JPH0765713A - Method for manufacturing impregnated cathode - Google Patents

Abstract

(57) [Summary] [Purpose] No gap is created between the sintered pellet and the cap. A process of performing CVD with a sintered pellet 100 obtained by sintering fine tungsten powder placed on a substrate 600, and forming a cap 200 by laminating molybdenum around the sintered pellet 100; The cap 200 is exposed to the side surface of the upper end portion and the cap 200 is sintered.
00, press fitting into one end of the dummy pipe 300, again forming the sleeve 400 with molybdenum on the side surface of the dummy pipe 300 and the side surface of the cap 100 exposed from the dummy pipe 300 by CVD, and the desired sleeve 400 Dummy pipe 30 after being laminated
It has a step of removing 0 and a step of providing the heater 500 inside the sleeve 400.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method of manufacturing an impregnated cathode.

[0002]

2. Description of the Related Art An impregnated cathode comprises a sintered pellet 100 and a sintered pellet 100 as shown in FIG.
It has a cap 200 into which is pressed, a cylindrical sleeve 400 into which the cap 200 is pressed into one end, and a heater 500 provided inside the sleeve 400.

The sintered pellet 100 is made by sintering fine tungsten powder so as to have a porosity of about 20%. BaO, CaO, and Al ₂ O ₃ are contained in the voids in a ratio of 4 :.
It is impregnated at a ratio of 1: 1. The cap 200 and the sleeve 400 are welded so that the heat from the heater 500 can be efficiently transmitted.

[0004]

However, the above-mentioned conventional impregnated cathode has the following problems.
That is, as shown in FIG. 3 (B), the sintered pellet 10
In order to press 0 into the separately formed cap 200,
A gap G is created between the sintered pellet 100 and the cap 200. This gap G is a portion where the sintered pellet 100 is not in contact with the cap 200, and thus causes the heat of the cap 200 not to be efficiently transferred to the sintered pellet 100. In this way, the gap G between the sintered pellet 100 and the cap 200 causes deterioration of electron emission. For example, when using three impregnated cathodes,
There is no problem if all three impregnated cathodes have the same gap G between the cap 200 and the sintered pellet 100, but there is a slight individual difference in the gap G between products, which is a problem.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for producing an impregnated cathode in which no gap is formed between the sintered pellet and the cap.

[0006]

According to the method of manufacturing an impregnated cathode according to the present invention, a CVD method is used in which a sintered pellet obtained by sintering a fine powder of a metal that emits electrons when heated is placed on a substrate. And a step of stacking and forming a cap with a desired metal around the sintered pellet, a step of exposing the side surface of the upper end portion of the cap and press-fitting the cap together with the sintered pellet into one end of the dummy pipe, and CVD again. In the step of forming a sleeve by laminating a desired metal on the side surface of the dummy pipe and the side surface of the cap exposed from the dummy pipe, the step of removing the dummy pipe after the desired sleeve is laminated, And a step of providing a heater inside.

[0007]

1 is a schematic sectional view of an impregnated cathode manufactured by a method for manufacturing an impregnated cathode according to an embodiment of the present invention, and FIG. 2 is an explanatory view showing a method for manufacturing the impregnated cathode. . It should be noted that substantially the same parts and the like as those of the conventional one are denoted by the same reference numerals and will be described.

In the method of manufacturing an impregnated cathode according to this embodiment, CVD is carried out with a sintered pellet 100 obtained by sintering fine powder of a metal that emits electrons when heated, placed on a substrate 600. A step of stacking and forming the cap 200 with a desired metal around the sintered pellet 100, and a step of exposing the side surface of the upper end portion of the cap 200 and pressing the cap 200 together with the sintered pellet 100 into one end of the dummy pipe 300. , The cap 1 exposed from the side surface of the dummy pipe 300 and the dummy pipe 300 by CVD again
00, a step of stacking and forming a sleeve 400 with a desired metal on the side surface of 00, a step of removing the dummy pipe 300 after the desired sleeve 400 is stacked and a step of providing a heater 500 inside the sleeve 400. have.

The sintered pellet 100 has, for example, a diameter of 1.
The columnar shape is 5 mm to 2.5 mm and the height is 0.5 mm to 1.0 mm. Such sintered pellet 10
No. 0 has a porosity of about 20% and is obtained by sintering fine tungsten powder. And in the gap, Ba
O, CaO and Al ₂ O ₃ are impregnated in a ratio of 4: 1: 1.

The sintered pellet 100 having the above structure
As shown in FIG. 2A, the substrate is placed on the substrate 600 and the CVD is performed. The substrate 600 has a recess 610 corresponding to the size of the sintered pellet 100. Therefore, the sintered pellet 100 can be stably used for the substrate 6
00 can be mounted.

In this state, CVD is carried out to obtain the sintered pellet 1
A cap 200 made of molybdenum or tungsten is laminated around 00 (see FIG. 2B). Here, the cap 200 is a sintered pellet 100 formed by CVD.
Since it is laminated around the periphery of the sintered pellet 1
There is no gap between the sintered pellet 100 and the cap 200 as in the case where 00 is press-fitted into the cap 200 formed separately. The growth thickness of molybdenum or the like to be the cap 200 is about 0.05 mm to 0.1 mm.

Here, since a part of the sintered pellet 100 is fitted in the concave portion 610 of the substrate 600, molybdenum or the like is not laminated and formed in that portion. Therefore,
After removing the sintered pellet 100 on which the cap 200 is laminated from the substrate 600, a step of cutting that portion is performed. However, when a substrate having no recess 610 is used, the cutting step need not be performed.

As shown in FIG. 2C, a sintered pellet 100 having a cap 200 laminated thereon is pressed into one end of a dummy pipe 300 made of copper. At this time, the cap 200 is not completely press-fitted into the dummy pipe 300, but the side surface of the upper end portion of the cap 200 is exposed.

In this state, CVD is performed again. Thereby, the side surface of the dummy pipe 300 and the dummy pipe 300
A sleeve 400 uniformly made of molybdenum or tungsten on the side surface of the upper end portion of the cap 200 exposed from the
Are formed (see FIG. 2D). Where the sleeve 4
Since 00 is laminated by CVD, it has higher adhesion than when the sleeve 400 is formed separately and the cap 200 is press-fitted. The growth thickness of molybdenum or the like that forms the sleeve is preferably up to about 0.1 mm.

Next, after cutting the portion 410 of the dummy pipe 300, which is formed in an extra layer at the other end, the dummy pipe 300 is melted and removed. Then, the sintered pellet 100, the cap 200, and the sleeve 400 that are almost integrated are completed.

The sleeve 40 having the above structure
When the heater 500 is provided inside 0, the impregnated cathode as shown in FIG. 1 is completed.

In the above-mentioned embodiments, the sintered pellet 100 has a cylindrical shape. However, the present invention is not limited to this, and the sintered pellet 100 may have an appropriate shape depending on the intended use. Of course.

Further, in the above-mentioned embodiment, molybdenum or tungsten is used as the material to be laminated by CVD, but the present invention is not limited to this, and an appropriate material is selected and used.

[0019]

According to the method of manufacturing an impregnated cathode according to the present invention, CVD is performed by carrying out CVD with a sintered pellet obtained by sintering fine powder of a metal that emits electrons when heated, placed on a substrate. A step of stacking and forming a cap with a desired metal around the bound pellet, a step of exposing the side surface of the upper end portion of the cap and press-fitting the cap together with the sintered pellet into one end of the dummy pipe, and again using CVD to form the dummy pipe. A step of forming a sleeve by laminating a desired metal on the side surface and a side surface of the cap exposed from the dummy pipe; a step of removing the dummy pipe after the desired sleeve is formed by laminating; and a heater inside the sleeve. And a step of providing. Therefore, a conventional gap does not occur between the sintered pellet and the cap. For this reason,
The efficiency of heat conduction from the cap to the sintered pellets can be increased, and electron emission is not adversely affected. Therefore, individual differences due to products can be further reduced.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an impregnated cathode manufactured by a method for manufacturing an impregnated cathode according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a method of manufacturing this impregnated cathode.

3A and 3B are diagrams of a conventional method for manufacturing an impregnated cathode, in which FIG. 3A is a schematic sectional view and FIG. 3B is an explanatory view showing the problem.

[Explanation of symbols]

 100 Sintered pellet 200 Cap 300 Dummy pipe 400 Sleeve 500 Heater

Claims (2)

[Claims] 1. A sintered pellet obtained by sintering fine powder of a metal that emits electrons when heated is placed on a substrate to form C.
Performing VD to form a cap by laminating a desired metal around the sintered pellet, exposing the side surface of the upper end portion of the cap to press the cap together with the sintered pellet into one end of the dummy pipe, and again. A step of stacking a sleeve of desired metal on the side surface of the dummy pipe and the side surface of the cap exposed from the dummy pipe by CVD;
A method of manufacturing an impregnated cathode, comprising: a step of removing the dummy pipe after a desired sleeve is laminated and a step of providing a heater inside the sleeve. 2. The method for manufacturing an impregnated cathode according to claim 1, wherein the cap and the sleeve are made of molybdenum or tungsten.