JPS5844643A - Manufacturing method of impregnate type cathode - Google Patents

Abstract

PURPOSE:To obtain a manufacturing method capable of simplifying and rationalizing the process and saving labor, by providing a process to shape a surface from a thin plate type cathode substrate aggregate impregnated with emitter, by means of laser processing and a number of cathode substrates on it. CONSTITUTION:A porous tungusten thin plate which is impregnated with an emitter that is, a cathode substrate aggregate 24 is sampling-processed by means of laser light processing so that each of the cathode substrates can obtain desired outer diameter dimensions as a cathode substrate 25. In other words, thanks to such a process of the cathode substrate, a number of (for example, for a thin plate of 30mm.phi in outer diameter dimensions, 100 substrates of 1.5mm.phi in outer diameter can be obtained) substrates with the same properties can be obtained from single thin plate, that means there is a quality control advantage. As compared with the conventional method in which the single substrate was obtained piece by piece and was impregnated with emitter, the manual work of an intermediate process and the taking in and out of materials can be reduced sharply.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to impregnated porous electrodes, and is particularly directed to improvements in the method of manufacturing the same.

The conventional manufacturing method for impregnated tungsten fibers can be explained in detail with reference to FIG. 1. FIG. After the cathode is completed, a general ζ27 material with an apparent specific gravity of about 16 is used in order to improve the emitter efficiency and prevent the formation of steam, and to improve the workability in the next cutting process. The holes are impregnated with copper. In the cutting process, the same figure tb) * lc) * (d
), the outer diameter is cut to a predetermined diameter, the face is cut to a predetermined diameter, and then the back surface is cut to a predetermined thickness. Next, this substrate undergoes the calibration process shown in (6) in the same figure, and in (f) in the same figure, it is heated in a hydrogen atmosphere to evaporate the steel or heated in a strong acid solution. Copper is removed by immersing the iron in the iron and dissolving it.

Thereafter, a molybdenum ruthenium (Mo--Ru) alloy is applied to the back surface of the substrate as shown in FIG.

One purpose of this process is to prevent the 11 ivy from emitting 'rA from the back surface of the substrate when the cathode is completed, as well as to prevent ψ from emitting electrons from the back surface, thereby reducing the leakage current fIL between the heater cathode.
(Iwx) is to be suppressed as much as possible.

In the same figure (step h7), barium calcium aluminate (generally 4BaO: IA40s:
It is often used at the blending ratio of I CaO, but it is necessary (
2. Changes will be made as appropriate. ) 13 is placed thereon and melted and impregnated in a hydrogen stream to form a cathode substrate 14. Specifically, this process involves placing a mixture of BaCO5e Altos +C1CO5 on the surface of the substrate, and first adding BaCos + C1CO5 to the surface of the substrate.
a. COl is decomposed and then melted and impregnated into the holes.

Next, in the step 11 in the same figure, the surface of the cathode substrate 14 is smoothed to remove excess emitter adhering to the coating/surface, and the inspection step and front/back discrimination step shown in FIGS. After that, in the first assembly process shown in FIG. 1 (1), the electrode support tube 15 made of Ta or the like is placed on the 7th wall with the electron emitting surface facing up, and η is held. The support tube 15 is welded to the connecting piece, which is attached to the cathode support plate 18 and provided for holding the support tube 15 by cutting out the end of the outer tube 19, using the second assembly machine in step m). A heater 17 is pressed into the support tube 15 to form the Sakaki body.The cathode is completed as an impregnated cathode, and after passing through the inspection process shown in FIG. .

However, each process in the manufacturing method for such an impregnated cathode is complicated, so there is a demand for streamlining the process and saving labor.

Therefore, an object of the present invention is to provide an extremely good method for manufacturing an impregnated cathode that meets the above-mentioned needs.

An embodiment of the present invention will be described in detail below with reference to the drawings.

In other words, FIG. 2(a) shows a rod-shaped porous tungsten sintered body 21 that serves as a base, and this porous tungsten sintered body is made as thick as possible (at present, the outer diameter is about 5011φ). It is possible to obtain a sintered rod of up to 100% of the total amount formed. After this porous tungsten sintered body is impregnated with copper into the pores to increase machinability, it is sliced into a thin plate as shown in tb) of the same figure.

At this time, the outer diameter cutting N can be omitted. This slicing process may be performed using a lathe process, but in the case of Daimon production, bar v A
The process can be further shortened by using a slicing machine called a slicing machine, or another method using a diamond cutter or the like may be used.

Next, this thin plate n is subjected to acid treatment or hydrogen treatment to remove the copper impregnated in the hole t51sI in the step tel in the same figure.
In the process shown in FIG. 1, the emitter is impregnated to form a thin plate-like substrate. That is, in this emitter impregnation step, the MU thin plate η is placed in a hydrogen furnace, and BaC0a* is deposited on top of this thin plate.
A mixture of All Os + CaCO5 was added to first thermally decompose BaCO5 and CaCO5 to form BaOCa.
After changing to O, the temperature of the furnace is further raised to change Ba0A403C.
This is carried out by making a solid solution of aO (barium calcium aluminate) resistant to melting and impregnating it into the pores of a porous thin tungsten plate. After that, in the process shown in the same figure (f), the excess emitter remaining on the surface of the thin plate-like substrate is removed with tungsten wool (rounded tungsten coil waste).
Remove by polishing. Prior to the emitter content step, if the final impregnated cathode is attached directly to the end of the cathode support tube as in the conventional case, the electron emitting surface of the substrate is What is necessary is to perform a step of coating the opposite side of the W retouched molybdenum ruthenium sickle and baking it in an inert gas or pure nitrogen.

Next, the porous tungsten thin plates impregnated with emitters, that is, the array of cathode substrate aggregates, are then processed with a laser beam in the process shown in FIG. It is extracted and processed to make it look like this. In other words, according to the manufacturing process of such a cathode substrate, a large number of identical pieces (for example, in the case of a thin plate with an outer diameter of 30 mm and a substrate with an outer diameter of 1.5 fins) can be obtained from a thin plate of 7 pieces. In addition to being advantageous in terms of quality control by providing a substrate with specific properties, it is also possible to reduce the amount of material in the handmade bundle in the intermediate process, compared to the conventional method of forming each substrate one by one and then impregnating the emitter. It is possible to significantly reduce the time and effort required for loading and unloading. The above laser processing is specifically carried out in the atmosphere or in an airflow that does not harm the cathode impregnated with nitrogen, alkone, hydrogen, etc., and the part to be processed is evaporated. Splash can be removed to the extent that shallow splashing is not recognized by changing the pulse width and repetition frequency of the laser beam.

In the conventional example, this machining was performed by electric discharge machining, but it includes 9. The thickness of the porous tungsten body of the type cathode is determined from the life of the cathode, etc., and the thickness is set at the bottom at 0.41111. Therefore 0.4! It takes at least 1.0 hours to punch out the porous tungsten thin plate II by electrical discharge machining. Furthermore, if a large number of pieces are to be removed, the power required for free machining at one time is the same, so the number of pieces x time cannot necessarily be said to be dredging, and there is a problem with the machining speed.

The present project is based on this laser processing, and the cutting part is rotated at 15 [gl] per second using a laser with a cutting width of soo na + m and a return of 15 KC.
A 1 m thick porous tungsten thin plate can be cut in about 2 minutes, which is twice as fast as the conventional method.

In the non-processing process (in Figure 2), there are many processes (a) to (f), which involve individual cutting (approximately 100 pieces) or unmanned processing (slicing), and there is no problem with machining costs, but electrical discharge machining In fact, it becomes unprofitable due to the time required for 1 piece (2), equipment cost, depreciation cost, and operating cost associated with this ζ2.

In this respect, although the equipment cost of the laser device is twice that of electric discharge machining, the machining speed is reduced, making it sufficiently profitable.

When cutting a porous tungsten thin plate using a laser beam, only a slight molten state (only on the surface of a single cut grain) can be seen on the cut surface (the same applies to this point discharge machining), and the cut surface is in good condition, indicating impregnation. Varicum, calcium, and aluminate also evaporate and evaporate in the cut surface layer, but there is no abnormality inside the cut surface, and it functions well as an entuter. (Also in this case, the same level as electric discharge machining) Laser machining has almost no problem in machining in the atmosphere, because the workpiece (porous tungsten impregnated with aluminate) is processed by repeating extremely short pulse widths. This is because the temperature of the surrounding area is cooled and the temperature does not reach the oxidation region because the evaporation is caused by localized instantaneous heating. Furthermore, it is completely safe in inert or reducing gases such as nitrogen, argon, and hydrogen.

Unlike point discharge machining, petroleum is used and there is no problem with free carbon during machining. Further, there is no necessity for post-treatment such as hydrogen treatment to remove free carbon.

Furthermore, the electron emitting surface is completely non-contact and is not subjected to processing distortion, so it is safe.

Thereafter, as shown in the upper part of the figure (h), a cap made of Mo or Ta is interposed and attached to the end of the cathode support. If you use this cap I, see Figure 2.
The molybdenum ruthenium brazing process of DL can be omitted (the process of distinguishing between the two front and back sides can be omitted, making it possible to simplify the assembly process. Alternatively, the cathode substrate that has gone through the ldl process in the same figure can be placed in the lower row of the same figure (h). As shown, the first assembly step is carried out by directly attaching the substrate to the end of the cathode support cylinder with the ivy-impregnated surface of the substrate as the surface.

The subsequent steps F are substantially the same as those shown in FIG. 1, and the impregnated mold km is completed.

Therefore, according to the present invention as described in detail above, the process of forming the cathode substrate in particular can be efficiently streamlined and the labor of intermediate processes can be significantly reduced, reducing the labor to one-tenth of the conventional process. It is possible to provide an extremely good method for manufacturing an impregnated pole.

It goes without saying that the glaze of the present invention can be modified without changing the gist of the invention.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing a conventional method for manufacturing an impregnated cathode, and FIG. 2 is a process diagram showing essential parts of an embodiment of the method for manufacturing an impregnated cathode according to the present invention. Sae... Thin plate-like substrate 5... Cathode substrate... Cap n... Cathode support cylinder

Claims (1)

[Claims] A first step of forming a thin plate-shaped porous tungsten sintered body from a rod-shaped porous tungsten sintered body, and a step of engraving ivy on the thin plate-shaped porous tungsten sintered body formed by this first step. The second step is to impregnate the cathode substrate, and the third step is to process the thin plate-shaped cathode substrate assembly impregnated with entuta into a predetermined shape from the surface by laser processing to form a large number of cathode substrates. A method for manufacturing an impregnated cathode, comprising: