JPS6047341B2 - electrical contact materials - Google Patents

Description

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

Ag-CdQ contacts are widely used as Ag-oxide contact materials.

The Ag-CdO contact has the contact resistance required for the contact material,
It exhibits excellent properties on average in terms of performance such as welding resistance and wear resistance, and has sufficient machinability for practical use, so it is useful for relays, no-fuse braking forces, power switches for household electronic equipment, etc. , is often used in load current ranges of several amperes or more. However, in recent years, as safety regulations have become stricter for various power switching devices,
Contact materials are now required to have better properties than ever before. Especially in household electronic equipment,
Switches are required to be easier to operate and more compact, and from a safety standpoint, there is a strong desire to improve both the performance of welding, which can lead to irreversible binding, and the ability to prevent 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 surge withstand current of diode 2 improves, resistors for diode protection are installed. There is a trend to make the resistance value of 3 extremely small and to reduce the operating power of the equipment. This causes the inrush current to become excessive for the switch 4, and when performing single-wave rectification as shown in the figure, the load current of the switch becomes directional, so as in the case of switching a DC load, Only the switch contacts on one pole side are extremely susceptible to wear and tear, causing the switch to become inoperable. From this point of view as well, improvements in welding resistance and abrasion resistance are desired. In addition,
In the figure, 5 is the load, and 6' is the capacitance. In view of the above points, the present invention provides a new contact material that can replace the Ag-CdO contact.
g-B1.

This paper proposes improvements in the characteristics of 03 oxide contact materials.

Bi in the Ag matrix. As disclosed in Japanese Unexamined Patent Publication No. 52-13356, the contact material in which 03 is dispersed has low contact resistance and excellent welding resistance, but the problem is that the amount of wear is low. It was found that there were many.

The inventors conducted various studies to improve this point, and A.
We have developed a material in which ZnO is dispersed in addition to Bl2O3 in the g matrix. However, even with this material, when used in an application where the load current has polarity, as shown in the figure, one pole of the switch contact was abnormally worn out due to transfer, and satisfactory results were not necessarily obtained. As a result of further improvements and studies on this material, the inventors added Sn oxide to it, converting Bl2O3 into Bl2O3.
By using oxides of 1 and Sn, the contact opening/closing performance could be greatly improved. That is, the contact material according to the present invention contains Zn oxide (Zn
O) and Bj-Sn oxide (Bl2Sn2O7) are dispersed as main oxides, and depending on the composition ratio of B1 and Sn, Bi oxide (Bl2O3), Sn oxide (SnO2), Bj-Zn oxide (Bl48ZnO73
), Zn-Sn oxide (SnZn2O4), etc., is an Ag monoxide composite contact material containing a small amount of Zn-Sn oxide (SnZn2O4), and the contained component composition is Bll. 5-5% by weight, Zn
2-10% by weight, SnO. The desired performance can be found in a relationship of 5 to 4% by weight and the balance being silver.

Particularly, remarkable opening and closing performance can be expected in a light operating force switch with a large polarized inrush current as shown in the figure. Next, the material of the present invention will be explained in more detail.

The contact material according to the present invention has an Ag matrix. niZn
oxide (ZnO) and B]-Sn oxide (BI2Sn
2O7) are dispersed, and their synergistic action brings out the contact characteristics. The latter oxide (Bl2STl2
O7) is made by combining the oxide of B1 (Bl2O3) and the oxide of Sn (SnO2) in a molar ratio of 1:2, 700 ~!
By heating at a temperature within the range of 900°C, an oxide having a pyrochlore structure is produced. 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 welding resistance and transfer wear. Therefore, as a method for dispersing the oxide h and Bi-Sn oxide in the Ag matrix, M-
A quaternary alloy of Zn-Bi-Sn is heated in an oxidizing atmosphere to form Zn, . A so-called internal oxidation method is used to selectively oxidize BjNSn, but in terms of Bi and Sn, when converted from the above molar ratio, Bi weight X. (5s
B1-Sn with the relationship that the weight y of n is 0.57 for both y/x
oxide (Bi2Srl2O7) can be generated.

However, since Bi tends to segregate in alloys, it is difficult to reliably convert it into a Bl-Sn arrangement by internal oxidation treatment, and a small amount of B1 oxide and Sn oxide are present individually. Sometimes. Also, as a matter of course, if the value of y/x becomes larger than 0.57, the chances of Bi oxide existing alone will decrease,
The Sn oxide content increases. It is clear that the opposite tendency will occur if the value of y/x becomes smaller than 0.57. However, when the Sn oxide increases alone, a spinel-structured Snzn2O4, which is a composite oxide with the Zn oxide mentioned above, is generated, and although the amount of wear decreases, the contact resistance increases and the workability deteriorates. It's also getting worse. This is presumed to be because the composite oxide of Sn oxide and Zn oxide is a thermally stable oxide and has extremely high hardness. On the other hand, when BI oxide increases alone, Zn
Bj48znO73, which is a composite oxide with the oxide of This is presumed to be because the composite oxide of the oxide of B1 and the oxide of Zn has a low melting point, easily recrystallizes during annealing, and oxide particles tend to increase in size. Therefore, if the composition ratio of Bi weight and Sn weight is 0.
A deviation much greater than 57 is undesirable for the use of the material of the present invention. In the material of the present invention, an oxide of Zn is contained in addition to the above-mentioned Bl--Sn oxide as an oxide dispersed in the Ag matrix. Ag-ZnO contact material containing Zn oxide has been known for a long time, but it is inferior to Ag-CdO contact material in terms of welding resistance and wear amount, so it is not put into practical use. There are few examples. However, in the material of the present invention, in coexistence with the other oxides mentioned above,
It shows excellent contact characteristics. The metal component composition of the Ag monoxide contact material of the present invention to bring out this characteristic is at least Bll. 5-5% by weight, Zn2-1% by weight
, SnO. 5 to 4% by weight, and the balance is Ag. BilZn. ．． Each minimum amount of Sn is a lower limit at which these oxides are effective in preventing welding and reducing transfer wear due to their synergistic action and are recognized to be effective for the purpose of the present invention. On the other hand, as for the maximum amount of each component metal, as for Bi, the welding resistance is improved as the content increases, but the consumption amount increases, and for Zn, the same tendency as Bi is observed. In addition, when the amount of Sn is higher than the ratio with Bi mentioned above, hard and brittle oxides are generated and workability is inhibited. Contact resistance from engagement,
Each has its own upper limit due to difficulties in processability. In addition, in the material according to the present invention, addition of a trace amount of Nl or CO oxide as an additive oxide leads to improvement in contact characteristics.

In particular, its addition can reduce wear and deformation by extinguishing arc discharge or increasing material hardness. The amount that can be added is 0.
On the other hand, the amount at which the addition effect is observed is 0.5% by weight or less.
05% by weight. If the amount of Ni or CO added exceeds the above amount, Ag. ．． Bi. ．． Zn. ．． When alloyed with Sn, it segregates due to its small solid solubility limit, and if it is oxidized in this state, it becomes more difficult to work and tends to have adverse effects, such as deterioration of properties in terms of welding resistance. The materials of the present invention explained above will be explained in more detail based on Examples.

According to the composition of the invention, Ag, . Bi,. Zn. ．． Sn
, and Ni. A total of 200y of CO was dissolved, and Ag-Bi
- and Zn-Sn were made as main components.

Melting was carried out using an alumina crucible in an argon atmosphere using a high frequency furnace. The molten metal is 15 x 30 x 70
It was cast into a T$L3 mold. The ingot thus produced was immediately rolled using a rolling mill to a thickness of 1770 mm.
7! Grind into scaly chips. Usually, Bj is 1
Ag alloys containing more than % by weight have almost no cold workability, so when an ingot with a thickness of 15T011 is rolled, it naturally cracks and is crushed into scale-like chips. This was heated in air at 6500C for 60 hours, and Bi.
．． Zn. ．． Sn and the like were selectively oxidized. Next, this was rolled again using a rolling mill to a thickness of 0.2mm. I used the following chips. At this time, the oxide particles dispersed in the Ag matrix by the above-mentioned oxidation treatment are crushed and made into fine particles, which greatly affects the machinability imparted to the final wire rod. 0.2? After cleaning, the chips with the following thicknesses were loaded into cylindrical molds of increased diameter and molded at a pressure of 8 tons/CTI. Next, this molded body was heated and sintered in air at a temperature of 800°C for 2 hours. Furthermore, this sintered body has a diameter of 2
Loaded into a 0.5wL warm heating mold and heated to 400℃ for 8 tons/
It was molded by applying a pressure of d for 1 minute and sintered again in air at a temperature of 800'C for 4 hours. Then, this sintered body was warm extruded at 550°C to 3°C. It was processed into a wire rod of the same diameter. Finally, after annealing at 650℃ for 1 hour, it is processed into a contact stud with a spherical head with a diameter of 5 degrees and a curvature radius of 7 degrees.
It was used as a sample for contact opening/closing tests. 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 as follows: contact force 30y, separation force 40y1, opening/closing speed 10cm/sec, and the commercial power supply voltage 1 as the test load.
00■, 60Hz1 diode protection resistor r=0.5Ω
, load R = 20Ω, and capacitance C = 1140 μF (three 350 WN 1380 pF capacitors for charging and discharging were connected in parallel). Therefore, the maximum peak of the rush current includes 282A1 steady state. The evaluation of the contact characteristics was based on the number of times welding during opening and closing 2-cut σ times under the above conditions, that is, the number of times a force exceeding 40y was required to open the contact, and 2-cut σ
This was done based on the amount of wear on the contacts, especially on the positive electrode side, after each cycle was opened and closed. The number of test samples was six each, and the minimum and maximum values of each characteristic are shown in the table. For reference, A as a comparative sample
Test results for g-CdO (by internal oxidation method) are also shown. As is clear from the results in the table, the contact material according to the present invention exhibits considerably superior values in both welding and wear characteristics as compared to the conventional Ag-CdO contact.

[Brief explanation of drawings]

The drawings are for explaining an example of a typical usage form of the electrical contact material according to the present invention. 1...Commercial power supply, 2...Diode, 3...Protective resistor, 4...Switch, 5...Load, 6... ...Capacitance.

Claims (1)

[Claims] 1. The main oxide dispersed in the Ag matrix is Zn.
oxide and Bi-Sn oxide, whose metal synthesis components are 1.5 to 5% by weight of Bi and Zn2 in terms of metal values.
~10% by weight, Sn0.5-4% by weight, and balance Ag
An electrical contact material characterized by a proportion of 2 The main oxide dispersed in the Ag matrix is Zn.
oxide and Bi-Sn oxide, whose metal synthesis components are 1.5 to 5% by weight of Bi and Zn in terms of metal values.
2 to 10% by weight, Sn 0.5 to 4% by weight, and at least one of Ni or Co 0.05 to 0.5
1. An electrical contact material characterized in that the percentage by weight and the balance are Ag.