JPS6336089B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a contact material for a vacuum shield breaker, which has excellent large current shearing characteristics and high voltage resistance.

Vacuum sheath breakers have advantages such as maintenance-free, non-polluting properties, and excellent sheath breaker performance, so the scope of their application is rapidly expanding. In addition, along with this trend, demands for higher voltage resistance and higher current resistance are becoming more severe. On the other hand, the performance of a vacuum shield breaker is determined to a large extent by the contact material inside the vacuum container.

Satisfactory characteristics of contact materials for vacuum shield disconnectors include (1) large shield breaking capacity, (2) high withstand voltage, (3) low contact resistance, and (4) low welding force. (5) low contact wear, (6) low cutting current, (7) good workability, and (8) sufficient mechanical strength.

In actual contact materials, it is quite difficult to satisfy all of these properties, and in general, materials are used that satisfy particularly important properties depending on the application, sacrificing other properties to some extent. This is the actual situation.

Conventionally, this type of contact material has been copper-bismuth (hereinafter referred to as Cu-Bi. Other elements and alloys made of combinations of elements are also indicated by element symbols), Cu-Cr-Bi, Cu- Co―Bi, Cu
-Cr, etc. were used. However, in the case of alloy contacts containing low melting point metals such as Cu--Bi, due to the high temperature heating during the evacuation process, some of the metal diffuses and evaporates from within the contacts, and adheres to the metal shield or insulating container inside the vacuum container. This is one of the major factors that degrades the withstand voltage of vacuum shields and disconnectors. In addition, when the load is switched on and off or when a large current is interrupted, evaporation and scattering of low-melting point metals occur, resulting in deterioration of withstand voltage and deterioration of shearing performance. Even with Cu-Cr-Bi, which has added Cr, Co, etc., which have excellent vacuum withstand voltage, to eliminate the above-mentioned drawbacks, the above-mentioned drawbacks caused by low-melting point metals are not fundamentally solved, and it cannot be used at high voltages and large currents. cannot be handled.
On the other hand, materials such as Cu-Cr, which are made of a combination of metals (Cr, Co, etc.) with excellent vacuum withstand voltage and Cu with excellent electrical conductivity, are inferior to contact materials containing low melting point metals in terms of welding resistance. Although it is slightly inferior to , it is often used in high voltage and large current ranges because of its excellent shearing performance and withstand voltage performance.
Furthermore, since there is a limit to the shearing performance of Cu-Cr alloys, we devised the shape of the contact,
Efforts have been made to improve shearing performance by generating a magnetic field by manipulating the current path in the contact, and using this force to forcibly drive a large current arc.

However, the demands for higher voltages and larger currents have become even more demanding, and it has become difficult to fully satisfy the required performance with conventional contact materials. Furthermore, in order to reduce the size of vacuum shields and disconnectors, conventional contact performance is not sufficient, and there is a need for contact materials with even superior performance.

This invention was made in order to eliminate the drawbacks of the conventional products as described above, and its purpose is to provide a contact material for vacuum shields and breakers that has excellent large current breaking characteristics and high withstand voltage performance. It is said that

We fabricated prototype contact materials by adding various metals, alloys, and intermetallic compounds to Cu, and conducted various experiments by incorporating them into vacuum shields and disconnectors. As a result, Cu,
Contact materials in which Cr and Ta are distributed as individual metals, tri- or bi-metallic alloys, tri- or bi-metallic compounds, or composites thereof have extremely excellent shearing performance. I found out.
The contact material for vacuum insulation and disconnection according to this invention is Cu
Cu, Cr, and Ta containing 35% by weight or less of Cr, 50% by weight or less of Ta, and a total of Cr and Ta of 10% by weight or more as other components.
are each distributed as a single metal, an alloy of three or two metals, an intermetallic compound of three or two metals, or a composite thereof.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a structural diagram of a vacuum switch tube, in which electrodes 4 and 5 are installed inside a container formed by a vacuum insulating container 1 and end plates 2 and 3 that close both ends of the vacuum insulating container 1, and an electrode rod 6, respectively. and 7 are arranged so as to face each other. The electrode 7 is joined to the end plate 3 via a bellows 8 so as to be movable in the axial direction without compromising airtightness. To prevent shields 9 and 10 from being contaminated with vapor generated by the arc,
They cover the inner surface of the vacuum insulating container 1 and the bellows 8, respectively. The structure of electrodes 4 and 5 is shown in FIG. The electrode 5 is brazed to the electrode rod 7 on the back side thereof with a brazing material 51 inserted therein. The electrodes 4 and 5 are made of a Cu--Cr--Ta based contact material according to the present invention.

FIG. 3 shows a photograph of the metal structure of a conventional Cu-Cr alloy contact material at a magnification of 100 as a comparative example. this is
This is a Cu-Cr alloy obtained by mixing Cu powder and Cr powder at 75% by weight and 25% by weight, forming and sintering.

Figure 4 shows a Cu-Cr-
A photograph of the metallographic structure of Ta alloy contact material at a magnification of 100 is shown. This is a mixture of Cu powder and Cr powder of 75% by weight each.
Cu―Cr― obtained by mixing, molding, and sintering a mixed powder containing 25% by weight and 10% by weight of Ta.
It is a Ta alloy. Note that the sintering was performed at about 1100° C. under conditions such that part of Cr and Ta reacted to form Cr ₂ Ta.

Figure 5 shows another embodiment of the present invention.
- Shows a photo of the metallographic structure at a magnification of 100 when a Ta alloy is sintered at a relatively low temperature that makes it difficult for Cr and Ta to form an alloy or intermetallic compound. This is the fourth
Cu made of the same blending ratio as the example shown in the figure.
This is an alloy obtained by molding and sintering Cr-Ta mixed powder. The alloy in Figure 4 contains Cr, Ta, Cr ₂ Ta in Cu.
It can be seen that the particles are uniformly and finely distributed. Also,
In the alloy shown in Figure 5, Cr and Ta are mainly distributed as single metals in Cu, and Cr ₂ Ta is hardly seen.

The results of various measurements or tests will be explained below.

First, from our experimental results, we found that in a contact alloy consisting of a binary alloy of Cu and Cr, the amount of Cr is 20 to 30% by weight.
Since we have confirmed that various performances are extremely excellent within the range of The changes in various properties of the alloy when the amount of Ta added is varied are shown.

Figure 6 shows the weight ratio of Cu and Cr in the alloy at 75:25.
This figure shows the relationship between the amount of Ta added to a fixed alloy and the electrical conductivity.The electrical conductivity decreases as the amount of Ta increases, but the relationship between Cu and Cr in the alloy
When the weight ratio of is fixed at 75:25, the amount of Ta can be used depending on the purpose, but it is particularly desirable that it be up to about 30% by weight.

In addition, the vertical axis in FIG. 6 shows the ratio when the electrical conductivity of Cu-25Cr is assumed to be 1, and the horizontal axis shows the amount of Ta added.

Figure 7 shows the weight ratio of Cu and Cr in the alloy at 75:25.
This figure shows the relationship between the amount of Ta added to a fixed material and contact resistance, and shows the same tendency as electrical conductivity. The vertical axis in Figure 7 is Cu-25 of conventional product a.
The ratio is shown with the value of weight% Cr alloy as 1.

Figure 8 shows the weight ratio of Cu and Cr in the alloy at 75:25.
The figure shows the relationship between the amount of Ta added and the shearing capacity of a material fixed at I know that there is.

Note that the vertical axis in FIG. 8 indicates the ratio with the value of the Cu-25 wt % Cr alloy of conventional product a being 1. As is clear from Figure 8, as the amount of Ta added increases, the shearing capacity increases, and at 10 wt% Ta, it is 1.7% compared to the conventional product.
The amount of Ta peaks at about 15% by weight.
If more Ta is added than this, the shear shear capacity will decrease. In other words, Ta and Cr coexist and their interaction increases the shearing performance, but if Ta and Cr are increased beyond a certain level, Cu, which has good conductivity, decreases in the alloy and the electrical conductivity of the alloy decreases. This is because the temperature and thermal conductivity decrease, making it difficult to quickly dissipate the heat input from the arc, and conversely worsening the shear breaking performance.

FIG. 9 similarly shows the relationship between the amount of Ta added and the withstand voltage performance. As is clear from the figure, when the amount of Ta is 5% by weight or less, there is only a slight difference from conventional product a (Cu-25% by weight Cr alloy), but as the amount of Ta added increases, the withstand voltage improves. An increase can be seen. Generally the total weight% of Cr and Ta
As the number increases, the withstand voltage performance tends to improve.

Next, we will show how the characteristics of the alloy change when the weight ratio of Cr to Cu is changed while the amount of Ta in the alloy is fixed at 30% by weight.

Figure 10 shows the relationship between the weight ratio of Cr to Cu and electrical conductivity.

Next, the amount of Ta added in the alloy was changed to 0, 1, 3, 5, 7,
Fixed at 10, 15, 30, 40, 50, 60% by weight,
FIG. 11 shows the relationship between shearing performance and Cr weight ratio when the weight ratio of Cr to Cu is changed in each alloy. Note that the vertical axis is conventional product a (Cu
-25 wt% Cr alloy) is expressed as 1,
The horizontal axis shows the weight ratio of Cr to Cu. As can be seen from the figure, the Cu-Cr binary alloy of conventional product a
There is a peak in sheath shear capacity when the Cr content is in the range of 20 to 30% by weight, and the same tendency occurs when the Ta content is fixed in the range of 1 to 15% by weight. In addition, when the amount of Ta is fixed at 15% by weight, the weight ratio of Cr to Cu is
A remarkable increase in shearing performance is seen from about 10% by weight (8.5% by weight for the entire contact material) to about 25% by weight for Cu (21.3% by weight for the entire contact material). On the other hand, when the amount of Ta is fixed at 30% by weight, the peak of the shear breaking capacity occurs when the weight ratio of Cr is 10 to 20% (7% to the entire contact material).
~14 wt%), and its peak value is Ta
It is slightly inferior to the alloy with a content of 15% by weight.

Figure 12 shows the relationship between Ta content and electrical conductivity in a binary alloy of Cu and Ta, and Figure 13 shows the relationship between Cu and Cr.
The relationship between Cr content and electrical conductivity is shown in the binary alloy. From both figures, the electric conductivity decreases as Ta and Cr increase, and for Ta, it decreases at about 50% by weight.
In addition, 40% by weight of Cr reaches the limit of electrical conductivity generally required for a plastic breaking contact;
Increasing Ta and Cr will have a negative effect on practical use due to current conduction, shearing, etc. Furthermore, as is clear from Fig. 11, when coexisting with Ta, the shearing performance is improved when the amount of Cr is 35% by weight or less based on the entire contact material, and when the amount of Cr is increased beyond that, However, the effect is not obtained. On the other hand, with regard to Ta, when it coexists with Cr, even a small amount of addition can improve the cracking performance, and it is practical when the amount of Ta is 50% by weight or less.
It should be noted that even if the amount of Ta is 50% by weight or more, there seems to be an effective range in terms of shearing performance.
As is clear from the figure, if Ta exceeds 50% by weight, the electrical conductivity is low and the contact resistance increases, making it difficult to put it into practical use as a disconnector for other than special purposes.

Furthermore, from Figure 11, the range in which the shearing performance is significantly improved (more than 1.5 times) compared to the conventional product is that the Ta content is 5 to 30% by weight, and the Cr content is 8 to 33% by weight relative to Cu. % by weight, ie 8×0.7≒5 to 33×0.9≈30% by weight based on the entire contact material.

Furthermore, from Fig. 11, for the entire contact material,
It was effective when the total content of Cr and Ta was 10% by weight or more, and when it was less than that, the shear cutting performance did not improve. Furthermore, as shown in FIG. 11, as the total content of Cr and Ta in the entire contact material gradually increases, it becomes difficult to manufacture, and when it exceeds 65% by weight, sufficient breaking performance and breaking performance cannot be expected, although it depends on the manufacturing method.

In addition, in the experimental examples shown in FIGS. 6 to 11, Cr
The intermetallic compound consisting of Cu and Ta, that is, Cr ₂ Ta, is formed, and various properties of the alloy in which Cr, Ta, and Cr ₂ Ta are uniformly and finely distributed in Cu are shown.
An alloy in which the sintering temperature is lowered and Cu, Cr, and Ta are distributed almost as single elements shows almost the same tendency, and has significantly greater shearing performance than the conventional Cu-25 wt% Cr alloy. has. but,
Cu―Cr― mixed, formed, and sintered with the same composition
It was found that Ta alloys that form intermetallic compounds of Cr and Ta have better cutting performance.

Although not shown in the figure, Bi, Te,
Low melting point metals such as Sb, Tl, Pb, Se, Ce, and Ca, alloys thereof, and intermetallic compounds thereof can be added in an amount of 20% by weight or less for low-sintering vacuum shields and breaker contacts. It has been confirmed that, as in the above experimental example, there is an effect of increasing the shearing performance and withstand voltage performance.

In addition, at least one of low melting point metals, alloys thereof, and intermetallic compounds thereof
When more than % by weight was added, the shearing performance decreased significantly. Furthermore, when the low melting point metal was Ce or Ca, the properties were slightly degraded.

As described above, according to the present invention, in addition to containing copper, other components include chromium of 35% by weight or less and tantalum of 50% by weight or less, and the total of chromium and tantalum is 10% by weight or more. Because of this feature, it is possible to obtain a contact material for a vacuum shield breaker which has excellent shear breaking performance and high withstand voltage performance.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the structure of a vacuum switch tube to which an embodiment of the present invention is applied, and FIG.
It is an enlarged sectional view of the electrode part of a figure. Figure 3 is a 100x metallographic photograph of a conventional Cu-25wt%Cr contact alloy produced by a sintering method, and Figure 4 is a Cu-25wt%Cr contact alloy produced by an embodiment of the present invention sintered at high temperature.
100 of the contact alloy with 10% by weight of Ta added to the mother alloy.
Fig. 5 is a 100x photo of the metallographic structure of a contact alloy having the same composition as Fig. 4 sintered at low temperature according to another embodiment of the present invention, and Fig. 6 is a photo of the contact of the present invention. A characteristic diagram showing the change in electrical conductivity when the amount of Ta added is changed for an alloy in which the weight ratio of Cr to Cu in the material is fixed at 75:25. A characteristic diagram showing the change in contact resistance when the amount of Ta added is changed for an alloy with a fixed Cr weight ratio of 75:25. Figure 8 shows the weight ratio of Cr to Cu in the contact material of this invention. A characteristic diagram showing the change in shear capacity when the amount of Ta added is changed for an alloy fixed at 75:25. Figure 9 shows the weight ratio of Cr to Cu in the contact material of this invention.
Characteristic diagram showing the change in withstand voltage performance when the Ta addition amount is changed for an alloy fixed at 75:25, 1st
Figure 0 shows Ta in the alloy in the contact material of this invention.
Figure 11 is a characteristic diagram showing the change in electrical conductivity when the weight ratio of Cr to Cu is changed when the amount is fixed at 30% by weight. ,5,7,10,15,30,40,
Regarding Cu when fixed at 50 and 60% by weight, respectively
Figure 12 is a characteristic diagram showing changes in shear capacity of alloys with varying weight ratios of Cr, and is shown for reference.
-Characteristic diagram showing the relationship between Ta content and electrical conductivity in Ta binary alloy, Figure 13 is shown for reference, and Cu-Cr
FIG. 2 is a characteristic diagram showing the relationship between Cr content and electrical conductivity in a binary alloy. DESCRIPTION OF SYMBOLS 1... Vacuum insulation container, 2, 3... End plate, 4, 5... Electrode, 6, 7... Electrode rod, 8... Bellows, 9, 10...
Shield, 51...brazing material, and the same reference numerals in the drawings indicate the same or corresponding parts, respectively.

Claims (1)

[Claims] 1 Contains copper, and other components include 35% by weight or less of chromium and 50% by weight or less of tantalum,
A contact material for vacuum shields and disconnectors characterized by containing a total of chromium and tantalum in a range of 10% by weight or more. 2. The contact material for a vacuum shield or breaker according to claim 1, which contains a total of chromium and tantalum in a range of 65% by weight or less. 3 5 to 30% by weight of chromium and 5 to 30% of tantalum
A contact material for a vacuum shield or breaker according to claim 1, characterized in that the content is in the range of 30% by weight. 4. Claims characterized in that copper, chromium, and tantalum are each distributed as a single metal, a tri- or di-metallic alloy, a tri- or di-metallic compound, or a composite thereof. The contact material for a vacuum shield or disconnector according to any one of Items 1 to 3. 5 Bismuth, tellurium, antimony, thallium,
Claims 1 to 3 contain at least 20% by weight of at least one of low melting point metals such as lead, selenium, cerium, and calcium, alloys thereof, and intermetallic compounds thereof. The contact material for a vacuum shield or disconnector according to any one of Item 4.