JPH07228933A - Contact material for vacuum valve - Google Patents

Abstract

PURPOSE:To obtain a contact material for vacuum VALVE, capable of reducing the frequency of the occurrence of restrike, by subjecting a composition system, consisting of a conductive component composed essentially of Cu, an arc resisting component composed essentially of Cr, and an auxiliary component containing W, Mo, etc., to solidification by cooling and then to melting. CONSTITUTION:A composition system, consisting of a conductive component composed essentially of Cu, an arc resisting component composed essentially of Cr, and an auxiliary component containing at least one element among W, Mo, Ta, and Nb, is solidified by cooling and then melted to prevent the occurrence of restrike, by which the contact material for vacuum valve is obtained. At this time, it is preferable to regulate the composition of this material so that it consists of, by volume, 40-75% of the above conductive component, 20-50% of the above arc resisting component, and >=1 of the above auxiliary component. Because the above auxiliary component has higher specific gravity than Cr and can enter into solid solution in Cr, the frequency of the occurrence of restrik can be reduced by adding the above auxiliary component and further shortening the solidification time of liquid phase to inhibit the occurrence of Cr-enriched phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact material for a vacuum valve, which has a reduced frequency of re-ignition.

[0002]

2. Description of the Related Art The characteristics required for a contact material for a vacuum valve are three basic requirements shown by performances such as welding resistance, withstand voltage, and breaking, and in addition, temperature rise and contact resistance are low and stable. Is an important requirement. However, it is impossible to satisfy all the requirements with a single metal because some of these requirements conflict with each other. For this reason, in many practically used contact materials, two or more kinds of elements that complement each other in insufficient performance are combined, and in a specific application such as for large current or high withstand voltage. The existing contact materials have been developed, and materials having excellent characteristics have been developed. However, the fact is that there are still some points that are still unsatisfactory with respect to the various required characteristics that are becoming stronger.

As a recent remarkable tendency, there is an expansion of circuits applied to a reactor circuit, a capacitor circuit, etc., and there is an urgent need to develop and improve contact materials. In particular, since a voltage that is twice as high as that of a normal circuit is applied to the capacitor circuit, a problem has arisen that the withstand voltage characteristic of the contact, particularly the suppression of re-ignition occurrence. To accommodate this,
Conventionally, a Cu-Cr contact material that is generally excellent in breaking performance and relatively good in withstand voltage characteristics has been used.

[0004]

However, although such Cu-Cr contact material can be applied to a high withstand voltage field to a certain extent, in a circuit with a more severe withstand voltage region and an inrush current, a There is a problem of ignition.
One of the reasons why the Cu-Cr contact material does not always exhibit sufficient characteristics in the high breakdown voltage region is that Cu-Cr fine phase generated on the contact surface due to opening and closing of the contact is mechanically higher than that of the contact base material. It is considered that the strength becomes high, and the slight welding locally generated by the inrush current causes peeling from the contact base material portion to form remarkable unevenness, resulting in electric field concentration / clamping. Therefore, it is considered that the reignition probability can be reduced by increasing the strength of the contact base metal.

Infiltration C obtained by infiltrating Cu into a Cr skeleton produced by sintering Cr powder, rather than solid-phase sintering Cu-Cr contact produced by mixing and sintering Cr powder and Cu powder.
The u-Cr contact showed a lower re-ignition rate. Also,
Cu-C with arc-melted consumable electrode made of CuCr
The r-contact showed an even lower re-ignition rate.

However, in the Cu-Cr contact manufactured by the arc melting method, local nonuniformity of the contact structure is caused by the two-phase separation of the Cu-rich liquid phase and the Cr-rich liquid phase generated during solidification cooling. It is formed. Since this Cr-rich portion is brittle in terms of material, cracks and chips occur when the contacts are opened and closed, which causes re-ignition. An object of the present invention is to provide a contact material for a vacuum valve, which can reduce the frequency of re-ignition.

[0007]

To achieve the above object, the present invention provides a conductive component containing Cu as a main component, an arc-resistant component containing Cr as a main component, and W, Mo, Ta, and Nb. A composition system comprising at least one auxiliary component,
The gist is that it was cooled, solidified, and melted.

[0008]

The reason why the Cr-rich phase is generated by the rapid solidification melting method is that the Cu-rich liquid phase and the Cr-rich liquid phase are separated into two phases before the molten liquid phase is solidified, and the Cr-rich liquid phase having a small specific gravity floats. To come. Therefore, we have
It was thought that the generation of the Cr-rich phase could be suppressed by shortening the time until the liquid phase solidifies and reducing the difference in specific gravity between the two phases. The shortening of the coagulation time is considered to be possible by increasing the number of coagulation nuclei. Further, it is considered that the reduction of the difference in specific gravity can be achieved by adding a component having a specific gravity larger than Cr and forming a solid solution with Cr.

Paying attention to the above matters, Cu and Cr
Further, at least one of W, Mo, Ta, and Nb is further added to perform rapid solidification, whereby the Cr-rich portion can be eliminated.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a vacuum valve to which the contact material for a vacuum valve of the present invention is applied, and FIG. 2 is an enlarged view of a main part of FIG. In these figures, the shut-off chamber 1 is an insulating container 2 made of an insulating material such as ceramics and formed into a substantially cylindrical shape.
And the metallic lids 4 and 5 provided on both ends thereof via the sealing mechanisms 3a and 3b, and are hermetically sealed in vacuum.

Further, a fixed electrode 8 and a movable electrode 9 are provided in the shut-off chamber 1 at ends of the pair of electrode rods 6 and 7 facing each other. In addition, the movable electrode 9
A bellows 10 is attached to the electrode rod 7 of the
While keeping the inside airtight in a vacuum, the pair of electrodes 8 and 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 the deposition of arc vapor, and a cylindrical metal container 12 is further provided in the shutoff chamber 1 so that the arc vapor to the insulating container 2 can be prevented. Is prevented from being attached.

On the other hand, the movable electrode 9 is, as shown in FIG.
It is fixed to the conductive rod 7 by a brazing material 13 or is crimp-connected (not shown) by caulking, on which a movable contact 14b is joined by a brazing material 15.

The fixed electrode 8 is almost the same except that the direction thereof is paradoxical, and the fixed electrode 8 is provided with a fixed contact 14a. An example of the method for manufacturing the contact in this embodiment will be described. For example, a manufacturing method of an arc melting method will be described as one of the rapid solidification methods. A consumable electrode having a contact target composition is manufactured by a powder metallurgy method, a plate material laminating method, or the like. This electrode is used as a consumable electrode (anode side) for arc melting, for example, after the inside of the arc furnace vessel is evacuated to 10 ⁻³ (Pa), high purity Ar, for example, is injected to suppress vaporization of the molten metal. Two
A vacuum degree of about 10 ⁴ (Pa) is obtained. Opposing water cooling C with a predetermined arc voltage / arc current and a predetermined consumption amount
An ingot having a predetermined composition is obtained in the u crucible.

Next, the evaluation results and the evaluation methods for the specific examples described later will be described. Against the background as described above, comparison was made between the main contact and the conventional contact at the frequency of re-ignition. A disc-shaped contact piece with a diameter of 30 mm and a thickness of 5 mm was attached to a demantable vacuum valve, and a 6 KV x 500 A circuit was installed.
The frequency of re-ignition at the time of breaking 2000 times was measured, two circuit breakers (6 valves) were measured, and the re-ignition occurrence rate was shown. When mounting the contacts, use baking heat (450 ° C
(* 30 minutes) was used, and the brazing material was not used and the heating associated therewith was not performed. Next, the evaluation results will be considered with reference to Table 1.

[0016]

[Table 1] Example 1-2, Comparative Example 1-3 A consumable electrode having a composition in which the Cr content of the arc-resistant material is constant at 50% by volume and the auxiliary component Nb is 0, 0.1, 1, 10, 30% by volume and the balance is Cu. Was manufactured from a laminated plate (Comparative Examples 1, 2 and
Examples 1, 2 and Comparative Example 3). About 35V arc voltage, 1.5
Ar was produced in a vacuum atmosphere of 2 × 10 ⁴ (Pa) with an arc current of KA. After processing into the contact shape described above, it was incorporated into the chamber and the re-ignition occurrence rate was evaluated. As a result, as shown in the table, in both Comparative Example 1 without Nb and Comparative Example 2 with a very small amount of Nb added, the re-ignition rate was 1.5%.
On the other hand, in Examples 1 and 2 in which 1,10% of Nb was added, the re-ignition occurrence rate was 0.6-0.7%, indicating good characteristics. However, Comparative Example 3 in which 30% of Nb was added
Although the re-ignition rate was 0.8, which was good, the contact resistance was large and not practical. Example 2-3, Comparative Example 4-5 The arc was used for the contact where the content of Cr as the main arc-resistant component was 10, 20, 50, 70% by volume with the Nb content of the auxiliary component being constant at 10% by volume. It was produced by the dissolution method. The arc current / voltage is the same as in the first embodiment. In Comparative Example 4 in which the amount of Cr added was 10%, the re-ignition occurrence rate was good at 0.7%, but the breaking ability was insufficient. Cr addition amount is 20,50%
The re-ignition occurrence rates of Examples 3 and 2 were 0.6 and 0.7%. Comparative Example 5 in which the amount of added Cr was 70% had a drawback that the re-ignition rate was improved but the contact resistance was large. Example 4-6 Although Examples 1-3 described above relate to the Cr—Nb—Cu system, even if Mo, Ta, or W is added instead of Nb, as shown in Example 4-6. , Shows good characteristics for reducing the occurrence of restriking. Also in the rapid solidification method,
Not only the arc melting method, but as shown in Examples 5-6, even when manufactured by the electroslag method, good characteristics are exhibited as in the arc melting method. Therefore, it is obvious that the same effect can be obtained even if the contact material is manufactured by another manufacturing method that satisfies the rapid solidification.

[0017]

As described above, according to the present invention, a conductive component containing Cu as a main component, an arc resistance component containing Cr as a main component, and at least one of W, Mo, Ta and Nb are contained. Since the composition system including the auxiliary component for cooling is solidified by cooling and melted, the frequency of re-ignition can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of a vacuum valve to which a vacuum valve contact material according to an embodiment of the present invention is applied.

FIG. 2 is an enlarged sectional view of an electrode 9 of FIG.

[Explanation of symbols]

 8, 9 ... Electrodes, 14a, 14b ... Contacts

Claims (2)

[Claims] 1. A composition system comprising a conductive component containing Cu as a main component, an arc-resistant component containing Cr as a main component, and an auxiliary component containing at least one of W, Mo, Ta and Nb, A contact material for a vacuum valve, which is characterized by being cooled, solidified, and melted. 2. The contact for a vacuum valve according to claim 1, wherein the conductive component is 40 to 75% by volume, the arc resistance component is 20 to 50% by volume, and the auxiliary component is 1% by volume or more. material.