JPH06228678A - Electrical contact material - Google Patents

Abstract

PURPOSE:To obtain an electrical contact material excellent in high welding resistance and consumption resistance and capable of plastic working by using a sintered alloy obtd. by uniformly dispersing a specified amt. of carbon fine powder having a specified grain size into silver. CONSTITUTION:This is a silver-carbon series electrical contact material constituted of a sintered alloy obtd. by uniformly dispersing, by weight, 0.01 to 0.5% carbon fine powder with <=1mum average grain size into silver and, if required, furthermore incorporating 0.1 to 5% Ni or 0.1 to 15% Cu therein. This material is excellent in high welding resistance and consumption resistance and is easily capable of plastic working as well when it warmed. The sintered alloy can be obtd. by blending powdery silver, nickel, and copper with about 1 to 20mum average grain size and fine powdery carbon with <=1mum average grain size in prescribed ratios, executing wet mixing using pure water added with alcohol as a mixing medium, drying the obtd. mixture, subjecting it to compacting and thereafter executing sintering in a vacuum or in a reducing atmosphere.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to improvements in silver-carbon based electrical contact materials.

[0002]

2. Description of the Related Art A silver-carbon electrical contact material is generally composed of an alloy obtained by mixing carbon powder having a particle size of several .mu.m or more with silver powder, compacted and sintered, and depending on the case, nickel of 0.1 to 5 wt. % Or copper may be contained in an amount of 0.1 to 15% by weight, both of which have excellent welding resistance and are often used in the light load medium current region.

By the way, most of the electrical contact materials are drawn into wires, processed into rivets while being supplied to a header processing machine, and attached to a base metal so that the contacts can be manufactured by an automatic processing machine. However, this silver-carbon sintered alloy is not suitable for plastic working, and it is true that it is cut out from the sintered alloy into a plate shape and used for a contact. Therefore, the cost of the obtained contact component is somewhat high. Was there.

It is an object of the present invention to provide a plastically workable silver-carbon based electrical contact material as well as many electrical contact materials.

[0005]

To achieve the above object, the electrical contact material of the present invention comprises 0.01 to 0.5% by weight of fine carbon powder having an average particle size of 1 μm or less uniformly dispersed in silver. It is characterized in that it is made of a sintered alloy.

[0006]

The carbon powder used in the present invention must be a fine powder having an average particle size of 1 μm or less. The smaller the particle size is, the more preferable is 0.1 μm or less. If necessary, nickel is 0.1 to 5% by weight, or copper is 0.1 to 15% by weight.
It may be included. Why plastic processing is possible by reducing the carbon powder dispersed in the silver sintered alloy,
The reason is considered as follows. That is, in a conventional sintered alloy using coarse carbon powder, a certain amount (usually several wt%) of carbon powder must be contained in order to impart infusibility, but this carbon amount is not Was made impossible. On the other hand, in the present invention, the amount of carbon required for imparting the non-welding property is 0.01 to 0.5% by weight by setting the carbon powder to 1 μm or less, preferably 0.1 μm or less.
It was reduced to the amount that can be plastically processed.

The silver powder, nickel powder, and copper powder used in the present invention may be ordinary powder metallurgy raw materials having an average particle size of about 1 to 20 μm. It is suitable to mix these metal powder and carbon fine powder by a wet method, the mixing medium is pure water, and alcohol may be added to prevent aggregation of carbon. The mixing method is not particularly limited, and various known mixers can be used.

The silver-carbon type electrical contact material of the present invention is obtained by drying the mixture, compacting it into a desired shape and sintering it in a vacuum or a reducing atmosphere. This sintered body can be extruded by heating, swaging, wire drawing with die drawing, riveting with a header machine,
It can be installed up to a base metal.

The silver-carbon based electrical contact material of the present invention also has an unexpected effect. That is, it has been conventionally known that this kind of contact material consumes a relatively large amount, but as a result of experiments, the material of the present invention was surprisingly consumed at a level comparable to that of the silver-oxide type contact material. Was shown. This result indicates that the electric contact material of the present invention can be used in the medium load region.

[0010]

Example: Silver powder having an average particle size of 20 μm, average particle size of 0.0
Carbon fine powder of 15 μm, nickel powder having an average particle diameter of 5 μm was used, and Ag-0.2C alloy of 0.2 wt% carbon, Ag-0.3C alloy of 0.3 wt% carbon and 0.3 wt of carbon were used. %, 3% by weight of nickel, 3 alloys of Ag-0.3C-3Ni alloy were manufactured, and their characteristics were investigated.
10Ni alloy, Ag-13CdO alloy, Ag-15Cd
Compared to O alloy.

The above three alloys were weighed in a large mortar with about 10 kg of silver powder, ion-exchanged pure water and 2.5% by weight of 10% ethyl alcohol aqueous solution were added and kneaded with a pestle, and the mixture was dried. After that, coarse silver powder was removed with a 235-mesh screen, the underside of the screen was collected, and a cylindrical molding die with a diameter of 70 mm was used to compact the powder with a 500 kg / cm ² hydraulic rubber press, and the compact was vacuumed for 12 hours at 850 ° C. The alloy billet was sintered.

The billet was reheated at 750 ° C. in a hydrogen atmosphere and subjected to extrusion molding to obtain a rod-shaped body having a diameter of 7 mm, which was swaged and die-drawn into a wire having a diameter of 2 mm. Table 1 shows the mechanical and electrical characteristics of this wire.
The header is processed from this wire and the movable contact R ₁₀ [(φ
4 x 1) (φ2 x 2.0) (mm)] and fixed contact F
[(Φ4 × 1) (φ2 × 2.2) (mm)] was obtained, and a performance evaluation test was performed on 50 contacts. The results are shown in Table 2 and Table 3, respectively.

The contact performance evaluation test was conducted in the following two ways. 1) AC200V, inductive load 30A, contact pressure 50g,
Dissociation force 50g. Open and close: 0.5 seconds on / 0.5 seconds off. 2) AC200V, inductive load 30A, contact pressure 100
g, dissociation force 100 g. Open and close: 05 seconds ON / 0.5 seconds OFF.

[0014]

[Table 1]

[0015]

[Table 2]

[0016]

[Table 3]

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 pressure, but also under medium contact pressure silver-nickel alloy, silver. -It can be seen that even when compared with the oxide alloy, the welding resistance is excellent and the wear resistance is almost the same level.

[0018]

According to the present invention, a plastically workable silver-carbon type electrical contact material is obtained. Moreover, this material has performance equivalent to that of the silver-oxide material in terms of wear resistance, and it is expected that the material can be applied to applications in which the number of times of opening and closing is large.

Claims (4)

[Claims] 1. An electric contact material comprising a sintered alloy in which 0.01 to 0.5% by weight of carbon fine powder having an average particle diameter of 1 μm or less is uniformly dispersed in silver. 2. The electrical contact material according to claim 1, which contains nickel in an amount of 0.1 to 5% by weight. 3. The electrical contact material according to claim 1, which contains 0.1 to 15% by weight of copper. 4. The electrical contact material according to claim 1, 2 or 3, wherein the fine carbon powder has an average particle diameter of 0.1 μm or less.