JPH04147901A - Production of ag composite particles for contact material - Google Patents

Abstract

PURPOSE:To easily produce a superior contact material by dispersing non-Ag particles for improving contact characteristics in pure Ag particles by mechanical compounding treatment and forming Ag composite particles. CONSTITUTION:Pure Ag particles 1 of 0.1-45mum mean particle size and non-Ag particles 2 such as Ni particles of 0.01-5mum mean particle size are put in a drum 21 and this drum 21 is filled with an inert gaseous atmosphere and rotated at a high speed. The particles 1, 2 are pressed against the inside 21a of the drum 21 by centrifugal force and receive high compressive strength and shear from the semicircular surface 23a of a fixed member 23 to cause compounding accompanied by the generation of heat. The non-Ag particles 2 are uniformly dispersed in the pure Ag particles 1 by 3-20wt.% and Ag composite particles 10 are obtd. as a superior contact material.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to, for example, Ag used in the manufacture of electrical contact materials for switching equipment such as relays, magnetic switches, and breakers.
Concerning a method for making composite particles.

[Conventional technology and problems]

Ag base contact materials include Ag-Ni contact materials and Ag-
So-called sintered type materials such as W-based contact materials, Ag-C
There are so-called internal oxidation type materials such as d0 type contact materials and Ag-5nol type contact materials. Sintered type Ag-N
The i-type contact material has good wear resistance and processability, and is suitable for Ag-
W-based contact materials are useful materials with features such as the ability to cut and break large currents. However, for example, Ag-Ni contact materials do not have sufficient welding resistance compared to internal oxidation type Ag-Cd0 type contact materials or AAg-3no type contact materials, so they are only used for low to medium loads. Therefore, it is desired to improve the welding resistance.

This Ag-Ni contact material has conventionally been manufactured as follows.

Non-A to strengthen contact characteristics is added to separately manufactured Ag particles.
Ni particles, which are g particles, are added and mixed, compression molded to obtain a molded body, and then the molded body undergoes a sintering process in which [firing-hot compression] is repeated two to three times, and then sintered. rear,
Usually, it is stretched in a stretching process. In the drawing process, the sintered body is usually hot extruded and then further wire drawn. The Ni particles are stretched in the drawing direction in the drawing process, and are dispersed in the contact material in the form of fibers with an average diameter of about 5 nm with the longitudinal direction oriented in the drawing direction. After drawing the wire, cut it into short pieces and use the cross section perpendicular to the drawing direction as the contact surface. That is, Ni is oriented and dispersed in the Ag matrix in the form of fibers with an average diameter of 5n in a direction intersecting the contact surface.

In order to improve the welding resistance, it is necessary to finely and uniformly disperse Ni on the contact surface. For example, Ag particles and Ni
Both particles have a particle size of 1m! If the fine particles were used at the bottom, the fine Ni particles would not be localized on the contact surface and would be evenly dispersed, but this is not actually the case. This is because the fine particles aggregate into large secondary particles at the stage of mixing the fine particles, and are eventually dispersed as large Ni particles. Normally, when the particle size becomes 5n or less, particle aggregation cannot be ignored.

In order to solve the problem of particle aggregation, it is conceivable to spray f4 hot water in which all of the Ag and Ni to be blended are melted together to form Ag particles in which fine Ni particles are dispersed, and then to mold and sinter the Ag particles. In this case, although particle aggregation is eliminated, Ag
It is difficult to secure a sufficient amount of Ni as a Ni-based contact material. The solid solubility limit of Ni in Ag in the above molten metal is approximately 6iet.
%, it is difficult to increase the Ni content of Ag particles to 6 wt % or more. When the molten metal contains an Ni amount exceeding 6 wt%, coarse Ni particles having a very large particle size will be mixed in the obtained particles. Undissolved Ni in the AgNi molten metal becomes coarse Ni particles and is mixed therein. These coarse Ni particles reduce formability and sinterability, leading to deterioration of welding resistance.

Even with sintered contact materials other than Ag-Ni contact materials,
The above-mentioned problems exist regarding fine dispersion of non-Ag particles for reinforcing contact characteristics.

[Problem to be solved by the invention]

In view of the above circumstances, it is an object of the present invention to provide a method capable of obtaining Ag composite particles in which a sufficient amount of fine non-Ag particles for reinforcing contact characteristics are dispersed in Ag.

[Means to solve the problem]

In order to solve the above problems, in the method for producing Ag composite particles for contact materials according to claims 1 to 5, pure Ag particles and non-Ag particles for reinforcing contact properties are granulated by mechanical compositing treatment to form non-A.
This is to obtain Ag composite particles in which g particles are dispersed.

For example, the mechanical compounding process of the present invention uses an apparatus including a rotatable drum and a fixing member having a curved surface facing the inner circumferential surface of the drum. This can be carried out by rotating a drum with particles and non-Ag particles charged therein to compress and shear both particles.

Examples of non-Ag particles for reinforcing contact characteristics include Ni
, w, MOIC, and WC, but are not limited thereto.

As claimed in claim 4, the average particle size of pure Ag particles and non-Ag particles for producing Ag composite particles is usually 0.
1 to 45 m, and 0.01 to 5 μm for non-Ag particles.

The appropriate content of non-Ag particles in the granulated Ag composite particles (the average content is 100 wt% for the entire Ag composite particles) varies depending on the type of non-Ag particles, but usually, as claimed in claim 5.
The content is about 3 to 20 wt%.

Hereinafter, the present invention will be explained more specifically, focusing on the case where the non-Ag particles are Ni particles.

Ni particles for producing Ag composite particles are smaller than Ag particles, and usually have an average particle size of about 0.01 to 5n. usually,
The particle size of the Ni particles is about 1/10 or less of the particle size of the Ag particles. If it exceeds 5 sins, it is difficult to achieve Ni fineness, and 0.0
If it is less than 1 sin, the particles are expensive, so cost increase becomes a problem. The pure Ag particles used have an average particle size of about 0.1 to 45 nm.

If the particle size exceeds 45n, granulation becomes difficult, and if the particle size is less than 0.1n, the particles are expensive, resulting in an increase in cost.

The Ni content of the Ag composite particles (the average content is 100 kt% for the entire Ag composite particle) is about 3 to 20 ivt%,
Preferably it is about 6 to 20 wt%. If it is less than 3 wt%, the contact properties will be weak, and if it exceeds 20 wt%, the electrical conductivity will decrease and the welding resistance will deteriorate.

Next, an apparatus for mechanically combining Ag particles and Ni particles will be explained. As a processing device, a high-speed, high-shear type mill as shown in FIG. 2 (for example, ■Ong Mill for Mechanofusion System manufactured by Hosokawa Micron) is used.

The processing device 20 in FIG. 2 includes a drum (cylindrical container) 21 that can be rotated at high speed by a motor (not shown), and a semicircular ceramic (for example, hard alumina) drum supported by a fixed arm 22 inside the drum 21. This is a configuration in which a columnar fixing member 23 is provided.

The fixing member 23 is fixed with a semi-cylindrical curved surface (curved surface) 23a facing the drum inner surface 21a, and while the drum 21 is rotating, the inner surface of the drum 21 moves in front of the fixed semi-cylindrical curved surface 23a. . The radius of curvature of this semi-cylindrical curved surface 23a is smaller than the radius of curvature of the drum inner surface 210.

When performing composite processing, pure Ag particles and Ni particles are introduced into the drum 21 (along with beads for the media side that are added as necessary), and the drum 21 is set in an inert gas atmosphere and the drum 21 is moved at high speed. Rotate. Then,
As shown in FIG. 3, pure Ag particles and Ni particles are pressed against the drum inner surface 21a by centrifugal force, rotate together with the drum 21, and rotate in the front region (A-B) of the semi-cylindrical curved surface 23a.
When the pure Ag particles and Ni particles are subjected to strong compressive force and shear force, they are combined with the generated heat.

When using media beads (for example, zirconia beads with a particle size of about 1 inch), the Ni particles first adhere to the beads and then to the pure Ag particles. in this way,
Ag composite particles can be easily produced using commercially available processing equipment.

The rotation speed of the drum is approximately 500 to 2000 times/min. The distance d between the semi-cylindrical curved surface 23a and the drum inner surface 21a is
Usually, it is about 1 to 5 cranes.

Next, a specific process for forming a composite of pure Ag particles and Ni particles will be explained with reference to the drawings.

As the drum 21 starts rotating, the Ni particles 2, which were in a weakly agglomerated state as shown in FIG. 1(a), become primary particles, and become pure particles as shown in FIG. 1(b). It adheres to the Ag particle 1, and then, as shown in FIG. 1(C), the Ni particle 2
are arranged regularly around the pure Ag particles 1, resulting in an ordered mixture state. Furthermore, due to the strong compressive force and shearing force acting between the particles, and the heat generated, as shown in Figure 1(d), the Ni particles 2 are incorporated into the pure Ag particles 1, and the mother particles are formed. Since it is soft pure Ag, it is easily granulated, and full-scale granulation begins. That is, as shown in FIG. 1(e), the Ag particles 1' adhere to each other and the first
As shown in Figure (f), plastic deformation and fusion occur, and Figure 1 (a)
As shown in the figure, round composite particles 10 are formed in which Ni particles 2 are dispersed in Ag. The processing time is usually about 30 to 120 minutes.

Since the base particles of the Ni particles 2 in the composite particles are soft pure Ag, they can easily enter the interior, and the original particle state can be maintained relatively easily.

The above is about the case of Ni particles, but other W, M
Similarly, in the case of high melting point non-Ag particles such as O, C, and WC, Ag
It can be made into composite particles. Note that different types of non-Ag particles, for example, W particles and Mo particles, may be added together to pure Ag particles to obtain Ag composite particles in which both W particles and Mo particles are dispersed.

When manufacturing conventional Ag Ni contact materials, pure Ag particles and Ni particles are mixed in a V-shaped mill before molding, but the particles are only stirred and mixed, not composited.
If we look at the mixed state in detail, the pure Ag particles and the Ni particles are individually separated.

Next, a description will be given of how a sintered type contact material is manufactured using the Ag composite particles obtained as described above.

First, Ag composite particles are pressure-molded to produce a molded body.

Next, this molded body is sintered. In the sintering process, usually
The molded body is subjected to [firing-hot compression] two or three times to form a sintered body. After sintering, the stretching process begins. In this drawing step, the sintered body is hot extruded and then further wire drawn. Stretching is usually
[Cross-sectional area before stretching] / [Cross-sectional area after stretching]
is 150 or more.

The N4 particles are elongated in the drawing direction in the drawing process.

After drawing the wire, it is cut into pieces in a direction perpendicular to the drawing direction, and the cut surfaces are used as contact surfaces. In the case of contact materials using Ni particles, which are usually cut and then riveted to make electrical contacts, the Ni is fibrous in the Ag base and oriented in a direction that intersects the contact surface (cut surface). The fibrous Ni is dispersed and exposed in the form of dots on the contact surface. The average diameter of fibrous N1 is
It is determined by the particle size of the initial Ni particles and the degree of stretching.
It is preferable that it is less than g.

[For production]

In the Ag composite particles of the present invention, a sufficient amount of non-Ag particles for reinforcing contact characteristics are dispersed. This is because the non-Ag particle material is not dissolved in Ag, but is dispersed by mechanical compositing treatment, and therefore is not subject to limitations due to the solid solubility limit of the non-Ag particle material with respect to Ag.

Since non-Ag particles exist scattered in the Ag composite particles without agglomerating, miniaturization can be easily achieved by using non-Ag particles with a small primary particle size.

In this way, since a sufficient amount of fine non-Ag particles for reinforcing contact characteristics is distributed to each Ag composite particle in advance, fine non-Ag particles are distributed even in contact materials manufactured using the same Ag composite particles. is dispersed in a sufficient amount without grooves, and, for example, in Ag-Ni contact materials, the welding resistance is improved.

The mechanical compounding process is carried out using a device equipped with a rotatable drum and a fixing member having a curved surface facing the inner peripheral surface of the drum, with pure Ag particles and non-Ag particles placed in the drum. A: Excellent contact materials can be made by rotating and compressing and shearing both particles.
g composite particles can be easily produced.

[Example] The present invention will be described in detail below. This invention is not limited to the following embodiments.

Example 1 - First, pure Ag particles with an average particle size of 0.5μ and an average particle size of 0.
．． The Ni content is 15% based on the total amount of 02μ Ni particles (the sum of all pure Ag particles and all Ni particles is 100wt%).
The particles were weighed so as to be % by weight and mechanically composited using the above-mentioned high-speed, high-shear mill to obtain Ag composite particles. In addition, during the mechanical composite treatment, the inside of the drum was made into an Ar gas atmosphere, zirconia beads with an average particle size of about 1 fl were used as a medium, and the treatment was performed for 5500 seconds.

The particle cross section (metallic structure) of the obtained Ag composite particles is shown in Section 4.
It is shown in Figure 5. FIG. 4.5 is a photograph taken by a scanning electron microscope, and FIG. 4 is a secondary electron beam (SEM image) photograph, and FIG. 5 is a characteristic X-ray (N i Kα image) photograph. especially,
Looking at FIG. 5, it is clearly seen that the white Ni portions are very fine and are widely dispersed without grooves.

Next, a contact material was obtained using the Ag composite particles.

First, Ag composite particles were pressure-molded to obtain a compact, and then
Firing and hot compression were repeated three times to obtain a sintered body. In addition, 1
The first firing was performed in a vacuum atmosphere, and the second and third firings were performed in a nitrogen atmosphere.

Subsequently, the sintered body was preheated and hot-extruded using a mold to be stretched, and then wire-drawn. After wire drawing, the wire was cut into pieces in a direction perpendicular to the wire drawing direction and then riveted to obtain a glue bent contact for contact performance evaluation.

Example 2 Pure Ag particles with an average particle size of 5μ and N with an average particle size of 0.2μ
A rivet contact for contact performance evaluation was obtained in the same manner as in Example 1, except that the total amount of i particles was weighed so that the Ni content was 10 wt%.

Example 3 Contact performance was measured in the same manner as in Example 1, except that pure Ag particles with an average particle size of 5μ and Ni particles with an average particle size of 0.02n were weighed so that the Ni content was 6 wt%. A rivet contact was obtained for evaluation.

Example 4 - Pure Ag particles with an average particle size of 0.1 n and an average particle size of 0°O
A glue-bent contact for contact performance evaluation was obtained in the same manner as in Example 1, except that 1 μm Ni particles were weighed so that the total Ni content was 3 ivt%.

Example 5 Pure Ag particles with an average particle size of 45n and Ni with an average particle size of 5n
A glue bed contact for contact performance evaluation was obtained in the same manner as in Example 1, except that the particles were weighed so that the total Ni content was 20 wt%.

Example 6 Pure Ag particles with an average particle size of 5n and W with an average particle size of 0.2n
A glue head contact for contact performance evaluation was obtained in the same manner as in Example 1, except that the total amount of particles was weighed so that the W content was 15 wt%.

Example 7 - Pure Ag particles with an average particle size of 5- and M with an average particle size of 0.2n
A glue bed contact for contact performance evaluation was obtained in the same manner as in Example 1, except that the Mo particles were weighed so that the total Mo content was 10 wt%.

Example 8 Pure Ag particles with an average particle size of 5n and C with an average particle size of 0.21
A glue head contact for contact performance evaluation was obtained in the same manner as in Example 1, except that the total amount of particles was weighed so that the C content was 20 wt%.

Example 9 Pure Ag particles with an average particle size of 5n and W with an average particle size of 0.2n
A glue bed contact for contact performance evaluation was obtained in the same manner as in Example 1, except that the C particles were weighed so that the WC content was 6 wt%.

- Comparative Example 1 - A contact material was obtained in the same manner as in Example 1 after a molded body was obtained by mixing pure Ag particles with an average particle size of 2On and Ni particles with an average particle size of 5N. Note that the Ni content is 10 wt%.

The welding resistance and wear characteristics of the rivet contacts of Examples 1 to 5 and Comparative Examples 2 and 2 were examined by ASTM tests (number of samples N=3). The test conditions are as follows.

The test results are shown in Table 1.

Load: Resistive load Voltage: 100V Current = 40A Number of switching:
50,000 cycles As shown in Table 1, the contact materials of the examples have good abrasion resistance and are much better in welding resistance than those of the comparative examples. Non-Ag for strengthening fine contact characteristics
It can be clearly seen that the contact performance is reflected in the fact that the particles are dispersed in a sufficient amount without any grooves.

〔Effect of the invention〕

As described above, according to the manufacturing method of the present invention, it is possible to obtain Ag composite particles in which a sufficient amount of fine non-Ag particles for reinforcing contact properties are dispersed in advance, and as a result, when these Ag composite particles are used, , it is possible to easily produce an excellent contact material in which a sufficient amount of fine non-Ag particles for reinforcing contact characteristics are dispersed without grooves.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing step by step the process of producing Ag composite particles as an example of the method of the present invention, and Fig. 2 is a diagram of the mechanical composite processing equipment used to carry out the method of the present invention. FIG. 3 is an explanatory diagram showing the state of the device during mechanical composite processing, and FIGS. 4 and 5 are cross-sectional views of the Ag composite particles of Example 1. This is an electron micrograph showing the metal structure. ■...Pure Ag particles, 2...Ni fine particles (non-Ag particles) 10...Ag composite particles 20...Mechanical composite processing device 21...Drum 21a...Drum inner surface 23...・Fixing member 23a... Semi-cylindrical curved surface (Curved surface agent Patent attorney Takehiko Matsumoto Figure 2)

Claims (1)

[Claims] 1. Ag in which pure Ag particles and non-Ag particles for reinforcing contact characteristics are granulated by mechanical compositing treatment and non-Ag particles are dispersed inside.
A method for producing Ag composite particles for contact materials to obtain composite particles. 2. The mechanical compounding process uses a device equipped with a rotatable drum and a fixed member having a curved surface facing the inner peripheral surface of the drum, and pure Ag particles and non-Ag particles are placed in the drum.
2. The method for producing Ag composite particles for contact materials according to claim 1, which is carried out by rotating a drum with the particles charged therein to apply compression and shear to both particles. 3. The method for producing Ag composite particles for contact materials according to claim 1 or 2, wherein the non-Ag particles are made of at least one of Ni, W, Mo, C, and WC. 4 The average particle size of pure Ag particles is 0.1 to 45 μm, non-Ag
The method for producing Ag composite particles for contact materials according to any one of claims 1 to 3, wherein the particles have an average particle diameter of 0.01 to 5 μm. 5 The non-Ag particle content of the granulated Ag composite particles is 3~
The method for producing Ag composite particles for contact materials according to any one of claims 1 to 4, wherein the content is 20 wt%.