JPS6269423A - Metallic part for electron tube and its manufacture - Google Patents

Abstract

PURPOSE:To prevent oxidation of metallic part, by forming a separated silicon oxide membrane over the surface. CONSTITUTION:At an end of a cylindrical cathode tube 2 housing a heater 1 therein, a bass metal 3 is inserted, over which an oxide membrane 4 is formed. At the other end of the cathode tube 2, an inside cathode support 6 is fixed by laser welding through a strap 5. A portion of the inside cathode support 6 is fixed by laser welding to a strap 7 which is a cylindrical form concentric with the cathode tube 2, while the inside cathode support 6 itself is made of Kovar alloy. The surface of the support 6 is covered with SiO2 membrane 6a. Since oxidation of the metallic part of the electron tube can be prevented in such a way, the cost, the manufacture, and the performance of the electron tube are extensively improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a metal component for an electron tube and a method for manufacturing the same.

[Technical background of the invention and its problems]

In recent television picture tubes, so-called interlocking picture tubes are used, which have a fast operation start time (quick image output time). Ru.

The interlocking type cathode body generally has a base metal on which an oxide coating is formed fixed to one end of the cathode tube, and the other end of the cathode tube is connected to an inner cathode support that is coaxial with the cathode tube and located at a predetermined interval on the outside of the cathode tube. The inner cathode support is attached directly or indirectly to the body, and the inner cathode support is fixed to the outer cathode support. In order to improve the interlocking nature of the cathode, the parts of the cathode structure (cathode support) are made of metals such as iron, nickel, etc., which are advantageous in terms of thermal design.
Kovar, which has cobalt as its main component, is selected, and in many cases problems such as oxidation are prevented by plating the surface with a metal that is difficult to oxidize, such as nickel.

This plating is used to prevent oxidation in the above-mentioned picture tube 3A manufacturing process, to prevent the cathode support from being exposed to high temperatures during cathode operation, and for material manufacturing and press processing reasons.
This is to prevent impurities with high vapor pressure such as manganese added to the material from evaporating and reducing the emission ability of the cathode.

However, plating the cathode support is not a fool's errand, as it increases costs, and the surface condition after shifting changes depending on the plating pretreatment conditions, which is important for maintaining the cathode's emission characteristics. This may cause a change in the cathode temperature.

[Purpose of the invention]

The present invention has been made in order to improve the above-mentioned drawbacks without making major changes to the structure and manufacturing process of the cathode.

[Summary of the Invention] The present invention is a metal part for an electron tube using a Kovar material containing iron, nickel, and cobalt as main components, which is characterized by having a precipitated silicon oxide film on the surface thereof.

Further, the present invention is a method for manufacturing a metal part for an electron tube, which is characterized in that a silicon oxide film is formed on the surface of the metal part mainly composed of iron, nickel, and cobalt by heat treatment at a temperature of 1050 DEG C. or less.

According to the present invention, metal parts can be prevented from being damaged by the formed silicon oxide film.

[Embodiments of the invention]

Hereinafter, the present invention will be described in detail with reference to the drawings.

Figure @1 is an example in which the present invention is applied to a cathode structure, and heater 1
At one end of the cylindrical cathode cylinder 2 containing a metal substrate 1!43
is fitted, and an oxide film 4 is formed on the base metal 3. The other end of the cathode tube 2 is fixed to a cylindrical inner cathode support 6 via a strap 5 (by laser welding). A portion of the inner cathode support 6 is formed into a cylindrical shape and is fixed to a strap 7 coaxial with the cathode tube 2 by laser welding. Now, the inner cathode support 6
is made of Kovar wood. FIG. 2 is a partially enlarged view of the cathode support 6 in FIG. 1, and the surface of the support is covered with a SiO* film 6a.
is coated, which is a feature of the present invention.

Next, a method for forming a 5i02 oxide film on the surface of the inner cathode support will be described.

In order to oxidize the silicon in the Kovar material to form a Si film on the surface, it is first necessary to determine the amount of silicon in the material and the oxidation conditions. Kovar (29Ni-170o
Table 1 shows the results of experiments conducted by changing the Sif in -0,4Mn-Fe) and the oxidation temperature.

If the amount of Si in Kovar increases, press workability will be affected, so the amount of Si is preferably in the range of 0.1 to 0.5.

(Left below) From this, it can be seen that a surface oxide film does not form in a dry hydrogen atmosphere.The more Sif in the material and the higher the humidified hydrogen treatment temperature, the thicker the oxide film becomes.

Next, to confirm through mounting tests, the cathode structure was exploded using an inner cathode support material that had been pressed, degreased, polished to remove deburrs, and heat treated with humidified hydrogen, and then incorporated into a color picture tube to confirm the emission life. . Here, since the surface of the inner cathode support was covered with Sin, it could not be welded by conventional resistance welding, so laser welding was used.

Figure 3 shows the emission life results. This is the Sin on the surface, the film is 5i600 in OF2 of EPMA analysis,
If it is 045 or higher, it seems that there is no problem.

It is also understood that in order to obtain such a large amount of Si and oxide film, the amount of Si in Kovar needs to be 0.10 or more, and the oxidation temperature needs to be 900" or more.

If the oxide film is thin, lower grade oxides will be formed on the surface during the heat process in the color cathode ray tube manufacturing process, which may decompose during operation, or may not be sufficient to prevent the evaporation of the pigeons, etc. contained in the Kovar. This is thought to lead to deterioration of emission characteristics.

Although the case of the inner cathode support using Kovar has been described above, it goes without saying that the present method can also be applied to metal parts for electron tubes using materials mainly composed of Fe--Ni.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to prevent the oxidation of metal parts for electron tubes whose main component is Fe-N1-(Co) without using means such as Ni plating, which reduces the cost of electron tubes. This provides significant advantages in terms of manufacturing technology and performance.

[Brief explanation of drawings]

Figure 1 is a diagram explaining the case where the present invention is applied to a cathode assembly, Figure 2 is a partially enlarged view of Figure 1, and Figure 3 is the emission when the cathode assembly of Figure 1 is applied to a color picture tube. A diagram explaining life characteristics. 6...Cathode support 6a...Sin, Membrane agent Patent attorney Norio Chika Ken Yudo Ogo Norio No. 1 Diagram 2 Diagram

Claims (2)

[Claims] (1) A metal part for an electron tube using a Kovar material whose main components are iron, nickel, and cobalt, characterized in that the metal part has a precipitated silicon oxide film on its surface. (2) The main ingredients are iron, nickel, and cobalt, and the content is 0.1 to 0.
．． A method for manufacturing metal parts for electron tubes, which comprises processing Kovar material containing 5% silicon into a predetermined shape and then heat-treating it in humidified hydrogen to form a silicon oxide film on the surface.