JPH10195556A - Manufacturing method of electrical contact material - Google Patents

Abstract

[57] [Problem] Silver, which can be plastically processed like other electrical contact materials, consumes a small amount in a light-load medium-current region, and is applicable to applications in a medium-load medium-current region. -To provide a method for producing a carbon-based electrical contact material. SOLUTION: A silver powder or a silver alloy powder and an average particle diameter of 0.1 or less are used.
A dry powdery mixture of 0.01 to 0.5% by weight of carbon fine powder having a particle size of 1 μm or less is compression-molded. Sintered in an atmosphere to form a sintered alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for producing a silver-carbon electrical contact material.

[0002]

2. Description of the Related Art In general, silver-carbon based electric contact materials are obtained by mixing silver powder and carbon powder having a particle size of several μm or more in a wet process, compressing the mixture, and sintering the obtained molded product. ,
Manufactured as a sintered alloy. In this manufacturing method, 0.1 to 5% by weight of nickel or 0.1 to 5% by weight of copper is sometimes added during mixing.
In some cases, nickel or copper is added to the obtained silver-carbon based electrical contact material by adding 1 to 15% by weight, but all electrical contact materials have excellent welding resistance and light load (contact force between contacts). About 10 to 70 g) and is widely used in a medium current region (about 20 to 50 amps). Regarding the method for producing this silver-carbon electrical contact material, the silver powder has an average particle size of 1%.
0.01 to 0.5% by weight of carbon fine powder having a particle size of less than μm is uniformly dispersed by wet mixing to improve the plastic workability of the obtained sintered alloy, thereby supplying the alloy wire rod to the header processing machine. A method for producing an electrical contact material that can be processed into a rivet has been proposed.

[0003] The silver-carbon based sintered alloy obtained by the proposed method has significantly improved wear resistance in a medium current region as compared with the silver-carbon based sintered alloy obtained by the above-mentioned general conventional manufacturing method. However, compared to other electrical contact materials such as silver-nickel alloy and silver-oxide alloy-based electrical contact materials, they consume much more and are not suitable for relays and switches that require long life. Was enough.

[0004]

SUMMARY OF THE INVENTION The object of the present invention is to achieve plastic working like other electrical contact materials, to reduce the amount of wear in a light-load medium-current region, and to achieve a medium-load (contact force of 70%).
It is an object of the present invention to provide a method for producing a silver-carbon based electric contact material which can be applied to applications in a medium current region.

[0005]

The object of the present invention is to provide a silver powder or a silver alloy powder having a mean particle size of 0.01 μm or less.
After compression-molding a dry mixed powder in which fine carbon powder is uniformly dispersed and containing 0.5% by weight of fine carbon powder, this molded product is sintered in a vacuum or in a reducing atmosphere to form a sintered alloy. The problem is solved by a method for producing an electrical contact material characterized by the following.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method of the present invention, first, a silver powder or a silver alloy powder and a carbon fine powder are dry-mixed to prepare a dry mixed powder in which the carbon fine powder is uniformly dispersed. This carbon fine powder has an average particle diameter of 0.1 μm or less, and is used in an amount of 0.01 to 0.5% by weight, preferably 0.1 to 0.3% by weight, based on the whole dry mixed powder. When the average particle size of the carbon fine powder exceeds 0.1 μm, the carbon powder tends to be consumed when used as a contact. On the other hand, if the amount of the carbon fine powder is less than 0.01% by weight, the welding resistance decreases, while if it exceeds 0.5% by weight, plastic working becomes difficult.

[0007] The mixing of the silver powder or silver alloy powder and the carbon fine powder is performed in a dry manner. Various known mixers can be used as the mixer. In addition, if the mixing is performed by a wet method, the carbon fine powder is aggregated, and a uniform dispersion state cannot be obtained.

In the present invention, the average particle size of the silver powder or silver alloy powder is preferably as small as possible, particularly preferably 10 μm or less. This is because, in the mixed system, the carbon fine powder adheres to the surface of the silver powder or the silver alloy powder to cause dispersion of the carbon fine powder, but the silver powder or the silver alloy powder is reduced due to the refinement of the average particle diameter. Is increased, and as a result, a more uniform dispersion state of the carbon fine powder is obtained.

When silver powder is used, Cu, Ni, P is added to the silver powder in order to strengthen the silver base in which the carbon fine powder is dispersed.
at least one selected from the group consisting of d, In and Sn
It is preferable to use a mixture of different metal powders. The amount of the metal powder to be used is 0.01 to 0.01 with respect to the whole dry mixed powder (in this case, the total amount of the silver powder, the carbon fine powder and the metal powder).
It is preferably 10% by weight, whereby the wear resistance of the obtained electrical contact material can be further improved. If the amount is less than 0.01% by weight, a sufficient strengthening effect cannot be obtained, while if it exceeds 10% by weight, the electrical conductivity of the electrical contact material tends to decrease and the workability tends to deteriorate. The type and more preferable content of the metal powder may be selected according to the use of the obtained electrical contact material. The average particle size of these reinforcing metal powders is preferably as small as possible for the same reason as in the case of silver powder or silver alloy powder, and particularly preferably 10 μm or less.

On the other hand, when a silver alloy powder is used, Cu and P are used as alloy components in order to strengthen the silver alloy base (silver).
at least one selected from the group consisting of d, In and Sn
Preferably, the alloy contains 0.05 to 10% by weight of the metal in the alloy. More preferred content of the metal element is
The total amount of the dry mixed powder, that is, in this case, the total amount of the silver alloy powder containing the metal element and the fine carbon powder is 0.05 to 0.05%.
10% by weight. If the content is less than 0.05% by weight, a sufficient strengthening effect cannot be obtained, while if it exceeds 10% by weight, the electrical conductivity of the electrical contact material tends to decrease or the workability tends to deteriorate. The kind and more preferable content of the metal component may be selected according to the use of the obtained electrical contact material.

When silver powder is used as a raw material, sintering causes alloying to proceed. However, since carbon acts to prevent diffusion, sintering takes longer than when silver alloy powder is used. In this regard, when a silver alloy powder is used as a raw material, the alloying is performed in advance, so that the time required for the alloying is saved, and there is an advantage that sintering can be completed in a shorter time than when the silver powder is used.

[0012] In addition, at least one of silver alloy powders selected from the group consisting of Ni, Co and Fe is used as an alloy component in order to prevent room temperature softening of the silver alloy base and to refine the crystal grains of the alloy. 0.01 to 0.5 of metal
%, Particularly preferably 0.1 to 0.3% by weight. More preferably, the content of the metal element is 0.01 to 0.5% by weight, especially 0% by weight, based on the total amount of the dry mixed powder, that is, the total amount of the silver alloy powder and the carbon fine powder containing the metal element. 0.1 to 0.3% by weight. If the content is less than 0.01% by weight, the effect of preventing room temperature softening cannot be obtained, while if it exceeds 0.5% by weight, the solid solution amount of these alloy components in the silver alloy base material is small, and the obtained electric power is low. They tend to be present as coarse particles in the contact material and reduce the welding resistance. In the case where these preventive metals are added and contained in powder form, desired effects cannot be expected for the obtained electric contact material.

Therefore, in the case of silver alloy powder, 0.05 to 10% by weight of at least one metal selected from the group consisting of Cu, Pd, In and Sn as alloy components, and N
at least one selected from the group consisting of i, Co and Fe
It is particularly preferred to contain 0.01 to 0.5% by weight of the seed metal. Next, the mixed powder of the silver powder or silver alloy powder and carbon fine powder obtained as described above is compression-molded into a desired shape. Compression molding conditions are pressure 500 ~ 2000kg / c
m ² is sufficient. As the compression molding machine, a known one such as a hydraulic rubber press can be used.

Finally, when the molded product obtained as described above is sintered in a vacuum or reducing atmosphere, the silver-carbon electrical contact material of the present invention is obtained as a sintered alloy. In this case, the sintering temperature differs depending on the alloy system, but usually, a temperature lower by 50 to 100 ° C. than the solidus temperature of the alloy is appropriate.
The sintering time may be appropriately selected according to the type of the alloy system.

[0015]

The present invention will be described below in more detail with reference to Examples and Comparative Examples. Example 1 Silver powder, Cu powder, Ni powder, Pd powder each having an average particle size of 5 μm,
Using In powder, Sn powder and carbon fine powder having an average particle size of 0.015 μm, six types of silver-carbon sintered alloy-based electrical contact materials shown in Sample Nos. 1 to 6 in Table 1 were manufactured, and their characteristics were measured. Investigations were carried out on Ag-10Ni sintered alloy system (numerical values are% by weight, the same applies hereinafter) (Comparative sample 1), Ag-13CdO sintered alloy system (Comparative sample 2), and Ag-15CdO sintered alloy system (Comparative sample 3). ) Compared to electrical contact material. The six types of sintered alloys are:
Silver powder, Cu powder, Ni powder, Pd powder, In powder, Sn powder, and fine carbon powder were weighed using the amounts described for each sample so as to be approximately 10 kg in total, and were dry-mixed with a rotary mixer. , Put this into a 70 mm diameter cylindrical mold, 500
It was compression-molded by a hydraulic rubber press of kg / cm ² , and the obtained compact was vacuum-sintered at 850 ° C. for 12 hours to obtain a sintered alloy billet.

The Ag-10Ni sintered alloy for comparison was prepared by wet-mixing a silver powder having an average particle diameter of 20 μm and a Ni powder having an average particle diameter of 5 μm by a ball mill, and then drying the same. It was put into a 70 mm cylindrical mold, compression-molded with a 500 kg / cm ² hydraulic rubber press, and the obtained molded body was vacuum-sintered at 850 ° C. for 12 hours to produce Ag-13C.
The dO sintered alloy uses CdO powder with an average particle size of 5 μm,
The above Ag-10N except that the vacuum sintering temperature was 700 ° C
i manufactured in the same manner as the manufacturing method of the sintered alloy.
The 15CdO sintered alloy was manufactured in the same manner as in the method of manufacturing the Ag-13CdO sintered alloy described above. Next, each sintered alloy billet was reheated in a hydrogen atmosphere at 750 ° C. and subjected to extrusion to obtain a rod having a diameter of 7 mm, which was swaged and drawn into a wire having a diameter of 2 mm. Table 1 shows the mechanical and electrical properties of this wire. The header is processed from this wire and the movable contact R10 [(φ4 × 1)
(Φ2 × 2.0) (mm)] and fixed contact F [(φ4 × 1)
(Φ2 × 2.2) (mm)], and a performance evaluation test was performed on 50 contacts.

The contact performance evaluation test was performed under the following two test conditions. 1) AC: 100 V, inductive load: 30 A, contact force between contacts: 50 g, contact separating force: 50 g, contact opening / closing: 0.
5 seconds ON / 0.5 seconds OFF. 2) AC: 200 V, inductive load: 30 A, contact force between contacts 100 g, contact separation force 100 g, contact opening and closing: 0.
5 seconds ON / 0.5 seconds OFF. From the results shown in Tables 2 and 3, the electrical contact material according to the manufacturing method of the present invention is not only excellent in welding resistance and wear resistance under a light contact force, but also under other conditions. It can be seen that compared to nickel sintered alloy-based and silver-oxide sintered alloy-based metal contact materials, they have excellent welding resistance and almost the same wear resistance.

Example 2 Average particle size 5 prepared by high-frequency melting and atomizing method
μm of each silver alloy powder (Ag-0.5Cu, Ag-0.5
Table 1 using Pd, Ag-0.5In, Ag-0.5Sn) and 0.2% by weight of carbon fine powder having an average particle size of 0.015 μm.
Of the silver-carbon sintered alloy-based electrical contact materials shown in Sample Nos. 7 to 10 and their characteristics were examined. These were compared with the Ag-10Ni sintered alloy-based Ag-13CdO manufactured in Example 1.
A comparison was made with the sintered alloy-based and Ag-15CdO sintered alloy-based electrical contact materials. The above four types of sintered alloy powders are approximately 10 k in total using the above-mentioned predetermined amounts of silver alloy powder and carbon fine powder.
Except for weighing the sample to obtain g, it was manufactured in the same manner as in the manufacturing method of Example 1. Using this as a sample, a performance evaluation test of a wire and a contact was performed in the same manner as in Example 1. From the results shown in Tables 2 and 3, the electrical contact material of the present invention is not only excellent in welding resistance and wear resistance under light contact force, but also under other medium-pressure silver-nickel bonding under medium contact force. It can be seen that, compared to gold-based and silver-oxide sintered alloy-based electrical contact materials, they have excellent welding resistance and have almost the same performance as wear resistance.

Example 3 Average particle size 5 prepared by high-frequency melting and atomizing method
μm of each silver alloy powder (Ag-0.2C-0.1Ni, A
g-0.2C-0.1Co, Ag-0.2C-0.1F
e) and 0.2% by weight of carbon fine powder having an average particle size of 0.015 μm
Were used to produce three types of silver-carbon sintered alloy-based electrical contact materials shown in Samples Nos. 11 to 13 in Table 1, and their characteristics were examined. These were compared with Ag-10Ni sintered alloy-based and Ag-13CdO sintered materials. The comparison was made with a bonding gold-based and Ag-15CdO sintered alloy-based electrical contact material. The three types of sintered alloys were manufactured in the same manner as in the manufacturing method of Example 1 except that the total amount of the silver alloy powder and the fine carbon powder was weighed to be approximately 10 kg using the above-mentioned predetermined amounts. A performance evaluation test of the wire and the contact was performed in the same manner as in Example 1. From the results in Tables 2 and 3, the electrical contact material of the present invention not only has excellent welding resistance and wear resistance under light contact force, but also has a silver-nickel sintered alloy system and silver under medium contact force. -It can be seen that compared to the oxide sintered alloy-based electric contact material, it has excellent welding resistance and has almost the same performance as wear resistance.

[0020]

[Table 1]

[0021]

[Table 2]

[0022]

[Table 3]

[0023]

According to the production method of the present invention, a silver-carbon electrical contact material which can be plastically processed as a sintered body can be obtained.
For example, the electrical contact material can be extruded by heating, processed into a wire by swaging or die drawing, and can be processed from rivet processing to mounting of a base metal by a header machine. Moreover, this electrical contact material has a wear resistance comparable to other electrical contact materials, and can be applied to applications in a medium load medium current region where switching is frequently performed.

Claims (5)

[Claims] 1. A dry mixed powder comprising a silver powder or a silver alloy powder and a carbon fine powder having an average particle diameter of 0.1 μm or less and 0.01 to 0.5% by weight, wherein the carbon fine powder is uniformly dispersed. After compression molding, sintering the molded product in a vacuum or reducing atmosphere to form a sintered alloy. 2. The method according to claim 1, wherein the silver powder or the silver alloy powder has an average particle size of 10 μm or less. 3. The dry mixed powder according to claim 1, wherein the dry mixed powder includes silver powder, and further includes at least one metal powder selected from the group consisting of Cu, Ni, Pd, In, and Sn. Content is 0.01 to 10% by weight
The method for producing an electrical contact material according to claim 1, wherein 4. The dry mixed powder contains a silver alloy powder, and the silver alloy powder contains at least one metal selected from the group consisting of Cu, Pd, In, and Sn as an alloy component. The method for producing an electrical contact material according to claim 1, wherein the content of the electrical contact material is about 1% by weight. 5. The dry mixed powder contains a silver alloy powder, and the silver alloy powder contains at least one metal selected from the group consisting of Ni, Co and Fe as an alloy component in an amount of 0.01 to 0.5. The method for producing an electrical contact material according to claim 1, wherein the content of the electrical contact material is about 1% by weight.