JPH09111369A - Ag-boron nitride electrical contact material excellent in deposition resistance and consumption resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an Ag-BN electrical contact material excellent in deposition resistance and consumption resistance by forming a mechanical alloying joining layer on the interface between fine BN grains, dispersedly distributed in a specific proportion in an Ag matrix, and this Ag matrix. SOLUTION: A structure, in which fine BN grains of <=1μm average grain size are dispersedly distributed by 0.5-6wt.% in an Ag matrix and a mechanical alloying joining layer exists in the interface between the BN grains and the Ag matrix, is formed. This structure can be obtained by mixing Ag powder of <=about 100mesh and BN powder of about 5-10μm average grain size, as raw material powders, in the prescribed proportion, introducing the resultant powder mixture into an attritor, and performing mixing for the prescribed time to apply mechanical alloying treatment. It is preferable to further apply heat treatment to the resultant composite powder in a nitrogen atmosphere at about 650 deg.C to stabilize the mechanical alloying joining layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an excellent welding resistance and wear resistance, and is substantially manufactured by mechanical alloying treatment and hot and cold working.
The present invention relates to a boron nitride (hereinafter referred to as BN) -based electric contact material.

[0002]

2. Description of the Related Art Conventionally, as an electric contact material, for example, as described in JP-A-53-78061,
An Ag-tin oxide (hereinafter referred to as SnO ₂ ) system is widely known, and this is an ordinary powder metallurgy method, that is, Ag powder as a raw material powder and SnO ₂ powder are blended and mixed, and then pressure is applied. It is also well known that it is manufactured by pressing into powder, sintering the green compact, subjecting the resulting sintered body to hot and cold working, and finishing to final dimensions.

[0003]

On the other hand, the performance of various electric and electronic devices has been remarkably improved in recent years, and accordingly, the electric contacts used in these devices are forced to be used under more severe conditions. Although there is a situation, the above-mentioned conventional Ag-
Since SnO ₂ -based electrical contact materials do not have sufficient welding resistance and wear resistance, the current situation is that they cannot be satisfied satisfactorily.

[0004]

Means for Solving the Problems Accordingly, the present inventors have
From the above viewpoints, as a result of research to further improve the welding resistance and wear resistance of the electrical contact material, as a result, Ag powder as a raw material powder is extremely stable thermally and has good lubricity. Boron nitride (hereinafter referred to as BN) is used, and this is blended into a predetermined blending composition, and the mixture is mixed with an attritor while applying strong impact, friction, and shearing. Is further miniaturized (in this case, it is desirable that the average grain size is 1 μm or less), the finely divided powder is uniformly dispersed and distributed in the Ag powder, and the interface between the Ag base and the fine BN powder is used. A mechanical alloying bonding layer is formed on the surface of the BN particles, and the electrical contact material formed by hot working and cold working from the composite powder in this state can be easily formed due to the thermal stability and lubricity of the BN particles. It had welding resistance, and BN
If an arc occurs due to the extremely fine particles, B
Since the extreme surface layer of N particles is oxidized and vaporized into B ₂ O ₃ , the arc extinguishing action is promoted, resulting in excellent welding resistance and wear resistance, which results in severe Even in practical use under the conditions, the presence of the mechanical alloying bonding layer makes the adhesion of the BN particles to the Ag substrate extremely strong and, in addition, provides excellent performance for a long period of time. That is the result of the research.

The present invention has been made based on the above research results, and fine BN particles having an average particle diameter of 1 μm or less are dispersed in an Ag matrix at a ratio of 0.5 to 6% by weight. Ag-BN excellent in welding resistance and wear resistance, having a structure in which a mechanical alloying bonding layer is present at the interface between the BN particles and the Ag matrix.
It is characterized by a system electric contact material.

In the electric contact material of the present invention,
The content ratio of the BN particles is set to 0.5 to 6% by weight, because when the content ratio is less than 0.5% by weight, excellent welding resistance and wear resistance provided by the BN particles can be secured. On the other hand, on the other hand, if its content exceeds 6% by weight, the workability is sharply lowered and the electrical resistance is remarkably increased, and preferably 1 to 4
% By weight is preferred. The average particle size of BN particles is 1μ.
m or less means that when the average particle size exceeds 1 μm,
This is because the contact resistance suddenly rises, the contact failure during opening and closing tends to occur, and the arc during opening and closing tends to concentrate on the BN particles, resulting in increased welding and wear at this portion. is there.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As raw material powders, Ag powder of 100 mesh or less and BN powder having a predetermined average particle diameter within the range of 5 to 10 μm are prepared, and these raw material powders are blended in a predetermined blending composition. , Insert this into an attritor, 5
A mechanical alloying treatment of mixing for a predetermined time within a range of 0 to 100 hours is performed to refine the BN powder, and the fine BN powder is dispersed in Ag powder through a mechanical alloying bonding layer to form a composite. A powder is formed, and then the composite powder is heat-treated in a nitrogen atmosphere at 650 ° C. for 2 hours (this heat treatment is performed in a non-oxidizing atmosphere.
This is preferably carried out under the conditions of holding at 300 to 700 ° C. for 1 to 3 hours), thereby stabilizing the mechanical alloying bonding layer, and subsequently, at a pressure of 8 ton / cm ² , a billet having a diameter of 70 mm. Press-molded into a green compact, and subjecting this green compact to hot extrusion at a temperature of 700 ° C,
Further, by warm rolling and wire drawing, a wire with a diameter of 1.9 mm was formed. From this wire, header processing was performed, and the content and average particle size as shown in Table 1 (from electron microscopic structure photograph by computer image diffraction) The electrical contact materials 1 to 6 of the present invention each having a structure in which the BN particles of (calculation) are distributed and distributed in the Ag matrix through the mechanical alloying bonding layer were manufactured.

Further, for the purpose of comparison, as a raw material powder,
After preparing Ag powder of 100 mesh or less and SnO ₂ powder having a predetermined average particle diameter within the range of 5 to 10 μm, blending these raw material powders into a prescribed blending composition and mixing for 20 hours in a ball mill, Diameter: 7 at pressure of 8 ton / cm ²
It is press-formed into a billet-shaped green compact of 0 mm, and this green compact is sintered under the conditions of holding at 900 ° C for 2 hours in the atmosphere, and the resulting sintered body is hot worked at a temperature of 700 ° C. And
Furthermore, a wire rod having a diameter of 1.9 mm was formed by warm working and wire drawing, and SnO ₂ particles having the content and the average particle size as shown in Table 1 were dispersed and distributed in the Ag matrix by the header processing from this wire rod. Conventional electrical contact materials 1 to 6 having textures were manufactured respectively.

With respect to various electric contact materials obtained as a result, using an ASTM electric contact tester, DC voltage: 24 V, making current: 210 A, breaking current: 42 A, energizing time: 1 second ON-9 seconds OFF, Contact force: 150g, dissociation force: 150g, number of times of opening and closing: 10,000 times, load: lamp, electrical test is performed, welding frequency and consumption amount are measured, and welding resistance and consumption resistance are based on these results. Was evaluated. Table 1 shows the results of these measurements.

[0010]

[Table 1]

[0011]

From the results shown in Table 1, all of the electrical contact materials 1 to 6 of the present invention have much better welding resistance and wear resistance than the conventional electrical contact materials 1 to 6. it is obvious. As described above, the Ag-BN-based electrical contact material of the present invention has a structure in which fine BN particles are dispersed and distributed in the Ag base material through the mechanical alloying bonding layer, and the mechanical alloying bonding layer serves to form BN. Since the adhesion of the particles to the Ag base material is remarkably improved, the BN particles have excellent wear resistance in combination with the improved adhesion resistance, and thus are practically used in various electric and electronic devices. When used, it exhibits excellent performance for a long time even when used under severe conditions.

Front Page Continuation (72) Inventor Koji Hoshino 1-297 Kitabukuro-cho, Omiya-shi, Saitama Prefecture Mitsubishi Materialial Co., Ltd. (72) Inventor Tsuru Kono 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsubishi Materialial Co., Ltd. (72) Inventor Nobuyuki Yamagishi, 46-1, Senfuku, Susono, Shizuoka Prefecture, Higashifuji Plant, Fuji Plant (72) Inventor, Akihiko Inaba, 46-1, Senfuku, Susono, Shizuoka Prefecture, Fuji Plant, Higashifuji Plant

Claims (1)

[Claims] 1. Fine Ag particles having an average particle diameter of 1 μm or less are dispersed and distributed in an amount of 0.5 to 6% by weight on an Ag base material, and an interface portion between the boron nitride particles and the Ag base material. An Ag-boron nitride-based electrical contact material having excellent welding resistance and wear resistance, which has a structure in which a mechanical alloying bonding layer is present.