JPS6229034A - Manufacture of electron tube parts with black film - Google Patents

Abstract

PURPOSE:To make it possible to fully heighten a heat radiation rate by forming a black film on the surface of the metallic parts of an electron tube by plasma- sprayed mixed powder consisting of titaniumoxide and the other oxide while performing heat treatment of said parts in a high temperature furnace having hydrogen atmosphere. CONSTITUTION:Firstly, powder of titaniumoxide and powder of alminium oxide are mixed for being subjected to plasma radiation to form a black coating 21 on the inner face of an anode cylinder. Next, heat treatment is performed at a temperature in the range of 700 deg.C-900 deg.C, for example, in the hydrogen atmosphere of 800 deg.C for 15min. Thereby, the thermal radiation rate can be heightened and stabilized at a relatively low temperature and moreover in a relatively short time of heat treatment.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method of manufacturing a transmitting tube, a microwave tube, an X-ray tube, and other electron tubes, and particularly relates to a method of manufacturing an electron tube component having a black coating on a predetermined surface of a metal component. Regarding the manufacturing method.

[Technical background of the invention and its problems] In order to increase the thermal radiation or heat absorption ability of the surfaces of various electrodes of electron tubes, a black film may be formed on the surfaces. Examples include Japanese Patent Publication No. 56-15110, U.S. Patent No. 4,029,
No. 828 or No. 4,132,916, a black coating is formed by plasma spraying a mixed powder of titanium oxide and other oxides such as aluminum oxide on the surface of a metal part. , this is approximately 1 in vacuum
A method is known in which heat treatment is performed at a high temperature of about 600° C. for several tens of minutes.

However, in the conventional method, in order to increase the thermal emissivity to a sufficient level, heat treatment must be performed at extremely high temperatures as described above. This method cannot be used for parts soldered using silver solder or the like.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and provides a method for manufacturing an electron tube component having a black coating that can sufficiently increase the thermal emissivity through heat treatment at a relatively low temperature and in a relatively short time. be.

[Summary of the invention]

The present invention is characterized in that a black film is formed by plasma spraying a mixed powder of titanium oxide and other oxides on the surface of a metal part for an electron tube, and the part is heat-treated in a high-temperature furnace in a hydrogen atmosphere. This is a method of manufacturing an electron tube component having a black coating.

[Embodiments of the invention]

Examples thereof will be described below with reference to the drawings. Identical parts are designated by the same reference numerals.

The embodiment shown in FIG. 1 is a method of forming a black coating on the inner surface of a copper anode of a transmitting multi-electrode electron tube. In the figure, reference numeral 11 is an anode cylinder made of copper or copper alloy, 12 is a radiator fixed to its outer periphery, 13 is a metal exhaust pipe, 14 is a cover, 15 is a ceramic insulating cylinder, 1
6 is a heater, 16m is a heater support structure, J7 is a cathode, 18 is a first grid, 19 is a second grid, and 20 is a grid support cylinder.

Then, a black coating 2 is applied to the inner surface of the anode cylinder 11.
1 is formed. This black coating 21 is for efficiently absorbing radiant heat from the cathode or each grid, reducing the temperature of the grid, and suppressing the occurrence of so-called grid emissions.

The black coating 21 is coated on the inner surface of one part of the anode cylinder by first mixing powder of titanium oxide (for example, TiO2) and powder of aluminum oxide (AL20.) and applying the mixture by plasma spraying. The wavelength of this sprayed film is 0.2-2.0μ
The average thermal emissivity in the m range was 0.89.

Therefore, this part is heat treated for 5 minutes in a hydrogen atmosphere at a temperature in the range of 700°C to 900°C, for example 800°C. In this way, a film with stable thermal emissivity can be obtained. This is assembled together with other electrodes into an electron tube. The thermal emissivity of the black film 21 obtained in this way in the wavelength range is:
The temperature was as high as 0.94, and there was almost no change even after heating. In this way, the emissivity can be increased and stabilized by heat treatment at a relatively low temperature and in a relatively short time.

In the above example, the base metal to which the black film is applied, that is, the electrode material, is copper, but stainless steel metal materials can also be used to form a black film with similar emissivity at approximately the same temperature and processing time. A coating could be obtained.

When the base metal is copper or stainless steel, the holding time is approximately 30 minutes when the treatment temperature in hydrogen is 700°C, and the holding time is approximately 30 minutes when the processing temperature is 900°C.
0 minutes is sufficient. When using a solder-plated part made of silver solder as a base metal, the heat treatment temperature in hydrogen should be kept at approximately 700°C, which is below the melting point of the silver solder. It is desirable that the holding time be about 30 minutes.

The embodiment shown in FIG. 2 is applied to a rotating anode of an X-ray tube. In the figure, reference numeral 3 denotes a rotating anode target, 32 a target substrate made of molybdenum, 33 a target metal layer such as tungsten, 34 a support iron made of molybdenum, 35 a similar nut, and 36 a cylindrical column made of copper. The rotor 37 is a bearing structure that rotatably supports the rotor, and 38 is an anode support. Therefore, a black coating 4 is applied to the back side of the target substrate 32 made of molybdenum.
1 and the outer periphery of the rotor 37 are similarly coated with a black coating 21.

These black coatings are intended to enhance heat radiation from the surfaces of these electrodes and improve heat dissipation.

The black coating 21 formed on the outer surface of the rotor can be formed by the same heat treatment as in the previous embodiment. On the other hand, the same oxide material as described above is plasma sprayed on the back surface of the single component of the target substrate 32 made of molybdenum to form a film. And this is in the temperature range of 1000℃~1200℃,
For example, heat treatment is performed for 15 minutes in a hydrogen atmosphere at 1100°C. As a result, the thermal emissivity of the black film is 0 before the treatment.
．． It rose from 88 to 0.95.

The reason for limiting the heat treatment temperature range in a hydrogen atmosphere is that below the lower limit, sufficient improvement in thermal emissivity and stability cannot be obtained, and above the upper limit, the film may become partially smooth. This is also because the emissivity does not improve.

In addition to the above, the material for the black coating is selected from magnesium oxide, calcium oxide, zirconium oxide, lanthanum oxide, yttrium oxide, cerium oxide, strontium oxide, hafnium oxide, etc. as the oxide mixed with titanium oxide. At least one oxide can be mixed. They may also contain small amounts of other metals.

〔Effect of the invention〕

As described above, according to the present invention, by depositing a mixed material of titanium oxide and other oxides by plasma spraying and heat-treating it in a hydrogen atmosphere, thermal radiation can be achieved at a relatively low temperature and in a short time. The rate can be increased and stabilized. Therefore, this black coating can also be easily formed on base materials having a relatively low melting point and on soldered metal parts. In addition, manufacturing efficiency can be increased.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view of main parts showing one embodiment of the present invention;
The figure is a longitudinal sectional view of a main part showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 11...Anode cylinder, 32...Target substrate, 36...Rotor, 21.41...Black coating. Representative Patent Attorney Suzue Takehiko Figure 1 Figure 2

Claims (3)

[Claims] (1) A black film characterized by plasma spraying a mixed powder of titanium oxide and other oxides on the surface of a metal part for an electron tube to form a black film, and then heat-treating this part in a high-temperature furnace in a hydrogen atmosphere. A method for manufacturing an electron tube component having a coating. (2) A patent claim in which the metal part to which the black coating is applied is made of copper, an alloy material mainly consisting of copper, or a stainless steel material, and is treated in a hydrogen atmosphere at a temperature in the range of 700°C to 900°C. A method for manufacturing an electron tube component having a black coating according to item 1. (3) The metal parts to which the black coating is applied are made of molybdenum or a material mainly composed of molybdenum, and the temperature is 100°C.
A method for manufacturing an electron tube component having a black coating according to claim 1, wherein the electron tube component is treated in a hydrogen atmosphere in a range of 0°C to 1200°C.