JPS6063835A - Method of producing contact alloy for vacuum bulb - 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 of manufacturing a contact alloy for a vacuum nozzle, which can reduce the rate of restriking.

[Technical background of the invention and its problems]

The characteristics required for contacts for vacuum pulp are welding resistance, withstand voltage, and high interrupting properties.

However, these three requirements require contradictory physical properties, so it is difficult to ideally balance them, so the priority requirements of the applied circuit should be prioritized first, and other requirements should be sacrificed slightly. This is the current situation.

For example, in conventional high-voltage, large-capacity vacuum breakers,
A CU gold alloy electrode contact containing a welding prevention component (Bi, Te, Pb, etc.) in an amount of 5 weight or less is known.

However, it is not sufficient in terms of withstand voltage to meet the recent demand for higher voltage.

In other words, because vacuum breakers have superior features compared to other circuit breakers, such as being small, maintenance-free, and environmentally friendly, their range of application has expanded year by year, and they have expanded beyond the conventionally commonly used As circuits are being applied to even higher voltage circuits, the demand for opening and closing special circuits such as capacitor circuits is rapidly increasing, so there is a need for even higher voltage resistance.

One of the important factors hindering the achievement of this goal is the re-ignition phenomenon and the re-ignition phenomenon.

Although the restriking phenomenon is regarded as important from the viewpoint of improving product reliability, not only prevention technology but also the direct cause of its occurrence have not yet been clarified.

With the above-mentioned increase in voltage resistance, contact materials are also required to have characteristics such as higher voltage resistance and a lower frequency of restriking phenomena.

In order to achieve high pressure resistance and non-re-ignition of the contact powder, it is necessary to minimize the amount of the welding prevention component, which is a fragile welding prevention component that causes a defect in pressure resistance, and to avoid excessive concentration of gas. It is desirable to reduce impurities, pinholes, etc. as much as possible, and to increase the strength of the contact alloy itself.

From these points of view, the aforementioned Cu-B1 alloy is not satisfactory.

In addition, although Cu-W contacts, which are other conventional contact materials, are quite good in terms of withstand voltage, this sintered contact alloy is prone to leaving bubbles and welding due to the manufacturing method. Since it contains a prevention material, it has the disadvantage that restriking phenomenon is likely to occur.

It is known that the frequency of such restriking phenomenon can be reduced to some extent by maintaining the heated state after the infiltration operation.

However, by holding the contacts in such a heated state, the anti-welding material, which typically has a high vapor pressure, is lost, which not only reduces the anti-welding performance but also causes the loss of the expensive anti-welding material. The economic loss is also large.

The present inventors made detailed observations on the total amount of gas released during the process of heating the contact material and the form of the release, and found that there is an important correlation between these factors and the occurrence of the restriking phenomenon. In particular, it has been discovered that the restriking phenomenon can be effectively suppressed by controlling the release of these gases, especially the release of gases that suddenly occur near the melting point, for each raw material that makes up the contact material. Ta.

In other words, when the contact material is heated, most of the adsorbed gas is degassed below the melting point, and the gas dissolved in solid solution near the melting point is released. However, if the contact material is further heated above the melting point, it will degas for a very short time. (for example, several milliseconds), but pulse-like sudden gas emissions (several to hundreds of bursts) are observed.

These sudden gases contain a small amount of C, H, CH, etc., but since they are mainly oxygen-based such as CO1CO2, 01, these sudden gases are caused by the decomposition of oxides contained in the contact phase material. It is thought that this is released by

According to the research conducted by the present inventors, contact materials that frequently cause restriking phenomena also release a large amount of sudden gas.

Therefore, based on the above findings, it is possible to prevent the restriking phenomenon by holding the contact material at a temperature higher than its melting point and releasing this sudden gas in advance.

However, contact materials for vacuum breakers contain a considerable amount of Cu, and in order to decompose and remove these oxides, a temperature of about 1200°C or higher is required at a vacuum level of 10-3 to 1σ'T'orr. Therefore, performing the above heat treatment on contact materials containing anti-welding materials such as B1XPbXTe and Sb, which have high vapor pressure, will result in loss of the expensive anti-welding materials, and will also damage the basic properties of the contact materials. This results in the loss of welding prevention performance, which is one of the most important functions.

On the other hand, when Bi, for example, is heated as a welding prevention material, it emits a plurality of gases extremely violently at around 400-550°C.

A part of such released gas combines with Cu, etc. during the temperature rising process to form a relatively stable compound, and part of it decomposes during the melting process, but the other part still remains and generates sudden gas. This is a contributing factor.

Such a sudden release of gas may be caused by, for example, purity 9919.
Even if 999% Bi is used as a raw material, oxidation or gas adsorption will still occur if left as it is.

The above observation indicates that in contact materials that include adhesion prevention properties, it is necessary to remove impurities that cause sudden gas by separate heat treatments for highly conductive materials such as Cu and adhesion prevention components. In addition, during the manufacturing or heat treatment process of the contact alloy, the liquid phase of the contact alloy, which is partially or entirely in a liquid state, comes into direct contact with the contact alloy, and the contact alloy is exposed to gases released from boats, plates, etc. It also suggests the need to control pollution.

Regarding the former finding, the present inventors recognized that heat treating the constituent elements individually to reduce sudden gas is effective to some extent, and that the probability of restriking also tends to decrease accordingly. ing.

Regarding the latter finding, the present inventors found that the material of the crucible in contact with the liquid phase and the physical and chemical conditions of its surface affect the form of sudden gas release and are also related to the probability of restriking. It was acknowledged that this is essential in order to reliably and efficiently improve the former's effect of reducing sudden gas release through control at the constituent element level of the contact point.

[Object of the Invention] An object of the present invention is to provide a method for manufacturing a contact alloy for vacuum pulp that reduces the frequency of restriking while maintaining the required anti-welding performance.

[Summary of the invention]

The present invention provides a method for manufacturing a contact alloy for vacuum pulp in which the contact alloy for vacuum pulp is manufactured in a process including a process of alloying, casting, refining, or sintering the contact alloy for vacuum pulp in a state in which a liquid phase exists in at least a portion of the contact alloy. At least one of the processes (especially the final process) is carried out in contact with an 8isN-based composition or powder, thereby reducing the frequency of outgassing from the contact alloy and reducing the repointing of the vacuum pulp. This is designed to reduce the probability of arc occurrence.

[Embodiments of the invention]

FIG. 1 is a front sectional view showing an example of the structure of a vacuum pulp to which the contact material according to the present invention is applied, and FIG. 2 is an enlarged view of the main parts thereof.

In FIG. 1, the breaking plan 1 is vacuum-tight with an insulating container 2 formed of an insulating material such as ceramic into a substantially cylindrical shape, and metal lids 4 and 5 provided at both ends of the container via sealing mechanisms 3+38. is sealed.

Furthermore, within the breaker guide 1, a fixed electrode 8 and a movable electrode 9 are disposed at mutually opposing ends of a pair of electrode rods 6, 7, respectively.

Furthermore, a bellows 10 is attached to the electrode rod 7 of the movable electrode 9, and while keeping the interior of the shutoff guide 1 vacuum-tight,
The pair of electrodes 8.9 can be opened and closed by the reciprocating movement of the electrode 9.

The bellows 10 is covered with a hood 11 to prevent arc vapor from adhering to it, and a cylindrical metal container 12 is further provided within the shutoff guide 1 to prevent arc vapor from adhering to the insulating container 2. It is prevented.

On the other hand, as the enlarged structure of the movable electrode 9 is shown in FIG.
A movable contact 14 is joined thereon by a brazing material 15.

Further, the fixed electrode 8 is also the same except that the direction is reversed, and the fixed electrode 11 is the same, and is provided with a fixed contact 14a.

The contact alloy produced according to the present invention is suitable for forming one or both of the contacts 14 + 14a as described above.

The materials used to produce contact alloys in the method of the present invention are not different from conventional materials.

In other words, as the highly conductive material, Cu, Ag, or both are used, and the maximum value of the amount is the amount minus the amount of the anti-welding material in the contact alloy, and the minimum value of the amount is the amount of the conductive material. From this point of view, about 15 - is necessary.

In addition, welding prevention materials include Bi, Pb, Te, 8
At least one of b is used, and these welding prevention materials are:
The amount depends on the degree of welding resistance required for the contact alloy.
．． It is used in a range of 15% per chill.

Furthermore, in addition to the above-mentioned melting type contact alloys, the present invention is also applied to the production and heat treatment of sintered type contact alloys selected from six selected from W, Mo, Cr, Tri, and their carbides for arc resistance.

An example of obtaining a contact alloy by the method of the present invention is as shown below.

In other words, for molten contact alloys, for example, the degree of vacuum is approximately I
10-”-I
The highly conductive components are melted at 1300° C., uniformly alloyed, and then cooled and solidified in a mold, or directional solidification is performed if necessary.

The technology of the present invention provides that at least one of the container cutting to accommodate the contact alloy during alloying in this manufacturing process, the mold type used during cooling assimilation, and the container cutting to accommodate the contact alloy during directional solidification is 8i. , N, is used.

For sintered contacts, for example, a mixed powder of about 100 to 400 meshes of arc-resistant powder and highly conductive material powder is used.
It is molded at a pressure of about 7 tons/d to obtain a 'C1 powder compact.

The obtained powder compact is subjected to preliminary sintering or main sintering in hydrogen or in a vacuum higher than 1×16′ mHP at a temperature of 1150° C. or higher.

Furthermore, if necessary, a highly conductive material is infiltrated to obtain a contact material.

The technology of the present invention covers preliminary sintering, main sintering,
The container material for accommodating the contact alloy during infiltration is to use a structure mainly composed of 8i, N.

A contact having a desired shape can be obtained by subjecting the obtained contact material to processing such as cutting and polishing, or plastic working such as forging or rolling, as required.

3 and 4 are layout diagrams of the manufacturing equipment used in the present invention, respectively, in which 21 is a contact alloy, 22 is a container for accommodating a contact alloy such as Haruho or Boat, 23 is a high-frequency heating coil, and 24 is an insulation Fig. 3 shows mainly Cu-
For the production of melt-based alloys such as B1 alloy, Fig. 4 mainly shows C
Used in the production of sintered alloys such as u-W alloys.

The present invention will be explained in more detail below using sample tests.

The contact material was evaluated under the following two conditions: sudden gas release and restriking probability.

A sample cut from a sudden gas release ingot is placed in a vacuum device for measuring sudden gas release, and heated at a constant rate from room temperature to a predetermined temperature exceeding the melting point (for example, in the case of CU-Bi, 1
250° C.), and the integrated value of the number of sudden releases during a certain period of standing (for example, 30 minutes in the case of Cu-B1) is measured in an ambient atmosphere with a degree of vacuum of 10 to 10 Torr.

A disc contact piece with a diameter of 30 mm and a thickness of 5 mm is attached to a demount pull type vacuum valve, and a 6 KV x 500 A circuit is connected to the
The frequency of restriking after 000 circuit breakers was measured and shown as the variation width (maximum and minimum) of the two circuit breakers (6 circuit breakers for pulp). When attaching the contacts, only baking heating (450° C., 30 minutes) was performed, and no brazing material or accompanying heating was performed.

The results of the sample tests are shown in Tables 1 and 2.

Example-1, Comparative Examples-1 and 2 A carbon melt with an inner diameter of 50j111 was used to melt approximately 200m of Cu into (
Comparative example-1), quartz melt (comparative example-2), 8i, N,
(Example-1) and the degree of vacuum is approximately 1OxmHg.
After melting and degassing at a temperature of 1,200° C., a welding prevention component was added, thoroughly stirred, and the mixture was cooled and solidified in the same crucible to obtain a contact alloy material having the composition shown in Table 1.

Next, each test piece cut into a predetermined shape from these contact materials was measured for the amount of sudden gas release and the probability of restriking using the test method described above, and the results are also listed in Table 1.

Comparing Comparative Examples 1 and 2 and Example 1 in Table 1, 81. It is clear that in the material using N, Rutsuho, both the number of sudden gas releases and the probability of restriking are low.

Impurities in the material of the carbon melt, or the surface of the carbon melt is shaped like a ball and has a relatively large surface area, may adhere to the surface or inside of the melt, or the internal gas may melt the contacts during the melting process. This tends to diffuse into the body, increase the total amount of gas in the contact material, and form a gas that is released suddenly at a certain temperature and time.

On the other hand, in quartz melting, part of the gas, mainly oxygen, released from the contact melt during the melting process reacts with the quartz surface, and the contact melt remains during melting, forming a gas that is suddenly released. It's easy to do.

For the above two rutsuho, Si by the method of the present invention,
N. When using a crucible, the above-mentioned disadvantageous phenomena are less likely to occur (
, 8isN, it has been shown that the gas intrusion from the surface to the contact melt is lower than the former two.

It is presumed that the above effect is due to the fact that the surface of No. 81, N has a higher vapor pressure than the former two, and the surface can be easily cleaned by evaporation by dry baking or the like.

Therefore, according to the above considerations, the gas emitted from the contact material enters the contact material at a higher speed and in a larger amount when the contact material is in a molten state. It is effective when applied when a liquid phase exists in some areas.

In addition, while the oxygen content of the material of Comparative Example-1 is 7 ppm, the oxygen content of Example-1 is reduced to 273 to 1/4, and not only the sudden gas but also the entire gas is reduced. It is thought that this also contributes to the reduction in the occurrence of restriking.

Example 2, Comparative Examples 3 and 4 Similar to the above example, approximately 2 KP of Cu was applied to carbon fibers with an inner diameter of 50mm (Comparative Example 3), quartz fibers (Comparative Example 4), and 8
I and N numbers are housed in (Example-2) and the temperature is about 10 degrees
mmHg, and at a temperature of about 1200°C, after adding the anti-welding component to each mold (S import N in Example-2, carbon in Comparative Example-2, and quartz in Comparative Example-3), the composition shown in Table 1 was poured into the mold. The contact alloy material shown was obtained.

Using these contact materials, the number of sudden gas releases and the probability of restriking were measured in the same manner as described above.

Comparing Example 2 and Comparative Examples 3 and 4 in Table 1, it is found that the difference in the material of the melt during casting after alloying has a significant effect on the characteristics.

That is, as is clear from Example 2, even during casting, Si and Nj metals have good properties in terms of sudden gas release and restriking probability. The reason for this effect is also explained in the above example.
1. Comparative Example - The same reason as considered in 2 and 3 can be cited.

Examples 3 and 4, Comparative Examples 5 and 6 Carbon (1) was used in the composting pot and mold during alloying and casting.
Comparative Example-5), quartz (Comparative Example-6), 87sN, and (Example-3) were used. Comparing these, it is clear from Table 1 that 5isN is superior in both the number of sudden gas releases and the probability of restriking.

Therefore, it is shown that using 86N4 at least in the final step is preferable to not using it. Moreover, the use of Si and N4 in each step of alloying, casting, and refining has of course shown to be effective (Example 4).

Examples 5, 6, 7, 8 In addition to the Cu-B1 alloy mentioned above as the contact material, Cu-
pb (Example-5), Cu-'I'e (Example-6)
), 8iaN is also effective for other contact alloys such as Cu-Ag-Bi (Example-8).

Examples - 9, 10, 11, 12, Comparative Examples - 7, 8, 9 The above describes examples and comparative examples in which contact materials are made by a melting method. It is effective when applied when obtaining materials.

The composition and test results in this case are shown in Table 2.

Paraffin is added to a mixture of all or a part of the required amount of powder of Cu or Ag, a welding prevention material such as BI, and powder of an arc-resistant material such as W and Cr, and the mixture is molded using approximately 2 tons or more. Edge, perform preliminary sintering at 900-1300″CJ.

When the entire amount of Cu i or Ag is used from the beginning, the temporary sintered body is subjected to main sintering at about 900 to 1300° C. to obtain a contact material. For a preliminary sintered body in which a portion of the total amount of Cu or Ag is used, a contact material is obtained by infiltrating the remaining amounts of C and U at about 1100 to 1300°C.

In each of the above processes, namely preliminary sintering, main sintering, and infiltration steps, the benefits of the boat or mounting plate that accommodates the contacts are as follows:
The same effect as in the case of the previous melting method was obtained regardless of the difference in the thickness of the sintered contact.

That is, when Comparative Example-7 and Example-9 are made to correspond, Cu-
By using this sintered 15tsN4 at the W contact point, it is possible to reconsider the probability of sudden gas and restriking occurrence, as described above.

Other examples Cu-Cr (Comparative Example-8, Example-10), A
The same tendency was obtained with g-WC-B i (Comparative Example-9, Example-11).

The fact that 81JN is used for both preliminary sintering and main sintering means that
Similarly, it maintains an excellent level.

〔Effect of the invention〕

As explained above, according to the manufacturing method of the present invention, by handling the contact alloy in a molten state in 8i, N, when manufacturing the contact alloy for vacuum valves, it is possible to reduce sudden gas release while reducing sudden gas release. , a contact alloy that reduces the frequency of restriking can be obtained, which is useful for increasing the reliability of vacuum valves.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing an example of the configuration of a vacuum valve to which the contact alloy according to the present invention is applied, Figure 2 is an enlarged view of its main parts, and Figures 3 and 4 are manufacturing equipment used in the present invention, respectively. 0 ■... Breaking plan 2... Insulating container 6.7... Electrode rod 8... Fixed electrode 9... Movable electrode 14, 148... Contact point 13. 15... Brazing metal 21... Contact alloy 22... Container 23... High frequency heating coil 24... Insulator

Claims (2)

[Claims] (1) A contact alloy for vacuum pulp is alloyed, cast, and sheathed in a state where at least a portion of the liquid phase exists. ! Alternatively, in a method for manufacturing a contact alloy for a vacuum nokulp which is manufactured by a process including a sintering process, at least one of the processes is performed in contact with a powder mainly composed of 8i3N. A method for producing a contact alloy for vacuum pulp. (2) The method for producing a contact alloy for vacuum pulp according to claim 1, wherein at least the final process is carried out in contact with a composition or powder mainly composed of St and N.