JPS6018738B2 - 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-CdO contact materials are widely used as Ag-metal oxide contact materials.

Ag-Cd○ contact material not only shows excellent performance on average in terms of properties such as contact resistance, welding resistance, and arc wear resistance required for contact materials, but also has Cd○, which is a relatively soft oxidation material. Since it is a material, the Ag-Cd○ material that contains it has sufficient machinability for practical use, so it can be used for loads of several amperes or more, such as relays, no-fuse breakers, and power switches for household electronic equipment. It is often used in electric current castles. However, in recent years, as safety regulations have become stricter for various power switches, contact materials have become increasingly strict.
More characteristics than ever before are required. In particular, power switches for household electrical equipment are required to be light in operation and compact, and on the other hand, from a safety standpoint, there is a risk of welding, which makes it impossible to separate, and arc consumption, which causes insulation deterioration. Improvement in performance is strongly desired. In addition, in recent years, with the rapid rise in the cost of Ag materials, there has been a trend to reduce the size of contacts from an economic standpoint, and as a result, the switching load per unit area of contacts has decreased. There is a need for materials that can increase the amount of In view of the above points, the present invention provides a contact material that can replace Ag-Cd○ contact material, and basically proposes improvements in the characteristics of Ag-Bi203 contact material. It is. A contact material in which Bi203 is dispersed in an Ag matrix is a contact material with low contact resistance and excellent adhesion resistance, as disclosed in Japanese Patent Laid-Open No. 52-133564, but it has drawbacks. , it was observed that the amount of arc consumption was large.

In order to improve this point, the inventors conducted various studies and developed A.
The material, in which Bj203 and Sn02 are dispersed and reacted in the g matrix, and converted into a composite oxide of Bi and Sn (Bi2S mountain 07), significantly improves arc wear resistance and also has excellent welding resistance. , it was found that it showed an improvement effect and was published. However, as mentioned above, the recent trend has been to reduce the shape of the contacts and increase the switching load per unit area. Begin to.

A cross section of the contact at this time is shown in FIG.
In the figure, 1 and 1' are bush point springs, 2 and 2' are Ag-oxide contacts, and 3 and 3' are Ag-rich layers. As the number of openings and closings further increases, the Ag-rich layer grows proportionally, so that the area of the Ag-rich layer on the entire contact surface becomes approximately proportional to the square of the number of openings and closings. As a result, the proportion of points in direct contact on the contact surface that are present in the Ag-rich layer is also proportional to the square of the point. Naturally, Ag
Since the welding-rich layer has poor adhesion resistance, the number of contacts that occur at the port begins to increase significantly. The trend is shown in Figure 2.
With respect to the number of openings and closings, the cumulative number of occurrences of sticking roughly shows a squared curve. The inventors continued to improve the material in which Bi-Sn oxide (Bi2S mountain 07) was dispersed in the Mug matrix, and found that ln and Zn oxides were used as a method to prevent the formation of an Ag-rich layer. It was found that adding and containing chlorine was effective. In this case, simply adding ln oxide is sufficient to prevent the formation of an Ag-rich layer, but adding ln oxide in a situation where Sn oxide is present significantly Since this significantly impairs workability, using Zn oxide while suppressing Sn oxide makes it possible to obtain a material suitable for the use of the material of the present invention. Next, the material of the present invention will be explained in more detail.

The material of the present invention has Bi-Sn oxide (Bi2S mountain 07) dispersed as the main oxide in the Ag matrix, and Sn oxide (S
n02), and in addition, ln oxide (1 ratio 0
3) and Ag in which a small amount of Zn oxide (Zn○) is dispersed.
It is a monoxide composite contact material. A part of the Zn oxide reacts with the Bi oxide (Bi203) to form a Bi-Zn oxide (for example, Z-ship i407) that has a melting point lower than the melting point of Ag, which improves the workability of the material. Indicates the function of improving. However, on the other hand, when Zn oxide reacts with Sn oxide, it may generate S-04 with a spinel-type structure and deteriorate workability.
It is not preferable to coexist with a large amount of oxides. The metal oxides dispersed in the Ag matrix of the material of the present invention are as described above, and the content thereof is, in terms of metal, when Bi exceeds 2% by weight and Sn exceeds 5% by weight. 2
The content is more than 4% by weight and up to 8% by weight without exceeding twice the amount, ln is 0.5 to 5% by weight, Zn is 0.1 to 4% by weight, and the balance is Ag. In this compositional ratio relationship, the desired performance can be determined and achieved, and a significant improvement in switching performance can be expected, especially when the switching current is large in a small contact as described above. The main oxide contained in the material of the present invention is Bi-S rudder oxide (Bi2
S&07) is a mixture of Bi oxide (Bi203) and Sn oxide (Sn02) in a molar ratio of 1:2 to 700
By heating at a temperature in the range of ~90,000 °C, it is produced as an oxide with a pyrochlore structure.

Its melting point is over 1200 oo, it shows sublimation property, and A
By dispersing it in the g matrix, the effect of improving welding resistance and abrasion resistance is large. As a method for dispersing the Bi-Sn oxide and ln, Zn oxide in the Ag matrix, a quinary alloy of Ag-Bi-Sn-ln-Zn is heated in an oxidizing atmosphere to disperse Bi, Sn. ,ln,Z
A so-called internal oxidation method is used to selectively oxidize n, but when it comes to Bi and Sn, when converted from the above molar ratio, Bi weight x and Sn weight y in the five-element alloy are y/x
．． 57, Bi2Sn207 can be generated.

However, since Bi is easily polarized in the alloy, it is difficult to reliably convert it into Bi-Sn oxide by internal oxidation treatment, and Bi oxide (Bi203
), an oxide of Sn (Sn02) may exist alone. Also, as a matter of course, the value of y/x above is 0.5
If it is larger than 7, the chances of Bi oxide existing alone will decrease, and the Sn oxide content will increase.
It is clear that if the value of y/x becomes 4.0 less than 0.57, the opposite tendency will occur. However, in the case where the material of the present invention is mainly used for small contacts with a large switching current, the value of y/x is larger than 0.57, and the Sn
Since the oxide of Bi-Sn coexists with the oxide of Bi-Sn, the amount of consumption is small. However, in the presence of ln oxides, an increase in Sn oxides significantly deteriorates workability and increases contact resistance. It can be said that it is desirable to add Zn to the minimum amount that can prevent this from occurring, and to add Zn instead of Sn to prevent deterioration in workability in a situation where Sn oxide and ln oxide coexist. Therefore, suppressing the amount of Sn to about 1 to 2 y/x shows preferable results for the use of the material of the present invention. The composition of the material of the present invention was determined under the above-mentioned conditions, and the composition in terms of metal is at least 2% by weight to 5% by weight of Bi, and a range in which Sn does not exceed twice the amount of Bi. So, 4
more than 8% by weight, In is 0.5 to 5% by weight, Zn is 0.1 to 4% by weight, and the balance is Ag. The minimum amount of each of these base metal components is determined for the intended use of the material according to the invention: Bj to provide welding resistance, Sn to arc wear resistance, ln to prevent Ag-rich layers to provide welding resistance, Zn is the lower limit at which each additive effect is recognized on workability, and the maximum amount of each is because Bi increases the bias in the ingot as shown in the examples below, and Bi203 existing alone increases arc wear. In addition, Sn is due to a decrease in processability, especially in the presence of Zn oxide, ln is due to a decrease in processability in the presence of Sn oxide, and Zn is due to a decrease in processability due to reaction with Sn oxide and Complex oxide increase with Bi is Bi-S
This is an upper limit that is restricted because it inhibits the formation of n oxide (Bi2Sn207) and increases arc consumption. In the material of the present invention, Ni oxide (Ni○) or Co oxide (Coo
) can be included. These oxides reduce arc consumption by extinguishing arc discharge in switching mechanisms in which the opening/closing speed of contacts is relatively slow, and in addition, it is observed that they improve the resistance to settling. The appropriate amount of these oxides to be added is 0.05 to 0.5% by weight in terms of metal. The minimum amount in this composition ratio is the lower limit value at which the above effect is recognized, and on the other hand, the upper limit is such that the solid solubility limit for Ag is small, so it is likely to be polarized when producing an ingot as shown in the examples below. As a result, it is not homogeneously dispersed in the Ag matrix, which deteriorates the processing properties and has an adverse effect on portability. 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, Sn, ln, Zn
A total of 200 ta of Ni or Co and Ag-
An ingot containing Bi-Sn-ln-Zn as a main component was produced.

The melting was carried out using an alumina crucible in an argon atmosphere using a high frequency furnace. The molten metal is 15 x 30
It was cast into a mold with a size of 7. The ingot thus produced was immediately ground into scale-like chips with a thickness of approximately one side using a rolling mill. This was heated in air at 70,000 C for 60 hours to selectively internally oxidize Bi, Sn, In, Zn, etc., and convert the Bi oxide into a composite oxide. Next, this was made into chips having a thickness of 0.2 willow or less using a rolling mill again. After cleaning this chip with a thickness of 0.2 mm or less, it was loaded into a cylindrical mold with a diameter of 2 mm and molded at a pressure of 8 tons/cm.Then, this molded body was placed in air at a temperature of 90,000 °C. It lasted for two hours.
Then, this sintered body was extruded at 600o0 using a trowel 3.
Processed into a wire with skin diameter. After that, by repeating line cutting and competitive dulling, wire rods with a diameter of 1.7 ribs were processed, and then wire rods with a diameter of 3 ribs were processed.
A contact stud having a spherical head with a radius of curvature of 5 ribs and 8 bars was fabricated and used as a sample for a contact opening/closing test. Contact characteristics were evaluated by tests conducted using the circuit shown in FIG.

That is, as the switch S, using an ASTM type tester, the contact force was 30 mm, the contact force was 40 mm, and the opening/closing speed was 10 times per inch.
The sample was opened and closed under conditions of opening and closing for seconds. The test load consisted of a commercial power supply frequency of 60 Hz, a voltage of 125 V, a diode protection resistor r = 1.250, a load R = 12.50, and a capacity C = 1140 peaks F. Therefore, the peak inrush current was 160 A, and the steady current was is 10A. The switch S2 is used to configure a circuit for discharging the charge of the capacitor C before the switch S is turned on. The evaluation of the contact characteristics is based on the number of welds when the contact is opened and closed 3×1 times under the above conditions, that is, the number of times a force exceeding 40 times is required to open the contact, and the number of times the contact is welded after opening and closing 3×1 times. This was done based on the amount of consumption. The test quantity was 6 pairs each, and the minimum and maximum values of each characteristic are shown in the table as the results. For reference, Ag-Cd and Ag-Bi-Sn were used as comparative samples.
Test results for materials made from alloys using a similar manufacturing method are also shown. As is clear from the results in the table, the contact material according to the present invention is superior to conventional Ag-Cd○ contacts in terms of welding and
It shows extremely excellent values in all wear characteristics.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a cross section of a contact during an opening/closing test of a conventional electrical contact material. FIG. 2 is a curve diagram showing the relationship between the number of times of opening and closing and the cumulative number of times of welding in the conventional example. FIG. 3 shows an example of a typical usage of the electrical contact material according to the present invention, which is used as a test circuit. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. The main oxide dispersed in the Ag matrix is Bi.
-Sn oxide, Bi-Zn oxide, Sn oxide,
It is an Ag-oxide based electrical contact material which is an oxide of In and an oxide of Zn, and its metal alloy component is B in terms of metal value.
i is more than 2% by weight and up to 5% by weight, Sn is more than 4% by weight and up to 8% by weight without exceeding twice the amount of Bi,
In: 0.5 to 5% by weight, Zn: 0.1 to 4% by weight
, the balance being Ag. 2 The main oxide dispersed in the Ag matrix is Bi
-Sn oxide, Bi-Zn oxide, Sn oxide,
An Ag-oxide electrical contact material which is one of In oxide, Zn oxide, Ni oxide or Co oxide, the metal alloy component is a metal value, B
i is more than 2% by weight and up to 5% by weight, Sn is more than 4% by weight and up to 8% by weight without exceeding twice the amount of Bi,
In: 0.5 to 5% by weight, Zn: 0.1 to 4% by weight
, Ni or Co in an amount of 0.05 to 0.5% by weight, and the balance being Ag.