JPH03108224A - Contact material vacuum valve - Google Patents

Abstract

PURPOSE:To concurrently obtain the excellent low current cutting characteristic and the high-frequency arc extinguishing characteristic by optimizing the content, ratio and existing state of Ag and Cu, and further atomizing the organization of a contact material. CONSTITUTION:A contact material for a vacuum valve is the Ag-Cu-Cr3C2 contact material for a vacuum valve containing a high conducting component of Ag and Cr and an arc-resistant component of Cr3C2, the content of the high conducting component is set as follows: the total quantity of Ag and Cr 40-80wt.%, the ratio of Ag in the total quantity of Ag and Cu 40-80wt.%, and the content of the arc-resistant component 20-60wt.%. The organization of the contact material is constituted of the matrix of the high conducting component, the discontinuous phase with the thickness or width 5mum or below, and discontinuous grains of Cr3C2 10mum. or below, and the discontinuous phase of the high conducting component is finely and uniformly distributed in the matrix at the interval 5mum or below.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Industrial Application Field) This invention relates to a sintered alloy used as a contact material for a vacuum valve, and more particularly, to a sintered alloy that is used as a contact material for a vacuum valve. This invention relates to a contact material for vacuum valves with improved characteristics.

(Prior Art) The contacts of a vacuum valve, which cuts off current in a high vacuum by utilizing arc diffusivity in a vacuum, are composed of two opposing fixed and movable contacts. When this vacuum valve is used to cut off the current in an inductive circuit such as a motor load, an excessive abnormal surge voltage may be generated, which may destroy the load equipment.

The cause of this abnormal surge voltage is, for example, a new phenomenon that occurs when a small current is cut off in a vacuum (current cutoff is forcibly performed without waiting for the natural zero point of the AC current waveform), or high-frequency arc extinction. This is due to phenomena etc.

The value Vs of the abnormal surge voltage due to the new phenomenon is expressed as the product of the surge impedance Zo of the circuit and the current cutoff value 1c, that is, Vs-ZO·Ic.

Therefore, in order to lower the abnormal surge voltage Vs, the current cutoff value 1c must be lowered.

In response to the above requirements, tungsten carbide (WC) and silver (
A vacuum switch using composite alloy contacts (Ag) was developed (Japanese Patent Application No. 42-68447, U.S. Patent No. 36
No. 83138), which has been put into practical use.

In this A g-WC alloy contact, the presence of (+) WC facilitates electron emission, (2) promotes evaporation of the contact material due to heating of the electrode surface due to collision of field emission electrons, and further, (3) The carbide of the contact material is decomposed by the arc, producing a charged body and exhibiting excellent low breaking current characteristics in connection with the arc.

In addition, other contact materials that exhibit low cutting current characteristics (low chopping characteristics) include bismuth (Bi) and copper (Cu).
), and this material has been put to practical use in vacuum valves (Japanese Patent Publication No. 35-14974, U.S. Patent No. 2975256, Japanese Patent Publication No. 41-1213).
No. 1, U.S. Pat. No. 3,246,979). Among these alloys, the one with BE of 10% by weight (hereinafter referred to as wt%) (Japanese Patent Publication No. 14974/1983) has appropriate vapor pressure characteristics, so it exhibits low cutting current characteristics, and
Bi containing Q, 5wt% (Special Publication Publication No. 41-1213
As a result of being segregated at grain boundaries, the alloy itself becomes brittle, achieves a low welding pull force, and is excellent in large current interrupting properties.

Other contact materials that obtain low breaking current characteristics include Ag and C.
An Ag-Cu-WC alloy in which the ratio with u is approximately 7:3 has been proposed (Japanese Unexamined Patent Publication No. 157015/1983).

In this alloy, Ag and Cu have unprecedented limitations.
It is stated that stable cutting current characteristics can be achieved by selecting the ratio of .

Furthermore, in Japanese Patent Publication No. 62-077439, the particle size of the arc-resistant material (for example, the particle size of WC) is 0.2 to 1 μm.
It has been suggested that this is effective in improving low breaking current characteristics.

(Problems to be Solved by the Invention) Vacuum circuit breakers are required to have low surge characteristics, and for this reason, conventionally, low breaking current characteristics have been required as described above.

However, in recent years, vacuum valves have been increasingly applied to inductive circuits such as electric motors, and high surge impedance loads have also appeared, so it is desired that vacuum valves have even more stable and low disconnection current characteristics. Of course, high-frequency arc-extinguishing characteristics (high-frequency current interrupting ability) must also be satisfied. This is because it has been found that in addition to surges caused by current interruption, surges caused by repeated high-frequency re-ignition pose a threat to load insulation.

Conventionally, there has been no contact material that satisfies both of these properties at the same time.

That is, the surge (overvoltage) caused by the current breaker can be improved by reducing the current breaker value, but the surge caused by repeated high-frequency re-ignition can be improved when dielectric breakdown occurs between the current breaker and the electrodes. The recovery voltage value increases by cutting off the high-frequency current that flows depending on the circuit conditions, and the recovery voltage value increases due to the repetition of the process of dielectric breakdown between the electrodes, which generates an excessive surge voltage. be. In this case, the surge is generated to extinguish the high-frequency current, and by improving the high-frequency arc-extinguishing characteristics to reduce the surge voltage, the generated surge can be reduced. It is necessary to improve and stabilize arc characteristics.

Alloy contact made of composite of WC and Ag (Patent application 1976-6)
No. 8447, U.S. Pat. No. 3,683,138), not only is the cutting current value itself insufficient, but no consideration is given to improving the high frequency arc extinguishing characteristics.

l Q w t% Bi and Cu composite alloy (Japanese Patent Publication No. 35-14974, U.S. Patent No. 297525
No. 6), the amount of metal supplied to the space between the electrodes decreased as the number of openings and closings increased, deterioration of the low breaking current characteristics appeared, and deterioration of the withstand voltage characteristics was also pointed out depending on the amount of high vapor pressure elements. There is. Furthermore, the high-frequency arc-extinguishing characteristics are not fully satisfied.

An alloy containing 0.5 wt% of Bi and Cu (Japanese Patent Publication No. 12131/1983, US Pat. No. 3,246,979) has insufficient low breaking current characteristics.

In addition, Ag with a weight ratio of Ag and Cu of approximately 7:3
-Cu-WC alloy (Japanese Unexamined Patent Publication No. 157015/1983)
Also, an alloy in which the particle size of the arc-resistant material is 0.2 to 1 μm (Japanese Patent Application Laid-Open No. 62-077439) does not sufficiently satisfy high frequency arc extinguishing properties.

This invention was made based on the above-mentioned background, and its purpose is to provide a vacuum breaker that has both excellent low breaking current characteristics and high frequency arc extinguishing characteristics, and that can meet the increasingly severe demands for vacuum circuit breakers. The purpose of the present invention is to provide contact materials for valves.

[Structure of the Invention] (Means for Solving the Problems) As a result of research and development to solve the above problems, the inventor discovered that Ag-Cu-Cr3 C2-based contact materials contain Ag and Cu. Having obtained the knowledge that it is effective to achieve the object of the present invention by optimizing the amount, ratio, and state of existence, and further refining the structure of the contact material,
This invention was completed.

That is, the contact material for a vacuum valve of the present invention contains Ag and C.
A contact material for an Ag-Cu-Cr3C2 vacuum valve containing a highly conductive component of u and an arc-resistant component of Cr3C2, wherein (a) the content of the highly conductive component is the same as that of Ag and Cu. The total weight (Ag+Cu) is 40 to 80 wt%, and the ratio of Ag to the total weight of Ag and Cu (Ag/
(Ag+Cu)] is 40 to 80 wt%, (b) the content of the arc-resistant component is 20 to 60 wt%, and (c) the structure of this contact material is that of the highly conductive component. a matrix and a discontinuous phase with a thickness or width of 5 μm or less, and a 10 μm
It consists of the following discontinuous grains of Cr5C2 (arc-resistant component), and the discontinuous phase of highly conductive component is 5 μm thick in the matrix.
The gist is that the particles are finely and uniformly dispersed at the following intervals.

In a preferred embodiment of the present invention, the arc-resistant component is TicSZrC in addition to Cr3C2.

One metal carbide selected from the group VCSNbC, TaC can be used.

When an arc-resistant component other than Cr3C2 is selected, the content of the highly conductive component (Ag+Cu) is 50 to 85 wt% for TiC and 40 wt% for ZrC.
~80wt%, 50-85wt% for VC, Nb
40-80wt% for C, 25wt% for TaC
~65 wt%.

In one aspect of the invention, the thickness or width of the highly conductive component is 5 μm.
In the part where the discontinuous phase of 5 μm or less is finely and uniformly dispersed in the matrix at intervals of 5 μm or less, the matrix of the highly conductive component and the discontinuous phase are each Cu in which Ag is dissolved. Solid solution and Ag solid solution in which Cu is dissolved, or Ag solid solution in which Cu is dissolved and A
It is a Cu solid solution in which g is dissolved.

In yet another preferred embodiment of the present invention, the highly conductive component exhibits a state in which discontinuous phases with a thickness or width of 5 μm or less are finely and uniformly dispersed in the matrix at intervals of 5 μm or less. The portion occupies at least 40 area percent of the total amount of highly conductive component.

(Function) In order to improve the current cutting property, it is extremely important to not only maintain the current cutting itself at a lower value, but also to reduce the width of its variation. The above-mentioned new current phenomenon is said to be closely related to the amount of vapor between the contacts (material properties include vapor pressure and heat conduction), electrons emitted from the contact material, etc. According to the inventors' experiments, the former It turned out that the contribution was larger. Therefore, it has been found that the current leakage phenomenon can be alleviated by making it easier to supply steam or by making contacts from materials that are easier to supply. The above-mentioned Cu-BL alloy is based on this point of view and has a low shear value. However, a fatal drawback is the low melting point (271°C) of Bi.
Baking at around 600°C or silver brazing at 800°C, which is usually performed in a vacuum valve, causes the movement and agglomeration of Bi due to melting, resulting in non-uniform presence of Bi, which is required to maintain current cutting properties. Become. For this reason, a phenomenon is observed in which the width of variation in the current cutoff value increases.

On the other hand, in the Ag-arc-resistant material alloy represented by Ag-Cr3C2, although it depends on the amount of Ag vapor at the boiling point of the arc-resistant material (Cr5C2 in this case), the C
The vapor pressure of Ag is significantly lower than the vapor pressure of Bi in the u-B1 system, so depending on where on the contact point (Ag or arc-resistant material) the arc leg is stuck, it can lead to insufficient temperature, or lack of steam. There is. As a result, it was confirmed that a variation width of the current cutoff value appeared.

It was thought that it was already possible to prevent the rapid temperature drop of the contact surface at the end of the current rupture using an alloy made only of a combination of Ag and an arc-resistant material and to maintain the arc. Furthermore, in order to improve the performance, we came to the conclusion that it is necessary to add some kind of auxiliary technology. As one idea for this improvement, the above-mentioned Japanese Patent Application Laid-Open No. 58-157015 suggests a technique of finely distributing crystal grains by forming a highly conductive component into an alloy of Ag and Cu.

This technology has stabilized the characteristics. The location where the arc is mainly fixed may be in the arc-resistant component or in the Ag-Cu alloy, and in both cases, the current phenomenon is alleviated (improved) by supplying Ag-Cu vapor. ,
When adhering to the arc-resistant component, some variation occurred.

On the other hand, by making the arc-resistant component more fine, the variation width can be improved. Therefore, it is suggested that the particle size of the arc-resistant component plays an important role in the current phenomenon, and
Considering the observation results that showed significant variation in contact materials where the arc-resistant component was found to be segregated to a size approximately 10 to 20 times the initial particle size, it was concluded that there is a specific range of particle size. Suggests.

However, as disclosed in JP-A-58-1.5701.5, it is important to control the amounts of Ag and Cu and the grain size of WC to predetermined values to improve the cutting current characteristics. Although significant technological progress has been made, these technologies have not been able to further improve low-breakage current characteristics, ensure high-frequency arc-extinguishing characteristics, and in particular have not been able to improve high-frequency arc-extinguishing characteristics.

As mentioned above, surges caused by repeated high-frequency re-ignitions are caused by current interrupters, which cut off the high-frequency current that flows depending on the circuit conditions when dielectric breakdown occurs between the electrodes, increasing the recovery voltage value, and further increasing the recovery voltage value between the electrodes. As the process of dielectric breakdown occurs is repeated, the recovery voltage value increases and an excessive surge voltage is generated. In order to suppress excessive surge voltage, it is desirable to allow the high-frequency current discharge that flows during dielectric breakdown in the microelectrode gap to continue arcing until the commercial frequency load current rises, without extinguishing the high-frequency current discharge.

When this commercial frequency load current rises, the breaker has opened to a sufficient gap length between the electrodes by the time it reaches the next current zero point, so dielectric breakdown between the electrodes will occur after this current zero point. The shutoff is completed without any occurrence or repetition. Therefore, no excessive surge voltage is generated as described above.

Furthermore, even if a subsequent arc does not occur, by reducing the high frequency arc extinguishing ability, the surge due to high frequency re-ignition will be reduced. That is, it is only necessary to improve the continuation characteristics of high-frequency current discharge in a small gap between electrodes.

In order to improve this continuous arc characteristic, in the present invention, first of all, Ag and Cu, which are highly conductive components, are made to coexist. Moreover,
■Ag solid solution with dissolved Cu and ■Cu with dissolved Ag
Form a matrix and a discontinuous phase (lamellar structure or rod-like structure) of the solid solution, and set the width or thickness of this discontinuous phase to 5 μm.
m or less, and this discontinuous phase is 5μ in the matrix.
By finely and uniformly dispersing the particles at intervals of m or less, the arc spot diameter is designed to be equal to or preferably smaller than the arc spot diameter. the result,
The melting point of Ag and Cu components (hereinafter referred to as arc maintenance material), which mainly share the function of maintaining and connecting the arc, is lowered and at the same time the vapor pressure is increased.

Then, secondly, the average particle size of the Cr3C2 grains is set to 10 μm or less, preferably 3.0 μm, more preferably 1.0 μm.
It is set as below. This requirement promotes dispersion of the arc sustaining material to a more highly finely dispersed state.

In other words, even if the content and ratio of the arc maintenance materials (Ag and Cu) are selected within a predetermined range, the following embodiments and
As shown in the comparative example, it is not possible to achieve both low cut-off performance and high-frequency arc-extinguishing characteristics. According to this invention, the arc maintenance material (
This makes it possible to further bring out the effects of highly refined structures of Ag and Cu, and to stabilize them.

In general, the charge of ions of materials with high vapor pressure in a vacuum arc tends to be low (see C, W).

Written by K 1sbllnr E rroslon and
I onlzatlon in the cathod
e S pot Reglons of'
Vacuui+ Arcs J, J
Internal or Applied Phy
sics, Vol.

44, Karasu, 7, p3074, 1973). That is, not only does the amount of evaporation increase, but also a large number of ions with low valences exist in the arc. Therefore, during high-frequency current discharge in the microelectrode gap, when the current reaches zero point, the amount of residual plasma existing in the microelectrode gap is smaller than when the arc sustaining material is only Ag or only Cu. In many cases, Ag and Cu exist under predetermined conditions. This is preferable in order to simultaneously ensure low timing and high-frequency arc-extinguishing characteristics, which are the objects of the present invention.

Furthermore, although the mass of Cu ions is lighter than that of Ag, the ion drift velocity at zero current point (930 m/s for Cu)
eeSAg (630 m/5ee) is large (see the above-mentioned document), the energy of Cu when colliding with the electrode is larger. This ion impact heats the electrode locally, and in combination with the effect of the amount of residual plasma mentioned above, even when the current reaches zero point during high-frequency small current discharge, a new cathode is generated on the electrode surface. This makes it easier to generate a cathode spot and improves the follow-on arc characteristics during high-frequency, small-current discharge.

Due to this improved follow-on characteristic, even if dielectric breakdown occurs when there is a small gap between the electrodes, the load current at the commercial frequency will rise more easily, resulting in a 0.5-cycle extension of the start-up time. As a result, the current reaches zero point after the electrodes are sufficiently opened, and an excessive surge voltage can be generated. In this way, by further refining the content of Ag and Cu, their ratio and existence state, and the particle size of Cr3C2, which is an arc-resistant component, in the present invention, low possession property and high-frequency arc-extinguishing properties can be achieved. can be improved at the same time.

(Example) The present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of the vacuum valve, and FIG. 2 is an enlarged sectional view of the electrode portion of the vacuum valve.

In FIG. 1, a shutoff chamber 1 includes an insulating container 2 formed of an insulating material into a substantially cylindrical shape, and sealing fittings 3 at both ends of the insulating container 2.
Metal lid body 4 a provided via a s 3 b
It is constructed in a vacuum-tight manner with s 4 b.

A pair of electrodes 7.8 attached to opposite ends of a conductive rod 5.6 are arranged in the breaker chamber 1, with the upper electrode 7 serving as a fixed electrode and the lower electrode 8 serving as a movable electrode. . Further, a bellows 9 is attached to the electrode rod 6 of the electrode 8 to allow the electrode 8 to move in the axial direction while keeping the interior of the breaker chamber 1 vacuum-tight. Further, a metal arc shield 10 is provided above the bellows 9 to prevent the bellows 9 from being covered with arc vapor. Further, a metallic arc shield 11 is provided in the cutoff chamber 1 so as to cover the electrodes 7.8, thereby preventing the insulating container 2 from being covered with arc vapor. Further, the electrode 8 is fixed to the conductive rod 6 by a brazing material 12, as shown in an enlarged view in FIG. 2, or is crimped and connected by caulking. Contact 13a is attached to electrode 8 by brazing 14. Note that the contact 13b is attached to the electrode 7 by brazing.

Next, an example of a method for manufacturing this contact material will be described.

Prior to manufacturing, arc-resistant components and auxiliary components are classified by required particle size. The classification operation can be carried out using a combination of sieving and sedimentation, for example, to easily obtain powder of a predetermined particle size. First, a predetermined amount of Cr3C2 with a predetermined particle size and Ag or A with a predetermined particle size.
A predetermined amount of gCu is prepared, mixed, and then pressure-molded to obtain a powder compact.

Next, this powder compact is pre-sintered at a predetermined temperature, for example, 1150°C for 1 hour, in a hydrogen atmosphere with a dew point of 150°C or less or a degree of vacuum of 1.3 x 10°'Pa or less, to form a pre-sintered body. obtain.

Next, a predetermined amount and predetermined ratio of Ag-Cu is infiltrated into the remaining pores of this pre-sintered body at 1150°C for 1 hour.
- Obtain a Cr3 C2 alloy. Infiltration is primarily carried out in vacuum, but is also possible in hydrogen.

Note that the ratio of conductive components in the alloy (Ag/(Ag+Cu
)] was controlled as follows. For example, an ingot having a predetermined ratio (Ag/(Ag+Cu)) was vacuum melted at a temperature of 1200°C and a degree of vacuum of 1.3 x 10° 2 Pa, cut, and used as a material for infiltration.Ratio of conductive components ( Another method for controlling Ag/(Ag+Cu) is that when making a temporary sintered body, a predetermined amount of part of the Cr3C2
The remaining Ag or (Ag+Cu
) can also provide a contact alloy with a desired composition.

Next, we will discuss the evaluation method used to obtain specific example data, which will be described later.
and evaluation conditions.

(1) Current resistance When a prefabricated vacuum valve with each contact attached and evacuated to 1O-3Pa or less was manufactured, and this device was opened at an opening speed of 0.68m/sec to cut off a small current with a delay. The disconnection current was measured. Breaking current is 20A (effective value), 50Hz
And so. The opening phase was randomly determined and the severing current was measured for three contacts when the contact was interrupted 500 times, and the average and maximum values are shown in the tables of FIGS. 3 to 5. In addition, the numerical value is the average value of the cutting current value of Example 2 in the same table.
It is shown as a relative value when it is set to 0.

(2) High-frequency arc-extinguishing characteristic When switching on and off a small current with a delayed power factor, if an overvoltage is generated on the load side due to current interruption, the difference between the overvoltage and the power supply voltage is applied between the poles of the vacuum valve.

If the voltage between the electrodes exceeds the withstand voltage value of the contact spacing, dielectric breakdown occurs and a discharge occurs, causing a transient high-frequency current to flow through the contacts.

When this high-frequency current is cut off, the process returns to the initial stage and an overvoltage appears, which again causes a discharge in the contact gap, and the process repeats. Such a repeated phenomenon is well known as a multiple re-ignition phenomenon. In circuit breakers with high high-frequency arc extinguishing ability, such as vacuum circuit breakers, large surge voltages may be generated due to multiple re-ignitions depending on the circuit conditions.
May threaten the insulation of load equipment (motors and transformers). Generally, it is said that the smaller the high frequency arc extinguishing ability, the more difficult it is to repeat the re-ignition and the smaller the generated surge.

In order to investigate this high frequency arc extinguishing characteristic for each contact, we manufactured a vacuum valve to which each contact was attached and evacuated to below 10'Pa.
V, 150 kVA (7) A load current cut-off test was conducted on a single + HI pressure vessel. A 6.6kV single-core CV cable with a length of 100m (conductor cross-sectional area 200mm2) is used between the breaker and the transformer.
).

The load current is 10A (effective value), and the opening speed of the breaker is 0.
．． 8 m/sec (average), the opening phase of the circuit breaker was controlled, and the circuit breaker was disconnected at the phase where multiple re-ignition occurred. The transient high-frequency current that flows through the contacts during multiple re-ignitions has a frequency determined by the inductance around the breaker and the stray capacitance on the power supply and load sides, and in this test, the frequency of the transient high-frequency current was approximately 100kHz. Ta. To measure the high-frequency arc-extinguishing ability, 20 breaking tests were performed for each contact, and the average value of the high-frequency arc-extinguishing ability after 1 ms had passed after contact opening was determined.

The values in the table are the high frequency arc extinguishing ability of Example 2 (current reduction rate di/dt [A/
The relative value is shown when 100 is 100 μ seconds].

(3) Contents of the test contacts The tables in FIGS. 3 to 5 show the material contents of the test contacts and their corresponding characteristic data together with comparative examples.

As shown in the table, the amount of (Ag+Cu) in the Ag-Cu-Cr3 C2 alloy is 17.7wt% to 92.2wt%,
The ratio of Ag and Cu (Ag/(Ag+Cu)) is O~1
00 wt%, and the state of existence of Ag and Cu, that is, the discontinuous phase (layered or/and rod-like structure) with a thickness or width of 5 μm or less of the highly conductive component is 5 μm or less in the matrix. For example, the ratio of the area occupied by the state of existence that is finely and uniformly dispersed at intervals of 75 to 100
Area % 1. Classified into 50 area %, 25 area %, and 10 area % or less. These are the cooling rates in the cooling process of each contact, i.e. 77°C below 1000°C or higher.
The average cooling rate for a temperature difference of 100° C. at any temperature in the temperature range up to 0° C. is obtained by adjusting it to the above area %. For example, it is obtained by solidifying while cooling, preferably at a rate faster than 6°C/min.

A speed slower than 0.6° C./min is disadvantageous to the dispersion of Ag and Cu.

Furthermore, we evaluated the contacts in which the particle size of the arc-resistant component (typically represented by Cr3C2) used was 0.1 .mu.m to 80 .mu.m, and the results were studied.

The table shows these conditions and the corresponding results.

Examples 1 to 3, Comparative Examples 1 to 2 Cr3C2 powder having an average particle size of 3.1 μm is prepared. Molding is performed while appropriately selecting a molding pressure in the range of zero to 8 tons/cm2 so as to adjust the amount of voids remaining after sintering. In this case, Example 3 with a large amount of (Ag+Cu) in the alloy (Ag+
Cu-80wt%), Comparative Example 2 (Ag+Cu-92,
2 wt%), either the molding pressure is particularly low, or a method is adopted in which a mixed powder is obtained by previously mixing a part of (Ag+Cu-) with Cr3C2 and then molded. After molding these mixed powders, in Example 1 and Comparative Example 1, for example, 11
Sintered at 00~1300℃, Cr3C2 or Cr3C
A 2-Ag-Cu sintered body is obtained. Examples 2-3, Comparative Example 2
Then, a sintered body is obtained by sintering at a lower sintering temperature. In this way, (Ag+
In the end, the amount of (Ag+Cu) in the Ag-Cu-Cr3 C2 alloy was 17.7 to 92.2 wt% (Comparative Examples 1 to 1). 2. Obtain the alloys of Examples 1 to 3). After processing these contact materials into a predetermined shape, the rupture performance and high frequency arc extinguishing characteristics were evaluated using the evaluation method and conditions described above.

As mentioned above, the evaluation of the cutting resistance was compared based on the characteristics when the samples were cut off 500 times. Comparative example 1~ in the table in Figure 3
2. (Ag+Cu) in the alloy as shown in Examples 1 to 3
The average value of the cut value in terms of amount is as shown in Example 2 (Ag+Cu=6
1.3wt%, Ag/(Ag+Cu)-74.6wt%
) is 1.0, Examples 1 to 3
, Comparative Examples 1 and 2 all have an increase of 2.0 times or less (deterioration of characteristics), but (Ag + Cu) ~ 17.7wt
% (Comparative Example 1) and (Ag+Cu)-92.2wt%
In Comparative Example 2, the maximum value increased, whereas in Examples 1 to 3, the maximum value stabilized at 2.0 times or less (good characteristics). ing.

In particular, the disconnectability of a contact with a small amount of (Ag+Cu), such as (Ag+Cu) -17.7 wt% (Comparative Example 1), is as follows:
If the circuit is shut off a large number of times, it can be seen that the disconnection performance deteriorates after about 2,000 openings and closings.

On the other hand, when evaluating the high-frequency arc-extinguishing characteristics, it was found that Example 2
Considering the characteristics of (Ag+Cu
) amount is 40 to 80 wt% (Examples 1 to 3), stable characteristics are shown, but when the amount of (Ag + Cu) is 17.7 wt%
(Comparative Example 1) and 92.2wt% (Comparative Example 2),
It is recognized that the relative value tends to increase (deterioration of characteristics), and the relative value exceeds 200. Therefore, Ag-Cu-
The amount of (Ag+Cu) in the Cr3C2 alloy is 40 to 80 wt from the viewpoint of the severability and high frequency arc extinguishing properties.
A range of % is preferred. Note that the properties of Example 2 were equivalent to or better than those of the conventional Ag-Cu-WC.

Examples 4 to 8, Comparative Examples 3 to 6 As mentioned above, even if the amount of (Ag+Cu) is in a preferable range, that is, in the range of 40 to 80 wt%, Ag-Cu-C
It has been found that if the ratio of Ag and Cu in the r3 C2 alloy is not appropriate, the severability and high frequency arc extinguishing properties deteriorate. That is, the value of (Ag/(Ag+Cu)) is 40 to 8
At 0 wt% (Examples 4 to 8), the preferred cutting time (
(relative value is 2.0 or less) and high frequency arc extinction characteristics (relative value is 2.0 or less)
0 or less) was obtained.

In addition, the value of (Ag/ (Ag+Cu)) is 96.8wt%
and 100wt% (comparison values 3 to 4), high thermal conductivity was achieved, and the value of (Ag/ (Ag+Cu)) was 20.5w.
In the case of t% to zero (Comparative Examples 5 to 6), a decrease in the first characteristics is observed mainly due to a quantitative shortage of Ag serving as a vapor source.

In Examples 1 to 8 and Comparative Examples 1 to 6, the amount of (Ag+Cu) and (Ag/
(Ag+Cu)] shows the same tendency.

Examples 9 to 10, Comparative Examples 7 to 8 The existence state of the Ag-Cu portion in the Ag-Cu-Cr3 C2 alloy, that is, the thickness of the highly conductive component or the discontinuous phase (layered or/and rod-shaped) with a width of 5 μm or less The proportion of the region in which the structure (Ag structure) is finely and uniformly dispersed at intervals of 5 μm or less in the matrix is determined by the above-mentioned conventional method.
+Cu) around 45wt%, (Ag/ (Ag+Cu)
) was prepared at around 70 wt %, and was heat-treated at a cooling rate after infiltration and at 800° C. to 1000° C. for about 1 hour for about 1 hour to obtain contacts having various area ratios (%). When this area ratio is 40% or more (Example 9.10), it is in the range of low rupture resistance and also shows good high-frequency arc extinguishing properties, whereas compared with small area ratios. In Examples 7 and 8, there was a deterioration in the disconnection performance, particularly a significant increase (deterioration) in the maximum value, and an increase (deterioration) in the high frequency arc extinguishing property. Therefore, the area ratio of the presence state of Ag and Cu is 4 in the (Ag+Cu) phase.
It is preferable that it be 0% or more.

Examples 11 to 16, Comparative Examples 9 to 10 F e s(o,
Ni is used as an auxiliary component to suppress the segregation of Cr3C2 or the presence of bores during the production of this alloy (represented by Ni).
. However, even if Ni is zero, Ag-Cu-Cr3 is carefully prepared to control segregation or bore formation.
The C2 alloy (Example 13) has no performance problems in terms of cutting resistance and high frequency arc extinguishing properties.

Industrially, a predetermined value (Ni amount - 1 wt%, Example 11
) The presence of Ni below means that the cutoff value is both the average value and the maximum value,
It is in the low range (Examples 11-12).

Even when Ni is zero, both the average and maximum relative values are 2.0 or less, which is within the practical range; however, at the maximum value, Ni
The amount was 1 wt%, 0.05 wt% (Examples 11-12
), there is a tendency for there to be differences and variations.

The presence of Ni is important for high frequency arc extinction characteristics.
In the range of 5wt% (Comparative Example 9) to zero, the relative value is within 200, and there is no problem in terms of characteristics, but at the maximum value of the rupture resistance, Ni-3 shows a high value (multiplying factor 2.3).
,5wt% are excluded, Ag-Cu-Cr3C2-N
Ni in the L alloy is preferably 1 wt % or less including NL-zero from the viewpoint of good severability and high frequency arc extinguishing properties.

Examples 14 to 16, Comparative Example 10 In Examples 1 to 12 and Comparative Examples 1 to 9 described above, Ni particle size of 1.5 μm was used. Affect the value.

That is, the severability is determined when the particle size of NL is 0.1 to 44 μm (
In all the ranges of Examples 14 to 16 and Comparative Example 10), the relative value is maintained at 200 or less and there is no problem, but when the Ni particle size is 44 μm (Comparative Example 10), the average value falls into a preferable range. However, it is degraded at the maximum value.

Therefore, the amount of Ni is 1 wt% or less (Examples 11 to 13
) in the Ag-Cu-Cr3 C2-Ni alloy
It can be seen that the particle size of 10 μm or less (Examples 14 to 16) is preferable.

Examples 17 to 19, Comparative Examples 11 to 12 The grain size of Cr3C2 shows an important relationship with the shredding properties and high frequency arc extinguishing properties of the Ag-Cu-Cr3C2 alloy. Cr3
When the particle size of C2 is 35 μm (Comparative Example 12), from the viewpoint of the cutting value, the relative value is 2.0 or less for both the average value and the maximum value, so there is no problem, but the high frequency arc extinguishing property is also deteriorated (relative value is 200 μm or less). above) was observed, and the particle size of Cr3C2 was 80 μm.
In (Comparative Example 11), the maximum value of the cutoff value exceeds 2.0 in relative value, and the dispersion becomes large.

On the other hand, the particle size of Cr3C2 was 10 μm or less (Example 17 to
In No. 19), both the average value and the maximum value of the cutoff value were extremely stable, and the high frequency arc extinguishing property also showed extremely favorable relative values. Therefore, the particle size of Cr3C2 is preferably in the range of 10 μm to 0.1 μm (Examples 17 to 19) (Table in FIG. 5). C
If the particle size of r3C2 is less than 0.1 μm, it is not only unsuitable for industrial use in terms of handling, but also causes excessive sinterability and unstable material properties.

Although Ni was mainly mentioned as an auxiliary component, pure Co
, even pure Fe, Ni-Co powder, C0-F
Even with e powder, the same effect as Ni was obtained.

Examples 20 to 24 In Examples 1 to 19 and Comparative Examples 1 to 2 described above, chromium carbide (Cr3C2) was used as the metal carbide, but titanium (Ti), zirconium (Zr), vanadium (V), Each metal carbide of niobium (Nb) and tantalum (Ta) also has a predetermined amount of (Ag+Cu), (Ag/ (
Ag+Cu)] Ag and C having the amount and predetermined existence form
When each of the ratios of u is within a preferable predetermined range, effects similar to those of Cr3C2 described above can be obtained (Examples 20 to 24 in the table of FIG. 5).

In addition, Ag-Cu-(Ag+Cu) in each of the above metal carbides
) The preferred range of the amount varied slightly depending on the type of metal carbide. That is, in the case of chromium carbide Cr3C2, as mentioned above, the amount of (Ag+Cu) is 40 to 80 w.
t%, but in other metal carbides, in order to satisfy both current carrying properties and high frequency arc extinguishing properties at the same time, it was necessary to set the numerical value within the following range. These numerical ranges were determined through experiments similar to those for Cr3C2 described above.

The amount of (Ag+Cu) is 50 to 85 wt% for titanium carbide (e.g. Tic) and 40 to 80 wt% for zirconium carbide (e.g. ZrC).
wt%, 50 to 85 wt% for vanadium carbides (e.g. VC), 40 to 80 wt% for niobium carbides (e.g. NbC), and 40 to 80 wt% for tantalum carbides (e.g. T).
aC) is in the range of 25 to 65 wt%.

As in the examples described above, the total amount of highly conductive material consisting of Ag and Cu (Ag+Cu) and the ratio of Ag and Cu (
By controlling the Ag/ (Ag + Cu)] ratio to a predetermined value, and by setting the average particle size of Cr3C2 to 10 μm or less and highly uniformly distributing the existence form of Ag and Cu, the current resistance can be lowered. It is possible to maintain and manage the variation with a small amount, and furthermore, the high frequency arc extinguishing characteristic can also be maintained at a sufficiently low level.

[Effects of the Invention] As detailed above, the present invention provides the following effects. That is, the current flow characteristics can be maintained low and variations can be managed to be small. Furthermore, high frequency arc extinction characteristics can also be maintained sufficiently low. Therefore, if the contact material of the present invention is used in a vacuum valve contact, a vacuum valve with excellent current carrying and blocking properties can be obtained, and a contact material that can fully meet the increasingly severe demands for vacuum circuit breakers is provided. be able to.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a vacuum valve to which the vacuum valve contact material according to the present invention is applied, and FIG. 2 is an enlarged sectional view of the electrode portion of the vacuum valve shown in FIG. 4
The figures and FIG. 5 are tables showing contents of contact materials according to examples of the present invention and corresponding characteristic data together with comparative examples. 1: Breaker 1 13a, 13b: Contacts.

Claims (4)

[Claims] (1) An Ag-Cu-Cr_3C_2-based vacuum valve contact material containing a highly conductive component made of Ag and Cu and an arc-resistant component made of chromium carbide (hereinafter referred to as Cr_3C_2), the highly conductive The content of sexual components is determined by the total amount of Ag and Cu (
Ag+Cu) is 40 to 80% by weight, and the Ag
The ratio of Ag in the total weight of Cu and Cu [Ag/(Ag
+Cu)] is 40 to 80% by weight, the content of the arc-resistant component is 20 to 60% by weight, and the structure of the contact material is a matrix of the highly conductive component and a thickness or width of 5 μm It consists of the following discontinuous phase and discontinuous grains of the arc-resistant component of 10 μm or less, and the discontinuous phase of the highly conductive component is finely and uniformly dispersed in the matrix at intervals of 5 μm or less. A contact material for vacuum valves characterized by: (2) In a portion exhibiting a state in which a discontinuous phase of the highly conductive component having a thickness or width of 5 μm or less is finely and uniformly dispersed in the matrix at intervals of 5 μm or less, the highly conductive component The matrix and the discontinuous phase of claim 1 are each a Cu solid solution in which Ag is dissolved and an Ag solid solution in which Cu is dissolved, or an Ag solid solution in which Cu is dissolved and a Cu solid solution in which Ag is dissolved. Contact material for vacuum valves. (3) In the structure of the contact material, there is a portion in which a discontinuous phase of the highly conductive component with a thickness or width of 5 μm or less is finely and uniformly dispersed in the matrix at intervals of 5 μm or less. 3. The contact material for a vacuum valve according to claim 1, wherein the contact material for a vacuum valve according to claim 1 or 2, wherein the highly conductive components occupy at least 40% by area of the total weight of the highly conductive components. (4) Highly conductive components consisting of Ag and Cu, Ti, and Z
An Ag-Cu-metal carbide contact material for a vacuum valve, comprising an arc-resistant component made of one of metal carbides selected from the group of r, V, Nb, and Ta, the highly conductive component being The total content of Ag and Cu (Ag+Cu) is
When the arc-resistant component is TiC, it is 50 to 80% by weight.
, 40-80% by weight for ZrC, 50-80% by weight for VC, and 40-80% by weight for NbC.
, and TaC are in the range of 25 to 65% by weight, and the ratio of Ag in the total weight of Ag and Cu [Ag/(Ag+Cu)] is 40 to 80% by weight, and the contact point The structure of the material consists of a matrix of the highly conductive component and a discontinuous phase with a thickness or width of 5 μm or less, and discontinuous grains of the arc-resistant component with a thickness of 10 μm or less, and the discontinuous phase of the highly conductive component is finely and uniformly dispersed in the matrix at intervals of 5 μm or less.