JPS6056408B2 - electrical contact materials - Google Patents

Description

[Detailed description of the invention] The present invention relates to electrical contact materials, particularly Ag-SnO.

One In. O. Concerning improvements in contact characteristics. Ag-metal oxide based materials are mainly used for electrical contacts of low voltage switchgear such as electromagnetic contactors.

In particular, Ag-CdO contact materials are widely used because they have a good balance of wear resistance, welding resistance, and low contact characteristics, but they are not very desirable because they contain domium, which is harmful to the human body. . Therefore, there is an urgent need to develop alternative contact materials. Ag-SnO2 is an Ag-metal oxide contact material that does not contain Cd.
, Ag-In2o3, silver-ZnO, Ag-MnO, and composites of these have been studied. Among these, Ag-SnO. -1 Le 03 series contacts are Ag-Cd
It is said to have contact characteristics that are almost the same as or better than 0-series contacts, and is being used in practice. Ag-SnO.

-In. O. The Sn content of the system contact is 3 to 11% by weight, I
The n content is generally 1 to 6% by weight. The manufacturing method is usually to melt and cast an Ag-Sn-In alloy and then roll it into a plate, which is heated to a temperature of 3000C to 750' in an oxidizing atmosphere with an oxygen partial pressure of 1 and 9/CTI or more.
Internal oxidation treatment is carried out for several tens to several hundreds of hours at a temperature range of 50°C. In this contact material, Sn and I
As the content of n increases, the abrasion resistance, welding resistance, etc. of the contact improve, but the contact resistance increases and the temperature characteristics are adversely affected. Moreover, when these alloying elements increase, SnO is formed on the contact surface during the internal oxidation treatment process. A film is likely to be formed, making it difficult to obtain a uniform internal oxide structure. Furthermore, the workability of the alloy deteriorates, and cracks and other failures occur more frequently during internal oxidation treatment. In addition, the above production method has the disadvantage that internal oxidation in the atmosphere is extremely difficult, requires a high-pressure treatment container, and that the internal oxidation treatment time is extremely long. An object of the present invention is to overcome the problems of the prior art as described above and to provide an electrical contact material having the following features: (1) The internal oxidation treatment process can be simplified.

(2) It is possible to lower contact resistance while maintaining wear resistance and welding resistance.

(3) Contact characteristics can be changed arbitrarily depending on the purpose.

(4) It is possible to select a wide range of contact shapes, and there is almost no material loss, making it very economical.

As mentioned above, in Ag-metal oxide contact materials, as the amount of metal oxide dispersed in Ag increases, the wear and welding characteristics improve, but the contact resistance of the opposite contact increases. , which has a negative effect on temperature characteristics.

Therefore, it is important to determine the total amount of metal oxides dispersed in Ag in accordance with the design specifications of the magnetic contactor while balancing the characteristics. Further, as a method for manufacturing the Ag-Sn-1n type contact, it is preferable that internal oxidation treatment can be performed in the atmosphere and that the process can be simplified. From the above point of view, as a result of conducting various tests and studies on Ag-Sn-1n contact materials, we found that the Sn content was 10 to 15% by weight, the I
A having an n content of 2 to 6% by weight and the balance being Ag
It has been found that by preparing a g-Sn-1n alloy as an alloy powder with a particle size of about 150 μm or less and using it as a raw material, internal oxidation can be performed in the atmosphere and it can be put to practical use as a contact for a magnetic contactor. However, contact materials with this composition have excellent wear resistance, welding resistance, and life characteristics because the ratio of metal oxide to Ag is high, but Ag-Cd
It has the disadvantage of higher contact resistance than O-based contact materials, and as a result, its range of use as a contact for an electromagnetic contactor has had to be limited. Thus, the present inventor has developed an alloy structure that differs from the conventional manufacturing method and concept of electrical contact materials. As a result of our studies, we found that by changing the dispersion state of Ag-Sn-1n oxide particles and Kg particles, we were able to maintain the excellent wear resistance and welding resistance of Ag-Sn-1n contacts. We have discovered that it is possible to provide an electrical contact material that can improve temperature characteristics.

According to the present invention, Ag-Sn-1n alloy particles containing 12% by weight or more and 1% by weight or less of SnO2 and 2.5% by weight or more and 7% by weight or less of In2O3 in Ag, There is provided an electrical contact material in which particles consisting of only 30% to 70% by volume are mixed.

If the SnO2 content is less than 12%, when mixed with A-silicon to form a contact, wear resistance and welding resistance will be poor, and the alloy particles for contact will not be effective. Furthermore, if the SnO2 content is 18% or more, internal oxidation treatment of the alloy particles becomes difficult. In addition, In2O3 has a range of 2.5 to 7.0% Ag-
Contributes to internal oxidation of Sn-1n alloy particles, and
It is also ideal for improving wear resistance and welding resistance of contacts. The contact material according to the present invention is composed of oxide particles of an Ag-Sn-1n alloy and a part of particles containing only Ag.
The chisel particles have a three-dimensional continuous structure.

In this contact material, the Ag-rich portion plays the role of a passageway that easily conducts and diffuses heat when arcing occurs, mitigating the temperature rise on the contact surface, and the oxide layer provides resistance to welding and wear. Particles play that role. Oxide particles and Ag
The proportion of chisel and particles will vary depending on the required contact duty. If the Ag-rich portion is large, the temperature rise will be extremely small, but consumption will increase and welding resistance will also decrease. Furthermore, the proportion of Sn and In in the oxide particles is also an important factor. By using particles with a high content of Sn (51n), it is possible to obtain various alloy structures, and thereby the contact characteristics can be controlled arbitrarily.As a result of various studies, The optimum SnO2 content in the Ag-Sn-1n alloy particles is 1 weight% or more and 1 weight% or less, and the In2O3 content is 2.5 weight% or more and 7 weight% or less. Ag-Sn-1
The volume ratio of particles consisting only of Ag to n-based alloy particles is 30
It has been found that a range of 70% to 70% has good contact characteristics.

SnO2 and I in oxide particles of Ag-Sn-1n alloy
The reason for setting the total amount of n2O3 to 14.5% by weight or more is that if it is less than 14.5% by weight, it becomes difficult to arbitrarily control the volume of the Ag-rich portion, and the resistance of the Ag-Sn-1n alloy oxide particles themselves increases. This is because wearability and welding resistance are reduced.

In addition, Ag-Sn-1n alloy oxide particles
If the proportion of Ag particles is less than 30% by volume, the contact resistance will increase, and conversely, if the proportion of Ag particles exceeds 70%, the welding resistance will be extremely reduced.
The range of % (capacity) is appropriate. Furthermore, in the contact material of the present invention, the particle size of Ag alone or Ag-Sn-1
By changing the mixing ratio of the oxide particles of the n-based alloy and the Ag-only particles, it is possible to arbitrarily control the structure morphology, and therefore the contact characteristics can be arbitrarily controlled. .

Furthermore, the contact performance of the contact material of the present invention is higher than that of conventional Ag-C.
Almost equivalent to dO type contacts, and Ag-Sn-1
The temperature characteristics, which have been a drawback of n-type contact materials, are greatly improved. It also has the advantage of being non-polluting and harmless to the human body. Furthermore, the present invention can be applied to improve the performance of electrical contact materials manufactured by powder metallurgy methods. The following examples illustrate the manufacture of contact materials according to the invention and the results of their performance tests.

Example First, Ag-11Sn-4.51 was produced by the atomization method.
N-alloy powder (diameter 150 μm or less) was produced and subjected to internal oxidation treatment at 700° C. in the atmosphere.

Internal oxidation reduces the composition of this alloy to 13% SnO2.
, InO3 becomes 5%. Next, the ratio of Ag-only particles (diameter 44 μm or less) to the Ag-containing oxide particles is 36% and 54% by volume, and after mixing in a ball mill for a certain period of time, the next step is carried out. Two types of contact materials were manufactured. Molding (3t/c) → Sintering (800°CX 2 hours, in the atmosphere) → Hot pressing (7t/CT115)
(50° C. x 9 seconds) The compositions of the obtained contact materials (a) and (x) were as follows.

Next, a contact test was conducted on the manufactured contact material.

The contact test was conducted under the following conditions by incorporating contacts into electromagnetic contactors with rated currents of 26 A and 50 A. The results obtained are shown in the table below.

For comparison, the following three types of contact materials (c), (d), and (e) were also tested.

(c) Ag-13Sn02-51n203: This is a comparative product manufactured through the above processing steps without adding Ag powder to the alloy powder.

(d) Ag-14Cd0: A conventional product manufactured by a melt processing method.

(E) Ag-3.5Sn02-101n203: A conventional product manufactured by a melting process.

From the above results, it can be seen that the performance of the contact material of the present invention is almost the same as or better than that of the conventional product, although the tendency differs depending on the rated operating current.

In particular, the temperature rise value is reduced, and its usefulness is recognized.
The contact material of the present invention obtained in the above example uses Ag powder with a diameter of 44 μm or less and is mixed in a ball mill.
Almost the same characteristics can be obtained by mixing with a mold mixer.

Claims (1)

[Claims] 1 For Ag-Sn-In alloy particles containing 12% to 18% by weight of SnO_2 and 2.5% to 7% by weight of In_2O_3 in Ag, particles consisting only of Ag have a volume ratio of 30% to 18% by weight. An electrical contact material characterized by being mixed at a ratio of 70% to 70%.