during the cathode manufacturing process, cathode T#, and operation. That is, in the cathode manufacturing process, the electron-emitting material is usually applied in the form of a carbonate of alkaline earth gold dust. Thereafter, it is incorporated into, for example, an electronic flash tube of a color cathode ray tube, heated in an exhaust system to decompose carbonates into oxides, and then pierced with nitrogen.

This decomposition reaction is shown, for example, as shown in equation (2), but at this time, a part of the 00g gas generated is (81%
Formula % (2) ) (31) This reaction (8) is a conflict that occurs on the surface of the base metal. 61 As mentioned above, since the lamp is in the non-reducing agent region directly below the surface of the base metal, the solid-dissolved rR element After diffusing into the base metal, for example, if the reducing agent is M9, Cij (4) formula ≦
2 An oxidation reaction as shown occurs. On the other hand, even during operation of the oxide cathode, the production of free Ba, which is parasitic to the electron emission of the electron-emitting substance, occurs separately into two reactions. Here, the reaction (6) occurs at the interface between the cathode substrate and the electron-emitting substance, while the reaction (reaction (6) occurs inside the cathode substrate as described above. I confirmed it.

In this way, both during the decomposition of carbonates and during cathode operation, the quantified reducing agent a is generated inside the cathode substrate, so that the interface C2 between the cathode substrate and the electron-emitting substance may impair the electron-emitting properties of the anode. No intermediate layer is formed.

Furthermore, by defining the thickness of the non-reducing agent region from the surface of the cathode substrate, the diffusion distance of oxygen can be controlled to a certain degree. This makes it possible to control the progress of the free barium production reaction of formula (6). As a result of the above steps, a cathode with excellent electron emission characteristics and long life can be obtained.

Fig. 2 1-Kan) is an electron-emitting substance, - is a polar substrate,
- is a reducing agent oxide particle and an mtt diffusion control layer. Here, the diffusion control layer is a layer in which a reducing agent is oxidized and exists continuously at the grain boundaries near the surface of the base metal, resulting in the formation of an oxide layer that is approximately half-column on the base metal surface. It is something. The cross-sectional structure of the unipolar substrate except for the internal diffusion control layer shown in FIG. 2 is the same as that in FIG. 1. A monopolar substrate having such a cross-sectional structure was produced, for example, in the following manner. A cold-rolled material of N1-based alloy containing an acid amount of reducing agent is used as the base m.
In this method, internal oxidation treatment is carried out by holding the sample as M at 1000° C. for 1 hour in an air flow of a mixed gas of CO and Co11 (partial pressure ratio 1:20). Through this treatment, the recrystallization phenomenon based on the internal 11S oxidation and the processing strain exerted on the substrate during compaction progresses during rliJ, and the crystal grains #'i present in the sifted oxidation layer. Grain formation is suppressed, grain boundaries are oxidized, and grain boundaries are b! ilt was added to obtain the base metal having the desired ILlr surface structure. Since it acts as a barrier to diffusion, it becomes a reaction site for the oxidation reaction of the reducing agent, as exemplified by the above equation, and its position is defined. ``This ensures the effect of preventing the formation of an intermediate layer that impairs the electron emission characteristics, and the diffusion distance of oxygen from the surface is at the same time 52. The diffusion control layer itself mainly controls the diffusion of the reducing agent.

The progress of the oxidation reaction of the reducing agent, that is, the consumption of oxygen, is regulated, and together these make it possible to control the production of free barium by reaction 12 of equation (5). For each of the above-mentioned effects, by using a cathode substrate having the cross-sectional structure shown in Fig. 2, it is possible to obtain an excellent electron emission property and a lifespan for long hemorrhoids. As for the manufacturing method of a cathode substrate having a round cross-sectional structure as shown in Hibiki 2, an example of which has already been described above, a method of subjecting the substrate metal to internal oxidation treatment is effective, and 4.
Usually, it must be carried out as a separate step at some point in step I, prior to applying the electron-emitting material to the cathode substrate 6. In this case, care must be taken to ensure that the desired cross-sectional structure of the base metal is not damaged in the process after the internal oxidation treatment process, such as in a process that involves the generation of new processing strain or a heat treatment process. I can't even stand my neck.

Object #'i of the present invention is to provide a method for manufacturing an oxide cathode structure, which allows the internal oxidation treatment step to also be used as a decomposition step of an alkaline earth metal carbonate into an oxide. o′#li ion-emitting substance.

The step of decomposing the carbonate coated with carbonate is indispensable in the normal oxide cathode manufacturing process. As a method for obtaining a cathode structure having a desired cross-sectional structure corresponding to the above-mentioned FIG. 1 or FIG. is carried out prior to. The base metal, which is an N1-based alloy containing a small amount of reducing agent, is heated to 900°C.
A step of heating the base metal to remove processing strain from the base metal, a step of applying new processing strain to C2 near the surface of the base metal on the side to which the electron-emitting substance is applied, and a step of heating the gruesome base metal at 750°C to 95°C.
The method consists of heating the cathode to 0 DEG C. and applying an electron-emitting substance in the form of carbonate to the surface of the cathode.

Some basic experiment results until the invention was completed C
Let me explain about two things.

First, the manufacturing process of a conventional oxide cathode structure is as follows.

A base metal of N1 base alloy or 6 containing a small amount of reducing agent obtained by compressing is brought into close contact with a nichrome ball rib, and then nicked. Rom sleeve #t in humidified hydrogen for selective oxidation
Heat treatment is performed at M900°C or higher. Next, the sleeve is combined with a cathode holder via a support provided in advance (2) to form a cathode structure. Heat treatment to remove tl'N600
Perform in a hydrogen stream at ℃. Finally, an oxide cathode structure is completed by applying a two-electron emitting substance to the surface of the two-substrate metal.

In such a manufacturing process, the inventors investigated two relationships C between the grinding of the base metal surface and the final heat treatment temperature.

First, as a pretreatment, a base metal heated to 1000°C was roughly contacted with a negative pole sleeve to assemble 62 monopolar bodies, and the base metal 4 surface was ground by 10 μm using a sand vapor and then divided into 6 groups, and these were sampled. A=600℃, B
, = 700℃, c = 750℃, D = 900℃,
IC=950℃,? = 1000°C respectively 2, (Ba.

Sr, co) coo R salt was applied and the heater was ignited to perform cathode decomposition. Substrate-4W for each sample
The state of the diffusion control layer was observed using an optical microscope and IIiPMA on the cross section of +, and it was found that A and B are the 3rd -
As shown in Figure 2, five diffusion control terms are observed on the base metal surface. The diffusion control layer parallel to the surface of C2, which seems to be the second cause, was more clearly observed, and some of the layers had echoes as shown in Figure 1.01 (Diffusion control layer on the surface) could hardly be seen. I couldn't help it. In addition, Fig. 3 (1llllt'! in 2 is the emissive material, 1 is the base metal, and 1 is the diffusion control layer. The lifespan when these samples A to F are installed in a 13-inch color cathode ray tube I) The results of the test are shown in Figure 4. It can be seen from the figure that samples 0~!! whose final heat treatment was 750°C or more and 950°C or less had good life test results.

Considering this result, it is found that since the decomposition of carbonate was carried out in the state where sample A-BFi processing strain remained, oxidation of the reducing agent and recrystallization near the base metal surface due to strain relief occurred simultaneously, and as a result, the diffusion control layer However, the reason for the poor life test results of samples A and B is
Due to the surprisingly large amount of residual machining strain, a diffusion control layer is generated just below the surface as shown in Figure 3, which severely inhibits the diffusion of MlA from B110 into the base metal, and as a result, free B This is thought to be due to the slower production speed of -.

On the other hand, Sample 0-1 had moderate processing strain and residual In, so it was formed as a single layer slightly inside the C-substrate metal surface in a state parallel to the C-surface as shown in FIG.

It is believed that this diffusion control layer enabled the generation of I: an appropriate amount of free Ba as described above.

In Sample 1, the processing strain was almost completely eliminated by heat treatment, so no diffusion control layer was likely formed.

For the same reason, the sandpenino illusion in the manufacturing process of the sample sample from the previous basic experiment: No grinding was performed, and the other conditions were the same as the sample sample -62 oxidation 41! When the diffusion control layer of the I cathode body was observed, the state was the same as that of sample F, and no diffusion control layer was observed.

The present invention has been made based on the results and considerations of the basic experiment g2 as explained above.

That is, according to the manufacturing method I of the present invention, in order to obtain a cathode substrate having a desired cross-sectional structure corresponding to the above-mentioned Figure 1 or Figure 2, no special internal S H ratio treatment step is required.
In addition, since the carbonate decomposition process is carried out near the final stage of the electron tube manufacturing process, the resulting substrate metal has a
Embodiments of the present invention are shown in FIGS.
This will be explained using figures.

Example 1 Thickness Q, 15 m made of a nickel-based alloy containing 0.06 weight tS of magnesium and 0.033 weight tS of silicon.
.

Sleeve m+ with a disc with a diameter of 1.3 sm as the base metal M
After being held at the i-end of the
.

After holding for 20 minutes, base metal-I was subjected to annealing for the purpose of removing residual processing strain and growing crystal grains.

Next, the cathode substrate surface I: Grinding that runs parallel to the diameter direction of one of the substrate metal disks and grinding that rotates around the central axis of the cathode substrate are performed at the same time.
7. Grind uniformly to a thickness of about 1oμm, and remove the hill distortion with Shintomo 1.
;Gave. The sleeve was then heated for 900 minutes in a hydrogen gas stream.
After holding at ℃ for 10 minutes, a ternary carbonate of alkaline earth metal (Ba, 8r, Cg) co@15111 was applied to produce an indirectly heated oxide monopolar structure, which was then coated with Calap2. Two electron guns were installed. After that, the cathode is heated with a heater while being evacuated according to the normal schedule to decompose the ternary carbonate into oxides.2Then, the tube is sealed, and the normal process is repeated to fabricate a colored tube, and the tube has a long service life. The test was conducted.

As a result, it has been found that the electron emission characteristics of this colored tube are superior to those of conventional tubes especially in long-term operation. A representative example of this result is shown in Section 4.
It was shown to. The curve A in the figure is based on the conventional oxide cathode assembly 62, and the curve A is based on the oxide cathode integrally produced according to Example 1.

According to the metal structure of the cross section of the cathode substrate before starting the tube life test (immediately after the tube was manufactured) &4!
Therefore, in the case of the manufactured cathode structure, it was confirmed that the 111-plane structure shown in FIG. 82 was often observed, and the state shown in FIG.

In Example 1, the processing forest is 4 parts I: # body metal is 1
An example of 0 μm grinding was shown, but in another experiment, the grinding amount Fi
It should be 3 μm or more and 20 μm or less〈: 5 μm to 10 μm
Confirm that the range of m is the best (7 0 or more, machining φ
Another means for imparting this property is shot peening using glass balls, ceramic balls, metal balls, etc., or dry or wet honing.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the state of dispersion of oxide particles of a reducing agent inside a base metal to explain the present invention. Figure 2 is a schematic cross-sectional view of the dispersion cathode body obtained by the present invention @8, and Figure 3 is a schematic cross-section of the conventional oxide-polar body -1.
Fig. 4 is a diagram showing the life test results when the oxide cathode structure obtained by the present invention and the conventional manufacturing method is used in a power 2-braun tube, and Fig. 1145 is a diagram explaining one embodiment of the present invention. . (7317) Representative Patent Attorney Noriyuki Chika (1 person) Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) A step of heating the base metal made of N1 base alloy containing a trace amount of reducing agent to 9 (10℃ or higher);
00° C. or above - a step of applying new processing strain to the surface 62 of the heated base metal on the side to which the electron-emitting substance is applied, and a step of applying the substrate metal to which the processing strain has been applied at 750° C. A method of manufacturing an oxide cathode structure taking into account the above circumstances. (2) A method for manufacturing an oxide cathode structure according to item 1 of the scope of patent 1h, characterized in that the step of imparting processing strain is grinding the surface layer of the base metal.