JPS59149616A - Method of treating vacuum valve insulating container - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for treating a vacuum valve insulating container.

[Technical background of the invention and its problems]

As shown in FIG. 1, a conventional vacuum valve has a vacuum container in which end plates 2 and 3 are provided at both ends of an insulating container 1, which is made up of two insulating cylinders 1a arranged side by side in the axial direction, and the inside is evacuated. is forming. The fixed electrode 4 is provided with an electrode 4C having a contact 4b on a current-carrying shaft 4a that passes through the end plate 2 in an airtight manner. Further, the movable electrode 5 is provided with an electrode 5C having a contactor 5b on an energizing shaft 5a movably sealed via a bellows 6 on the end plate 3. A fixed shield 7 is provided on the fixed electrode side, an intermediate shield 8 is provided in the middle of the vacuum container, and a fixed shield 7 is provided on the movable side.

Such a shield 7.8 protects the electrode 4,
This plays a major role in preventing the metal vapor generated between the holes 5 and 5 from adhering to the inner wall of the insulating container 1. However, since the insulating tube 1a is located near the fixed shield 7 and the intermediate shield 8', the breakdown voltage is reduced. this is,
When a high voltage is applied to the vacuum knob, a secondary electron avalanche occurs on the surface of the insulating tube 1a. The relationship between the primary electron collision energy and the secondary electron emission efficiency δ (E) at this time is the characteristic curve δ (El) shown in Figure 2. In Figure 2, the vertical axis is 2
The secondary electron emission efficiency δ(E), and the horizontal axis indicates the electron collision energy E [eV, l. According to this fIJl line δ(E), positive charges are accumulated when the insulating cylinder la is made of alumina (A1203). The electrons emitted from the insulating cylinder 1a multiply by a secondary electron avalanche, and eventually lead to dielectric breakdown. Therefore, a precursor breakdown current due to electron avalanche flows at a relatively low voltage, resulting in a low breakdown voltage.

As a method to solve this problem, a method was previously discovered in which the inner surface of the insulating cylinder 1a was coated with chromium oxide (hereinafter referred to as "or", "o3"). This is achieved by coating with Cr2O3 as shown in Figure 2.
The secondary electron emission efficiency δ(E) is always 1 or less, suppressing the secondary electron avalanche and improving the breakdown voltage. However, such a device has the following drawbacks.

Generally, the surface of an insulating container made of alumina or the like is covered with a layer of adsorbed gas of several tens of layers. For this reason, vacuum pulp is heat-treated while being evacuated after assembly to remove the adsorbed gas layer on the surface of the solid and the occluded gas inside the solid. Through these treatments, the vacuum pulp is maintained at a high vacuum level and has a good vacuum life. A vacuum evaporation method is known as a Cr2O3 coating method. Before assembling the vacuum pulp, the inner surface of the insulating container is vacuum-deposited for 0r20s.
When coating is performed, fcOr203 on the adsorbed gas layer
The layer will be coated. If such an insulating container is used, the adsorbed gas layer will not be removed even if heat treatment is performed. For this reason, the degree of vacuum of the vacuum pulp gradually decreases, and the vacuum life becomes significantly worse. Also, in an unstable state, 0r2
Since the 03 layer is coated, pinholes and cracks are likely to occur in the 0r203 layer.

For these reasons, an insulating container coated with Or20g cannot be used for a vacuum valve, and at present it is not possible to provide a vacuum valve suitable for high voltage r.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for treating a vacuum pulp insulating container with excellent over-the-air pressure resistance by effectively coating the insulating container with 0r203.

[Summary of the invention]

In the present invention, when the coating material of the insulating container is alumina,
Coat the inner surface of the insulating container with 0r208 at a temperature of 2000 C to 35000 C using vacuum evaporation at a temperature of 2000 C to 35000 C. A method for treating a vacuum valve insulating container is characterized in that it is coated with (,:3r203).

[Embodiments of the invention]

A method of coating Cr2O, which is an embodiment of the present invention, will be explained. The present invention provides Or20. h') When coating the insulating container 1 before assembling the vacuum pulp, vacuum evaporation is performed while heating the insulating container 1 [xl) 0r20. Form a layer.

During the heating process of the insulating container 1, gas is released as shown in FIG. 3, and the amount Q of gas released is the adsorbed gas from the surface of the insulating container 1 and the occluded gas inside. Heating the insulating container significantly increases the amount of gas released. Ql is the amount of gas released at which a predetermined vacuum life of the vacuum pulp can be obtained. The temperature of the insulating container that can obtain more than Q+ is 2 for Q1 borosilicate glass, which varies depending on the material.
50°C or higher, and in the case of ceramics, 450°C or higher. At such a temperature, the adsorbed gas layer on the surface of the insulating container is largely removed, and the 3r203 layer is coated in a stable state, so pinholes and cracks in the Cr2O3 layer do not occur. When the temperature is near the melting point, the 0r203 layer forms pinholes and holes.
Generates a tsuk. For this reason, heating the insulated container may cause
For borosilicate glass it should be 200-350°0, for ceramics K 450-1000°0. As a result, the 0r203 layer on the surface of the insulating container does not generate pinholes or cranks, and has high adhesion strength.
It also provides a long vacuum life as a vacuum valve.

Therefore, the withstand voltage performance of the vacuum valve is Cr2O.

coating becomes possible.

〔Effect of the invention〕

As detailed above, 0r20. According to the table, by using a coated insulating container, the specified vacuum life of the Makabe valve can be obtained and the insulation performance is improved, so it is possible to provide a method for processing the vacuum valve insulating container suitable for high voltage. .

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing a conventional vacuum valve, FIG. 2 is a characteristic curve diagram showing secondary electron emission characteristics in a conventional vacuum valve, and FIG. 3 is a gas emission characteristic related to an embodiment of the present invention. FIG. 1a...Insulating cylinder, 1b...Cr2O3 coating surface, ■-Insulating container, 2, 3... End plate, 4...
Fixed electrode, 5... Movable electrode, 6... Bellows,
7... Fixed nold, 8... Intermediate/-ld. Fig. 1 Fig. 2 Electronic balance/Dingwinter N-E

Claims (1)

[Claims] A pair of electrodes that can be brought into and out of contact with each other is arranged in a vacuum container consisting of an insulating container and an end plate that closes the insulating container, and at least one of the pair of electrodes is movably sealed to the end plate via a bellows. In the vacuum valve, the insulating container is made of alumina, and the inner surface of the insulating container is coated with chromium oxide by vacuum evaporation at a temperature of 450°C to 1000°C. (Cr20s)
or the insulating container is made of borosilicate glass, and the inner surface of the insulating container is coated with chromium oxide (CrtOs) by vacuum evaporation at a temperature of 200°C to 350°C. How to treat valve insulation containers.