JPH0325821A - Contact for vacuum valve - Google Patents

Abstract

PURPOSE:To control low the generation frequency of arc by forming an intermediate layer made of the metal having a melting temperature higher than that of the high conductive component of a contact for Ag-Cu group vacuum valve on the junction surface of the contact and an electrode. CONSTITUTION:A metal intermediate layer 11 is provided on the electrode function surface of a contact substrate 10 made of the Ag-Cu alloy including the firing-proof component in the high conductive component with a plating method such as a chemical method or an electrical method or an ion plating method. Fe, Co, Ni and Cr are desirably used as the material for the intermediate layer. The desired proper degree of the junction material against Cu or Ag is more than 1 weight %. The described intermediate layer is thereby comprised between the junction surface of the contact substrate and the junction material (wax material) to prevent a contact of the contact and the melted junction material to be generated at the time of junction of the contact to the electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a contact for a vacuum valve, which includes a metal intermediate layer on at least the surface of a contact base that is bonded to an electrode.

(Prior Art) FIG. 3 shows the structure of a conventional general vacuum valve, which includes a cylindrical insulating container 20 and a valve attached to both end surfaces of the container through sealing fittings 21 and 22. metal end plate 23,
24 constitutes a container, and a cutoff chamber 25 is formed inside. A first conductive rod 26 is fixed in the cutoff chamber 25 by passing through the end plate 23 in an airtight manner, and a second conductive rod 27 is provided so as to be movable in the axial direction by penetrating the end plate 24. .

At opposite ends of the first conductive rod 26 and the second conductive rod 27, there are a fixed electrode 29 with a contact 28 and a movable electrode 31 with a contact 30. A bellows 34 is attached between the second conductive rod 27 and the end plate 24 for airtightness. A bellows force bar 35 is also sunk into the bellows 34 to protect it from arc vapor between the contacts 28,30.

Further, an arc shield 36 is provided to protect the insulating container 20 from arc vapor, and opening and closing operations are performed by a drive mechanism and a conductive rod 27 (not shown).

Here, the details of the fixed electrode 29 and the movable electrode 3 will be explained using an example of the movable electrode 1 with reference to FIG.

The movable electrode 31 is attached to the conductive rod 27 via a brazed portion 32, and is attached to the contact point 3 via a brazed portion 33.
0 is attached.

Conventionally, such contact materials include CuBi series and Cu.
-Te system, Cu-W system, Cu-WC system, Ag-W system, A
Alloy materials such as g-WC, Cu-Cr, and Cu-Tt are used as appropriate depending on the purpose.

(Problems to be Solved by the Invention) In general, contacts for vacuum circuit breakers are brazed with electrodes in a hydrogen reducing atmosphere or a nitrogen or vacuum atmosphere.

By the way, in conventional contacts where Ag-Cu alloy is used as a conductive component that is a constituent of the contact material, during the process of brazing the electrode and the contact, the contact is melted due to the melting of the bonding material. There is a problem that the constituent Ag-Cu alloy flows out. The Ag-Cu alloy that flows out in this way creates unevenness on the surface of the electrode,
By adhering to the surface, it leaves the surface rough.

With such an electrode having a rough surface, it was not possible to obtain the shutoff performance required for a vacuum valve in terms of restriking characteristics, and there was also a major problem in terms of reliability.

The present invention has been made in view of the problems of the prior art described above, and an object of the present invention is to provide a contact for a vacuum valve that is highly reliable in terms of quality, particularly in terms of withstand voltage.

[Structure of the invention]

(101 Steps to Solve the Problem) The vacuum valve contact of the present invention is made by adding an arc-resistant component to a highly conductive component made of Ag and Cu.
A Cu-based vacuum valve contact, 1% by weight based on at least one of the highly conductive components constituting the contact.
The present invention is characterized in that an intermediate layer made of a metal having a solid solubility above and a melting temperature higher than that of the high conductivity component is formed on at least the joint surface of the contact with the electrode.

As shown in FIGS. 1 and 2, the vacuum valve contact of the present invention has a metal intermediate layer 11 formed between a contact base 10 and an electrode bonding surface of the contact base 10 by a chemical method, an electric method, or an ion method. It can be obtained by providing it by a plating method such as brating.

By providing the above-described intermediate layer between the bonding surface of the contact base and the bonding material (for example, wax +4), contact between the contact and the melted bonding material that occurs when bonding the contact to the electrode can be prevented. It becomes possible to prevent rL- as much as possible. Therefore, it is possible to effectively prevent the Ag-Cu alloy, which is a component of the contact, from flowing out of the contact due to contact with molten metal (joining material). This makes it possible to prevent corrosion caused by contact with molten metal and the occurrence of irregularities on the electrode surface due to adhesion of molten metal.

It is important that the metal of the intermediate layer provided on the contact base has good compatibility with the contact base and the bonding material.

From the viewpoint of electrical conductivity, an alloy containing Cu and Ag as main components is used as the bonding material. Therefore, Cu as the metal of the intermediate layer
Alternatively, those having solid solubility with Ag are preferable. Further, from the viewpoint of melting the contact and reducing contact with the contact material, it is preferable that the material has a higher melting point than the bonding material and has a thickness of at least 1 μm or more.

From this point of view, the material for the intermediate layer of the present invention is as follows:
Fe, Co, N1 and C' are particularly preferably used. Further, the solid solubility in Cu or Ag mentioned above is preferably 1% by weight or more.

Further, the contact of the present invention is made of Ag and Cu as highly conductive components and contains an arc-resistant component. 6
Ag is 5% by weight and accounts for the total weight of Ag and Cu.
It is preferable that the ratio is 40 to 80% by weight.

Furthermore, the arc-resistant components are TiSZr, VSNb, Ta
Carbides and/or borides of sCr, MO, W, and La are preferably used, and the content of these arc-resistant components is preferably in the range of 35 to 75% by weight.

As described above, when the vacuum valve contact of the present invention is brazed to an electrode, the contact components do not leak due to melting of the bonding material, and surface roughening of the electrode due to leakage can be prevented. No deterioration of restriking characteristics occurs, and therefore a highly reliable vacuum valve can be obtained.

(Example) The contact of the present invention will be specifically explained in accordance with the manufacturing method.

First, predetermined amounts of WC and CO powder, and Ag and Cu powder (
or Ag-Cu alloy powder) and mix them. Thereafter, the powder compact is obtained by pressure molding.

Subsequently, this powder compact is placed in a hydrogen atmosphere with a dew point of -50°C or lower, or a vacuum degree of 1.3X10-'P.
Preliminary sintering is performed at a predetermined temperature, for example, 1150° C.×IH, at a temperature lower than a, to obtain a preliminarily sintered body.

Subsequently, a predetermined amount and predetermined ratio of Ag-Cu is infiltrated into the remaining pores of this pre-sintered body under the conditions of 1150°C x IH'' to obtain an Ag-Cu-Co-WC alloy. Infiltration is primarily carried out in hydrogen, but it is also possible in a vacuum.

Ag-Cu-WC alloy manufacturing method without Co, C
The method for producing an alloy in which O is replaced with another metal, and the method for producing an alloy in which WC is replaced by another carbide or boride, are almost the same as described above.

Examples 1 to 3, Comparative Examples 1 to 2 In order to investigate restriking characteristics, when producing the aforementioned square contacts shown in Table 1, the difference between the bonding material and the bonding surface of the contact was (Excluding the contact surface), when there is no intermediate layer (Ni) (Comparative Example-1) and the thickness of the intermediate layer is 0. 2
, 1.0, 4.0, and 15.0 μm (Comparative Example-2, Examples-1 to 3).

The restriking characteristics measured by the method described below are shown in Table 1 below.

According to the results, when the thickness of the intermediate layer was 0.82 μm (Comparative Example-2), the restriking characteristics were significantly inferior, and there was no significant difference from the case without the intermediate layer (Comparative Example-1).

On the other hand, if the thickness of the intermediate layer is 1 μm or more (Example 'A-
In cases 1 to 3), there was no abnormality in the restriking characteristics. When the electrode surfaces of Examples 1 to 3 after evaluation were observed, no contact component or bonding material (Ag-Cu) was observed to be attached to the electrode surfaces.

On the other hand, a large amount of Ag-C was found on the electrode surface of Comparative Example-1.2.
Unevenness due to the adhesion of the u component was observed, and outflow and adhesion of Ag-Cu were observed not only on the electrode surface but also on the contact side.

In Comparative Example 1.2, these factors are thought to have caused the deterioration and dispersion of restriking characteristics.

From the above, it was found that insertion of an intermediate layer of 1 μm or more is effective for joining the contact and the electrode.

Examples 5 to 7, Comparative Examples 3 to 4 In the above Examples 1 to 3 and Comparative Examples 1 to 2, the content of the conductive component (Ag+Cu) was around 40 wt Oo and the ratio thereof. Although we have described the case where (Ag/Ag+Cu) is around 72wt%, the present invention technology for improving restriking characteristics by inserting an intermediate layer can be applied to other methods as shown in Table 1. Although the a effect was also observed in the amount of the quadricomponent (AI+(:u)), the other electrical characteristics (temperature rise characteristics) Therefore, the application of the present invention is determined when the content of the conductive component in the contact material is 25 to 65 wt% (Examples 5 to 7).

That is, as shown in Table 1, the content of conductive components is 3! (
When Ag+Cu) was 12.7 wt% (Comparative Example 13), it was found that the temperature rise characteristics measured by the method described later were extremely high, so it was excluded from the contacts to which the technology of the present invention is applied.

Although Ni was used as the material for the intermediate layer in Examples 1 to 3 and Comparative Example 2, Fe, Co, and Cr (Examples 5 to 7) were also used as shown in Table 1. Maintenance and improvement of restriking characteristics can be seen.

Furthermore, the conductive content (Ag+Cu) is 91.1wt.
% (Comparative Example-4), the temperature rise characteristics are favorable and the restriking characteristics are also favorable, but due to too much m (Ag+Cu) of the conductive component, welding occurred frequently. Therefore, it is excluded from the contacts to which the technology of the present invention is applied.

Examples 8 to 10] 0, Comparative Examples 5 to 6 The technique of the present invention, which involves inserting an intermediate layer, is extremely effective in suppressing restriking, as shown in Examples 8 to 10 and Comparative Example 5. I found out something.

However, as mentioned in Examples 5 to 7 and Comparative Examples 3 to 4, it is necessary to consider the influence on other electrical characteristics, and as shown in Table 1, the cutting current characteristics , the ratio of conductive components Ag and Cu (Ag/Ag+Cu) is 40.
Contacts with a content of 0 wt% or more are preferred. Therefore, A g / A g + C u of the contact material to which the technology of the present invention is applied
The ratio is 40. It is limited to Owt% or more.

In addition, the ratio of Ag and Cu in the conductive component (Ag/Ag+C
When u) is 92.7 wt% (Comparative Example-6), when the proportion of Ag is large, the frequency of restrike occurrence varies significantly, and the occurrence rate is rarely high, which is not preferable. Therefore, the technology of the present invention has a ratio of conductive components in the contact material of 40.0 to 80.0. Limited to Owt%.

Implementation fl-11 to fl-14 Although the above-mentioned Examples 1 to 10 and Comparative Examples 1 to 6 have shown WC as an arc-resistant component of the contact material, the present technology can be applied to contacts made of other arc-resistant materials. material, e.g. Mo2C
-C' IrC point material made of carbide such as 3C2 (Examples 11 to 12), or other arc-resistant material, such as TiB -Z
Boride 2 such as rB2 (Examples 13 and 14) is also effective in suppressing the occurrence of restriking.

Examples-1 to 10 and Comparative Examples-1 to 6 described so far are as follows:
Ag-C, which is the main component of the bonding material (wax material), is used in the intermediate layer.
The case where components (Fe, NiSCO, etc.) with a higher melting point than u are used is shown, but when AI is used as the intermediate layer, Ag, Cr, Al, etc. may flow onto the electrode surface due to the low melting point of AI. , as a result, the re-ignition frequency is 0.
It is as high as 6 to 1.8%, and its suppression effect is poor. In addition, the above shows the case where a metal having solid solubility with the bonding material is used as the intermediate layer, but when W is used as the intermediate layer, the degree of fixation with Ag/Cu, which is the main component of the bonding material, is Contacts were observed to fall off due to the low temperature.

Therefore, the intermediate layer must have a melting point higher than that of the -9:-Δ component (Ag-Cu) and a degree of solubility in any of the conductive components.

In Examples 1 to 14 and Comparative Examples 2 to 6 described above, the intervention conditions for the ψ interlayer, which is the technology of the present invention, are as follows:
As shown in Table 1, we used the method of providing an intermediate layer on the entire surface except for the contact points, but almost the same effect can be obtained by providing an intermediate layer only between the contact surface and the bonding material. .

Next, we will discuss the accounting method.

A disc-shaped contact piece with a restriking characteristic diameter of 30III1 and a thickness of 5mm is attached to a demounted pull type vacuum valve, and a 6KV x 500A
I'l cut off the circuit 2000 times! Measure the frequency of restrike of
It is shown as the variation width (maximum and minimum). When attaching the contacts, baking heating (450° C., 30 minutes) was performed.

The contacts were attached to the electrodes using 72Ag-Cu brazing material at 800° C. in a hydrogen atmosphere.

Temperature characteristics On the other hand, the temperature rise characteristics are as follows: electrodes with the same electrode conditions as above are placed facing each other, and a contact force of 50
The maximum temperature was determined at the movable shaft when a current of 40 OA was applied continuously for 1 hour at 0 kg. Note that the temperature is a G value that includes the ambient temperature of approximately 25° C., and is a comparative value that also includes the influence of the heat capacity of the holder to which the stove is attached.

Current cutting characteristics A prefabricated vacuum valve with each contact attached and evacuated to 10-3 Pa or less was manufactured, and this device was opened at an opening speed of 0.8+n/sec to cut off a small current with a delay. The current was measured. Breaking current is 20A (effective value), 50H
I made it z. The opening phase was randomly determined, and the cutting current when the contacts were cut off 500 times was measured for three contacts, and the width of the variation was shown.

〔Effect of the invention〕

As detailed above, the vacuum valve contact of the present invention is configured such that a specific ψ interlayer is inserted on at least the surface of the contact, so that the frequency of restriking can be suppressed to a low level. It has an excellent effect on improving product quality.

[Brief explanation of drawings]

1 and 2 are longitudinal cross-sectional views of a contact for a vacuum valve showing an embodiment of the present invention, and FIG. 3 is a longitudinal cross-sectional view of a vacuum valve.
FIG. 4 is an enlarged sectional view of the electrode portion of the vacuum valve of FIG. 3. DESCRIPTION OF SYMBOLS 10... Contact base, 11... Width layer, 20... Insulating container, 21... Sealing metal fitting, 25... Breaking chamber, 26
... Conductive rod, 27... Conductive rod, 28... Contact, 2
9... Fixed electrode, 30... Contact, 31... Movable electrode, 34... Bellows, 35... Bellows force bar,
36...Arc shield, 32...Brazing part, 33
...Brazing part.

Claims (1)

[Claims] 1. A contact for an Ag-Cu vacuum valve comprising a highly conductive component consisting of Ag and Cu containing an arc-resistant component, wherein the highly conductive component constituting the contact comprises: at least 1
An intermediate layer made of a metal having a solid solubility in the species of 1% by weight or more and a melting temperature higher than that of the highly conductive component is formed at least on the joint surface of the contact with the electrode. A contact for a vacuum valve, which is characterized by: 2. The content of the highly conductive component is such that the total weight of Ag and Cu (Ag+Cu) is 25 to 65% by weight, and the proportion of Ag in the total weight of Ag and Cu [Ag
/(Ag+Cu)] is 40 to 80% by weight, and the content of the arc-resistant component is 35 to 75% by weight, the contact for a vacuum valve according to claim 1. 3. The vacuum valve contact according to claim 1, wherein part or all of the arc-resistant component is made of a carbide of Ti, Zr, V, Nb, Ta, Cr, Mo, or La. 4. The vacuum valve contact according to claim 1, wherein the arc-resistant component comprises a boride of Ti, Zr, V, Nb, Ta, Cr, Mo, W or La. 5. The contact for a vacuum valve according to any one of claims 1 to 4, wherein the contact contains at least 1% by weight of at least one of Co, Ni, and Fe as an auxiliary component. 6. The vacuum valve contact according to any one of claims 1 to 5, wherein the intermediate layer is made of at least one of Fe, Co, Ni, and Cr. 7. Claim 1, wherein the thickness of the intermediate layer is 1 μm or less.
Contacts for vacuum valves.