JPS599828A - Heating cathode and production process thereof - Google Patents

Abstract

PURPOSE:To produce the captioned heating cathode which is excellent in electron emissivity and sputtering resistance and does not generate a spark even if a high voltage is applied on said cathode, by introducing into said cathode the oxides of alkaline-earth metal elements, the oxides of alkali metal elements and/ or the oxides of rare earth elements that are emitter material whose work function is small and whose wear caused by ion impulse is also small. CONSTITUTION:A liquid or paste is thus prepared by mixing 1-50wt% of more than one kind of organic metal selected from the alkoxide and carboxylic salts group containing such metal which may be any one of alkaline-earth metal elements, alkali metal elements or rare earth elements, 5-95wt% of more than one kind of organic solvent selected from alcohol, ester or the like, and more than one kind of substance selected from higher alcohol-system high boiling point substance, glyceride, polyhydric alcohol whose boiling point is 150-400 deg.C, or the like; when said liquid or paste is stuck onto a cathode substrate 2 said organic metal is decompoed by heating and an amorphous emitter layer 3 including more than one kind of metal oxide selected from the oxides of alkaline-earth elements, the oxides of alkali metal elements and the oxides of rare earth elements is formed and stuck onto said cathode substrate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heated cathode in which an amorphous emitter layer made of a material containing a metal oxide with excellent electron emitting properties is deposited on a cathode substrate, and a method for manufacturing the same.

Conventionally, heated cathodes used in vacuum tubes, discharge tubes, electron guns, etc. have a small work function, as shown in Figure 1, in order to improve electron emission performance and ion impact resistance.
In addition, a material consisting of a metal oxidation amount such as an oxide of an alkaline earth metal element, an oxide of an alkali metal element, or an oxide of a rare earth element, which is less abraded by ion bombardment, is fixed on the cathode substrate 2 as an emitter layer 6. So-called oxide cathodes are often used. For example, for alkaline earth metal elements such as barium (Ba), strontium (Sr), and calcium (Ca), from the viewpoint of handling and storage, it is necessary to use single or binary elements that can be maintained in a stable state in the air. Carbonate (BaCO5, (Ba@Sr)COg, (B
a@Sr@Ca) COs, etc. is deposited on the cathode substrate 2 in the form of F, and the carbonate is heated to the thermal decomposition temperature (1,000 to 1,500°C) by high frequency heating, electric heating in vacuum, etc. It is raised and decomposed to produce single or binary oxides (
Bad, (Ba-8r)0, (Ba-8r-Ca)0
The emitter layer 3 was sintered on the cathode substrate 2 as F. However, the emitter layer 3 of the heating cathode 1 described above
Because metal oxide particles are simply physically bonded together, they lack mechanical strength and are prone to sputtering by electrons and ions despite using materials that are resistant to ion bombardment. , the life of an electron tube incorporating such an electrode 1 is shortened, and the formed emitter layer 6
is porous and has many irregularities on its surface, which causes sparks due to electric field concentration at high voltages. Furthermore, in the emitter layer forming method described above,
There were problems such as the need to separately prepare a process for decomposing carbonates into oxides, and a high-frequency heating device and a power supply device used in the above process.

The present invention has been made to solve the above problems, and uses an oxide of an alkaline earth metal element, which is an emitter material that has a small work function and less wear due to ion bombardment.
An oxide of an alkali metal element and/or an oxide of a rare earth element is introduced into the cathode in such a state that the properties of the alkali metal can be sufficiently exhibited, and the cathode has excellent electron emission and spatter resistance, and even when high voltage is applied. To provide a heated cathode that does not generate sparks, and also to provide a method for manufacturing a heated cathode that does not require a high-temperature heating step, therefore does not require a special device for high-temperature heating, and is easy to manufacture.

That is, the heated cathode of the present invention is made of a material containing on a cathode substrate at least one metal oxide selected from the group of oxides of alkaline earth metal elements, oxides of alkali metal elements, and oxides of rare earth elements. The method for producing the heated cathode described above is based on a structure in which an amorphous emitter layer is deposited. 1 to 50% by weight of one or more organic metals selected from the group, 5 to 95% by weight of one or more organic solvents selected from the group of alcohols, esters, aldehydes, carboxylic acids, ketones, hydrocarbons and terpenes, and higher alcohols. High boilers, glycerides, boiling point 15
Polyhydric alcohol, paraffin, temperature between 0℃ and 400℃,
Vaseline, lanolin, rosin, cellulose polymer compounds, carboxylic acids having 8 or more carbon atoms, polyesters, polyaldehydes, polyalcohols, polyethers, polyamide polymer compounds, amino acids2. By mixing with one or more substances selected from Risidol Sen to form a liquid or paste, and attaching it to the cathode substrate and heating, the above-mentioned organic metals are decomposed to produce oxides of alkaline earth metal elements and oxidation of alkali metal elements. The present invention is characterized in that an amorphous emitter layer containing one or more metal oxides selected from the group of metal oxides and rare earth element oxides is deposited on the cathode substrate.

An embodiment of the present invention will be described below based on the drawings.

FIG. 2 is an enlarged sectional view showing the structure of an emitter layer deposited on a cathode base of a heated cathode according to an embodiment of the present invention, in which 1 is a heated cathode, 2 is a cathode base, Reference numeral 6 indicates an amorphous emitter layer formed on the cathode substrate 2.

The cathode substrate 2 is made of a conventionally used cathode material such as F, Ni, Cr, W or an alloy thereof, and the emitter layer 3 is made of lanthanum chromate (LaCrOs) as a metal oxide containing an oxide of a rare earth element. ) is formed by. This emitter layer 5 contains 1.7 weight 31% chromium propionate and 6 lanthanum propionate.
By mixing 6% by weight of butyl acetate or 847% by weight of butyl alcohol and 10% by weight of cetyl alcohol and depositing the mixture in a liquid state on the cathode substrate 2 and heating, the alkoxides of chromium and lanthanum are decomposed and chromium ( It is formed on the cathode substrate 2 as an amorphous adhesion layer made of lanthanum chromate (LaCrOs), which is a composite metal oxide of Cr) and lanthanum (La). However, the above-mentioned thermal decomposition temperature is sufficient if it is 100°C or higher, and the working temperature (400 to 600°C) in the sealing process of the electron tube incorporating the heated cathode of the present invention is sufficient.
can be used. The emitter layer of lanthanum chromate formed by the above manufacturing method has a melting point of 2.500.
℃ or more, and since it has a very amorphous shape, it has excellent ion bombardment resistance.

Similarly, the metal oxide material forming the emitter layer is not limited to the above-mentioned lanthanum chromate, but other representative materials include BaO and MgO.

SrO etc. (oxides of alkaline earth metal elements), C52Q
Na20XK2O, etc. (oxides of alkali metal elements)
, Cent, Y2O5, Qd20g, etc. (rare earth element oxide), BaO-8rO, etc. (alkaline earth metal element composite oxide), BaO*La2O5, etc. (alkaline earth metal element and rare earth element composite oxide), C8O・LaO etc. (composite oxide of alkali metal elements and rare earth elements), Ba0
-Al 20s (a composite oxide of an alkaline earth metal element and a non-emitter metal element), and the like. These metal oxides include, for example, barium octylate 2 to 10
0% by weight and 5% by weight of turpentine oil, 75 to 86% by weight of kerosene and 10% by weight of cetyl alcohol (for BaO layer formation, liquid), barium lauryl oxide 2 to 10% by weight.
% by weight, 65 to 77% by weight of octyl alcohol, 1 to 5% by weight of glycerol stearate, and 20% by weight of decyl alcohol (for forming a BaO layer).

paste), 10% magnesium caprate, 81.5% by weight of butyl alcohol, 8% by weight of stearyl alcohol, and 0.5% by weight of propyl cellulose (for forming MgO layer, liquid), barium butyrate 1.65% by weight 1.17% by weight of strontium propionate, 94.18% by weight of butyl alcohol and 6% by weight of cetyl alcohol (for forming BaO-8rO layer, liquid);
A mixture of 6% by weight of nocurium butyrate, 8% by weight of lanthanum butyrate, 75% by weight of butyl alcohol, 10% by weight of cetyl alcohol, and 4% by weight of stearic acid (BaO.Al2
(for O3 layer formation, liquid), or barium octylate 4% by weight, aluminum butylade 5% by weight, octyl alcohol 60% by weight, kerosene 20% by weight, lauryl alcohol 5% by weight, cetyl alcohol 5% by weight, and glycerol stearate. 1% by weight (BaO・A
For forming 120s layer.

The organic metal is decomposed using the temperature (400 to 600 degrees Celsius) during the manufacturing process of electron tubes. It is obtained by depositing on the cathode substrate.

As explained above, according to the present invention, the work function is small;
In addition, a material containing at least one of oxides of alkaline earth metal elements, oxides of alkali metal elements, and oxides of rare earth elements, which is less abrasive due to ion bombardment, is firmly adhered as an amorphous emitter layer on the cathode substrate. Since the heated cathode thus formed is obtained, it has excellent electron emission properties and spatter resistance, and the surface of the emitter layer is uniform and smooth, so it is possible to obtain a heated cathode that does not generate sparks even under high voltage. . Furthermore, according to the manufacturing method of the present invention, the metal alkoxides or carboxylates can be decomposed into metal oxides at the working temperature in the manufacturing process of electron tubes, so there is no need for a high-temperature heating process or special heating. No equipment or power supply is required, and the heated cathode can be easily manufactured.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view showing the structure of an emitter layer formed on a cathode base of a conventional heated cathode, and FIG. 2 is an emitter layer formed on a cathode base of a heated cathode according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view showing the structure of FIG. 1... Heated cathode 2... Cathode base 6... Emitter layer Patent applicant Okaya Electric Industry Co., Ltd. - Giken Kagaku Co., Ltd.

Claims (1)

[Scope of Claims] 1) Consisting of a material containing at least one metal oxide selected from the group of oxides of alkaline earth metal elements, oxides of alkali metal elements, and oxides of rare earth elements on a cathode substrate. A heated cathode characterized by having an amorphous emitter layer deposited thereon. 2) 1 to 50% by weight of one or more organic metals selected from the group of alkoxides and carboxylates of metals containing alkaline earth metal elements, alkali metal elements, or rare earth elements, and alcohols, esters, aldehydes, carboxylic acids, and ketones. 5 to 95% by weight of one or more organic solvents selected from the group of hydrocarbons and terpenes, higher alcohol-based high boilers, glycerides, polyhydric alcohols with a boiling point of 150°C or more and 400°C or less, paraffin, vaseline, lanolin,
By mixing one or more substances selected from rosin, cellulose-based polymer compounds, carboxylic acids having 8 or more carbon atoms, polyesters, and polyaldehydes to form a liquid or paste, and depositing the mixture on a cathode substrate and heating it. The organic metal was decomposed and selected from the group of oxides of alkaline earth metal elements, oxides of alkali metal elements, and oxides of rare earth elements. A method for producing a heated cathode, comprising forming an amorphous emitter layer containing one or more metal oxides on the cathode substrate.