JPS6023178B2 - electrical contact materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a silver-oxide electrical contact material produced by an internal oxidation method.

Silver-cadmium oxide contacts have been widely used as silver-oxide electrical contact materials manufactured by internal oxidation methods. Silver-cadmium oxide contact materials have a relatively well-balanced combination of low contact resistance, welding resistance, arc wear resistance, and dielectric withstand voltage performance required for contacts, making them ideal for relays, contactors, safety breakers, and wiring. Used in small to large current ranges, such as circuit breakers. However, the use of cadmium in the contact components makes it less desirable during manufacturing.

On the other hand, among silver-oxide-based contact materials, there are contact materials that do not use cadmium, such as those based on silver-tin oxide and indium monoxide, silver-zinc oxide, and silver-manganese oxide.

Although silver-tin oxide and indium monoxide systems have melt resistance and dielectric strength and voltage resistance, they have a drawback of high contact resistance.

Furthermore, although the silver-zinc oxide system has excellent contact resistance characteristics, it has drawbacks in welding resistance and arc wear resistance. In this way, contact materials that do not use cadmium still have problems in terms of contact characteristics.

By the way, with the miniaturization of switching equipment, improved performance, and the rise in the price of silver raw materials, it is increasingly desired to improve contact performance and thereby reduce contact volume.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a silver-tin oxide, indium monoxide, and cadmium monoxide-based electrical contact material that is highly practical, has high performance welding resistance, and has low contact characteristics.

Next, the features of the present invention will be described.

The present invention has been developed as a result of considering the drop-off resistance, dielectric withstand voltage characteristics, and contact characteristics associated with the switching of large currents and rated currents of contacts. , 5-12% indium, 0.2-15% cadmium,
By internally oxidizing an alloy containing 0.01 to 1% nickel and 5% or less antimony, it has excellent contact properties and can achieve welding resistance, dielectric strength resistance, and arc consumption resistance. As is well known, the internal oxidation alloy of silver-cadmium oxide and tin monoxide has a high hardness with extremely fine precipitates of tin oxide.

Since cadmium oxide evaporates easily, it forms a cohesive band of oxide on the surface, making it a tough alloy. Therefore, the alloy has good welding resistance, and the temperature rise at the contact point during energization is low. However, as the amount of cadmium oxide increases, the dielectric strength and voltage resistance deteriorate. On the other hand, the internal oxidation alloy of silver-tin oxide and indium monoxide is a combination of tin oxide and indium oxide that is thermally stable, reduces contact wear, and improves dielectric strength characteristics, but the amount of tin and indium is If the amount increases, an agglomerated band of oxides will be formed on the contact surface layer during internal oxidation, making internal oxidation difficult and limiting the amount of tin and indium that can be added to silver.
Also, the contact resistance value becomes high. Recently, the amount of silver in contacts is small, and there is a demand for contact materials with excellent anti-sinking properties, dielectric strength and contact characteristics.

The present invention should satisfy such requirements.As a result of various studies,
Cadmium oxide prevents the agglomeration of tin and indium oxides, improves contact resistance characteristics, greatly increases the oxidizable limit, increases the amount of oxides dispersed in silver, and improves welding resistance. be.

Furthermore, by adding cadmium, indium, and tin to silver, Cd2, which is a fine composite oxide, is formed during internal oxidation.
Forming Sn04 and Cdl-04 and dispersing them in a silver base increases the fire resistance and improves the settling resistance compared to those in which a single oxide is dispersed.

Antimony forms a complex oxide, Cd3SQ06, which further promotes this effect and has the effect of keeping contact resistance low. In the alloy of the present invention, the lower limit of tin is set to exceed 4% because if the content is lower than this, the amount of tin oxide is small and there is no special welding resistance effect. % because if it exceeds this value, the contact characteristics will become unstable when the contact is opened and closed at the rated current, and internal oxidation will become difficult, especially when manufacturing the alloy. If the lower limit of indium is less than 5%, the amount of complex oxide formed will be small and the effect will be small, and if the upper limit is more than 12%, the internal oxidation will become unstable due to the combination with tin and cadmium. The lower limit of cadmium was set at 0.2% because it has little effect in preventing the agglomeration of dispersed oxides, and the amount of complex oxides formed with tin and indium is small, weakening welding resistance and low contact characteristics. . The reason why the upper limit value is set to 15% is that if it exceeds this value, the arc wear resistance and dielectric strength resistance will deteriorate. In addition, nickel has the effect of making the crystal grains of cadmium, tin, and indium oxides in silver finer and more uniform.In particular, a large amount of indium is contained in a silver-cadmium-tin alloy to improve and stabilize welding resistance. It has the effect of making These effects and the effect of improving workability appear from a nickel content of 0.01%, but if it exceeds 1%, the welding resistance decreases and uneven agglomeration occurs, so the upper limit was set at 1%. The reason why the amount of antimony added was set at 5% is that if more than this amount was added, processability would deteriorate. Next, in order to further clarify the characteristics of the electrical contact material of the present invention, typical examples of specific gas contacts will be described.

An alloy having the alloy composition shown in Table 1 is melted and cast, and processed into plates and wires, or grains and fibers.

This is oxidized in a 700qC atmosphere, assembled and extruded.
I got the wire by wire drawing. Connect the wire rod to the head of a part of a sphere with a diameter of 8 h and a thickness of 1.4 on the side with a radius of 3. A shaft with a diameter of 2.5 and a length of 2.5 ribs is connected to the head. A rivet contact with the same shape was obtained.

This rivet-like contact was incorporated into a commercially available safety breaker, and an overload test, a temperature rise test after the durability test, and a short circuit test after the overload test were conducted under the conditions shown in Table 2. The number of times it took to reach (welding resistance) and the dielectric strength voltage (insulation resistance) were measured. The results are shown in Table 3. For comparison, an Ag-10%Cdo contact was also added. As described above, the material according to the present invention is an excellent electrical contact material that has both contact characteristics and anti-sagging properties, and can be applied particularly to breakers, which are responsible for switching rated currents and switching abnormal currents, and has its effects. It was recognized that the system demonstrated the

Table 1 Table 2 Temperature test '1} Voltage AC220V, current 15V, power factor 0.8,
50 times of opening/closing '2) Voltage AC220V, current 20A,
Power factor 0.8 Opening and closing times 5000 times [3} Voltage AC220
V, current 20A, temperature rise measurement of contact part Short circuit test '1' Voltage AC 220V, current 15M, power factor 0.8, number of opening and closing 5q groups '21 Voltage AC 220V, fin flow 150 peaks L power factor 0.75 Under the following conditions, conduct a cut-off (0) test and a make-off (CO) test for each pole, then perform the same test for two poles, and then repeat the make-break (CO) test for two poles until welding is achieved. The number of times it reaches is calculated.

In addition, the dielectric strength voltage is determined by the two-pole interrupting (0) test, the closing-breaking (C
O) After the test, the insulation resistance between the terminals was determined. Table 3

Claims (1)

[Claims] 1. In weight ratio, tin is more than 4.0 and up to 10.0%, indium is 5 to 12%, cadmium is 0.2 to 15%, and nickel is 0.01 to 1%. and the remainder silver, a part of which is oxidized by an internal oxidation method. 2.In terms of weight ratio, tin is more than 4.0 and up to 10.0%, indium is 5-12%, cadmium is 0.2-15%, nickel is 0.01-1%, and antimony is 5% or less. and the remainder silver, a part of which is oxidized by an internal oxidation method.