KR20140001901A - Method for producing ag-oxide-based electrical contact material and electrical contact material produced by the method - Google Patents

Abstract

[Problem] The Ag-oxide type electrical contact material containing Zn has not been put into practical use as an electrical contact material because of its low plastic formability, which is indispensable for the manufacture of electrical contacts, and because it is difficult to carry out almost rolling. [Measures] Fine pieces obtained by causing a large number of fine cracks at grain boundaries by pulverizing Ag alloy containing Zn under oxygen partial pressure of 0.5 to 5.0 MPa and oxidation temperature of 600 to 900 ° C. And / or a method for producing an Ag-oxide-based electrical contact material in which the powder is compression molded into a desired shape, followed by sintering and extrusion processing into a predetermined shape.

Description

METHOD FOR PRODUCING AG-OXIDE-BASED ELECTRICAL CONTACT MATERIAL AND ELECTRICAL CONTACT MATERIAL PRODUCED BY THE METHOD}

The present invention relates to a method for producing an Ag-oxide based electrical contact material and to an electrical contact material produced thereby.

Conventionally, as a manufacturing method of an electrical contact material, the alloy used as a raw material is produced by the melting method, rolling process, press working, etc. are processed to a contact shape, and after performing internal oxidation process, there exists a manufacturing method by the oxidation method. .

Furthermore, after the alloy used as a raw material is produced by a dissolution method and processed into a sheet material or the like, fine pieces are produced by press cutting or the like, the fine pieces are subjected to internal oxidation treatment, and then compression molded into a predetermined shape. There exists a manufacturing method by the preliminary oxidation method which processes a compression-molded material into a wire steel or a board | plate material by extrusion processing, and then processes it to a contact shape (for example, refer patent document 1).

Moreover, there exists a manufacturing method by the powder sintering method which carries out compression molding of a metal powder to a predetermined shape, sinters, and rolls and processes it into a contact shape (for example, refer patent document 2).

Patent Document 1: Japanese Patent Application Laid-Open No. 7-258769 Patent Document 2: Japanese Patent Application Laid-Open No. 9-111364

For example, when attempting to manufacture an electrical contact using an alloy having a composition containing Ag, Zn, Te, Cu, and Sb, the plastic workability of the Ag alloy containing Zn is poor, which is indispensable for the manufacture of the contact. Since it is difficult to process, such as rolling, it is difficult to manufacture by the post-oxidation method and the preliminary oxidation method which are conventional manufacturing methods of an electrical contact.

In addition, even when some plastic working is possible, if the internal oxidation treatment is performed after processing into a contact shape, a large number of minute cracks are generated at the grain boundaries due to oxidative expansion, and thus become very fragile. Difficult to use As described above, the Ag-oxide-based electrical contact material containing Zn is not practically used as an electrical contact material because of its low plastic formability, which is indispensable for the manufacture of electrical contacts, and the difficulty of performing rolling processing.

However, if the Ag alloy containing Zn can have a practical performance as an electrical contact material, it becomes possible to lower the unit cost of the contact material used in large quantities, thereby providing a desirable electrical contact material for mass production.

The present invention is intended to solve such a problem.

Accordingly, the present invention provides a low plastic formability, which is characteristic of Ag alloys by this composition, to produce Ag-oxide-based electrical contact materials containing Zn, and generates many fine cracks at grain boundaries under specific internal oxidation conditions. Attention was drawn to very vulnerable properties. In the present invention, after the ingot is produced by the dissolution method, the internal oxidation treatment is performed in the ingot state to generate a large number of fine cracks in the grain boundary, thereby making it very fragile. Then, the internal ingot treatment is performed by grinding the ingot. After obtaining the three pieces or powder of Ag alloy which has been finished, the three pieces or powder of the Ag alloy are subjected to compression molding to a desired shape, and then sintered, and then processed into an electrical contact material of a wire rod or a plate by extrusion, and finally The contact shape can be processed.

The present invention performs the internal oxidation treatment at an oxygen partial pressure of 0.5 to 5.0 MPa and an oxidation temperature of 600 to 900 ° C. According to the experiments so far, the internal oxidation does not proceed outside these internal oxidation conditions, and the Ag alloy containing Zn cannot obtain necessary properties as the internal oxidation contact, and also generates a large number of fine cracks at the grain boundary. This is because it could not be made into a fragile state and could not be made into fine particles or powder necessary for compression molding the material.

Here, the point which was discovered by experiment about the cause which a large number of micro cracks generate | occur | produce in a grain boundary by the internal oxidation process in this invention is described.

Conventionally, when the Ag-Sn-In-based material, which is the mainstream of electrical contacts, is internally oxidized, the material expands slightly when oxides are generated inside the material, but many fine cracks do not occur at grain boundaries.

When the Ag-Sn-In-based material is internally oxidized, Sn or In in the Ag alloy diffuses toward the material surface in order to solve the concentration gradient such as Sn or In in the Ag alloy resulting from internal oxidation on the material surface. Do it. In this case, since the diffusion rate of Sn or In is faster than the rate at which O ₂ diffuses from the surface of the material during internal oxidation, some oxides aggregate in the material, resulting in a large number of oxides and a small number of oxides. . Among these, the location with low oxide concentration is a state which is easy to plastically deform. In the case where expansion due to oxide formation accompanying internal oxidation occurs, fine cracks do not occur because a portion having a low oxide concentration and easily susceptible to plastic deformation absorbs deformation due to the expansion.

However, when the Ag-based material containing Zn according to the present invention is internally oxidized, the Ag alloy has a slower diffusion rate of Zn at the time of internal oxidation than Sn or In and a faster diffusion rate of O ₂ from the material surface. The formation of oxides in the mixture is fast, and the oxides are uniformly dispersed throughout, making it difficult to aggregate the oxides. For this reason, compared with Ag-Sn-In type material, since all the malleability is low and it cannot absorb the expansion of the oxide which arises at the time of internal oxidation, many fine cracks generate | occur | produce in a grain boundary. In particular, this phenomenon was remarkably confirmed under the internal oxidation conditions exemplified in the present invention.

By the manufacturing method illustrated by this invention, it becomes possible to manufacture an electrical contact using the Ag type material containing Zn which was conventionally difficult to manufacture an electrical contact, and is an electrical contact which is more excellent in contact performance than the conventional contact material. It has become possible to manufacture.

According to the experiments so far, as an Ag-based material containing Zn, Ag is 98.7-50 mass%, Zn 1-40 mass%, Te 0.1-3.0 mass%, Cu 0.1-5.0 mass%, Sb 0.1-2.0 mass% It was found that it was possible to manufacture the compound formulated as an electrical contact having excellent contact performance.

In addition, when Zn was added to Ag, it was found that by adding three elements of Te, Cu, and Sb together, it was possible to manufacture an electrical contact having excellent contact performance. The blending ratio of these three elements is such that the effects of wear resistance and welding resistance are lost below the minimum value. In addition, it was found that when the above maximum values were respectively exceeded, the amount of oxide was too large to increase the contact resistance, which in turn caused the temperature to rise, thereby causing the deposition phenomenon.

The reason for setting the blending ratio of Zn to 1 to 40% by weight is that it is not meant to be added because the desired effect of the oxide is not obtained at less than 1% by weight. Because it is thrown away.

In addition, by experiments, adding at least one of 0.5 to 8.0% by weight of Sn, 1.0 to 6.0% by weight of In, and 0.1 to 0.3% by weight of Ni to the alloy controls the oxide to be uniformly deposited to refine the grains. It was found to be valid.

The reason for setting the blending ratio of Sn, In, and Ni as described above is that when the Sn is less than 0.5% by weight, the In is less than 1.0% by weight and the Ni is less than 0.1% by weight, the oxides are uniformly controlled to refine the grains. Because no effect could be obtained. This is because when Sn exceeds 8.0% by weight and In exceeds 6.0% by weight, oxides aggregate to generate internal oxidation defects, and when Ni exceeds 0.3% by weight, uniform dissolution becomes difficult.

In addition, by experiment, it was found that by adding at least one of Mn, Ga, Mg, and Bi in the range of 0.01 to 0.3% by weight, it is possible to further improve the performance as an electrical contact. This is because the wear resistance and the welding resistance can be improved by depositing a fine oxide in the crystal structure. Moreover, it was found that the effect was not obtained when the amount of addition was less than 0.01% by weight, and when the content was more than 0.3% by weight, oxides aggregated to cause internal oxidation defects.

It was found that the electrical contact by the electrical contact material of the present invention is excellent in general electrical properties such as welding resistance, arc resistance, and low contact resistance, and has excellent characteristics in various contact uses.

Thereby, it became possible to provide the electrical contact material which contains Zn in Ag alloy, and is low in cost, and suitable for mass production as a contact material used in large quantities.

The Example of this invention is described by Table 1. FIG.

The material of each Example shown in Table 1 was melt | dissolved into the ingot of thickness 20mm, width 50mm, and length 50mm by melt | dissolution, and internal oxidation process is performed about 800 hours at 800 degreeC and oxygen pressure of 0.5 MPa in an ingot state. .

The ingot is then milled using a mill to produce shreds and / or powders. The produced fine pieces and / or powder were compression molded into a desired shape, followed by sintering, to a wire rod having a diameter of 4 mm by extrusion, and to a wire rod having a diameter of 2 mm by drawing and heat treatment. At this time, the processing rate was 75%.

Next, the wire rod was subjected to a molding process using a molding press so as to have a thickness of 0.8 mm, a width, and a length of 2.5 mm, and then a welding test was performed at DC 200, 300, and 350V.

Furthermore, for comparison, two examples of Ag-Sn-In-based pre-oxidized contacts were produced as comparative examples, and comparative tests were performed.

Document number Composition (mass%) Welding Wear resistance Contact resistance Ag Zn Te Cu Sb Sn In Ni Mn Ga Mg Bi Example 1 50.0 40.0 3.0 5.0 2.0 ○ △ △ Example 2 98.7 1.0 0.1 0.1 0.1 △ ○ ◎ Example 3 86.4 1.0 0.1 0.1 0.1 8.0 4.0 0.3 ◎ ○ △ Example 4 86.6 4.0 1.0 2.0 1.0 1.0 4.0 0.1 0.30 ○ ○ ○ Example 5 83.2 8.0 1.0 0.5 0.7 6.0 0.3 0.30 ◎ ○ ◎ Example 6 89.1 2.0 0.5 0.8 0.8 2.5 4.0 0.3 0.01 ○ ◎ ○ Example 7 88.3 3.0 0.8 0.5 0.8 2.0 4.0 0.3 0.20 0.10 ◎ ◎ ◎ Example 8 91.2 3.0 1.0 2.0 1.0 0.5 1.0 0.3 0.01 ○ ○ ◎ Example 9 72.5 20.0 2.0 1.5 1.2 0.8 1.5 0.3 0.15 0.05 ◎ ○ ○ Example 10 62.1 30.0 2.5 0.8 0.5 1.5 2.0 0.3 0.20 0.10 ○ ○ △ Example 11 51.6 40.0 3.0 0.5 0.3 1.0 3.0 0.3 0.30 ◎ △ △ Example 12 60.7 25.0 2.0 2.0 1.8 4.0 4.0 0.3 0.10 0.10 ◎ △ ○ Example 13 72.4 15.0 2.5 1.0 0.8 6.0 2.0 0.2 0.05 0.05 ◎ ◎ △ Conventional Example 1 90.2 5.0 4.5 0.3 ○ △ ○ Conventional Example 2 88.0 8.2 3.5 0.3 ◎ △ △

* Test voltage: DC 200, 300, 350V Number of tests: 30 times each ◎: Very good ○: Good △: Normal

Claims (5)

Ag alloy containing Zn is subjected to internal oxidation treatment under oxygen partial pressure of 0.5 to 5.0 MPa and oxidation temperature of 600 to 900 ° C. to generate a large number of fine cracks at grain boundaries, and to obtain fine particles and / or powder obtained by pulverizing them. A method for producing an Ag-oxide type electrical contact material, characterized by compression molding into a desired shape, followed by sintering and extrusion into a predetermined shape. The method of claim 1,
Ag-oxide containing Zn as Ag 98.7-50 mass%, Zn 1-40 mass%, Te 0.1-3.0 mass%, Cu 0.1-5.0 mass%, Sb 0.1-2.0 mass% Method for producing a system electrical contact material. 3. The method of claim 2,
A method for producing an Ag-oxide type electrical contact material, characterized by further adding at least one of 0.5 to 8.0% by weight of Sn, 1.0 to 6.0% by weight of In, and 0.1 to 0.3% by weight of Ni. The method of claim 3,
0.01-0.3 mass% of at least 1 sort (s) of Mn, Ga, Mg, and Bi was further added, The manufacturing method of the Ag-oxide type electrical contact material characterized by the above-mentioned. An Ag-oxide based electrical contact material prepared according to claim 1.