JPS5850304B2 - Denkisetsutenzairiyo - Google Patents

Description

[Detailed description of the invention] The present invention relates to silver-oxide based electrical contact materials.

Conventionally, silver-cadmium oxide-based electrical contact materials, which have excellent arc resistance, welding resistance, etc., and low contact resistance characteristics, have been widely used as medium-load contact materials.

However, despite its excellent contact properties, such silver-cadmium oxide contact materials have problems in handling during manufacturing, and since they usually contain about 5 to 15% cadmium, there are some materials that do not contain cadmium. There has been a demand for the development of a material that is comparable in size and properties to this material.

Therefore, silver-oxide-based materials that do not contain cadmium can be, for example, alloys such as silver-zinc oxide, silver-tin oxide, or silver-antimony oxide, but precipitates may precipitate in needle shapes during internal oxidation. The welding resistance and abrasion resistance are poor due to coarsening, segregation, and precipitation, which is unsatisfactory.

Furthermore, this type of electrical contact material requires a manufacturing process in which the material is formed into a contact shape and then oxidized from the surface of the contact, but the oxidation rate during oxidation is so low that it is not suitable for industrial use. There were many drawbacks such as no.

The present invention addresses these points and improves the problems of the contact materials described above, and aims to provide a contact material that has excellent welding resistance and shortens internal oxidation time. .

The electrical contact material of the present invention is a silver-oxide contact material containing silver as a main component, and contains at least one of zinc, tin, and antimony in the chain, and at least one of tellurium and selenium in the chain. It contains 10% by weight and is oxidized.

Thus, the contact material of the present invention can be easily manufactured, for example, in the following manner.

First, as raw materials, at least one of zinc, tin, and antimony, at least one of tellurium and selenium, and silver are mixed and dissolved in a predetermined composition ratio, and finally an ingot with a substantially uniform composition is produced. do.

Next, a piece of the shape desired as a contact is cut out of this ingot, and this piece is heated at 500°C to 900°C in an oxidizing atmosphere.
By performing internal oxidation treatment with C, an electrical contact material containing an oxide of a predetermined metal can be obtained.

The amount of tellurium and selenium in the electrical contact material of the present invention is 0.
．． The selection method for 03-10wtg□ is based on the following reasons.

In other words, at least one type of tellurium and selenium is 0.0
If it is less than 3% by weight, it will not be significantly effective in shortening the internal oxidation time and improving welding resistance, and if it exceeds 10% by weight, the contact resistance will increase and the width of variation will increase, making it difficult to obtain the desired electrical contact. This is because the materials are not available.

Conventionally, the amount of zinc, tin, and antimony was limited to a maximum of 10% due to productivity constraints, but in the present invention, silver is It is possible to perform up to the maximum solid solubility of each element based on .

The maximum solid solubility is 22.3% by weight at 710°C (29.0% by weight at 258°C) for the silver-zinc system, and 7% for the silver-tin system.
In a 12.5 wt% silver-antimony system at 24°C, 70
8.0% by weight at 2°C.

On the other hand, the minimum amount is determined by the ratio of zinc oxide, tin oxide, and antimony oxide in the chain, which have adhesion resistance and synergism, but due to tellurium and selenium's other effect of improving solubility resistance, When based on silver, the content is preferably up to 0.1% by weight.

Next, a specific example of improving the internal oxidation rate will be described with respect to the embodiment of the present invention.

Table 1 shows the internal oxidation rate for each composition ratio (wt%) for typical compositions as well as reference examples.

The oxidation conditions at this time were treatment in air at 650° C. for 90 hours.

That is, as is clear from Table 1, by adding tellurium and selenium, internal oxidation progresses and is promoted.

Being able to shorten the internal oxidation time is very advantageous from an industrial standpoint.

The reason why at least one of tellurium and selenium promotes internal oxidation efficiency is thought to be as follows.

All or part of tellurium and selenium in the alloy are
It combines with silver and precipitates mainly at grain boundaries, but this precipitate increases the grain boundary strain, increasing the grain boundary diffusion of oxygen and further increasing the density of zinc, tin, and antimony formed on the alloy surface. This is thought to be because tellurium and selenium destroy the film and assist oxygen infiltration.

Furthermore, regarding the improvement of contact characteristics regarding the embodiments of the present invention,
A specific example will be described.

Table 2 shows typical examples of the present invention including reference examples.
The contact characteristics for each composition ratio (weight %) are shown.

The test conditions for the contact characteristics were AC200V, resistive load,
Opening, contact force pot 100g, opening and closing once per second from 2OA to 5
The current was increased by 1 OA every time X10" was opened and closed, and the current value before welding occurred was evaluated as the welding limit current.

As is clear from Table 2, by adding tellurium and selenium, the welding eye field current can be increased by 30 to IOA.

The effect is remarkable.

By adding tellurium to contain tellurium oxide,
The following may be the reason for the improvement in welding resistance.

Since tellurium oxide exhibits sublimation properties at relatively low temperatures, it sublimates and dissociates due to the arc heat during arcing, and then adheres to the contact surface again.

This cycle of sublimation → dissociation → oxygen release → reoxidation → adhesion contributes to the arc-extinguishing effect and the smoothing effect on the contact surface, improving and stabilizing the contact characteristics, and preventing the adhesion of oxidized tellurium. It is believed that the welding resistance is improved due to the low mechanical strength properties.

Selenium oxide also has chemical and mechanical properties similar to those of tellurium oxide, and is thought to improve contact characteristics through a similar mechanism.

In the examples, silver-zinc system, silver-tin system, and silver-antimony system were described, but tellurium and selenium can be added to the silver-multiple oxide system in which zinc, tin, and antimony are used as oxides. showed the same effect.

As described above, the presence of tellurium and selenium is extremely effective industrially because it improves contact characteristics and improves productivity by improving internal oxidation efficiency.

Claims (1)

[Claims] 1. Electricity characterized by being made by oxidizing an alloy containing 0.03 to 10% by weight of at least one of tellurium and selenium to a main component containing at least one of zinc, tin and antimony in the chain. Contact material.