JPS5960827A - Method of producing contact alloy for vacuum breaker - 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 manufacturing a contact material for a vacuum breaker,
In particular, the present invention relates to a method of manufacturing a contact alloy that suppresses the occurrence of the restriking phenomenon.

[Technical background of the invention and its problems]

Vacuum circuit breakers have superior characteristics compared to other circuit breakers, such as being small, lightweight, maintenance-free, and environmentally friendly.In recent years, the range of their application has been gradually expanded. Applications are being made from circuits to even higher voltage circuits, for example 72 kV or higher. As pressures become higher, there is a demand for the development of contact materials that have even higher withstand voltages and less occurrence of restriking phenomena. To meet this demand, BI has been used as a contact material for high-voltage, large-capacity vacuum breakers.

It is difficult to say that Cu-based alloys containing adhesion prevention components such as Pb and 'l'e are necessarily satisfactory.

In order to obtain a contact material that is unlikely to cause restriking even under high pressure as described above, it is generally necessary to (1) minimize the amount of brittle adhesion prevention components that tend to cause defects in pressure resistance, and (2) reduce gas It is desirable to reduce impurities, pinholes, etc. as much as possible.On the other hand, as mentioned above, Bi,
Contact alloys containing elements with high vapor pressure such as PB and Te tend to generate bubbles in the ingot, and especially when casting into a small diameter mold, many bubbles occur near the surface or inside the ingot. Serious casting defects such as cracks and cavities often occur. In order to prevent such defects from occurring, a unidirectional solidification method is also used, but in this case as well, the occurrence of the restriking phenomenon associated with the addition of the above-mentioned welding prevention component is not necessarily sufficiently suppressed. The reality is that there is not.

[Purpose of the invention]

In view of the above-mentioned circumstances, it is an object of the present invention to provide a method for manufacturing a contact material for a vacuum breaker, which maintains desired welding resistance and reduces the occurrence of the restriking phenomenon due to the addition of a welding prevention component. The purpose is to

[Summary of the invention]

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. It has been found 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 of the raw materials that make up the material. 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, about milliseconds), but a sudden gas release (several to hundreds of bursts) is observed. These sudden gases contain a small amount of C2H2, CH4, etc., but since they are mainly oxygen-based such as CO1CO□ and 0°, these sudden gases are released by the decomposition of oxides contained in the contact material. considered to be a thing. According to the research conducted by the present inventors, contact printing materials that often cause restriking phenomena include:
There are also many sudden gas releases. 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, for example, 10-
Since a temperature of approximately 1,200°C or higher is required at a vacuum level of ~10-Torr, Bi, pb, which has a high vapor pressure,
Performing the above heat treatment on contact materials containing anti-welding materials such as Te%sb will result in loss of the expensive anti-welding materials, and will also reduce the anti-welding performance, which is one of the basic functions of contact materials. Lost. On the other hand, when B1, for example, is heated as a welding prevention material, it emits multiple types of gas extremely violently at around 400 to 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 occur, for example, if the purity level is 9.
Even if 9.9999% Bi is used as a raw material, it is still observed when left in a state where oxidation or gas adsorption progresses.

The above observation indicates that in contact materials containing anti-adhesion materials, it is necessary to remove impurities that cause sudden gas through separate heat treatments for highly conductive materials such as Cu and anti-adhesion materials. Suggests sex. The method for manufacturing a contact alloy for a vacuum breaker of the present invention is based on such knowledge, and the first step is to melt and heat-treat a highly conductive material made of Cu and/or Ag at 1200°C or higher in advance. , a molten metal of this heat-treated highly conductive material at 1000 to 1300°C is mixed with a welding prevention material made of at least one of B1%Pb, Te, and Sb, which has been separately heat-treated for melting at a temperature of 400 to 1000°C. It is characterized by being cooled, solidified, and alloyed.

Furthermore, the effect of the separate heat treatment of the highly conductive material and the welding prevention component described above was also found when obtaining an infiltration material for a sintered contact alloy. That is, in the second method of manufacturing a contact alloy for a vacuum breaker of the present invention, an infiltration material is obtained according to the first method, and then W is added separately.

A compacted sintered body of an arc-resistant material selected from Mo, Cr, Ti, and their carbides alone or a mixture of this and a highly conductive material consisting of Cu and/or Ag is prepared, and this compacted sintered body is prepared. The method is characterized in that the body is melted and impregnated with the infiltrating material.

[Detailed description of the invention]

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

In the following description, "%" representing the composition is N
Based on quantity.

FIG. 1 is a front sectional view showing a configuration example of a vacuum breaker to which the contact material of the present invention is applied, and FIG. 2 is an enlarged view of the main parts thereof. Referring to the drawings, a breaking plan 1 includes an insulating container 2 made of an insulating material such as ceramic and having a substantially cylindrical shape.
and metal lids 4 and 5 provided at this end via a sealing mechanism 3.3a, and are vacuum-tightly partitioned.

However, inside this cutoff guide 1, a pair of electrode rods 6.7
A fixed electrode 8 and a movable electrode 9 are arranged at mutually opposing ends of the electrode. Further, a bellows 10 is attached to the electrode rod 7 of the movable electrode 9, so that the pair of electrodes 8.9 can be opened and closed by the reciprocating movement of the electrode 9 while keeping the interior of the breaker guide 1 vacuum-tight. Also this bellows 1
0 is covered by a hood 11 to prevent arc vapor from adhering to it, and there is also a cylindrical metal container 12 inside the shutoff guide 1.
is provided to prevent arc vapor from adhering to the insulating container 2.

On the other hand, as the enlarged structure of the movable electrode 9 is shown in FIG. A movable contact 14 is joined by a brazing material 15. Further, the detailed structure (not shown) of the fixed electrode 8 is almost the same except that the direction is reversed, and K is the fixed contact 14a.
is provided.

The contact alloys produced in accordance with the present invention are suitable for constructing contacts 14, 14a as described above.

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

That is, Cu and/or Ag are used as the highly conductive material, and when producing a melt-type contact alloy according to the first method of the present invention, these highly conductive materials are mixed with the remainder of the components described below. and when manufacturing the sintered contact alloy according to the second method, the amount of the contact alloy
It is used in an amount making up 65%.

In addition, as welding prevention materials, Bi, Pb, Te, s
At least one of b is used, and these bath adhesion prevention materials have a range of 0.1 to 0.1 to
It is used in an amount range of 15%.

Furthermore, according to the second method of the present invention, as the arc-resistant material when manufacturing the sintered contact alloy, W, MO, c
A selection of r% TI and carbides thereof is used, and these are used in amounts that make up the balance of each component listed above.

Next, a process of manufacturing a contact alloy from each of the above-mentioned materials by the first method of the present invention will be explained.

First, the above-mentioned highly conductive material was placed in a crucible and heated to 1200°C.
Heat treatment is performed at a temperature higher than that. Heat treatment conditions vary depending on the type of highly conductive material; for Ag, 126°C or higher is sufficient, but for Cu, 1300°C or higher, especially 1500°C
The above is preferable. Heat treatment is IXIQ Torr,
It is preferable to carry out in the following vacuum or H2 atmosphere,
The heat treatment time varies depending on conditions such as temperature. For Cu, in the case of a temperature of 1300° C., it is preferable to conduct the heat treatment for 10 minutes or more. As a result, Cu2O, C
Oxides such as uO are decomposed to obtain a highly conductive material in which these impurities are further reduced.

On the other hand, the above-described melt heat treatment is also performed on the anti-welding material at a lower temperature of 400 to 1000°C. This is to prevent the loss of the welding prevention material, which has a high vapor pressure, and to effectively remove the sudden gas component that causes the restriking phenomenon.The atmosphere is a vacuum of 10-2 to 10-'Torr. Alternatively, H2 atmosphere is preferable, and the heat treatment time is 10 to 3
Approximately 0 minutes is appropriate.

Next, the welding prevention material heat-treated in this manner is added to the molten metal of the highly conductive material heat-treated as described above at 1000 to 1300° C., and the mixture is melt-mixed. Generally, the temperature of the molten metal of the highly conductive material is lower than the above-mentioned heat treatment temperature to prevent loss of the welding prevention material during mixing. The highly conductive material may be one that is once cooled and solidified after the heat treatment and then melted again. On the other hand, it is preferable to add the welding prevention material to the molten metal of the highly conductive material and mix it as soon as possible after the heat treatment. This is because once the anti-welding material is heat-treated,
This is because, if solidified, even if left in a desiccator at room temperature, the formation of explosive gas components will progress and become a factor in the occurrence of restriking.

It is desirable that the melt mixing be completed within ω minutes in a vacuum of about 10 to 10 Torr. A contact alloy according to the first method of the invention is obtained by cooling and solidifying the molten mixture. In cooling solidification, a crucible is used as an infiltration material for a contact alloy in a lower temperature range than a high temperature range in a furnace, in accordance with the zone melt method.

That is, as in the production of normal sintered contact alloys, about 100 to 400 meshes of arc-resistant material powder alone or in combination with highly conductive material powder are added with The raw material powder obtained by adding approximately % A rough-in is molded at a pressure of about 1 to 7 tons/cIL2, and the molded body is sintered at a temperature of 1000°C or higher in a non-oxidizing atmosphere to reduce the porosity. A sintered body with a capacity of about % is obtained.

At this time, the temperature is 1150℃ for sintering the compact containing the highly conductive material.
It is desirable to perform heat treatment at a temperature higher than that.

On the other hand, an infiltration material is obtained by carrying out exactly the same operation as in the first method for the welding prevention material and the remainder of the highly conductive material, which is preferably at least twice the weight of the welding prevention material.

The sintered body is immersed in the molten metal of the infiltrant, or the molded body of the infiltrant and the sintered body are laminated, and the molten metal of the former is allowed to enter the voids of the sintered body, and then cooled and solidified. A contact alloy according to the second method of the invention is thus obtained.

[Examples of the invention, comparative examples]

Comparative Example 1 Approximately 32. ? of Bi (approximately 0.8% weighed considering evaporation loss during melting) and Cu of approximately 4K9 in a crucible with an inner diameter of 70 fl at 1200°C and a vacuum of 10-' Torr.
After alloying under the conditions of heating for about 15 minutes, zone melting was performed for lead minutes at a moving speed of 2 steps/minute, and the length was about 111 mm.
Obtained an ingot. The total amount of gas released during this period was 3 to 5 ppm, and the number of bursts of gas released was 9 to 33 times.

After processing the above ingot into a contact, it was assembled into a test vacuum valve, and a current of 6 kV and 415 A was interrupted 2000 times. The number of restrikes during shutdown was 2.8 times (2.4%).

Example 1 The same amount of B1 as in Comparative Example 1 was placed in a quartz tube at a vacuum degree of 7×1O.
-3 Torr and a temperature of approximately 850°C for 10 minutes, the product was separately heated to a maximum of 1580'C at the same degree of vacuum, held for 1 hour, and immediately poured into molten Cu whose temperature was lowered to 1200'C. '15 at Torr level vacuum
After alloying by holding for a minute, the mixture was cooled and solidified at a rate of 21 minutes over a period of about ω minutes.

The amount of gas released after the alloying process was 0.1 ppm or less, and the number of sudden gas emissions was 0. The obtained alloy was processed in the same manner as in Comparative Example 1 to obtain a contact, and the same breaking test was performed. However, no restrike was observed.

Comparative Examples 2-7. Examples 2 to 6 The procedure was the same as in Comparative Example 1 or Example 1, except that the presence or absence of pretreatment of the raw materials and its conditions were changed, or 329 pb or 32.
A contact alloy was obtained using Te No. 9 as a welding prevention material.

These conditions and the results of the breaking test for the obtained contact alloys are summarized with the results of Comparative Example 1 and Example 1, and are listed in Table 1 below. It can be seen that the occurrence of restriking can be significantly reduced by pre-treating the raw material according to the method. Furthermore, when comparing the cases where only the anti-adhesive material or only the highly conductive material is pretreated as in Comparative Examples 2 and 3, the former has a greater effect, but the embodiment of the present invention in which both are pretreated is not as effective. It turns out that there isn't.

Furthermore, the pretreatment temperature of the bath adhesion prevention material is not effective at 350°C (Comparative Example-4), and at least 400°C (Example-4).
is necessary. The pretreatment atmosphere is not only vacuum but also H2
An atmosphere can also be used (Example-4).

〔Effect of the invention〕

As described above, according to the present invention, the highly conductive material and the anti-welding material constituting the contact alloy are individually heat-treated under different conditions, and then alloyed, thereby preventing loss of the anti-welding component. A contact alloy for a vacuum breaker is obtained which effectively reduces the occurrence of restriking.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing an example of the configuration of a vacuum breaker to which the contact alloy according to the present invention is applied, and FIG. 2 is an enlarged view of the main parts thereof. DESCRIPTION OF SYMBOLS 1... Breaking plan, 2... Insulating container, 6, 7... Electrode rod, 8... Fixed electrode, 9... Movable electrode, 14.1
4a... Contact, 13.5... Brazing material.

Claims (1)

[Claims] 1. A highly conductive material made of Cu or/and Ag is melt-heat treated in advance at 1200°C or higher, and the heat-treated highly conductive material is heated in a bath water of 1000 to 1300°C, and separately heated. Jime 40
Bi, pb, melt heat treated at a temperature of 0 to 1000°C
1. A method for producing a contact alloy for a vacuum breaker, which comprises mixing a welding prevention material consisting of at least one of Fe and Sb, and solidifying the mixture by cooling to form an alloy. 2. A patent claim characterized in that a highly conductive material is melted and heat-treated at 1200°C or higher, once cooled and solidified, and then re-melted at 1000 to 1300°C, and the molten metal is mixed with a separately heat-treated welding prevention material. A method for producing a contact alloy for a vacuum breaker according to item 1. 3. After melt heat treatment of high 4-electroconductivity material at 1200℃ or higher, 10
A method for producing a contact alloy for a vacuum breaker according to item 1, which is characterized in that the temperature is lowered to 00 to 1300° C. and immediately mixed with a separately heat-treated anti-welding material. 4. A highly conductive material made of Cu and/or Ag is prepared in advance.
Melting heat treated at 200℃ or higher, 1000-1300℃ molten metal of this heat-treated highly conductive material and a separate 400℃
Bi, pbS melt heat treated at a temperature of ~1000”C
An infiltration material is obtained by mixing a welding prevention material containing a small amount of Fe and Sb (both of which are one type of welding prevention material), and separately prepared with W, Mo, Cr, 'rl.
A compacted sintered body of an arc-resistant material selected from these carbides alone or a mixture of this and a highly conductive material made of Cu and/or Ag is prepared, and the compacted sintered body is infiltrated with the above-mentioned infiltration. A method for producing a contact alloy for a vacuum breaker, the method comprising melting and impregnating a material. 5. Production of a contact alloy for vacuum shield breakers as set forth in claim 4, characterized in that the powder sintered body is heat-treated at 1000 to 1300°C in advance and then melted and impregnated with an infiltrant. Method.