JPS5816039A - Manufacture of electrical contact material - Google Patents

Abstract

PURPOSE:To manufacture a silver-oxide type electrical contact material with superior thermal stability and low contact resistance by subjecting the whole of an alloy to internal oxidation treatment at a low temp. under a low pressure of atmospheric oxygen, raising the temp. or the pressure of oxygen, and carrying out internal oxidation treatment >=1 time. CONSTITUTION:The whole of an alloy such as an Ag-Sn-In-Ni alloy is subjected to internal oxidation treatment at a low temp. such as 450-700 deg.C under a low pressure of atmospheric oxygen such as <=5 atm. After raising the oxidation temp. and/or the pressure of oxygen, internal oxidation treatment is carried out >=1 time. Thus, by repeating internal oxidation >=2 times under different conditions, the hardness distribution, heat resistance, etc. are considerably improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a silver-oxide contact material.

Requirements for electrical contact materials include high welding resistance, high erosion resistance, maintaining low contact resistance, and high arc wear resistance.

Conventionally, as a method for manufacturing electrical contacts that meet these requirements, an internal oxidation method in which a silver alloy is heated in an oxidizing atmosphere has been widely adopted.

The properties of internally oxidized alloys are significantly influenced by the oxidation conditions. In particular, the precipitation reaction and the shape, size, and distribution of the precipitated oxide particles change depending on the oxygen pressure and oxidation temperature, and the mechanical strength, heat resistance, and electrical properties of the alloy are greatly affected. - In terms of heat resistance and wear resistance, it is desirable for electrical contact materials to have oxide particles precipitated in the internal oxidation region uniformly distributed in an optimal size and shape. In addition, from the viewpoint of electrical conductivity and low contact resistance, it is necessary that the contacts have appropriate hardness and high electrical conductivity.

Conventionally, when internally oxidizing electrical contact materials, the oxidation temperature and atmospheric oxygen pressure were kept constant or varied, and the entire alloy was internally oxidized only once.

With this method, when oxidation progresses internally, the oxide becomes coarse, the dispersion state of the oxide particles becomes uneven, and the shape and size of the oxide particles cannot be adjusted, resulting in high hardness and low conductivity. There are drawbacks to doing so.

The present invention has been made in view of the above points, and provides a method for manufacturing a silver-oxide electrical contact material that has good machinability, excellent welding and heat resistance, and good electrical conductivity.

That is, the alloy is heated to a low temperature of 450°C to 700°C, and
The whole is subjected to internal oxidation treatment under a low atmospheric oxygen pressure of up to about 5 atm, and then the oxidation temperature and/or the atmospheric oxygen pressure are raised twice to higher than the first oxidation temperature and atmospheric oxygen pressure. This is a method of manufacturing an electrical contact material, characterized by performing the above internal oxidation treatment.

Next, the features of the present invention will be described. The present invention was developed as a result of considering the hardness distribution of the contact, mechanical properties such as high-temperature hardness, heat resistance, and contact resistance; It was found that there was a significant improvement. In other words, in order to uniformly distribute the oxide particles, internal oxidation at a low temperature of 450° C. to 700° C. results in better particle distribution than in high temperature oxidation, and the hardness distribution in the oxidation region becomes average. However, due to the low temperature oxidation, the hardness of the alloy is high, the precipitation reaction does not proceed sufficiently, and the electrical conductivity is low. -On the other hand, when internal oxidation is performed at high temperature and high pressure, the precipitated oxide particles tend to become coarse, so the distribution of the oxide particles becomes uneven.

It has been found that it is effective to perform internal oxidation treatment two or more times in order to homogenize the distribution of oxide particles and to obtain appropriate hardness and high conductivity. That is, by oxidizing at a low temperature of 450 DEG C. to 700 DEG C., the diffusion of solute elements is suppressed and the precipitated oxide particles are uniformly distributed, thereby satisfying the basic requirements of wear resistance and welding resistance. Next, internal oxidation is carried out under conditions of elevated oxidation temperature and oxygen pressure to sufficiently carry out the oxide precipitation reaction, and the conductivity is increased by growing the particles precipitated by low-temperature oxidation and adjusting the shape and size of the particles. , to make the hardness distribution uniform and appropriate.

By combining the internal oxidation treatments, the characteristics of the dispersion-strengthened internal oxidation alloy can be exhibited, and an electrical contact material with excellent welding resistance, wear resistance, and low contact resistance can be obtained.

In order to effectively exhibit the effect of combining two or more internal oxidations, the temperature should be as low as 450°C to 700°C and the oxygen pressure should be reduced to about 5 atzOs to accelerate the reaction in the low-temperature oxidation and to remove the oxides. In order to prevent agglomeration, and then to increase the oxidation temperature rather than the oxygen pressure in the second internal oxidation treatment, it is desirable to adjust the precipitated particles and promote the precipitation reaction. The reason why the lower limit of the oxidation temperature was set at 450° C. in the first internal oxidation treatment is that if the temperature is lower than this, the oxidation time becomes extremely long and is impractical. The upper limit was set at 700°C because the effect of the second time becomes smaller if the temperature is increased any higher. Oxygen pressure is about 5 atm.

The reason why it is set at 02 is because if it is increased more than this, the effect of the second time will be smaller.

The second internal oxidation may also be carried out in several steps, and the temperature may be increased only or by increasing oxygen pressure.

Next, the present invention will be specifically explained using examples.

Alloy composition Ag-5,O5n-8,0I n-0,1Ni
After melting and casting to form an ingot, specimens of 10XIOX1#LIL were cut out from the ingot, and then internally oxidized under the oxidation conditions shown in Table 1'. The results of measuring the hardness distribution and electrical conductivity (%IAC9) of this alloy are shown in Table 1. In order to investigate the high-temperature properties of the products of the present invention, high-temperature hardness was measured. The results are shown in Figure 1. l is A in Table 1, 2 is D in Table 1
It is.

As is clear from the results shown in Table 1, all contact alloys (A-C) that have undergone internal oxidation treatment two or more times have improved conductivity.
It was confirmed that the hardness distribution became uniform.

Next, a contact test was conducted to examine the welding resistance and low contact resistance of the product of the present invention. The alloy made with the alloy composition and internal oxidation conditions shown in Table 1 was processed and a copper screw was attached to form a 5J'x 1.
4x2.5*x2.5x80R contacts were obtained.

This composite contact was incorporated into a commercially available safety breaker, and temperature tests and short circuit tests were conducted under the following conditions to evaluate its welding resistance and low contact resistance. The results are shown in Table 8.

Temperature test ■Voltage AC220V, current 150A, power factor α8. 50 times of opening and closing ■Voltage AC 220V, current 20A, power rate o, 8. 5000 times of opening/closing ■ Voltage AC 220V, current 20A, temperature rise measurement of contact part Short circuit test
220V, current 150A, power factor o, 8. 50 times of opening and closing Voltage AC 21V, current 1500A, power factor 0.751 pole 0-C [now 2 poles 0-CC key 2 poles Co] Repeat until welded, and at the same time observe the amount of arc generation above Table 8 As is clearer, it was confirmed that by performing the internal oxidation treatment two or more times, the temperature rise value was lower than that when the internal oxidation treatment was performed only once, and excellent welding resistance was exhibited.

As explained above, since the electrical contact material of the present invention is a contact material that has been sufficiently internally oxidized, it has excellent thermal stability, low contact resistance, and excellent welding resistance. The value is great.

[Brief explanation of drawings]

Figure 1 is a diagram showing the hardness at high temperatures of a conventional alloy and the alloy of the present invention, and Figures 2 and 8 are micrographs of cross sections of the alloy according to the present invention magnified 100 times and 1,000 times, respectively. . l2 Invention alloy 2: Conventional alloy shore 1

Claims (1)

[Claims] (1) In the method for producing a silver-oxide-based electrical contact material,
The alloy is first subjected to internal oxidation treatment at a low temperature of 450°C to 700°C and a low atmospheric oxygen pressure of 5 atm or less, and then the oxidation temperature and/or oxygen pressure are changed to - A method for producing an electrical contact material, characterized by performing internal oxidation treatment at least once at elevated temperature and oxygen pressure.