JPS58181837A - Electric contact material - Google Patents

Abstract

PURPOSE:To obtain an Ag-oxide composite electric contact material improved in resistances to fusion and attrition, by dispersing Bi-Sn and Sn oxides in an Ag matrix, and specifying alloying components. CONSTITUTION:The electric contact material prepd. by dispersing Bi-Sn oxide (Bi2Sn2O7) and Sn oxide (SnO2) in an Ag matrix by an internal oxidation method and adjusting metallic alloying components in it to 2-2.9wt% Bi, 6.1-10% Sn, optionally 0.1-2% in total of one or more of Ni, Co, Misch metal, Zn, etc. and the balance Ag, all being expressed in terms of metals. When this composite contact material is used as an electric switch or the like, it exhibits excellent result in both of resistances to fusion and attrition as compared with a conventional Ag-CdO contact.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrical contact material in which a metal oxide is dispersed in a 5g IJ square.

Mug-CdO contact materials are widely used as mug-oxide composite contact materials that utilize metal oxides. Ag
-Cd○ contact material is the contact resistance required for contact material,
Due to its average performance in terms of welding resistance and arc wear resistance, it is used in relays, power switches for household electrical equipment,
It is often used in the load current range of several amperes or more, such as electromagnetic switches for general industry.

However, in recent years, there has been a strong demand for improvements in contact resistance and insulation resistance of the various power switches mentioned above in accordance with safety regulations. On the other hand, as electric equipment becomes more semiconductor-based, various electronic components are desired to be made smaller, and power switches are no exception. This requirement is contradictory in terms of safety regulations such as reducing the distance between contacts, and in addition, recently, with the rapid increase in the cost of mug materials, it has become necessary to increase the size of the contacts from an economical point of view. There is a tendency to reduce the contact area, and as a result, there is a demand for materials that can handle a large switching load per unit area of the contact.

A contact material in which bismuth oxide is dispersed in an Ag matrix is a contact material with low contact resistance and excellent welding resistance.
The problem was found to be a large amount of wear and tear.

As a result of various studies to improve this point, the inventors first added Sn in addition to Bi oxide to Mug Mad IJ gas.
oxide is added, and both oxides are reacted to form Bi.
We proposed a material in which -Sn oxide (Bi25n20z) is dispersed.

This contact material shows good properties in terms of welding resistance and abrasion resistance, but as mentioned above, the recent trend is to reduce the shape of the contact and increase the switching load per unit area. Then, as the number of openings and closings increases, the contacts deform,
A mug-rich layer from which oxides were removed was formed in the periphery, which tended to deteriorate contact characteristics, particularly welding resistance. The cross section of the contact at this time is shown in FIG. In the figure, 1.1' is the contact spring, 2.2' is the mug-oxide contact, and 3.3' is the mug-rich layer. As the number of openings and closings increases, the mug-rich layer grows proportionally, so
The area of the mug-rich layer on the entire contact surface increases as if in proportion to the square of the number of openings and closings. As a result, the proportion of true contact points on the contact surface that exist in the mug-rich layer also increases, and as a matter of course, the mug-rich layer has poor welding resistance, so the number of times the contact welds is increased. begins to increase significantly.

The present invention has been made in view of these points, and it is an object of the present invention to provide an improved Mug-Bi25n207-based electrical contact material. That is, the inventors added Bi-Sno oxide (Bi2Sn207) to the Ag-7 trix.
As a result of continued improvement studies on materials containing dispersed
Sn oxide (
It has been found that increasing the amount of B1-8n oxide (Bi2Sn207) by a sufficiently large amount is effective.

Hereinafter, the electrical contact material of the present invention will be explained in detail.

The electrical contact material of the present invention has B1-5 in the Ag matrix.
n oxide (Bi25n207) and sn oxide (S
This is a mug-oxide composite contact material containing nO2), and the amount of oxide contained is Bi2 to 2.9 in metal equivalent value.
% by weight, Sn 6.1 to 10% by weight, and the balance is 5 g.

The above-mentioned mugma) In the IJ gas, oxide of Bi-Sn (Bi25n207) and oxide of Sn (5nO2)
In contact materials in which B125n207 is dispersed, there is an overall tendency for the welding resistance to increase as the Bi content, that is, the content of B125n207 oxide, increases.
As mentioned above, when a high load is applied to a small contact, if the content of B1 is large, the contact surface is significantly deformed, and the tendency shown in FIG. 1 is likely to occur. Therefore, even though the material is highly resistant to welding, as the number of openings and closings increases, welding tends to occur.

On the other hand, when the Sn content, that is, SnO2 increases.

Although the effect of improving the welding resistance of the material itself is small, the deformation described above is small and the tendency shown in FIG. 1 is unlikely to occur. Therefore, if the number of openings and closings increases, the rate of welding will eventually decrease. This phenomenon is
This is probably due to the instability of Bi25n207 in the thermal behavior of Bi25n20y and SnO2 against arc discharge and Joule heat, and also due to the difference in mechanical strength, hardness, etc. The Sn oxide (B12S02o7) is a Bi minide (
By heating an oxide of Sn (5nO2) at a molar ratio of 1:2 at a temperature within the range of 700 to 900°C, it is produced as an oxide having a yellow curb structure.

It has a melting point of 1200'C or more, exhibits sublimation properties, and can improve welding resistance by dispersing it in IJ gas. Therefore, as a method for dispersing Bi-Sn oxide in an Ag matrix, a so-called internal oxidation method is used in which a ternary alloy of Mug-Bi-Sn is heated in an oxidizing atmosphere to selectively oxidize B1 and Sn. However, if converted from the above molar ratio, the amount I of B4 in the ternary alloy and the weight y of Sn are '/x''= 0.57 (7) In the relationship, Bi
-Sn oxide (Bi25n207) can be generated. However, in this relationship, B1 and Sn alloyed with Mug are reliably Bi-S through internal oxidation.
It is difficult to convert it into the oxide of n (Bi25n207), and in particular, B1, which is difficult to dissolve in solid form in mug, segregates and becomes B1.
It tends to exist as monooxide (Bi203). As a result, when Bi oxide (Bi203) is present, as mentioned above, when a high load is applied to the contact surface with a reduced diameter, the contact surface becomes rough and deformed, resulting in an undesirable situation. . From this point of view, it is necessary to prevent B1 oxide from existing alone by internally oxidizing a ternary alloy in which a sufficient amount of Sn is arranged relative to the amount of bismuth. On the other hand, when the amount of Sn becomes excessive, the influence of Sn oxide (5n02) comes to strongly dominate the characteristics. For example, if a large amount of Sn oxide is contained, phenomena such as an increase in contact resistance or a decrease in machinability will occur. However, when a high load is applied to a small-diameter contact, an increase in contact resistance is likely to be prevented by the cleaning effect of the contact surface due to sublimation of B1-8n oxide, and the drawbacks of an excessive amount of SN are significant. eased.

The electrical contact material of the present invention has excellent contact properties for the purpose of the present invention due to the synergistic effect of the B1 and sn oxides with low sublimation temperatures and the tin oxides with high sublimation and decomposition temperatures as described above. However, in order to bring out these characteristics, the balance by weight should be made of mug. In these component compositions, B1 is within a range in which desirable characteristics can be obtained for the above-mentioned uses.

Furthermore, Sn is desirably more than 6% by weight in view of the strength against deformation described above, and is limited to an upper limit of 10% by weight in view of contact resistance, material processability, and the like.

In addition, in the material according to the present invention, additional oxides include Ni, Co, and Mitsushi metal.

Adding Zn oxide leads to improved contact characteristics. In particular, it has been recognized that the addition of Ni, Co, and Mitsushi metal reduces the amount of wear due to the extinguishing effect of arc discharge or the increase in material hardness. Furthermore, when Zn oxide is added, the effect of improving machinability is observed. The preferred addition range of these oxides is 0.1 to 2% by weight as a metal component.

EXAMPLES In order to make the invention described above more specific, examples will be shown next.

(Example) According to the composition of the present invention, Te, Mug, Bi, Sn,
Ni.

Go, Zn, Misosh Metal (Lantern,
(containing 93% by weight or more of rare earth metals such as cerium, neodymium, praseodymium, etc.) was weighed in a total of 20 og. This was dissolved, sprayed with pressurized nitrogen gas, and heated at 200 Orp.
It was injected onto a stainless steel disk with a diameter of 400~ and rotating at speeds of 0.5~1N and rapidly cooled.

Converts into flaky powder with a thickness of 0.1S or less. This allows B1, which tends to segregate, to be homogeneously dissolved in the powder, and as the amount of sn increases, the progress of internal oxidation in the next process is slowed down, so internal oxidation can be performed quickly, and machining as a final material is possible. improvement in performance is expected. The powder is then heated in air at 760° C. for 20 hours to selectively oxidize added metals other than mug, resulting in a powder containing an oxide having a matrix of mug. This powder was loaded into a cylindrical mold with a diameter of 2%, molded under a pressure of 8 tons/-, and further sintered at 900°C for 2 hours. Next, this sintered body is processed into a wire rod having a diameter of 2 to 2 by warm extrusion at 66°C. After that, cold working and annealing were repeated until the diameter was 1.
The wire rods were processed into wire rods with diameters of 2.7X and 8'X, and further processed into contact studs having a spherical head with a diameter of 2.7X and a radius of curvature of 8'X, and used as samples for contact opening/closing tests.

The contact characteristics were evaluated by a test using the circuit shown in FIG. That is, using an ASTM type tester as the switch S1, the contact force was 3o9, the opening force was 4og, and the opening/closing speed was 10
cm/sec, and the test load was a commercial power supply frequency of 60 Hz, a voltage of 125 V, and a diode protection resistor r.
= 2.4Ω, load R-26Ω, capacitance C=760μF
And so. Therefore, the peak of the rush current is 80 μm, and the steady state is 5 μm.

The switch S2 constitutes a circuit for discharging the charge of the capacitor C immediately before turning on the switch S1.

The evaluation of the contact characteristics was based on the number of times welded when opening and closing 3 x 10' under the above conditions, that is, the number of times welded in order to open and close the contacts. ! Number of times a force exceeding 9 was required and 3×10
This was determined by the amount of contact wear after opening and closing.

The test quantity was 6 pairs each, and the minimum and maximum values of each characteristic are shown in the following table. As a comparative sample, Mug-1d○ (CdO
: 13.5% by weight) The properties of the alloy are also shown.

(Margin below) As is clear from the above explanation and the results in the table.

The electrical contact material according to the present invention exhibits superior f values in both welding and wear characteristics compared to conventional mug-CdO contacts, and is of great industrial value. .

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the state of a conventional electrical contact material after an opening/closing test, and FIG. 2 is a wiring diagram of a test circuit for the electrical contact material according to the present invention. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 5'♂

Claims (2)

[Claims] (1) The main oxides dispersed in Mug Mado IJ gas are Bi, -8n oxide (Bi25n207) and S
n oxide (SnO2), whose metal alloy components are at least 2 to 2.9% by weight of Bi, S
An electrical contact material comprising 6.1 to 10% by weight of n, with the remainder being Ag. (2) The main oxides dispersed in the mug matrix are Bi-Sn oxide (Bi25n207) and Sn oxide (Sn02), and the metal alloy components thereof are at least B12 in metal equivalent value. ~2.9% by weight
, 6.1 to 10% by weight of Sn and a total of 0.1 to 10% of one of N1°CO, Mitsushmetal, and ZnO.
An electrical contact material characterized in that it contains 2% by weight and the remainder is mug.