JPS6227143B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing 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. Electrical contact materials are designed so that the oxide particles that precipitate in the internal oxidation area have an optimal size and
It is desirable that the shape be uniformly distributed. 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 electrical contact materials are subjected to internal oxidation treatment,
Internal oxidation treatment has been carried out over the entire area of the alloy only once by keeping the oxidation temperature and atmospheric oxygen pressure constant or varying it. In 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.
It has the disadvantages of high hardness and low electrical conductivity. 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 conductivity. In other words, the alloy is heated to 450℃~
The entire body is internally oxidized at a low temperature of 700°C and a low atmospheric oxygen pressure of approximately 5 atm.Then, the oxidation temperature and/or atmospheric oxygen pressure are changed to the first oxidation temperature and atmospheric oxygen pressure. This is a method for producing an electrical contact material, characterized in that internal oxidation treatment is performed two or more times at a pressure higher than the pressure. Next, the features of the present invention will be described. As a result of considering the hardness distribution of the contact, mechanical properties such as high-temperature hardness, heat resistance, and contact resistance, the present invention has been developed to improve the hardness distribution heat resistance by performing internal oxidation two or more times under different conditions. It turned out that there was a huge improvement. In other words, in order to uniformly distribute oxide particles, if internal oxidation is performed at a low temperature of 450°C to 700°C, the particle distribution will be better than in high temperature oxidation, and the hardness distribution in the oxidation region will be averaged. However, since the oxidation is performed at a low temperature, 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 internally oxidized at high temperature and high pressure, the precipitated oxide particles tend to become coarse, so the distribution of the oxide particles becomes non-uniform. 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°C to 700°C, the diffusion of solute elements is suppressed and the precipitated oxide particles are uniformly distributed, 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 particles precipitated by low-temperature oxidation are grown to adjust the shape and size of the particles, thereby increasing the electrical conductivity. increase,
Uniform and appropriate hardness distribution. By combining internal oxidation treatments, it is possible to exhibit the characteristics of a dispersion-strengthened internal oxidation alloy and obtain an electrical contact material with excellent welding resistance, wear resistance, and low contact resistance. In order to effectively demonstrate the effect of combining two or more internal oxidation treatments, it is necessary to use a low temperature of 450℃ to 700℃ and an oxygen pressure of about 5 atm.O ₂ to promote reaction and oxide aggregation in low temperature oxidation In the second internal oxidation treatment, it is desirable to increase the oxidation temperature rather than the oxygen pressure in order 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 not practical. Also, the upper limit is 700
The reason why the temperature was set at ℃ is because the effect of the second time becomes smaller if the temperature is raised any higher. The reason why the oxygen pressure was set at approximately 5 atm.O ₂ is because if it were raised any higher, the effect of the second injection would be smaller. The second internal oxidation treatment may be divided into several times and the temperature may be increased sequentially or by increasing oxygen pressure. Next, the present invention will be specifically explained using examples.
After melting and casting the alloy composition Ag-5.0Sn-3.0In-0.1Ni to make an ingot, 10×
A specimen of 10 x 1 mm was cut out and then internally oxidized under the oxidation conditions shown in Table 1. The results of measuring the hardness distribution and electrical conductivity (%IACS) 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. 1 is A in Table 1, and 2 is D in Table 1.

[Table] As is clear from the results shown in Table 1, it was confirmed that all contact alloys (A to C) subjected to internal oxidation treatment twice or more had improved conductivity and uniform hardness distribution. Next, a contact test was conducted to examine the welding resistance and low contact resistance of the product of the present invention. The alloys prepared with the alloy composition and internal oxidation conditions shown in Table 1 were processed and attached with copper screws to obtain contacts of 5φ x 1.4 x 2.5φ x 2.5 x 30R. 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 3. Temperature test Voltage AC220V, current 150A, power factor 0.8, number of opening and closing times 50 times Voltage AC220V, current 20A, power factor 0.8, number of opening and closing times
5000 times Voltage AC220V, current 20A, contact temperature rise measurement short circuit test Voltage AC220V, current 150A, power factor 0.8, number of switching: 50 times Voltage AC220V, current 1500A, power factor 0.75 1 pole O - Co = 2 poles O ―Co〓Repeat until welding two poles of Co, and observe the amount of arc generated at the same time.

【table】

[Table] As is clear from Table 3 above, it was confirmed that by performing internal oxidation treatment two or more times, the temperature rise value was lower than when it 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 the drawing]

FIG. 1 is a diagram showing the hardness at high temperatures of a conventional alloy and the alloy of the present invention, and FIGS. 2 and 3 are micrographs of cross sections of the alloy according to the present invention magnified 100 times and 1000 times, respectively. 1... Alloy of the present invention, 2... Conventional alloy.

Claims (1)

[Claims] 1. In the method for manufacturing silver-oxide electrical contact materials, 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 oxidized. A method for producing an electrical contact material, which comprises carrying out one or more internal oxidation treatments at a temperature and/or oxygen pressure higher than the first temperature and oxygen pressure.