JPS6022052B2 - electrical contact materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a silver-oxide contact material, particularly a silver-bismuth oxide contact material, and aims to improve the properties thereof.

Silver-cadmium oxide contacts are widely used as silver-oxide contact materials.

Silver-cadmium oxide contacts have the required contact resistance,
Because it exhibits excellent average characteristics in terms of performance such as welding and wear resistance, it is used in load current ranges of several amperes or more, such as relays, no-fuse breakers, and power switches for household appliances. However, since cadmium is used as a component, it is not a desirable material for manufacturing, and is becoming a material that is not suitable for general society. As silver-based contact materials, the use of silver-nickel, silver-carbon, silver-tungsten, etc. is also considered for the above applications, but they are insufficient in terms of contact resistance, welding resistance, wear resistance, etc. The situation is such that it is difficult to construct a contact switch that is inferior and satisfactory. The present invention has been made in view of the above points, and is basically a proposal for improving the characteristics of silver-bismuth monoxide contact materials.

The silver-bismuth oxide contact material has the electrical conductivity of bismuth oxide,
It is a contact material that utilizes sublimation, has low contact resistance, and has excellent resistance to hakama sticking. However, it is inferior in wear resistance, and in this respect there is still room for it to be comparable to silver-cadmium oxide contacts. As a result of various studies on the abrasion resistance of silver bismuth monoxide as a component, the present inventors found that the addition of at least one or more of indium and zinc oxides significantly improved the abrasion resistance. Furthermore, we found that properties were improved in terms of welding resistance due to the synergistic effect with bismuth oxide.

Next, the present invention will be explained in further detail.

The contact material according to the present invention which is mainly composed of silver-bismuth oxide and further contains at least one of indium and zinc oxides is composed of metal elements with low toxicity, and in its manufacture. Since these are all composed of elements that dissolve solidly in silver ground, it is possible to melt and alloy them using the so-called Naito oxidation method, and of course, a powder sintering method can also be used.

The composition ratio of the oxides dispersed in the silver base is 1.5 wt % to 1 wt % of bismuth oxide, and 0.5 wt % to 1 wt % of at least one of indium oxide and zinc oxide. If the amount of bismuth oxide is less than 1.5 wt%, it is difficult to recognize its effect, and if it exceeds 1 t%, there will be little improvement in the properties even if it is added, and it is rather difficult to use it practically. In this respect, losses in other aspects such as deterioration of workability increase. indium oxide,
The total amount of zinc oxide added is 0.5 wt% or more, which is silver-
This is the minimum amount found necessary to improve the properties of bismuth oxide contact materials. On the other hand, its striations are t%.
If more than this is added, there will be problems in terms of increased contact resistance and workability. In addition, when manufacturing by the internal oxidation method, in order to prevent coarsening of crystal grains, nickel, cobalt, iron-based transition metals such as iron and transition metals such as silver and solid solution, especially bismuth such as iron, are added. However, if elements that are difficult to form a solid solution are added in large quantities, improvements can be seen in terms of wear resistance and workability.

The amount added is at most 0.5 wt% as the amount of oxide. If more than 0.5 wt% is added, it will segregate due to its small solid welt limit, and if it is oxidized in this state, it will have an adverse effect in terms of processing and properties will deteriorate in terms of resistance to settling, which is an undesirable condition. becomes.

Moreover, if the amount is less than 0.1M%, the effect will be small. As shown in the Examples below, the material created in this way has excellent performance that surpasses silver cadmium monoxide in terms of wear resistance and welding resistance over a large current range from several A to several hundred A. shows. Such performance is difficult to obtain simply by incorporating bismuth oxide into a silver base, and it cannot be obtained even by dispersing indium or zinc oxides in a silver base. It is recognized that the effect can only be achieved by the coexistence of both. Although the details of the reason for this are still unclear, it is thought that the sublimation properties of bismuth oxide (sublimation point 1010°C) and the fire resistance of indium and zinc oxides work together to exhibit such characteristics. .
Examples according to the present invention will be shown below.

Example 1 200 mesh silver powder, bismuth oxide powder, indium oxide powder, and zinc oxide powder were mixed homogeneously using a dry ball mill according to the weight ratio shown in the table, and then put into a cylindrical mold with a diameter of IQ on the side. After pressure molding at a pressure of 1 ton/kg, it was heated and sintered at 800°C in the atmosphere.

Further, this sintered body was pressurized at a pressure of 8 tons/ground using the mold, and then heated and sintered at 800° C. in the atmosphere again. The obtained baked striped body was formed into a cylindrical rod shape with a diameter of 5 ribs by hot extrusion and wire drawing. Thereafter, a contact point having a spherical head with a curvature of 7 radius was cut out from this and used as a contact point. Example 2 Each metal piece of silver, bismuth, indium, nickel, and iron was weighed to have the weight composition ratio shown in the table, and the total weight was 300.
First, only silver was dissolved in the atmosphere in an alumina crucible, and the temperature was maintained at 1200 q0. At this point, bismuth and other metal elements were added, stirred with an alumina crucible, and then cast into a 15-diameter iron cylindrical mold. .

After that, the surface layer was cut on both sides to make 12 ribs in diameter, and then 70
Primary internal oxidation was performed for 10 feeding hours in a 0qo oxygen stream. This was wire-drawn using a round die in the order of diameter 10 skins → 8 sails → 6.5 legs → 5 ribs under the condition of intermediate sintering anchor at 700° C. for 3 hours in the atmosphere. After that, this was processed into a cylindrical bar with a length of 5 bars, and a second test was carried out under the conditions of 12 field hours in an oxygen atmosphere at 700°C.
Perform the next internal oxidation, and then change one side of the cylindrical section to a radius of 7
The spherical surface on the side was processed into a contact point. Example 3 Each metal piece of silver, bismuth, zinc, and nickel was weighed to have the weight composition ratio shown in the table, totaling about 300 g. After melting as in Example 3, the ingot was milled using a stamp mill to determine the particle size. As an alloy powder of about 0.3 to 0.5 ribs,
This was internally oxidized at 700°C in an oxygen stream for 100 hours.

Next, this powder was coagulated by the same treatment as in Example 1.
Extrusion, stretching, and contact processing were performed. Example 4 Regarding a part of the above Example 3, after the second dawning, the temperature was further increased to 0. After heating for an hour, it was rapidly cooled in water and then processed between contacts.

The contacts made based on the manufacturing method examples shown above are
An opening/closing test was performed using a TM type contact tester.

The contact test is as follows. Voltage: ACIOOVr
ms, Current: 50A plate s Contact force: 3 females
Understanding ability: 4 female opening/closing times: 2 x 1 times The number of times welding occurred and the amount of contact wear in this test are shown in the table.

For reference, results for commercially available silver cadmium oxide (internal oxidation method) are also shown. As shown in the table, the silver-bismuth oxide contact material itself exhibits better adhesion resistance than the silver-cadmium oxide contact, but the wear resistance is 2 to 2.
That's five times as many.

However, silver-bismuth oxide with indium and zinc oxides is comparable to cadmium oxide in terms of adhesion resistance and abrasion resistance. It shows significantly superior performance. In particular, in the case of samples in which bismuth oxide is heated above its melting point and rapidly cooled during production, the bismuth oxide transforms into the r-type, which is highly sublimable, so that the performance is further improved. As described above, the material according to the present invention is a contact that is based on a silver-bismuth oxide contact material and has further improved performance.
It is of high industrial value and exhibits contact performance that is one step superior to conventional silver-cadmium oxide contacts.

Claims (1)

[Claims] 1. 1.5 wt % to 12 bismuth oxide in a silver base
1. An electrical contact material comprising 0.5 wt% to 8 wt% of at least one kind selected from oxides of indium and zinc dispersed therein. 2 1.5 wt% to 12 bismuth oxide in silver base
0.5 wt% to 8 wt% of at least one of the oxides of indium and zinc, and 0.1 wt% to 0.5 wt% of iron group transition elements.
% electrical contact material.