JPH0973846A - Contact material for vacuum valve and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contact material for a vacuum bulb which is able to contribute toward realizing a vacuum bulb which is able to withstand a high voltage and is able to interrupt a large current. SOLUTION: A composition is made wherein there are contained copper, chromium particles a mean particle size of which is not greater than 30μm, and chromium particles a mean particle size of which is greater than 30μm. Surface condition of a CuCr contact brought about by breaking is caused to be such that chromium is dissolved as much as possible in a cu liquid phase by containing chromium particles a mean particle size of which is small, and breaking performance is thereby improved without deteriorating withstand voltage characteristics.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a contact material for a vacuum valve and a method for manufacturing the same.

[0002]

2. Description of the Related Art As the characteristics required for a contact material for a vacuum valve, there are three basic requirements shown for welding resistance, withstand voltage and interruption, and in addition to this, temperature rise and contact resistance are low and stable. Is an important requirement. However,
Some of these requirements are conflicting, so
It is not possible to meet all requirements with a single metal species. For this reason, in many practically used contact materials, two or more kinds of elements that complement each other in lacking performance are combined and suitable for a specific application such as for large current or high voltage. Development of contact materials
Although materials having excellent properties have been developed as such, vacuum valve contact materials that sufficiently satisfy the requirements for higher breakdown voltage and large current interruption have not yet been obtained.

For example, a CuBi contact material (Japanese Patent Publication No. 41-121) has been used as a contact material having a large current and improved resistance to welding.
31), CuTe contact (Japanese Patent Publication No. 44-23751)
It has been known. A CuCr contact is known as a contact aiming at high current and high breakdown voltage (Japanese Patent Publication No.
35101). Also, a CuCrBi contact is known as a contact with improved welding resistance of the CuCr contact (Japanese Patent Publication No. 61-41091).

However, although contact materials having excellent characteristics have been developed, no contact material has yet been obtained that sufficiently satisfies the requirements for higher breakdown voltage and higher current interruption. is there.

[0005]

As described above, there is a problem that it is necessary to provide a contact material which has the ability to interrupt a large current more than the current contact and has excellent withstand voltage characteristics. There is.

The present invention has been made in view of the above,
An object of the present invention is to provide a contact material for a vacuum valve and a method for manufacturing the same, which can contribute to the realization of a high withstand voltage and a large current interruption of the vacuum valve.

[0007]

When the electric current is cut off, an arc is formed between the contacts and the contact surface is melted by the arc. In the case of a CuCr-based contact, since the melting point of Cu is lower than that of Cr, melting of Cu starts first, and then Cr dissolves in the Cu liquid phase to form a CuCr liquid phase.
However, since the CuCr binary system has a two-phase separation region in the liquid phase, and the breaking time, that is, the arc generation time is completed within a short time of about 10 ms or less, the molten form of Cr becomes important. . That is, if the Cr particle size is small, it will dissolve in the Cu liquid phase within a short time, but if the Cr particle is large, not all of the Cr will be completely dissolved, and the Cr will be locally dissolved. The particles remain, and since the Cr particles are lighter than the Cu liquid phase, they float and form a non-uniform phase on the contact surface. Therefore, when the Cr particles are large, the amount of Cr dissolved in the Cu liquid phase is small.
Compared with r particles, the CuCr solution has a lower viscosity, droplets and the like are easily generated, and withstand voltage characteristics tend to deteriorate. Further, when the Cr particles are floated on the contact surface, the local Cr-rich phase easily causes cracks on the contact surface, which also promotes deterioration of withstand voltage characteristics.

Therefore, the surface condition of the CuCr contact due to interruption is preferably such that Cr is dissolved in the Cu liquid phase as much as possible, that is, the contact base material contains a large number of fine Cr particles. It has been found that they tend to have good blocking performance.

On the other hand, since the vacuum valve is a switch element using a high vacuum inside the valve as an insulator, it is naturally important to maintain the degree of vacuum inside the valve. Particularly, in recent years, as vacuum valves have become smaller, the size of vacuum containers has been reduced, and it is important to reduce the amount of oxygen, nitrogen, and hydrogen contained in the contacts. As described above, it is more effective to make the Cr particles finer for the breaking performance and the withstanding voltage performance. However, as is well known, fine powder causes an increase in the amount of adhering gas due to an increase in the specific surface area, resulting in a decrease in the breaking performance. Becomes a factor.

From the above two points of the amount of Cr dissolved in the Cu liquid phase and the gas content of the contact point, it is effective to use both fine powder Cr and coarse Cr powder as raw material powders as the best values. I found that.

Therefore, according to the present invention of claim 1,
Chrome particles with an average particle size of 30 μm or less, and an average particle size of 3
The gist of the present invention is to contain chromium particles having a diameter of more than 0 μm.

That is, according to the first aspect of the present invention, by including the chromium particles having a small average particle diameter, the breaking performance is improved without lowering the withstand voltage characteristics.

The present invention according to claim 2 is, in the invention according to claim 1, characterized in that at least one kind of Mo, W, Nb, and Ta is contained.

According to the second aspect of the invention, Mo,
By adding W, Nb, and Ta, the viscosity of the CuCr solution is increased and the withstand voltage characteristic is improved.

According to a third aspect of the present invention, in the invention according to the first aspect, at least one of Ti, Zr and Y is contained so that the total content is 0.5 to 5% by volume. Is the gist.

According to the invention of claim 3, Ti, Z
By adding the required amounts of r and Y, the low melting point of copper is locally achieved and the barrier performance is improved.

According to a fourth aspect of the present invention, in the first aspect of the invention, at least one of Bi, Te and Sb is contained so that the total content is 0.5 to 3% by weight. Is the gist.

In the invention of claim 4, Bi, T
By adding the required amounts of e and Sb, the welding resistance is further reduced and the load on the mechanism is reduced.

The present invention described in claim 5 provides the invention according to claims 1 to 4.
In any one of the inventions described above, the average particle size is 30
The gist is that the content of the chromium particles of μm or less is 3 to 30% by volume.

According to the fifth aspect of the invention, the content of the chromium particles having an average particle diameter of 30 μm or less is set to an appropriate amount to ensure the improvement of the barrier performance.

The present invention according to claim 6 is the same as claims 1 to 5.
In any one of the inventions described above, the average particle size is 30
The gist is that the total content of the chromium particles having a size of not more than μm and the chromium particles having an average particle size of more than 30 μm is 25 to 65% by volume.

According to the sixth aspect of the invention, the content of the chromium particles with respect to copper is set to an appropriate amount to ensure the improvement of the barrier performance.

The present invention according to claim 7 is the same as claims 1 to 6.
In any of the inventions described above, the summary is that the total content of oxygen, nitrogen and hydrogen in the contact is 980 ppm or less.

In the invention according to claim 7, the gas content in the contact is suppressed to a predetermined amount or less to prevent the breaking performance from being deteriorated.

According to the invention of claim 8, after molding a mixed powder containing copper and chromium particles having an average particle size of 30 μm or less and an average particle size of more than 30 μm, the melting point of copper in a non-oxidizing atmosphere. The main point is to sinter below.

According to the eighth aspect of the present invention, it is possible to accurately manufacture a contact material having an improved breaking performance without lowering the withstand voltage characteristic.

According to a ninth aspect of the present invention, in the eighth aspect, the mixed powder is Mo, W, Nb or Ta.
The gist is to contain at least one or more of them.

According to the invention of claim 9, CuCr
It is possible to accurately manufacture a contact material having an improved withstand voltage characteristic by increasing the viscosity of the solution.

According to a tenth aspect of the present invention, in the invention according to the eighth aspect, the total content of the mixed powder is 0.5 to 5% by volume of at least one kind of Ti, Zr and Y. It is a gist to contain such.

According to the tenth aspect of the present invention, it is possible to accurately manufacture a contact material having a locally low melting point of copper and improved breaking performance.

According to an eleventh aspect of the present invention, in the invention according to the eighth aspect, the mixed powder has a total content of at least one of Bi, Te and Sb of 0.5 to 3 inclusive.
It is a gist to contain it so that it may be a weight%.

According to the eleventh aspect of the present invention, it is possible to accurately manufacture a contact material having a further reduced welding resistance and a reduced load on the mechanism portion.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below based on specific embodiments.

First, the structure of a vacuum valve to which the contact material of the present invention is applied will be described with reference to FIGS.

FIG. 1 shows the structure of the vacuum valve. In FIG. 1, reference numeral 1 denotes a shut-off chamber.
Is an insulating container 2 formed of an insulating material in a substantially cylindrical shape.
And the metallic lids 4a and 4b provided on both ends thereof with the sealing metal fittings 3a and 3b interposed therebetween to form a vacuum-tight seal. A pair of electrodes 7 and 8 attached to opposite ends of the conductive rods 5 and 6 are arranged in the shutoff chamber 1, and the upper electrode 7 is a fixed electrode and the lower electrode 8 is movable. It is used as an electrode. A bellows 9 is attached to the conductive rod 6 of the movable electrode 8 to enable the electrode 8 to move in the axial direction while keeping the inside of the shutoff chamber 1 vacuum-tight. An arc shield 10 is provided to prevent the bellows 9 from being covered with arc vapor. 11
Is a metal arc shield that is provided in the shutoff chamber 1 so as to cover the electrodes 7 and 8 and prevents the insulating container 2 from being covered with arc vapor. Furthermore, the electrode 8
As shown in the enlarged view of FIG. 2, the brazing portion 12 is attached to the conductive rod 6.
It is fixed by or is crimped by caulking. The contact 13a is fixed to the electrode 8 by brazing 14. In addition, 13b in FIG. 1 is a fixed side contact.

The contact material according to the present invention is suitable for forming both or one of the contacts 13a and 13b as described above.

Next, the embodiment of the present invention will be described in detail in comparison with a comparative example. Prior to that, an evaluation method of each contact will be described.

(1) Withstand voltage characteristics With respect to each contact alloy, a lithographic electrode and a needle electrode, which are mirror-finished by buffing, have a constant distance between both electrodes of 0.5 mm.
In a vacuum atmosphere of the order of 10 −4 Pa, the voltage value was measured when the voltage was gradually increased and a spark was generated, and this was determined as the static breakdown voltage value. The measurement data shown in Table 1 below is an average value after three repeated tests,
It is shown as a relative value when the value of the CuCr contact shown in Comparative Example 1 described later is 1.0.

(2) Breaking performance After the manufactured contact material was processed into a disk shape having a diameter of 40 mm and a thickness of 5 mm, it was incorporated into a predetermined vacuum valve and the applied voltage was kept constant at 7.2 KV, and the breaking current was changed from 8 KA to 1 ~
Whether or not to block was judged by increasing by 1.5 KA. The characteristic is that the value of the CuCr contact shown in Comparative Example 1 is 1.0
The relative values are shown as

Comparative Example 1 Cr powder having an average particle size of 100 μm and Cu powder having an average particle size of 45 μm were mixed at a ratio of 1: 1 and then 7 Ton / cm ²
After molding the green compact with a molding pressure of 1050 ° C. × 1 Hr. Sintering was carried out under the above sintering conditions. Further, after remolding at a molding pressure of 7 Ton / cm ² , sintering was performed under the same conditions to obtain a contact material. After processing into a predetermined shape, a static pressure resistance characteristic and a breaking performance test were conducted.
This characteristic value is used as the reference value of the contact evaluated in the following.

Examples 1, 2, 3 and Comparative Example 2 In addition to the powder used in Comparative Example 1, the average particle size was 4, 10,
Four kinds of Cr powder of 30,75 μm were prepared. 15% by volume of these powders, the above-mentioned average particle diameter of 100 μm of Cr
After sufficiently mixing the powder with 35% by volume and the balance being the Cu powder, contacts were manufactured by the same manufacturing process as in Comparative Example 1 (Examples 1, 2, 3 and Comparative Example 2, respectively). When the static breakdown voltage characteristics and the breaking performance were evaluated, the static breakdown voltage characteristics of all the contacts showed values equivalent to those of Comparative Example 1. On the other hand, as for the breaking performance, the one to which comparatively fine particles of 4, 10 and 30 μm were added showed better characteristics than the conventional contact,
The one to which Cr particles having an average particle diameter of 75 μm was added showed only the same performance as the contact of Comparative Example 1.

Comparative Example 3, Examples 4, 1, 5 and Comparative Example 4 Using two kinds of Cr powders having an average particle size of 4 μm and 100 μm and Cu powder having an average particle size of 45 μm, 4 μm Cr powder, 100 μm Cr powder, The ratio of the 45 μm Cu powder is 40:10:50, 30:20:50, 15: 3, respectively.
Five kinds of mixed powders of 5:50, 3:47:50 and 1:49:50 were manufactured. After that, the green compact was molded at a molding pressure of 1 Ton / cm ² , and then in a vacuum atmosphere of 10 −2 Pa, 1050 ° C. × 1 Hr. Sintering was carried out under the above sintering conditions. Further, after remolding at a molding pressure of 7 Ton / cm ² , sintering was performed under the same conditions to obtain contact materials (Comparative Example 3, Examples 4, 1 and 5, Comparative Example 4). When the static pressure resistance characteristics were evaluated, it was confirmed that 4 μm of Cr particles, which were fine Cr powder, were
The one with 0% by volume added had a large gas content and showed a low withstand voltage characteristic. However, the contact added with 30% by volume or less showed withstand voltage characteristics equivalent to the contact of Comparative Example 1. Regarding the breaking performance, the comparative example 3 having a large gas content showed a low value, but the others showed better characteristics than the contact of the comparative example 1.

Comparative Example 5, Examples 6, 2, 7 and Comparative Example 6 Using two kinds of Cr powders having an average particle size of 10 μm and 100 μm and Cu powder having an average particle size of 45 μm, 10 μm Cr
The ratio of powder, 100 μm Cr powder, 45 μm Cu powder,
10: 0: 90, 15:10:75, 15: 3, respectively
Five kinds of mixed powders of 5:50, 15:50:35 and 15:75:10 were produced. After that, 7 Ton / cm ²
After molding the green compact with a molding pressure of 1050 ° C. × 1 Hr. The sintering was performed under the sintering conditions of (Comparative Example 5, Examples 6, 2, 7, and Comparative Example 6).
When the electrical characteristics were evaluated, Comparative Example 5 with a low total Cr content did not have sufficient withstand voltage characteristics, and Comparative Example 6 with a high total Cr content of 90% by volume did not provide sufficient breaking performance. . Other contacts having a Cr content of 25 to 65% by volume were able to obtain favorable characteristics in both withstanding voltage characteristics and breaking performance.

Comparative Example 7 and Example 8 Cr powder having an average particle size of 30 μm and an average particle size of 45 μm
After mixing the Cu powder of Example 1, a contact was manufactured in the same step as Comparative Example 1 (Comparative Example 7). The average particle size is 100μ
m powder and 45 μm Cu powder were mixed, then filled in rubber rubber, and hydrostatically molded to obtain φ50 mm × 1000
mm powder compacts were produced. Furthermore, 1000 ° C. × 1 Hr.
Sintering was carried out in a vacuum under the conditions described above to obtain a sintered body. This was subjected to consumable arc melting under a condition of 30V-1500A in a low-pressure Ar atmosphere, and the average particle diameter of Cr was 5 μm of 30 μm.
A 0 vol% Cr-Cu contact was obtained (Example 8). When these contacts were electrically evaluated, Comparative Example 7 produced by the solid phase sintering method had a large gas content, and also showed inferior values to Comparative Example 1 in withstand voltage characteristics and breaking performance. However, in Example 8, even though most of the Cr particles were 30 μm or less, the gas content was small, so that the withstand voltage characteristics and the breaking performance were good. Therefore, it can be seen that the fineness of the Cr particles in the direction in which the gas content is not increased improves the withstand voltage characteristics and the breaking performance in a favorable direction.

Examples 9, 10, 11, 12, 13, 14 Cr powder having an average particle size of 10 μm, Cr powder having an average particle size of 100 μm and Cu powder having an average particle size of 45 μm were used as basic raw materials, and W having a particle size of 3 μm was further added. 50% by volume Cr using powder
(Including 10 μm Cr: 15% by volume) -1W-Cu, 40
Cr (including 10 μm Cr: 15% by volume) -10W-C
u, 25Cr (including 10 μmCr: 15% by volume) -25
Three types of mixed powders of W-Cu were manufactured. These powders were subjected to the same steps as in Comparative Example 3 to obtain a sintered body, and then,
It was re-molded under a molding pressure of 7 Ton / cm ² and was again sintered under the same conditions to obtain contacts (respectively Examples 9, 10, 1).
1). Moreover, 40Cr (of which,
10 μm Cr: 15% by volume) -10Mo—Cu powder was produced, and 50 μm Nb powder was used.
(μmCr: 15% by volume) -1Nb-Cu mixed powder was produced, and further, W powder of 7 μm and Ta powder of 40 μm were used, and 40Cr (10 μmCr: 15% by volume) -5W
-5Ta-Cu powder was produced. Using these three types of mixed powders, contact materials were obtained in the same steps as in Example 9 (Examples 12, 13, and 14 respectively). When the same electrical evaluation was carried out on these six types of contact materials, the withstand voltage characteristics were better than those of the contact of Comparative Example 1, and the breaking performance was also higher than that of the contact of Comparative Example 1.

Examples 15 and 16 Cr powder having an average particle size of 10 μm, Cr powder having an average particle size of 100 μm and Cu powder having an average particle size of 45 μm are used as basic raw materials, and further, Ti powder of 100 μm, Zr powder of 80 μm and 100 μm. 50% Cr by volume using Y powder of
(Including 10 μm Cr: 15% by volume) -0.5Ti-C
u, 45Cr (including 10 μmCr: 15% by volume) -2Z
Two kinds of mixed powders of r-3Y-Cu were manufactured. These powders were subjected to the same steps as in Comparative Example 3 to obtain a sintered body,
Furthermore, it is re-molded at a molding pressure of 7 Ton / cm ² and again
Contact was obtained by sintering under the same conditions (Example 15,
16). When similar electrical evaluations were carried out on these contact materials, the withstand voltage characteristics were similar to those of the contact of Comparative Example 1, but the breaking performance of the contact of Comparative Example 1 or more was shown.

Examples 17 and 18 Cr powder having an average particle size of 10 μm, Cr powder having an average particle size of 100 μm and Cu powder having an average particle size of 45 μm were used as basic raw materials, and further, Bi powder of 150 μm, Te powder of 150 μm, and 150 μm. Sb powder of 50% by volume Cr
(Including 10 μm Cr: 15% by volume) -0.5Bi-C
u, 45Cr (including 10 μmCr: 15% by volume) -2T
Two kinds of mixed powders of e-1Sb-Cu were manufactured. These powders were subjected to the same steps as in Comparative Example 3 to obtain a sintered body, which was then re-molded at a molding pressure of 7 Ton / cm ² and sintered again under the same conditions to obtain a contact. (Each Example 1
7, 18). When similar electrical evaluations were carried out on these contact materials, the withstand voltage characteristics were similar to those of the contact of Comparative Example 1, but showed a breaking performance higher than that of the contact of Comparative Example 1.
Less tripping force was sufficient.

Table 1 shows a summary of the above results.

[0049]

[Table 1]

Not only the above-mentioned embodiment but also other than this embodiment, it is possible to improve the breaking performance by combining the Cr particle size and suppressing the gas content.
It is obvious that the withstand voltage characteristic can also be improved by adding another refractory metal such as. Further, T
By adding an active metal such as i, the barrier performance is improved, and by adding a low melting point metal such as Bi,
It is obvious that the tripping force can be reduced.

[0051]

As described above, according to the first aspect of the present invention, by containing chromium particles having a small average particle diameter, the surface state of the CuCr contact due to interruption is as much as possible in the Cu liquid phase. Since it was made to dissolve,
It is possible to improve the breaking performance without lowering the withstand voltage characteristics of the conventional CuCr contact, which can contribute to the realization of high withstand voltage and large current breaking of the vacuum valve.

According to the second aspect of the invention, Mo, W,
Since Nb and Ta are added, the conventional CuCr
The withstand voltage characteristic can be improved by increasing the viscosity of the CuCr solution as compared with the contact.

According to the invention of claim 3, Ti, Z
Since the required amounts of r and Y were added, the conventional CuC
The lower melting point of copper can be achieved more locally than the r contact, and the breaking performance can be improved.

According to the invention of claim 4, Bi, T
Since the required amounts of e and Sb were added, the conventional Cu
It is possible to further reduce the welding resistance as compared with the Cr contact point and reduce the load on the mechanism section.

According to the invention of claim 5, the content of the chromium particles having an average particle diameter of 30 μm or less is set to an appropriate amount, so that the breaking performance can be improved as compared with the conventional CuCr contact.

According to the sixth aspect of the invention, since the content of the chromium particles relative to copper is set to an appropriate amount, the breaking performance can be improved as compared with the conventional CuCr contact.

According to the invention described in claim 7, by suppressing the gas content in the contact to a predetermined amount or less, it is possible to prevent the breaking performance from being lowered.

According to the invention described in claims 8 to 11,
It is possible to accurately manufacture a contact material having improved withstand voltage characteristics and breaking performance.

[Brief description of drawings]

FIG. 1 is a sectional view of a vacuum valve to which the present invention is applied.

FIG. 2 is an enlarged cross-sectional view of a contact portion of the vacuum valve.

[Explanation of symbols]

 1 Isolation chamber 2 Insulation container 3a, 4a Sealing metal fittings 4a, 5b Lid body 5,6 Conductive rod 7 Fixed electrode 8 Movable electrode 9 Bellows 10, 11 Arc shield 12, 14 Brazing part 13a Movable side contact 13b Fixed side contact

Front page continued (72) Inventor Atsushi Yamamoto No. 1 in Toshiba Fuchu factory, Fuchu, Tokyo (72) Inventor Takashi Kusano No. 1 in Toshiba Fuchu city, Tokyo, Fuchu factory

Claims (11)

[Claims] 1. A contact material for a vacuum valve, which contains copper, chromium particles having an average particle diameter of 30 μm or less, and chromium particles having an average particle diameter of more than 30 μm. 2. The vacuum valve contact material according to claim 1, wherein the vacuum valve contact material contains at least one or more of Mo, W, Nb, and Ta. 3. The vacuum valve contact material according to claim 1, wherein at least one of Ti, Zr, and Y is contained so that the total content is 0.5 to 5% by volume. Contact material for vacuum valves. 4. The vacuum valve contact material according to claim 1, wherein at least one of Bi, Te, and Sb is contained so that the total content is 0.5 to 3% by weight. Contact material for vacuum valves. 5. The contact material for a vacuum valve according to claim 1, wherein the content of the chromium particles having an average particle diameter of 30 μm or less is 3 to 30% by volume. 6. The total content of the chromium particles having an average particle diameter of 30 μm or less and the chromium particles having an average particle diameter of more than 30 μm is 25 to 65% by volume. The contact material for a vacuum valve according to Crab. 7. The contact material for a vacuum valve according to claim 1, wherein the total content of oxygen, nitrogen and hydrogen in the contact is 980 ppm or less. material. 8. After molding a mixed powder containing copper and chromium particles having an average particle size of 30 μm or less and an average particle size of more than 30 μm, sintering is performed at a temperature not higher than the melting point of copper in a non-oxidizing atmosphere. A method of manufacturing a characteristic contact material for a vacuum valve. 9. The mixed powder is Mo, W, Nb, Ta.
9. The method for producing a contact material for a vacuum valve according to claim 8, wherein at least one of the above is contained. 10. The vacuum according to claim 8, wherein the mixed powder contains at least one kind of Ti, Zr, and Y such that the total content thereof is 0.5 to 5% by volume. Manufacturing method of valve contact material. 11. The mixed powder has a total content of 0.5 to 3 of at least one of Bi, Te and Sb.
9. The content is 8% by weight.
A method for producing the contact material for a vacuum valve according to claim 1.