JPH03216932A - Method of manufacturing oxide cathode - Google Patents

Abstract

PURPOSE: To extend a service life of a carbonate salt solid solution and improve electric discharge characteristics by applying a penta-atom (Ba, Sr, Ca, Sc, Y) carbonate salt solid solution onto a cap and manufacturing an electronic radiation material layer. CONSTITUTION: This cathode comprises an oxide cover layer 1, base body metal 2, a slib 3, and a heater 4. Sc, Y nitride salt and tri-atom carbonate salts (Ba, Sr, Ca) are manufactured simultaneously as a blend nitride salt, a carbonate salt precipitation agent is added thereto to obtain a penta-atom carbonate salt, this is well blended with an adhesive, ball-meal to prepare a suspension solution, applied onto a base body metal 2 in a method such as spraying and electric welding, and superior dispersion effect to blending of a powder state is obtained. Thus, by eliminating non-uniform dispersion shown by powder blending, a service life is extended, and electronic discharge characteristics can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for producing an oxide cathode for electron tubes, and in particular improves the method of adding Sc and Y to extend the life of Mihara carbonate solid solution. The present invention relates to a method for manufacturing an oxide cathode for an electron tube, which obtains a better dispersion effect and improves the lifetime and electron emission characteristics.

Conventional technology According to the conventional technology, heat-treated scandium, isotrium, etc. are added to Mihara carbonate solid solution in the form of oxides in a predetermined ratio, and this is mixed with a suitable adhesive (mainly nitrocellulose) and an organic solvent ( isoamyl acetate alcohol, etc.)
Make a mixed solution with.

Thereafter, this is ball-milled to make a suspension, and this suspension is applied to the base metal (Ca) by spraying, electrodeposition, etc.
ρ) Apply on top. Then, the electron gun is assembled and sealed in a tube, and it is used as an electron-emitting substance through processes such as thermal decomposition and activation. It can be used in different forms other than oxide (llydroxide
Nitrate, etc.) may also be used.

Problems to be Solved by the Invention However, when adding scandium, i-7thorium, etc. using the conventional method, the scandium, isothorium, etc. are mixed with the Mihara carbonate powder in a powdered state, so it is not possible to add them uniformly. Unable to obtain a mixture of states.

In particular, when adding scandium or intrium powder to a suspension after making a suspension using a ball mill, there is a risk that the crystals of Mihara carbonate may be broken. Difficult to use method.

Furthermore, since scandium and isotrium are added in small amounts, there is a disadvantage that unless they are sufficiently dispersed, the above-mentioned improvement in life characteristics and electron emission characteristics cannot be expected.

Objects of the present invention and means for solving the problems The present invention has the following features:
It was devised to improve the above disadvantages, and in order to obtain a sufficient dispersion effect, Sc, Y nitrates and Mihara carbonates (Ha, Sr, Ca) are simultaneously produced as a mixed nitrate aqueous solution. Then, a carbonate precipitant is added to this to obtain Gohara carbonate, which is thoroughly mixed with an adhesive and ball-milled to create a suspension, which is then applied onto the base metal using methods such as spraying or electrodeposition. By doing so, it is possible to obtain a dispersion effect superior to that obtained by mixing powders.

Example Hereinafter, the present invention will be described in detail based on the accompanying drawings.

In the figure, 1 is an oxide coating layer, 2 is a base metal, 3 is a sleeve, and 4 is a heater. Next, a method for producing a Mihara carbonate suspension for oxide cathode without addition of scandium or isotrium will be described.

1) Into a nitrate aqueous solution of Ba, Sr, Ca with a predetermined composition, II) Nag C Owl or (NH4)Z
Add CO3 precipitant (Ba, Srs Ca) 0
After preparing 3 and Mihara carbonate solid solution, (2) wash, filter and dry it to obtain Mihara carbonate solid solution powder.

■) Mix Mihara carbonate solid solution O5] powder with a suitable adhesive and an organic solvent at a predetermined ratio, ■) Disperse this by a method such as a ball meal to obtain a carbonate suspension, ■) This is applied onto the base metal by a method such as spraying.

Roughly, a cassob, which is a part of an electron gun, is completed through the process (1-Vl) above.

The conventional method for adding powders of Sc and Y compounds is to mix the powders of Sc and Y compounds at a predetermined ratio in the above (rV) process, and then perform the post-processes of (V) and (■). Alternatively, (V) and (Vl) may be added to a carbonate suspension at a predetermined ratio and mixed by a method such as a ball meal, followed by the subsequent process of (Vl).

In the above conventional method of adding Sc and Y, since they are mixed in powder form, it is difficult to expect a sufficiently uniform dispersion effect due to differences in specific gravity and aggregation between the substances. It is also expected that a sufficiently uniform dispersion effect can be obtained after a long period of time.

In order to improve this, instead of powders of Sc and Y compounds, Ba, Ca, etc.
, Sc and Y are added to Sr nitrate to prepare a nitrate aqueous solution having a predetermined composition, and the above steps (■ to ■) are performed.

By obtaining Gohara carbonate solid solution powder instead of Mihara carbonate solid solution powder in the process of (fV) above, compound powder (
This eliminates the difficulty in dispersibility that occurs when adding Sc and Y).

The particulate form of Gohara carbonate to which trace amounts of Sc and Y were added maintained the chip-like particulate form shown in Mihara carbonate, and since it was in a carbonate state like Mihara carbonate, K was removed during the exhaust process. During one decomposition, it is thermally decomposed into oxides, and the carbon dioxide produced is discharged into the pipe, so it has no effect on the atmosphere inside the pipe.

Effects of the Invention The carbonate solid solution produced according to the present invention differs from the existing Mihara carbonate in that Gohara carbonate to which two substances (Sc and Y) are added is obtained, so that the non-uniformity shown in the powder mixture can be obtained. Elimination of such dispersibility has the advantage of being expected to improve lifespan and electron emission characteristics.

[Brief explanation of drawings]

The attached drawing shows a rear cross section of a typical oxide cathode structure. ■...Oxide coating layer, 2...Base metal, 3...Slab, 4...Heater

Claims (2)

[Claims] (1) In the production of oxide cathodes for electron tubes, Gohara (Ba,
A method for producing an oxide cathode, comprising obtaining a carbonate solid solution (Sr, Ca, Sc, Y) and coating it on a cap to produce an electron emitting material layer. (2) The carbonate solid solution is Mihara carbonate (Ba, Sr,
2. The method for producing an oxide cathode according to claim 1, wherein the oxide cathode is Gohara (Ba) Sr, Ca, Sc, Y) carbonate containing Ca), particularly scandum and yttrium.