JPH11269579A - Silver-tungsten/wc base sintered type electric contact material and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simply obtain a low contact resistance material composition excellent in deposition resistance and wearing resistance at a low cost by sintering mixed powder containing W or WC as an arcing resistant component. Ag as a high electric conductive component and a P-containing sintering-assistant to obtain a specified composition. SOLUTION: The mixed powder containing Ag and W or WC and the P- containing sintering assistant is press-molded into a desired shape and this green component is sintered in a reducing atmosphere at the m.p. of Ag or lower. As the P-containing sintering assistant, it is desirable to use a phosphorus alloy or a phosphorus oxide of Fe-P base, Ni-P base, Co-P base, Cu-P base, or the like. In this way, a sintered material containing 9-90 wt.% Ag, 9-90 wt.% W or WC, 0.01-1.0 wt.% P and, if necessary, <=25 wt.% of one or more kinds among Fe, Ni, Co and Cu is obtained. This sintered material consisting essentially of W or WC as an arcing resistant component and Ag as a high electric conductive component is obtd. by promoting the sintering with the P-containing sintering assistant to be used for an electric contact material having low contact resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sintered electrical contact material containing Ag-W, and more particularly to an electrical contact material used in a medium-to-large current load region.

[0002]

2. Description of the Related Art Conventionally, electric contact materials are used for wiring breakers, such as wiring breakers, electromagnetic contactors, switches, relays, and the like. Among them, the contact material for a large current region is an Ag-W system, which is used in a medium load current region (several tens to several hundreds).
In A), an Ag-WC-based material was used. Ag-
For a contact material obtained by simply forming a W-based or Ag-WC-based material by sintering, it is difficult to densify by sintering, and the contact resistance cannot be kept low. As an improvement, A
It has been known to use a g-WC-C system as a fixed contact. This Ag-WC-C type contact material is a sintered type for sintering Ag, WC and graphite, and since graphite is soft, sintering is relatively easy. At the time of occurrence, the reduction action by graphite gasification suppresses the oxidation of W during the contact arc,
It is used practically because the contact resistance can be kept low (for example, Japanese Patent Publication No. 49-30434).

In the production of conventional Ag-W and Ag-WC contact materials, an infiltration method is used to reduce contact resistance and to maintain the strength and arc resistance of the contact material. I was In this method, Ag and W powders are pressed and formed into a molded body having a desired shape.
By heating in the range of 60 to 1300 ° C., a melt of Ag is formed around the W or WC particles in the molded body and penetrates into the voids, and a small amount of the insufficient Ag melt is formed at substantially the same temperature. Infiltration in addition to the body, infiltration and densification to produce electrical contact materials. Ag-W / W by this infiltration method
The C-based contact material has excellent arc resistance and strength and is used as an electrical contact in the middle current region. In particular, it is movable with respect to the Ag-WC-C (graphite) -based fixed contact. It was used as a side contact.

[0004]

However, the Ag-WC-C based contact material obtained by the above sintering is soft in strength and has a problem in life when used for a contact on the movable side. In addition, the contact material obtained by the infiltration method requires an infiltration process. In this process, Ag is infiltrated into the voids of the molded body, and then surface treatment is performed by removing excess Ag on the surface of the molded body. Post-processing was required, which required a large number of manufacturing steps and increased costs.

[0005] From such a fact, Ag-W system or Ag-W
In the WC system, a low-cost construction method such as non-working by the shape and Ag infiltration method has been proposed and put to practical use. However, although the contact material was slightly reduced in cost by reducing the number of processes, it was not drastically improved. An Ag-oxide contact material has been proposed and put into practical use as a low-cost material in place of this. This material generally has a rated current of 100
Although it is used for a circuit breaker of A or less, the welding resistance is not good at a rated current of 225 A or more, and the contact resistance increases.

An object of the present invention is to provide an electrical contact material which is excellent in welding resistance and wear resistance and has low contact resistance by sintering an Ag-W or Ag-WC system.
Another object of the present invention is to provide a method for easily and inexpensively producing an Ag-W or Ag-WC electric contact material by sintering.

[0007]

According to the present invention, sintering is promoted by a sintering aid containing P as a main component and containing W or WC as an arc resistant component and Ag as a highly conductive component. In this case, the electrical contact material having low contact resistance is formed by using the dense sintered body.

The electrical contact material of the present invention has a structure in which W or WC of solid particles are dispersed in an Ag matrix,
The P component in the P-containing sintering aid enhances the wettability and reactivity of the surface of the W or WC particles, promotes the sintering between the W particles and the transfer of Ag between the W particles, The purpose is to make the skeleton more rigid, thereby improving hardness and electrical conductivity. The contact material of the present invention contains Ag and W or WC and P, and in order to promote the sintering property, 0.01% or less by weight% or less.
Contains 1.0% or less of a P component, thereby reducing the contact resistance of the contact as a dense sintered structure.

The method for producing an electrical contact material according to the present invention comprises the steps of:
From a mixed powder containing WC and W or WC and a P-containing sintering aid into a required compact, and then sintering the compact by heating it to a temperature equal to or lower than the melting point of Ag in a reducing atmosphere. , Electrical contact material.

Thus, the electrical contact material of the present invention is made of Ag
Low cost with improved density ratio, hardness, and electrical conductivity even in sintering below the melting point, and having electrical contact performance (welding resistance, wear resistance, low contact resistance) equivalent to conventional infiltration contact materials It is possible to provide a simple electrical contact material. In addition, since the method for producing an electrical contact material of the present invention includes a P sintering aid, sintering is promoted, the density ratio, hardness, and conductivity of the contact are improved, and the same as a conventional infiltrated contact material. The electrical contact material having the electrical contact performance (welding resistance, wear resistance, low contact resistance) of the present invention can be provided at low cost.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION
And 9 to 90% of Ag and 9 to 90% of W or its carbide.
And a sintered electric contact material composition containing 0.01 to 1.0% of P. The composition range of Ag and W or WC is
Preferably, each is 29 to 70% (% by weight, the same applies hereinafter).
In particular, in order to obtain a soft and highly conductive contact material, a large amount of Ag is contained, and W or its carbide is relatively reduced. On the other hand, in order to increase the arc resistance, it is better to lower the Ag content and increase the W or WC content. It is appropriately selected depending on the use of the contact and the current capacity of the circuit to be cut off.

P is a sintering promoting component, and the surface oxide of W or WC is reduced by the reducing action of P at the time of sintering, and the activated W or WC particles strengthen the interparticle bond. It improves the electrical performance. In the present invention, the content of P in the contact material composition is 0.01 to
A range of 1.0% (% by weight, hereinafter the same) is used.

If the P content is less than 0.01%, the effect of promoting sintering cannot be sufficiently obtained. On the other hand, if the P content exceeds 1.0%, the electrical conductivity decreases, and the contact material becomes brittle due to the P content. Usually, the contact material is brazed to a specific contact support member and used as a contact. However, if the P content is large, cracks are likely to occur in the brazed portion due to the impact of repeated opening and closing operations. In this respect, the P content is particularly preferably 0.03 to 0.7%.

The composition of the present invention contains 25% by weight
Also included are those containing one or more selected from the following Fe, Co, Ni and Cu. These transition metals are used as arc-resistant components similarly to W or WC, and are added as necessary. Further, these transition metals may be metals added from a later-described P alloy as a sintering aid. .

The contact material of the present invention is a sintered body formed by sintering Ag and W or WC and a P-containing sintering aid. The significance of this sintering is that the compact of the mixed powder of the metal Ag and the metal W or the carbide WC thereof and the P-containing sintering aid is heated at a sintering temperature lower than the melting point of Ag and sintered in a solid Ag state. Say that you will be tied. However, the P-containing sintering aid itself may be melted if it is sintered in the state of solid Ag.

The P-containing sintering aid used for the contact material may be any one that can promote sintering in the compact at the above-mentioned sintering temperature. For example, phosphorus alone, preferably phosphorus Oxide and phosphorus alloy are good. As a P-containing sintering aid,
In particular, a phosphorus alloy is preferred because phosphorus can be prevented from being scattered and evaporated during sintering and can be easily added to and mixed with the compact, and a phosphorus alloy or a phosphorus compound of a transition metal is particularly preferred. For example,
Alloys such as Fe-P, Ni-P or Co-P and Cu-P can be used.

These alloys are pulverized and uniformly mixed with the mixed raw material. In particular, for the Ni-P-based, Co-P-based, and Cu-P-based alloys, for example, water atomized powder is preferably used. The Fe-P-based alloy may be a pulverized powder. These phosphorus alloys have, for example, a P content of 1 to 40.
% Material can be selected. In particular, a Ni-P alloy having a P content of 1 to 7% is preferably used.

As the oxide of phosphorus, for example, P ₂ O ₅ (phosphorus pentoxide or phosphorus tetroxide) can be used. Since the oxide of phosphorus contains no other metal components, Ag and W
Alternatively, it can be preferably used as an electrical contact material containing no metal other than WC.

In the method for producing an electrical contact material of the present invention, a mixed powder containing Ag and W or WC and the above-mentioned P-containing sintering aid is prepared. Although the form of the mixed powder is not particularly limited, usually, the Ag powder and the W or WC powder are prepared in advance to a desired particle size and mixed with the P-containing sintering aid. Alternatively, as the mixed powder, a composite particle in which Ag is previously plated, deposited, or otherwise attached to the surface of W or WC particles having a required particle size can be used.

From the above mixed powder, a compact having a required shape as an electric contact is formed by pressure. For the compression molding of the mixed powder, compression molding using a mold by a press molding machine or the like can be used. Next, the molded body is placed in a heating furnace such as an electric furnace, and then Ag
Is heated to a temperature equal to or lower than the melting point of sintering and allowed to cool. The atmosphere during sintering needs to be reducible so as not to oxidize W or WC, and an atmosphere of CO gas or H ₂ gas is used. In particular, sintering is preferably performed in a hydrogen atmosphere or a hydrogen stream.

The sintering temperature is such that the melting point of Ag is 960 ° C. or less and the sintering is easy, for example, it is preferably in the range of 700 to 950 ° C., and particularly preferably in the range of 850 to 930 ° C. to promote sintering. . By sintering at a temperature equal to or lower than the melting point of Ag, sintering proceeds in the presence of a P-containing sintering aid while maintaining the shape at the time of pressure molding, and the porosity of the sintered body is reduced. And a dense structure can be obtained.

The method for producing an electrical contact material by sintering according to the present invention has almost the same welding resistance as Ag-W and Ag-WC contact materials infiltrated at the Ag melting point or higher. Contact material having electrical performance of wear resistance and low contact resistance can be manufactured, and there is no excess Ag after sintering.
Since the molding accuracy is relatively high, post-processing for removing excess Ag is not required. Therefore, it is possible to improve the yield of the raw material silver, reduce the number of processes and simplify the sintering process, and reduce the manufacturing cost. Can be.

[0023]

(Example 1) In a mixed powder in which W and a highly conductive component Ag were mixed in equal amounts as arc resistant components, P was added so that the P component became 0.15% P in the whole sintered body. The contained sintering aid was added and mixed. The compounded powder mixture was compression-molded in a mold with a pressing machine at a molding pressure of 6 t / cm ² to have a length of 8 mm.
mm, a width of 8 mm and a thickness of 2 mm were formed into a pressure-formed body.
Next, a sample of this pressed compact was placed in an electric heating furnace at a temperature of 900 ° C. or lower, which was equal to or lower than the melting point of Ag (960 ° C.) in a hydrogen atmosphere.
Heated for 0.5 hour and sintered.

The type of the P-containing sintering aid is changed,
Ni-P alloy (P content 5%, water atomized powder), Fe
-P alloy (P content 18%, pulverized fine powder), Cu-P alloy (P content 8.3%, water atomized powder), P ₂ O ₅ (P
Content 50%, reagent). Before and after sintering
The dimensional shrinkage and density ratio during sintering were measured, and the hardness (H
RB) and conductivity (% IACS). Table 1 shows the results
Shown in

[0025]

[Table 1]

As is clear from Table 1, an example (sample N) in which the P content was 0.15% by adding a P-containing sintering aid.
o. 1-4) have a high shrinkage of 3% or more, a theoretical density ratio of 88% or more, and an excellent electrical conductivity of 53% IACS or more. Comparative Example No. As compared with No. 5, sintering promotion was recognized. It can also be seen from this table that the addition of P increases the hardness HRB of the contact material. Furthermore, from this table, it can be seen that as a P-containing sintering aid, the Ni-P alloy has the greatest improvement in shrinkage, hardness, conductivity, and others. Therefore, in the following examples, Ni-P alloy was exclusively used.

Example 2 Ni-P as an arc resistant component W or WC and a highly conductive component Ag and P containing sintering aid
The alloy powder was mixed and similarly pressed using a 6 t / cm
Pressure molding at a molding pressure of ² and sintering this molded body in a reducing atmosphere at a temperature of 960 ° C. or less, length 8 mm, width 8 m
m, a sintered body having a thickness of 2 mm was obtained. Utilizing Ni-P (P content: 5%) alloy powder of the P-containing sintering aid described in Example 1 and changing the P content, dimensional shrinkage, density ratio, hardness, conductivity The rate was measured. Table 2 shows the results.

[0028]

[Table 2]

As is clear from Table 2, the example (sample N
o. 6 to 11) have a density ratio of 82% or more and a hardness of HRB
The effect of adding the P-containing sintering aid is 45 or more. On the other hand, in Comparative Examples (Nos. 12 and 13), when the P content was less than 0.01% with respect to the sintered body, the hardness was low and the effect of adding the P-containing sintering aid was sufficiently obtained. I can't. If the P content exceeds 1.0%, the conductivity decreases and the contact material becomes brittle due to the action of P, and cracks occur on the brazing surface.

Example 3 Ni-P as a sintering aid containing the arc resistant component W or WC and the highly conductive components Ag and P
Alloy powder (P concentration 5%) was mixed, and molding pressure was 6t /
The compact molded under pressure in cm ² is 900
C. to obtain a sintered body having a length of 8 mm, a width of 6 mm, and a thickness of 2 mm.

This was brazed to a base metal of the contact supporting member to form a movable contact, and the fixed contact was formed using a contact material of 85% Ag-2.2% by weight-remainder WC. This is attached to a magnetic contactor and AC20
The switching test was performed 3000 times with a circuit of 0 V, 100 A, and a power factor of 0.52%. Table 3 shows the results of measuring the consumption and contact resistance at that time.

[0032]

[Table 3]

In the circuit breaker for wiring, Comparative Example No. The contact infiltrated with the composition No. 24 was used in a general manner in combination with the movable-side contact using the Ag-graphite-WC system described above as the fixed-side contact.

As apparent from Table 3, the examples (sample N
o. Nos. 15 to 21) are contact materials sintered at a temperature equal to or lower than the Ag melting point. However, the contact consumption and the contact resistance are comparable to those of infiltration type (infiltration type) Ag-W type contacts (sample No. 24). Performance was obtained. On the other hand, in the comparative examples of P-free sintering (Sample Nos. 22 and 23), both the amount of consumption and the contact resistance increased, and the electrical contact performance was remarkably lowered. In the short-circuit test, both Examples and Comparative Examples were able to shut off, and the welding resistance was good.

[0035]

As described above, the electrical contact material according to the present invention comprises a main component consisting of W or WC as an arc resistant component and Ag as a highly conductive component, a P-containing sintering aid, Since it is a sintered mold made by sintering, it is at least equivalent in performance to the commonly used Ag-W or Ag-WC infiltration contact material in welding resistance, wear resistance, and low contact resistance. It is suitable as an electrical contact material for circuit breakers, switches and the like, and can be used particularly as a low-cost contact material.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI C22C 27/04 101 C22C 27/04 101 29/08 29/08 H01H 1/02 H01H 1/02 A F 11/04 11/04 C (72) Inventor Kazuhiro Masano 12-32 Taiseicho, Neyagawa-shi, Osaka Japan Science Metallurgy Co., Ltd.

Claims (14)

[Claims] 1. A sintered electrical contact material composition comprising 9 to 90% by weight of Ag, 9 to 90% of W or WC, and 0.01 to 1.0% of P by weight%. 2. The composition according to claim 1, wherein the composition has a F content of not more than 25% by weight.
3. The electrical contact material composition according to claim 2, comprising at least one selected from the group consisting of e, Ni, Co and Cu. 3. An arc resistant component comprising W or WC.
And Ag as a highly conductive component, and a P-containing sintering aid, and a sintered electrical contact material obtained by sintering. 4. The electrical contact material according to claim 3, wherein the P-containing sintering aid is a phosphorus alloy. 5. The phosphorous alloy according to claim 1, wherein the phosphorus alloy is Fe-P, Ni-P,
5. A Co-P alloy or a Cu-P alloy.
An electrical contact material according to claim 1. 6. The electrical contact material according to claim 3, wherein said P-containing sintering aid is an oxide of phosphorus. 7. The method according to claim 1, wherein the electric contact material is 0.0% by weight.
The electrical contact material according to claim 3, containing 1 to 1.0% P. 8. A mixed powder containing Ag and W or WC and a P-containing sintering aid is press-formed into a desired shape, and then the compact is heated to a temperature lower than the melting point of Ag in a reducing atmosphere. Manufacturing method of electrical contact material to be sintered. 9. The method according to claim 8, wherein the sintering is performed in a hydrogen atmosphere.
The production method described in 1. 10. In the above-mentioned molded product, 0.01% by weight.
The production method according to claim 8, which contains 1.0 to 1.0% of P. 11. The electrical contact material according to claim 8, wherein the P-containing sintering aid is a phosphorus alloy. 12. The phosphorous alloy is made of an Fe—P system, Ni—P
9. An alloy, a Co-P alloy or a Cu-P alloy.
12. The electrical contact material according to any one of claims 11 to 11. 13. The electric contact material according to claim 8, wherein the P-containing sintering aid is an oxide of phosphorus. 14. The contact material according to claim 8, wherein said contact material contains 9 to 90% of Ag, 9 to 90% of W or WC, and 0.01 to 1.0% of P by weight%. A method for producing the electrical contact material according to any one of the above.