JP2695939B2 - Contact material for vacuum valve - Google Patents

Description

Description of the Invention [Object of the Invention] (Industrial application field) The present invention relates to a sintered alloy used for a contact material of a vacuum valve. The present invention relates to a vacuum valve contact material having improved wear characteristics.

(Prior Art) The contacts of a vacuum valve that performs a large current interruption or a rated current switching in a high vacuum by utilizing arc diffusivity in a vacuum are composed of two opposed fixed and movable contacts. .

Characteristics required for such a contact for a vacuum valve include: (1) good welding resistance against current interruption or switching; (2) good interruption characteristics; and (3) withstand voltage characteristics. Good thing is. These have been emphasized as the three most basic requirements, research on new alloy systems, research on electrode structures,
A variety of studies have been made, including research on mechanisms, and dramatic progress has been made on these three basic requirements.

On the other hand, in recent years, with the severer use conditions of consumers,
Diversification of the load is in progress. As a result, a vacuum pulp is required that can maintain the above three basic requirements at a certain level and further emphasize other characteristics (load requirements such as applied circuits and devices). Although there are many such cases in recent years, the current situation is to apply a valve one rank higher from a series of vacuum valves of standard specifications. As a result, the system becomes larger and the economy is lost. For example, as described above, there are many demands for ensuring the contact resistance and wear resistance while securing the three basic requirements as described above.

As a contact material that satisfies the above three basic requirements, a Cu-Bi alloy containing a welding prevention component such as Bi in an amount of 5% by weight (hereinafter referred to as wt%) or less is known (Japanese Patent Publication No. Sho 41). -1213
No. 1). This Cu-Bi-based contact is excellent in large current interrupting characteristics because brittle Bi is present at a crystal grain boundary, thereby embrittlement of the alloy itself and realization of a low welding trip force.

On the other hand, a vacuum valve using a contact of an alloy in which WC and Ag are combined has been developed (Japanese Patent Application No. 42-63447, U.S. Pat.
No. 3138), which has been put to practical use. The Ag-WC contact exhibits excellent characteristics such as arc resistance and welding resistance due to the contribution of the high melting point and high hardness of WC.

Further, Japanese Patent Application Laid-Open No. 53-35174 discloses a Cu-WC-Bi-W alloy in which the welding resistance of the above-mentioned sintered alloy is further improved.

(Problems to be Solved by the Invention) It is important for a vacuum valve contact material to be compatible with the above three basic requirements and other requirements (contact resistance and wear resistance) emphasized by customers. Has become.

However, since some of these requirements have conflicting relationships, it is impossible to satisfy all the requirements with a single metallic material. For this reason, in many practical contact materials, two or more types of elements that can mutually compensate for the insufficient performance are combined, and a contact suitable for a specific application such as for a large current or a high voltage is used. Materials have been developed, and materials having excellent properties have been developed. However, a contact material for a vacuum valve that sufficiently satisfies the demand for higher reliability has not yet been obtained.

That is, although the high melting point component is advantageous for the arc resistance related to wear, the high melting point material generally has high hardness characteristics, so that the contact area of the contact portion is small, and the contact resistance value is maintained at a low level. Is disadvantageous.

In the Cu-Bi-based contact material described above, the welding resistance is ensured by utilizing the fragility of the material, so that not only has a fatal defect in wear resistance, but also the surface roughness due to current interruption or switching. As a result, the contact resistance characteristics vary greatly.

In the case of the Ag-WC contact material, Ag selectively evaporates relatively early with the passage of current interruption or the number of switching operations,
A portion where Ag does not exist locally occurs and the contact resistance increases and varies. Further, this causes an increase in contact wear.

On the other hand, in Cu-WC-Bi-W contact materials, the improvement of the welding resistance of Cu-W contacts has been measured by the synergistic effect of WC and the presence of Bi in particular. There is still variation in wear characteristics.

The present invention has been made based on the above-mentioned background, and an object of the present invention is to stabilize contact resistance characteristics and maintain and improve wear resistance characteristics while maintaining the above three basic requirements at a constant level. It is another object of the present invention to provide a contact material for a vacuum valve which can be secured at the same time and can respond to increasingly severe requirements.

[Constitution of the Invention] (Means for solving the problem) As a result of research and development for solving the above problem, the present inventors have found that a conductive component made of Ag or / and Cu and W
For contact materials consisting of arc resistant components such as Bi and welding resistant components such as Bi, the content of Ag and Cu, the particle size distribution of arc resistant components, and the use of welding resistant components For example, the inventor found that the present invention is effective for achieving the object of the present invention, and completed the present invention.

That is, the contact material for a vacuum valve of the present invention is 20 to 50 wt.
% Of conductive component consisting of Ag and / or Cu and 50-80 wt%
Of at least one of W, Mo, WC and Mo ₂ C, and Bi, Pb, Sb of less than 0.5 wt% or Te, Se of less than 2 wt%
And a welding-resistant component comprising at least one of the following:
The particle diameter of the arc-resistant component is in the range of 0.1 to 5 μm, and among these particle diameters, particles in the range of 1 to 5 μm are 20 to 50 wt.
%, Particles in the range of 0.3-1 μm are 40-70 wt%, 0.3 μm
m or less in a range of 5 to 40 wt%, the size of the arc resistant component is suppressed to 5 μm or less, and the welding resistant component and the arc resistant component are dissolved in the conductive component. The point is that they exist independently of each other.

In a preferred embodiment of the present invention, the contact material for a vacuum valve having the above structure further comprises a C particle having a particle size of 5 μm or less.
Contains 1 wt% or less (excluding zero) of a correction component composed of at least one of o, Ni, and Fe.

(Operation) In order to improve the contact resistance characteristics, in addition to maintaining the contact resistance value itself of the contact at a lower value, it is also extremely important to reduce the variation width thereof. Conventionally, to stabilize the contact resistance described above, the contact force given to the contact and the total amount of the conductive components (Ag, Cu) of the contact material itself have been focused on, and if necessary, the particle size of the arc resistant component has been adjusted. Stabilization has been achieved by measures such as adjusting to a predetermined value.

However, according to the findings of the present inventors, the technical measures conventionally performed as described above are insufficient for maintaining the contact resistance itself at a low value and further reducing the variation width. Simply making the particle size of the active component fine and uniform within the predetermined range as described above does not provide good results in the contact material of the present invention for the purpose of solving the above-mentioned problems. In particular, it is completely unsatisfactory to stabilize the contact resistance characteristics while exhibiting an arc-resistant function when interrupting or opening / closing a current.

That is, differences in surface damage due to arcs during current interruption or switching (for example, surface roughness due to surface irregularities, local melting, scattering of particles, etc.) depend on the amount of arc-resistant components and the state (degree of segregation, particle size, etc.). The method in which the particle size of the arc-resistant component is fine and uniform depends on the method described above, and the variation width of the wear value is small, and as a result, the variation width of the contact resistance value is also small, which is preferable. However, in recent years, the capacity of a vacuum valve has been increased to increase the voltage and the current, and in diversification of loads, application to, for example, a capacitor circuit has been performed. Under such conditions, when a vacuum valve using a contact that merely makes the particle size distribution of the arc resistant component fine and uniform is applied to the above-mentioned capacitor circuit, particularly, the abnormal wear phenomenon and the contact resistance value. Significant outliers occur. The cause is that when the arc concentrates on a local part of the contact surface, the arc resistance component is evenly distributed, so the apparent arc resistance is inferior, the selective scattering of the highly conductive components made of Cu and Ag, It is seen that melting and accompanying irregularities are promoted, which is considered to be the cause.

As described above, particularly in the case of intense arc concentration such as application to a capacitor circuit, if the particle size of the arc-resistant component is fine and uniform, there is a problem in the resistance to the arc. It also has an adverse effect on contact resistance characteristics. Therefore, it is better to disperse the particle size of the arc-resistant component having a high arc-resistant function to some extent within a predetermined range in order to simultaneously secure the stabilization of the contact resistance characteristics and the improvement of the wear-resistant characteristics. Things.

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

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

In FIG. 1, a shut-off chamber 1 includes an insulating container 2 formed of an insulating material in a substantially cylindrical shape, and sealing fittings 3 at both ends thereof.
A metallic cover 4a, 4b provided via a, 3b is formed in a vacuum-tight manner.

A pair of electrodes 7 and 8 attached to opposing ends of the conductive rods 5 and 6 are disposed in the cut-off chamber 1. The upper electrode 7 is a fixed electrode and the lower electrode 8 is a movable electrode. . A bellows 9 is attached to the electrode rod 6 of the electrode 8 to enable the electrode 8 to move in the axial direction while keeping the inside of the shut-off chamber 1 vacuum-tight. A metal arc shield 10 is provided on the bellows 9 to prevent the bellows 9 from being covered with the arc vapor. In addition, poles 7 and 8
A metallic arc shield 11 is provided in the shut-off chamber 1 so as to cover the insulating container 2, thereby preventing the insulating container 2 from being covered with the arc vapor. Further, the electrode 8 is fixed to the conductive rod 6 by a brazing portion 12 as shown in an enlarged manner in FIG. Contact 13a
Is attached to the electrode 8 by brazing. In addition, contact
13b is attached to the electrode 7 by brazing.

Next, an example of a method for manufacturing the contact material will be described. Prior to production, the arc resistant components and auxiliary components are classified according to the required particle size. The classification operation is performed by using, for example, a sieving method and a sedimentation method in combination to easily obtain a powder having a predetermined particle size. First, an arc resistant component having a predetermined particle size, for example, a predetermined amount of WC and a predetermined amount of Ag and / or CU having a predetermined particle size are prepared, mixed, and then pressed to form a powder compact. obtain.

Next, the powder compact is pre-sintered at a predetermined temperature, for example, 1150 ° C. × 1 hour, in a hydrogen atmosphere having a dew point of −50 ° C. or less or a degree of vacuum of 1.3 × 10 ⁻¹ Pa or less. obtain.

Next, a predetermined amount and a predetermined ratio of Ag-Cu are infiltrated into the remaining pores of the temporary sintered body at 1150 ° C for 1 hour to obtain an Ag-Cu-WC alloy. The infiltration is performed mainly in a vacuum, but is also possible in hydrogen.

The same applies to Ag-Cu-WC in which the auxiliary component Co is blended. WC is preliminarily mixed with either or both of Ag and Cu to obtain a temporarily sintered body.

The ratio of the conductive component in the alloy [Ag / (Ag + Cu)]
Was controlled as follows. For example, an ingot having a predetermined ratio [Ag / (Ag + Cu)] is set to a temperature of 1200.
Vacuum melting was carried out at a temperature of 1.3 ° C. and a degree of vacuum of 1.3 × 10 ⁻² Pa. Ratio of conductive component [Ag / (Ag + C
Another method of controlling u)] is to prepare a pre-sintered body by mixing a predetermined amount in WC in advance and then infiltrating the remaining Ag or (Ag + Cu). A contact alloy having a composition can be obtained.

Next, an evaluation method and evaluation conditions for obtaining specific example data described below will be described.

The contact material was processed to a diameter of 20 mm, and the surface was polished with paper. After polishing, the contact resistance was measured. The measurement conditions of the contact resistance were such that a direct current of 10 A was passed, the voltage drop at the contact portion was measured, and the measured value was regarded as the contact resistance. After measuring the contact resistance, the mass of the contact was measured and placed in a vacuum demountable chamber. The current was opened and closed after the degree of vacuum in the vacuum demountable chamber became higher than 10 ⁻³ Pa. Current value when switching current is 10
It was set to 0A10Hz. The polarity of the current was fixed so that the movable side became the cathode. In addition, the arc time was fixed at about 45 ms.

After switching the current 100 times, the contacts were taken out of the vacuum demountable chamber and the mass was measured. The mass change before and after the current switching (the cathode side at the time of the current switching) was determined to calculate the consumption amount. Further, the contact resistance was measured by the method described above, and the rate of increase was calculated based on the difference in the contact resistance before and after the current switching.

Contents of Test Contact FIGS. 3 to 5 show the material contents of the test contact and the corresponding characteristic data together with comparative examples. As shown in the table, while changing the amount of the conductive component in the alloy in the range of 12.0 wt% to 81.2 wt%, the particle size distribution of the arc resistant component in the alloy was 5 μm or more, 1 to 5 μm, 0.3 to Alloys were classified into classes of 1 μm and 0.3 μm or less, and these were blended in predetermined amounts, respectively, to prepare alloys.

In addition, also about the auxiliary component added to an alloy, the alloy was prepared, respectively, in the case of no auxiliary component and in the case of Fe, Co, and Ni. In addition, for the welding resistance component added to the alloy, the same and the case of Bi, Pb, Te, Se, Sb,
Each alloy was prepared and its amount was varied in the range of 0.1-6%.

Examples 1 to 3 and Comparative Examples 1 and 2 As an arc-resistant component, W having a particle size of 5 μm or more was removed.
A mixed powder having a ratio of 30:60:10 by weight is prepared by classifying the powder into three stages of ５5 μm, 0.3-1 μm, and 0.3 μm or less. The molding is performed while appropriately selecting the molding pressure in the range of zero to 8 ton / cm ² so as to adjust the amount of residual voids after sintering. In this case, Example 3 having a large amount of Cu in the alloy (Cu =
50.0 wt%) and Comparative Example 2 (Cu = 81.2 wt%) employ a method in which the molding pressure is particularly reduced, or a mixed powder in which a part of Cu is mixed with W in advance is molded. After molding these mixed powders, in Example 1 and Comparative Example 1, for example, 11
Sintering is performed at 00 to 1300 ° C. to obtain a W sintered body. Examples 2-3,
In Comparative Example 2, a sintered body is obtained by sintering at a lower sintering temperature. In this way, in the voids of the sintered bodies having different void amounts,
Cu infiltration and finally the amount of Cu in the Cu-WC alloy is 12.0 to 81.2
An alloy of wt% (Comparative Examples 1-2, Examples 1-3) is obtained.

In addition, Bi selected as a welding-resistant component, a Cu-Bi alloy is produced, a method of infiltrating Cu-Bi and a method of mixing in a W skeleton and infiltrating Cu into a W-Bi skeleton are appropriately selected. An alloy containing about 0.2% Bi was obtained.

As described above, the evaluation of the contact resistance characteristics is performed by comparing the value measured for the contact surface in the machined state, 100 A, and the value measured after 100 times opening and closing, and obtaining the weight difference before and after the predetermined opening and closing to obtain wear resistance. Were compared.

As shown in Comparative Examples 1 and 2 and Examples 1 to 3 in the table of FIG. 3, the contact resistance characteristics decrease before the opening and closing when the Cu content in the alloy increases, and tend to depend on the Cu content. However, in the contact resistance characteristics after opening and closing a predetermined number of times, when the amount of Cu is small and the content is 12 wt% (Comparative Example 1), the contact resistance characteristics are high even though the wear resistance is low and stable, and variations are observed. . This is considered to be the effect of residual W due to the remarkable selective evaporation of copper.

On the other hand, when the amount of Cu in the alloy was 81.2 wt% (Comparative Example 2), the wear resistance was large, the contact surface was highly uneven, and the contact resistance was unfavorably affected. Therefore, as an advantageous contact material for achieving both wear resistance and contact resistance characteristics, the amount of the conductive component (in this case, Cu) in the material is 20 wt% to 50 wt%.
% (Examples 1 to 3) is preferable.

Examples 4 to 6 and Comparative Examples 3 to 9 The particle size distribution of the arc resistant component in the alloy was classified into four stages as described above.

W is a representative of the arc resistant component, the particle size distribution is 1 to 5 μm,
When the thickness is 5 μm or more (Comparative Example 3), the contact resistance after opening and closing significantly increases, and the consumption is large.

Such a tendency is also observed in Comparative Examples 4 to 9 in which the particle size distribution of the arc-resistant component is not blended in a predetermined range in a well-balanced manner, whereas the particle size distribution of the arc-resistant component is in the range of 1 to 5 μm. Is in the range of 20 to 50% by weight and 0.3 to 1 μm.
In Examples 4 to 6 in which の も の 70 wt% and 0.3 μm or less are present in 5 to 40 wt%, and those in the three ranges coexist at the same time, the wear resistance and the contact resistance characteristics are compatible in a favorable state. When three of the above particle size ranges do not coexist and any two of them have no compatibility between wear resistance and contact resistance characteristics (Comparative Examples 7 to 7).
9). That is, even if the distribution of the arc-resistant components classified into the above three satisfies any two, for example, those having a particle size of 1 to 5 μm
65 wt% (Comparative Example 6), 90 wt% with a particle size of 0.3-1 μm
% (Comparative Example 4), with a particle size of 0.3 μm or less being 60 wt%
In the case of (Comparative Example 5), both characteristics are not compatible.

Therefore, in order to achieve both contact resistance characteristics and wear resistance, at least the particle size distribution of the arc resistant component in the contact alloy is classified into the three stages described above, and these are mixed in an amount within a predetermined range. It is necessary to be.

Examples 7 to 12 and Comparative Example 10 In Examples 1 to 6 and Comparative Examples 1 to 9, the amount of Bi present in the contact material was about 0.2 wt%, but Bi is limited to this value. Neither is necessary, and up to the contact point containing 0.5 wt% (Example 8), both characteristics can be obtained. However, when the amount of Bi is 3.5 wt% (Comparative Example 10), remarkable deterioration of characteristics in terms of wear resistance is observed, and therefore, it is excluded.

At a lower Bi content of 0.1 wt% (Example 7), both characteristics are extremely stable. Further, the desired effect of the present embodiment can be obtained even when the amount of Bi is zero (Examples 9 to 12).

Examples 13 to 24, Comparative Examples 11 to 12 Although the above-mentioned welding resistance component was an example in which Bi or not used at all, other components Pb (Example 13), Sb (Example 14), Te
(Example 15) and Se (Example 16) have the same effect as long as the particle size distribution of the arc-resistant component is within a predetermined range.

In addition, the conductive component may be Ag (Examples 13 to 14) other than Cu, or Ag-Cu alloy (Example 24) if the particle size distribution of the arc resistant component is within the above-described predetermined range. Similar effects are obtained. As described above, in the case of Te and Se as welding resistance components, when 6 wt% is present (Comparative Examples 11 and 12), the wear resistance is significantly deteriorated. For this reason, it is out of the purpose of achieving both the wear resistance and the contact resistance characteristics, and when the welding resistance component is Te or Se, the alloy of the present embodiment is applied to an alloy having a limit of 2 wt% (Examples 15 to 16). Shall apply.

The type of the arc resistant component is mainly W in Examples 1 to 9 and Comparative Examples 1 to 10, but other types of the arc resistant component are WC, Mo ₂ C, Mo, and WC-Mo _2. Even if C is used, the same effect is obtained if the particle size distribution of the arc-resistant component is within the above-mentioned predetermined range.

On the other hand, the presence or absence of the auxiliary component in the alloy, the difference in type is not particularly affected, and the same effect can be obtained if the particle size distribution of the arc resistant component is within the above-described predetermined range as described above. I have.

As in the above-described embodiments, in a contact material composed of an arc-resistant component such as W and Mo, a conductive component such as Cu and Ag, and a welding-resistant component such as Bi if necessary, Ag or / And the total amount of Cu is 20 to 50 wt%, and the particle size distribution of the arc resistant component is divided into three stages of 1 to 5 μm, 0.3 to 1 μm, and 0.3 μm or less, and these are respectively 20 to 50% and 40 to 70% , 5 to 40%, so that the compatibility between the contact resistance characteristic and the wear resistance characteristic, which have become problems in recent years with the expansion of the application range of the vacuum circuit breaker and the severer use conditions, have been achieved. It is possible to sufficiently cope with the issue of the demand for sex.

[Effects of the Invention] As described above in detail, the present invention has the following effects. That is, stabilization of contact resistance characteristics and maintenance and improvement of wear resistance characteristics can be simultaneously secured, and a contact material for a vacuum valve having even higher reliability can be provided.

[Brief description of the drawings]

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

Continuing from the front page (72) Inventor Mitaka Honma 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant Co., Ltd. 56) References JP-A-62-77439 (JP, A) JP-B-51-12818 (JP, B1)

Claims (2)

(57) [Claims] 1. An electroconductive component comprising 20 to 50% by weight of Ag and / or Cu, and an arc resistant component comprising 50 to 80% by weight of at least one of W, Mo, WC and Mo ₂ C, 0.5% by weight or less Bi, P
A contact material for a vacuum valve, comprising b, Sb, or a welding-resistant component comprising at least one of Te and Se of 2% by weight or less, wherein the particle size of the arc-resistant component is in a range of 0.1 to 5 μm. In
Among the particle diameters, particles in the range of 1 to 5 μm are 20 to
50% by weight, particles in the range of 0.3 to 1 μm are mixed in a ratio of 40 to 70% by weight, and particles in the range of 0.3 μm or less are mixed in a ratio of 5 to 40% by weight, and the size of the arc-resistant component is 5 μm or less. A contact material for a vacuum valve, wherein the welding-resistant component and the arc-resistant component are present independently of the conductive component without being dissolved in the conductive component. 2. A vacuum according to claim 1, wherein said auxiliary component comprises at least 1% by weight (excluding zero) of an auxiliary component comprising at least one of Co, Ni and Fe having a particle size of 5 μm or less. Contact material for valves.