JPS6018737B2 - electrical contact materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electrical contact materials, particularly Ag-metal oxide composite contact materials.

Ag-Cdq contact materials are widely used as Ag-oxide-based contact materials.

Ag-Cd○ contact material not only exhibits excellent properties on average in terms of performance such as contact resistance, anti-seizure, and wear resistance required for contact materials, but also has sufficient machinability for practical use. Therefore, they are often used in load current ranges of several amperes or more, such as relay no-fuse breakers and power switches for household electronic equipment. However, in recent years, as safety regulations have become stricter for various power switches,
Contact materials are now required to have better properties than ever before. Especially in household electrical equipment,
Switches are required to be easier to operate and more compact, and on the other hand, there is a strong desire to improve performance in terms of both welding, which can lead to failure from a safety standpoint, and wear and tear, which can lead to deterioration of dielectric strength. Furthermore, as shown in the figure, in devices that obtain DC power for operation by directly rectifying AC power from commercial power supply 1, as the anti-surge current characteristics of diode 2 have improved, a resistor for diode protection has been added. The resistance value r of 3 is made extremely small,
There is a tendency to try to reduce the operating power of equipment as much as possible. This causes an excessive inrush current to the switch 4, and when performing single-wave rectification as shown in the figure, a gutter characteristic occurs in the load current of the switch 4, so it is Similarly, only the switch contacts on one pole side become extremely worn out due to relocation, resulting in inoperable failures of the switch. From this point of view as well, it is desired to improve the resistance to settling and abrasion. Note that 5 in the figure is a load, and 6 is a capacitance. In view of the above points, the present invention provides Ag-C
The present invention provides a contact material that can replace the d○ contact material, and basically proposes improvements in the properties of Ag-Bi203 contact material.

A contact material in which Bi2Q is dispersed in an Ag matrix is a contact material with low contact resistance and excellent welding resistance, as disclosed in Tokusekki Sho 52-1 Paper No. 56, but The drawback is that there is a lot of wear and tear.

The inventors conducted various studies to improve this point, and developed Ag
We have developed a material in which ln203 is dispersed in addition to Bi203 in the matrix. However, even with this material, if it is used in an application where the load current has polarity, as shown in the figure, one pole of the switch contact will be abnormally worn out due to transfer, and it may not be possible to obtain satisfactory results. It didn't work out. The inventors added Bi2 in the top-packed g matrix.
We continued to improve the material in which 03 and ln203 were dispersed, and added Sn oxide to change Bi203 to Bi-S.
By using the n oxide Bi2Sn207, it was possible to see a remarkable improvement in the contact opening/closing performance. That is, the material of the present invention contains an ln oxide (ln203) and a Bi-Sn oxide (Bi2
Sn207) is dispersed as the main oxide, and B
Depending on the composition ratio of i and Sn, Bi oxide (Bi20
3) or an Ag-oxide composite contact material containing a small amount of Sn oxide (Sn02), the contained component composition of which is Bil. 5 to 5% by weight, ln3 to 8% by weight (excluding 3% by weight), Sno. The desired performance can be observed and achieved in a relationship of 5 to 4% by weight and the balance being Ag.

In particular, in a light actuation switch with a large inrush current as shown in the figure, a significant improvement in opening and closing performance can be expected. Next, the material of the present invention will be explained in more detail.

The contact material according to the present invention has ln oxide (ln203) and Bi-Sn oxide (Bi2S
n207) are dispersed and their synergistic action brings out the contact characteristics. The latter oxide (Bi2S~0
7) is a Bi oxide (Bi203) and a Sn oxide (
700 to 900q of Sn02) at a molar ratio of 1:2
When heated at a temperature within the range of 0.05 to 30.0 m, it is produced as an oxide with a pyrochlore structure. Its melting point is 1200° C. or higher, it exhibits sublimation properties, and by dispersing it in an Ag matrix, it has a remarkable effect of improving settling resistance and transfer wear. Therefore, in the Ag matrix, the above ln oxide, Bi-Sn
As a method of dispersing the oxide of Ag-1n-Bi-
A quaternary alloy of Sn is heated in an oxidizing atmosphere to form ln,B
A so-called internal oxidation method is used to selectively oxidize Bi and Sn, but in terms of Bi and Sn, when converted from the above molar ratio, Bi weight x and Sn weight y in the quaternary alloy are y/x.
A Bi-Sn oxide (Bi2S mountain 07) can be generated in the relationship of 0.57.

However, since Bi tends to segregate in alloys, it is difficult to reliably convert it into Bi-Sn oxides by internal oxidation treatment, and Bi oxides and Sn oxides are present in slightly heavy amounts alone. Sometimes. Naturally, if the value of y/x is greater than 0.57, the chances of Bi oxide existing alone will decrease, and S
The oxide content of n increases. The value of y/x above is 0
．． It is clear that if it becomes smaller than 57, the opposite tendency will occur. However, when Sn oxide increases alone,
Although the amount of wear mentioned above is reduced, the contact resistance increases and the workability deteriorates, so it is preferable that the value of y/x is 2 or less. On the other hand, Bi alone increases, which is not suitable for the purpose of the present invention. Such a phenomenon occurs when an oxide of ln coexists. On the other hand, when there is a large amount of ln oxide, it reacts with the oxide of Sn,
The contact resistance increases significantly, and the resistance to settling tends to deteriorate at points where the opening/closing speed of the switch contact is slow. Naturally, there is a limit to the amount of oxide that can be dispersed in the Ag matrix. be. The metal composition of the Ag-oxide contact material of the present invention to bring out excellent contact properties is as follows:
At least Bill. 5-5% by weight, ln3-8% by weight (
However, 3% by weight is excluded), Sno. It consists of 5 to 4% by weight and the balance being Ag. The minimum amounts of Bi, ln, and Sn are the lower limit values at which the effect of addition is recognized for the intended use of the material according to the present invention. Also, the maximum amount of each is
Regarding Bi, if it exceeds the solid solubility limit when producing an alloy ingot as shown in the examples below, it tends to become unbalanced. As a result, Bi oxide is unevenly distributed alone in the Ag matrix, leading to an increase in consumption. This value is limited to avoid this phenomenon. As mentioned above, ln is a value that is limited in terms of portability when the contact resistance and the opening/closing speed of the switch contact are slow. Sn is added to convert Bi oxide into Bi-Sn oxide and eliminate transfer consumption, but in the presence of ln oxide, as the amount added increases, the contact resistance tends to increase and the processing hall is also limited to the amount mentioned above. In addition, in the material according to the present invention, addition of a certain amount of Ni or Co oxide as an additive oxide leads to improvement in contact characteristics. In particular, it has been found that the amount of wear and deformation can be reduced due to the quenching effect of arc discharge or the increase in material hardness. The amount that can be added is 0.5% by weight or less in the metal synthesis composition, and the amount in which the effect of addition is recognized is 0.05% by weight. If it is added in an amount exceeding the above amount, it will segregate during ingot production as shown in Examples below, and as a result, it will not be homogeneously dispersed in the Ag matrix, resulting in deterioration of processability. Moreover, adding too much is not desirable because it has an adverse effect on solubility resistance. The materials of the present invention explained above will be explained in more detail based on Examples.

According to the composition of the present invention, Ag, Bi, ln, Sn and Ni, Co were dissolved in a total amount of 200 ta, Ag-Bi-ln-
An ingot containing Sn as a main component was produced.

Melting was carried out using an alumina crucible in an argon atmosphere using a high frequency furnace. The molten metal was cast into a mold measuring 15 x 30 x 7 m3. The ingot thus produced was immediately ground into scale-like chips with a thickness of 1 willow or less using a rolling mill. Usually, Ag alloys containing 1% by weight or more of Bj have almost no cold workability, so the thickness is 1% by weight.
When five ingots are rolled, they naturally crack and are crushed into scaly chips. This is 700oo
The sample was heated in air for 60 hours to selectively oxidize Bi, In, Sn, etc. Next, this was made into chips with a thickness of 0.2 or less using a rolling mill again. At this time, the oxide particles dispersed in the Ag matrix by the above oxidation treatment are
It has a great impact on machinability when it is pulverized and made into a final wire rod. After the chips with a thickness of 0.2 mm or less are cleaned, they are loaded into a cylindrical shape with a diameter of 8 mm.
Molded with ton/ground pressure. Next, this molded body was
It was heated and brazed in air at a temperature of 80 qo for 2 hours. Furthermore, this sintered body was loaded into a warm heating mold with a diameter of 20.5 legs, and
After applying a pressure of 0,000,8 tons/kg for 1 minute, sintering was performed again in air at a temperature of 780 q0 for 4 hours. This non-consolidating body was then processed into a wire rod with a diameter of 3 ribs by warm extrusion of 550 qo. Finally, after annealing at 700° C. for 1 hour, it was processed into a contact stud having a spherical head with a diameter of 5 ribs and a curvature radius of 7, and used as a sample for a contact opening/closing test. Contact characteristics were evaluated by tests performed using the circuit shown in the figure.

That is, using an ASTM type tester as the switch S, the opening/closing conditions were configured such that the contact force was 30 mm, the separation force was 40 mm, and the opening/closing speed was 10 skins/second, and the commercial power supply voltage was 10 w as the test load.
, 60Hz, diode protection resistor r = 0.50, load R = 200, capacity C = 1140μF (350μF for charging and discharging)
W. 380〃F capacitors were connected in parallel). Therefore, the maximum peak of inrush current is 28
2A, Hiroshi Tsunejo. The evaluation of the contact characteristics is based on the number of welds during 2×n opening/closing under the above conditions, that is, the number of times a force exceeding 40 degrees was required to open the contact, and the wear of the contact after 2×n opening/closing. This was determined based on the amount of consumption, especially the amount of consumption on the positive electrode side. The number of test samples was 6 pairs each, and the minimum value of each property is shown in the table. For reference, Ag-Cd○ is used as a comparison sample.
Test results (based on internal oxidation method) are also shown. As is clear from the results in the table, the contact material according to the present invention exhibits extremely superior values in both portability and wear characteristics as compared to the conventional Ag-CdO contact.

The simple explanatory drawings are for explaining one example of a typical usage form of the electrical contact material according to the present invention.

Claims (1)

[Claims] 1. The main oxide dispersed in the Ag matrix is In.
and Bi-Sn oxide, in which the metal synthesis components are Bi1.5 to 5% by weight and In3 to 8% in terms of metal.
% by weight (not including 3% by weight), 0.5 to 4% by weight of Sn within a range not exceeding twice that of Bi, the balance being Ag
An electrical contact material characterized by a proportion of 2 The main oxide dispersed in the Ag matrix is In
and Bi-Sn oxide, in which the metal synthesis components are Bi1.5 to 5% by weight and In3 to 8% in terms of metal.
% by weight (excluding 3% by weight), 0.5 to 4% by weight of Sn within a range not exceeding twice that of Bi, and 0.05 to 0 of at least one of Ni or Co.
．． An electrical contact material characterized in that the proportion is 5% by weight and the balance is Ag.