JPH06346172A - Electrical contact material - Google Patents

Abstract

PURPOSE:To obtain an inexpensive material excellent in workability, wear resistance, and welding resistance by specifying copper, aluminum, chromium, and iron. CONSTITUTION:This electrical contact material has a composition consisting of, by weight, 30-70% copper, 1-11% aluminum, 3-9% chromium, and the balance Fe. An oxidation-resisting protective film can be formed by the aluminum. Further, the formation of an oxide film causing noise can be inhibited by the chromium. By this method, the inexpensive material excellent in workability, wear resistance, and resistance can be obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to electrical contact materials.

[0002]

2. Description of the Related Art Conventional electrical contact materials include Au alloys and P
T-based alloys, Ag alloys and the like are used depending on their respective applications. However, all of these metals are precious metals and are expensive, and one system cannot be used for all purposes. For example, Au-based alloys are very stable without being oxidized, but have the drawbacks that they easily cause welding and have a small current-carrying capacity, and are used only for small electric power. Also, Ag-based alloys have a contact resistance. Is the lowest
Although it is ideal as a contact material, it has the drawback that it forms sulfur and sulfide in the atmosphere to form a high-resistance film.
In addition, it is mechanically soft and has poor spring characteristics. Therefore, although Pd or the like is added, it becomes expensive, the resistance increases, and the electrical characteristics deteriorate.

[0003]

As described above, there has been a problem that the current electrical contact materials are inexpensive and have no good wear resistance and welding resistance. The present invention provides a material that has excellent wear resistance and welding resistance and is inexpensive, although it has a slightly higher resistance value than these existing contact materials.

[0004]

The present invention has been obtained as a result of various experiments in order to fundamentally solve the above-mentioned problems, and the gist thereof is that copper is used in a weight ratio. Content of 30-70%, aluminum content of 1-
It is an electric contact material containing 11%, a chromium content of 3 to 9%, and the balance of iron and inevitable impurities.

[0005]

The present invention will be described in detail below. As an electric contact material, an alloy of copper and iron was studied in order to be inexpensive, have low resistance and obtain appropriate strength. However, it became clear that this binary alloy has very poor workability and cannot be manufactured by a normal process. Therefore, as a result of conducting various experiments, it was found that the addition of chromium and aluminum enhances the workability, and is excellent in wear resistance and welding resistance as a material for electrical contacts.

The reasons for limiting the composition of the material of the present invention will be described below. Iron and copper are elements that cause two-phase separation, and they hardly form a solid solution at room temperature, and even at 1000 ° C., the solid solution of iron in copper is about 3%. That is, the metal structure is a mixed gas of an iron phase and a copper phase, and the ratio is almost constant regardless of the temperature. However, the reason for setting the copper content to 30 to 70% is that if it is less than 30%, the oxidation resistance is deteriorated, and if it is more than 70%, the room temperature and the cooling strength are lowered, and the cost is increased. The above range was set.

Aluminum is an important element for forming an oxidation resistant protective film, and also serves as a solidifying material for suppressing α-γ transformation. Aluminum content of 1-11
%, Because if it is less than 1%, the workability is not good. On the other hand, with respect to the upper limit concentration of aluminum, aluminum is solid-solved in steel at about 9% at room temperature, but if it is higher than that, β phase appears, so that the workability is remarkably lowered and the practicality is poor. However, in the iron-copper material, as the addition amount of aluminum increases, more aluminum comes into solid solution in the iron phase than in the copper phase, so that it can be substantially dissolved up to 11%. Also in the experiment, if the content exceeds 11%, cracks occur during processing during contact production, resulting in a significant decrease in product yield.

Next, the effect of chromium will be described. The contact material is used for a long time, but if it is not used for a long time, an oxide film is formed on the surface, which causes noise. However, it became clear that the addition of chromium reduces this noise. It is thought that this is because chromium has improved the oxidation resistance of the alloy. The amount of chromium added is
It has been found that 3-9% is optimal. If it is 3% or less, this effect is thin, and if it is 9% or more, the electric resistance becomes large, and it is not worth the cost.

Next, the manufacturing method will be described. Each metal is mixed in a predetermined composition and melted. The furnace used is
A vacuum furnace or an atmospheric furnace can be used. 1500
After the temperature is raised to about ℃, it is poured into a mold and cooled. After that, rolling is performed to form a plate. After that, wire drawing is performed for the sliding material, and cutting and processing are performed for the open / close type contact material before use.

[0010]

【Example】

[Example 1] 50 kg of copper and 5 kg of aluminum content,
Chromium content of 7kg and iron of 38kg were blended together in a vacuum furnace for 15
The temperature was raised to 20 ° C. and the mixture was melted and poured into a mold. The analysis results at this time were: copper: 50% by weight, aluminum: 5% by weight, chromium: 7% by weight, iron: 38% by weight. This was rolled and drawn into a wire having an outer diameter of 2 mm and a length of 5 mm. this,
The resistance elements were assembled as a brush for sliding by bundling them in a plane. As the test method, the volume knob was rotated 10,000 times, and the characteristics after a predetermined number of rotations were examined. The investigation items are contact resistance, noise characteristics, and the degree of wear. The results are shown in Table 1. In addition, Ag-20% Pd material was used for the comparative example.

[0011]

[Table 1]

As is clear from Table 1, in the comparative example, the surface roughness became large, and it became unusable after 30,000 times.
On the other hand, in the example of the present invention, it could be used without problems even after 60,000 times.

Example 2 Copper (50 kg), iron (38 kg), aluminum (10 kg) and chromium content (4 kg) were blended, heated to 1560 ° C. in a vacuum furnace, melted and poured into a mold. The analysis results at this time are as follows: copper: 49% by weight, aluminum: 9.
It was 8% by weight, chromium: 4% by weight, iron: 37% by weight. This was rolled and drawn into a wire having an outer diameter of 2 mm and a length of 5 mm. Similar to Example 1, these were bundled in a plane to form a sliding brush, and a resistance element was assembled. As the test method, the volume knob was rotated 10,000 times and the characteristics after that were investigated. The investigation items are contact resistance, noise characteristics, and the degree of wear. The results are shown in Table 2. In the comparative example, Ag-
10% Pd material was used.

[0014]

[Table 2]

As is clear from Table 2, in the comparative example, the surface roughness was large, and the sample was unusable after 25,000 times, whereas in the examples of the present invention, it could be used without problems even after 70,000 times.

Example 3 35 kg of copper, 52 kg of iron, 9 kg of aluminum and 4 kg of chromium were weighed, heated to 1560 ° C. in a vacuum furnace, melted and poured into a mold. The obtained material was rolled and swaged to form a disk having an outer diameter of 20 mm and a length of 10 mm. This was attached to the contact part of the vacuum switch. The vacuum switch is for opening and closing in a container whose inside is kept in a vacuum. Since it does not break the arc when opening and closing in the atmosphere, it is performed in vacuum and is used for high pressure opening and closing. Vacuum switch test voltage is 6000
It was set to V, and the power supply was cut off 1000 times. The surface condition and contact resistance after the test were investigated. A Pt-Ni-based material was used for the comparative example. Ni was 5%. The results are shown in Table 3.
Shown in.

[0017]

[Table 3]

In the comparative example (Pt-Ni system), after that, 20
It became unusable after 00 times.

[0019]

As described above, according to the present invention, it is possible to provide a material which is excellent in wear resistance and welding resistance and is inexpensive.

Claims (1)

[Claims] 1. A copper content of 30 to 70%, an aluminum content of 1 to 11%, and a chromium content of 3 to 9 by weight.
%, The balance being iron and unavoidable impurities, which is an electric contact material.