JPS6018735B2 - electrical contact materials - Google Patents

Description

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

Silver is generally widely used as an electrical contact material because it has excellent conductivity and is cheaper than gold.

However, as the switching load increases, defects such as welding, wear due to discharge, and transfer begin to occur. Therefore, attempts have been made to develop various materials to improve these defects.
One of these was a silver-cadmium oxide alloy. Since this material exhibits excellent switching ability for a relatively wide range of switching devices, it is currently widely used as a contact material for switches in industrial equipment as well as consumer equipment. However, although silver-cadmium oxide alloys exhibit very good properties, they still have deficiencies.

That is, in switching equipment, when the opening/closing speed of the contacts is relatively slow or when the opening force of the contacts is small, there is a tendency that welding or wear is likely to occur. In addition, in recent years, cadmium has become a material that is socially suitable for pollution prevention measures. An object of the present invention is to provide a novel material that exhibits excellent performance against deposition, wear due to discharge, etc. as described above.

The present invention essentially improves the properties of silver bismuth monoxide contact materials. Silver-bismuth oxide contact material is
Utilizing the conductivity and sublimation properties of bismuth oxide, it is one of the materials with low contact resistance and excellent anti-sticking properties. However, the wear resistance was poor, and there was still room for improvement in this respect. As a result of various studies on the wear resistance of silver-bismuth oxide as the main component, the inventors found that a material obtained by adding tin oxide to this alloy and heating it sufficiently was found to be It has been found that wear resistance is significantly improved, and further improvements in properties are observed in terms of welding resistance. However, on the other hand, the processing facility was forced to decline. This phenomenon was presumed to be due to the fact that general silver alloys have little tendency to recrystallize under annealing conditions, and therefore the hardness after phosphorus annealing remains quite high for a silver-based alloy. As a result of various experimental studies aimed at improving the processability of the above-mentioned materials, the inventors discovered that the objective could be achieved by adding at least one type of copper or zinc oxide, and developed the invention. did. less than,
The electrical contact material according to the present invention will be explained in detail.

The contact material of the present invention basically has the following constituent components.

That is, bismuth tin oxide (Bi
2S 07), bismuth oxide (Bi203), bismuth steel oxide (CMBiv○w), and bismuth zinc oxide (ZnxBiY02).
A form in which more than one species is dispersed (hereinafter referred to as form 1), a bismuth tin oxide (Bi2Sn207) and a tin oxide (SN02) in a silver matrix, and a bismuth steel oxide (
Biv○w) and bismuth zinc oxide (ZnxBi
Y02) is in a dispersed form (hereinafter referred to as form 2). In addition, these forms of materials include copper oxide (CJO) and zinc oxide (Zn○
) etc. are often included. In addition, the above U, V,
W, ×, Y, Z are integers, and according to the inventors' experiments, analysis by
407, ZnBi approximately 073, etc. are recognized to exist. Bismuth tin oxide (Bi
2S Buddha 07) contains bismuth oxide (Bi203) and tin oxide (Sn02) in a molar ratio of 1:2 between 700 and 900.
By heating at a temperature within the range of preferably 750 to 900 degrees Celsius, a composite oxide having a yellow-green right-sided structure is produced.

Its melting point is over 1200o○ and exhibits sublimation. When this bismuth tin oxide is dispersed in the silver matrix, there is little tendency to recrystallize as described above, and the hardness is relatively high even after normal sintering. When this characteristic is used in a switching contact mechanism with strong impact force, the surface deformation of the contact,
It is characterized by low wear. The material according to the present invention further includes bismuth oxide (Bi2) in the silver matrix.
03) or contains tin oxide (Sn02). When the former oxide is contained, in addition to the above-mentioned characteristics, it has excellent welding resistance, and when the latter is contained, it has excellent arc wear resistance. The crab material of the present invention contains at least one type of copper or zinc oxide as the basic component, and the addition of these oxides imparts recrystallization to the structure after the material is sintered. It has the effect of

This effect has a molar ratio of 0.0 to bismuth oxide.
It can be seen and produced by adding 7 mol% or more,
This gives the material the ability to process, making it possible to process fine contact shapes. On the other hand, when added in large quantities, Bi2S
This is not preferable because the formation of oxide Q07 is hindered and arc consumption tends to increase. The upper limit of the amount added is 1.3 mol % based on the bismuth oxide. As mentioned above, these copper or zinc oxides are dispersed in a silver matrix as a bismuth composite oxide, but this composite oxide usually has a melting point lower than the melting point of bismuth oxide Bi203. There is. However, if it is melted at a temperature of 870 pm or higher and then rapidly cooled, it will be converted into an oxide that exhibits reforming properties.
Its sublimation temperature is higher than the melting point of silver, 960.5 oo. Such a phenomenon is also seen in the bismuth oxide Bi203, where Q-Bi203, which has a melting point of 825qo, is
It changes to y-Bi203 which shows a sublimation temperature of 0 or higher. Materials subjected to the treatment of melting and quenching the oxides described above exhibit improved adhesion resistance compared to materials without such treatment. In the material according to the present invention, addition of nickel oxide as an additive oxide leads to improvement in contact characteristics.

In particular, in the opening/closing mechanism where the opening/closing speed of the coin point is relatively slow,
Due to the quenching effect on arc discharge, arc consumption is reduced and welding resistance is improved. A method of manufacturing the above-mentioned material will be explained next.

This material can be produced based on a general method for producing silver-metal oxide materials. In other words, it is possible to manufacture alloys such as silver, bismuth, tin, copper, zinc, and nickel by internal oxidation, and it is also possible to manufacture silver powder, bismuth oxide tin powder, tin oxide powder, oxidized steel powder, zinc oxide powder, etc. It is also possible to manufacture by a powder sintering method in which the materials are mixed, compressed, molded, and then heated and sintered. However, when using the internal oxidation method, the oxidation rate of each metal element is different, and the oxidation rate of tin is particularly slow, so it is difficult to oxidize, so the heating temperature and heating time are sufficient to form a composite oxide with bismuth. It is necessary to set the conditions.

Approximately suitable conditions are temperature 700-900℃,
It takes 20 to 20 field hours. The oxidation time tends to be shorter when the oxidizing atmosphere is, for example, oxygen than when it is air. Similarly, depending on the shape of the material being oxidized,
It is easy to understand that the oxidation time may be longer or shorter. In the case of the powder sintering method, although it is not necessary to perform internal oxidation treatment, it goes without saying that heat treatment is required so that bismuth oxide and tin oxide can react to form a composite oxide. However, since the reaction generally progresses through the heat treatment during brazing, the reaction can be completed by allowing a slightly longer competitive time. The effective composition range of the electrical contact material according to the present invention as described above is as follows.

first. When attempting to obtain the electrical contact material of the present invention by internal oxidation method, 1.5 to 6. wt% bismuth, 0
．． 1-6% by weight tin, 0.016-1. Ag composed of a weight% of one or more types of steel or zinc and the balance Ag
When the alloy has a composition before internal oxidation and nickel is added as an additional metal, the composition is 0.1 to 0.
A suitable amount is 5% by weight.

When using the powder compaction method, a powder mixing ratio should be selected that approximately corresponds to the composition of the above-mentioned alloy after internal oxidation treatment. That is, bismuth oxide (Bi203) is 1
．． 6-6.5% by weight, tin oxide (Sn02) 0.1
~7.5% by weight, 0.02 to 1.5% by weight of one or more of copper oxide (Cu0) or zinc oxide (Zn○)
, and the remainder Ag, the characteristics of the material of the present invention can be obtained by brazing a mixture of additional compositions.

When adding nickel oxide (Ni○), the appropriate amount is 0.1 to 0.65% by weight. In the above composition range, each minimum value indicates the lower limit at which the effect of their addition is recognized. The maximum value of bismuth or bismuth oxide, tin or tin oxide is a value that is limited by machinability, and in particular, when using the internal oxidation method, if the tin content exceeds the above upper limit, normal When machining is applied, such as rolling, wire drawing, extrusion, etc., cracks occur in the material. In addition, although the welding resistance of bismuth improves as its content increases,
Desired results cannot be expected from materials exceeding the upper limit of the composition due to increased consumption. The upper limit values for copper and zinc are determined based on the tendency of arc wear as described above. However, no improvement effect on characteristics was observed.
In the above composition range, which of the two forms mentioned above is determined by the content ratio of bismuth and tin, or in particular, bismuth oxide and tin oxide, and roughly speaking, the value of the weight ratio of bismuth and tin. is larger than 1.76, or when the weight ratio of bismuth oxide and tin oxide as oxides is larger than 1.55, form 1 is obtained, and in the opposite case, form 0 is obtained.

As a special case, Bi203 is in the intermediate state between forms 1 and 0.
It goes without saying that there are also some that do not contain Sn02. EXAMPLES In order to specifically illustrate the material of the present invention, Examples will be described below.

Example 1 According to the composition of the invention, silver, bismuth, tin, copper, zinc,
Nickel was melted to produce an ingot containing silver, bismuth, and tin as main components.

The amount of melting was 200 minutes using an alumina crucible and a high frequency furnace in an argon atmosphere. Molten metal is 15 x 3
It was cast into a mold with a diameter of 0x7 and 3 cm. The ingot thus obtained was immediately rolled using a rolling mill to a thickness of 0.
After pulverizing into scale-like chips with a diameter of 2 to 0.5, the chips were loaded into a cylindrical mold with a diameter of 20 and molded at a pressure of 2 tons/unit. Next, this molded body was consolidated for two hours in an oxygen stream of 800 oo, and at the same time internal oxidation of the chip was performed. Furthermore, this sintered body was pressed again under a pressure of 8 tons, and then sintered in air at 900 qo for 5 hours. This sintered body,
Subsequently, it was warm extruded at 550 pm to form a cylinder with an IQ cape diameter. Then, the rolling reduction rate for one pass was set to 14 to 2.
The wire was drawn into green wood with a diameter of 5 willows by repeating the procedure of adding 83,000 and 3 hours of slowing at every 35 to 40%. Finally, it is processed into a spherical contact stud with a radius of curvature of 7 ribs,
It was annealed at 830qo for 1 hour. The contact studs made in this manner were subjected to the auxiliary opening/closing test described below. Example 2 After making a cylindrical rod with a diameter of 1 rib in the same manner as in Example 1, it was heated to 900°C at the stages of light 1 rib, 8 ribs, and 65 sides.
, heating for 2 hours and cooling with water were repeated to draw a wire rod with a diameter of 5 skin.

Finally, we processed it into a spherical contact stud with a radius of curvature of 7 ribs, and
After heating for 1 hour and cooling with water, it was subjected to the contact opening/closing test described below. Example 3 According to the composition of the invention:
A total of 50 pieces of silver powder, bismuth oxide powder, tin oxide powder, oxidized steel powder, zinc oxide powder, and nickel oxide powder that had been passed through a 200-mesh filter were mixed in a dry ball mill.

After being loaded into a cylindrical mold with a diameter of 12 ribs, it was pressure-molded at 4 tons/h and heated and sintered at 800 pm for 1 hour. This molded body was pressed again at 8 tons and heated at 800 qo for 1 hour. After that, the diameter is 11 by extrusion between the sleeves and wire drawing.
It was processed into a wire rod with 10 sides, 9 ribs, 8 fences, 6.5 sails, and 5 skins. Nukazuchi is 1 at 800qo for each wire drawing stage.
It took time. The wire thus produced was processed into a contact rivet similar to that in Example 1, and then phosphoroused at 70,000 for 1 hour, which was used as a test sample. Example 4 A contact iron was made in the same manner as in Example 3, and then heated to 900qC.
The sample was heated for 2 hours and further cooled with water to prepare a sample for the opening/closing test described below.

The contact studs made by the above manufacturing method have a hardness (H
v, Vickers hardness 0.5k9) and contact characteristics.

The contact characteristics were evaluated by the amount of wear after opening and closing 2×1 times under the following conditions.

The results are summarized in Table 1. Opening/closing test conditions (AS
(by TM type testing machine) Voltage: 100V (AC) Fin current: 50A (power factor cos? = 1) Contact force: 3M Separation force: 40mm Opening/closing speed: 10/sec Opening/closing frequency: 2 x 1 times Number of samples: 6 pairs Table 1 shows the minimum and maximum values of each characteristic value.

The test results of silver-cadmium oxide (internal oxidation method) and silver-bismuth oxide (internal oxidation method and powder compaction method) are also shown as comparison samples. A part of the prepared sample was analyzed for the oxide component phase by X-ray diffraction in a state of five ribs in diameter.

The results are shown in Table 2. Further, Table 3 shows the hardness of samples made based on the same manufacturing method by removing copper or zinc oxides from the electrical contact material composition of the present invention.

Comparative sample 4 is compared with sample number 3 or 4 in Table 1, in which copper and zinc oxides are removed. In the same way,
Comparative sample 5 is assigned sample number 5, comparative sample 6 is assigned sample number 8,
9 and 10, the silver-bismuth oxide contact itself is resistant to welding and exhibits better performance than the silver-cadmium oxide contact, but the amount of wear is It is 2 to 5 times more numerous. On the other hand, silver
The electrical contact material of the present invention, which contains a composite oxide of bismuth and tin, has greatly improved the amount of wear and tear, provides a material of European quality in terms of hardness, and has improved processability. It is also a practical material. Table 1 Table 2 Table 3

Claims (1)

[Claims] 1. At least bismuth tin oxide (
A silver-oxide composite material in which Bi_2Sn_2O_7) is dispersed, and the metal component composition contained in this material is bismuth 1.5 to 6.0% by weight in terms of metal,
0.1 to 6% by weight of tin, 0.0 or more of copper or zinc
An electrical contact material comprising 16 to 1.2% by weight and the balance being silver. 2 At least bismuth tin oxide (
A silver-oxide composite material in which Bi_2Sn_2O_7) is dispersed, and the metal component composition contained in this material is bismuth 1.5 to 6.0% by weight in terms of metal,
0.1 to 6% by weight of tin, 0.0 or more of copper or zinc
16-1.2% by weight, nickel 0.1-0.5% by weight,
and the balance being silver.