JPH04289139A - Silver-oxide type electrical contact material - Google Patents

Abstract

PURPOSE:To reduce the amt. of Cd used in an electrical contact material made of an Ag-CdO alloy in consideration of pollution control. CONSTITUTION:In order to reduce the amt. of Cd used in an electrical contact material made of an Ag-CdO alloy, 0.1-6.2wt.% (expressed in terms of Sb) Sb oxide, 0.1-20.0wt.% (expressed in terms of Cd) Cd oxide, 0.05-4.3wt.% (expressed in terms of Sn, In and Zn) oxides of Sn, In and Zn and 0.01-2.0wt.% (expressed in terms of Te and Li) oxides of Te and Li are dispersed in Ag as a base.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to silver-oxide electrical contact materials.

0002

[Prior Art] Various electrical contact materials have been used in the past, but silver-cadmium oxide contacts in particular have the characteristics required for electrical contacts, such as welding resistance, abrasion resistance, and low contact resistance. Due to its excellent properties, there is a lot of demand for it, and the material has been repeatedly improved and there is a lot of academic research, so it can be said that this type of material and manufacturing technology have reached their limit. However, as is known, this silver-cadmium oxide electrical contact material involves many steps in its manufacturing process, such as melting, hot processing, high-pressure oxidation, analysis, and recovery, which easily discharge cadmium from the system. Naturally, efforts must be made to prevent emissions, and as a result, pollution prevention equipment becomes necessary, especially as production equipment expands, which requires a large amount of cost and equipment, and this is likely to develop into an energy resource problem. There is. For this reason, manufacturers of silver-cadmium oxide electrical contact materials have taken sufficient measures to prevent this problem, but just because these measures are sufficient does not mean that they are responding to the social situation regarding pollution. Unfortunately, just such a point of contact would have an impact on production prices due to huge capital investment. Furthermore, dispersing cadmium oxide in Ag has a cleaning effect on the contact surface,
Although it is certainly effective in improving electrical characteristics such as reducing welding force, this effect has been particularly effective in AC circuits, and in DC circuits where the polarity does not change, the contact material When used, there is a significant problem in that the welding resistance is relatively poor and the contact resistance increases due to the opening and closing of the contacts. The cause of this is proposed to be that anode components migrate from the anode side to the cathode side of the contact, forming a type of altered layer at the cathode connection section that is different from the contact base material.This defect is due to the fact that cadmium oxide It can be said that it is a fate that cannot be resolved.

0003

[Problems to be solved by the invention] The problem to be solved is to solve the problem of pollution caused by Cd, and to
The development of new materials comparable to O-based electrical contact materials is attracting attention, and for example, techniques have been announced that involve dispersing La oxide in silver. The rationale for such a development is A.
Generally speaking, oxides with a lower vapor pressure than cadmium oxide are more effective at dissipating components dissipated from the contact surface due to arcs generated when opening and closing electrical contacts than cadmium oxide. This is because it is said that even if the amount of oxide added to Ag is small, it is effective because the amount of supplementation from inside the contact is reduced.

0004

[Means for Solving the Problems] Therefore, in view of the above points, the present inventors reexamined the role of cadmium-free oxides in contributing to contact characteristics, rejected preconceived notions, and conducted repeated research. As a result, they came to the conclusion that the cleaning effect on the surface of electrical contacts and various phenomena against arcs, such as arc-extinguishing effects, are most closely related to the physical properties of the added oxide, especially the temperature characteristics of its vapor pressure. Based on this idea, we focused on oxides with a higher vapor pressure than cadmium oxide in the temperature range of about 500 to 1500°C, and by incorporating less toxic Sb oxide into Ag,
It was confirmed that the contact surface cleaning effect was equivalent to or better than that of the Ag-CdO type. Furthermore, from this point of view, various proposals have been made regarding the possibility that synergistic effects can be exhibited by dispersing metal oxides other than Sb in Ag. The present invention was made based on the above research process, and contains not only the above-mentioned Sb oxide in Ag, but also Sn oxide, which has a vapor pressure higher than that of CdO in the temperature range of about 1500 to 4000°C, and about 500
By dispersing In and Zn oxides, which have lower vapor pressures than CdO in the temperature range of ~4000°C, the combination of these metal oxides can more closely approximate the behavior of the synthetic vapor pressure of CdO, and their synergistic effects This allows for excellent contact characteristics to be exhibited.

A more important element is that in addition to dispersing the metal oxides mentioned above, oxides of Te and Li are also dispersed to improve the serious defects of the conventional contacts caused by CdO. In other words, as is known, with the complicated operation of equipment, the contact surfaces of the switches that control the opening and closing of the equipment are heated to a high enough temperature that they melt due to arc heat and Joule heat. Since the temperature will drop to room temperature, a thermal cycle between high temperature and room temperature will be repeated. Incidentally, the non-oxidized surface (Ag surface) of the contact is fixed to a base material made of Cu, Cu-Zn, etc. with silver solder or the like. There is a difference in the coefficient of thermal expansion of Ag and Ag-CdO.
A phenomenon occurs in which the surface of the contact deforms into an arched shape at the boundary between the two, causing the contact to peel off from the base material, and the contact in the peeled portion develops into loss and wear. In the present invention, by adding the above-mentioned Te and Li, when the above-mentioned Sb, Sn, In, and Zn are about to appear as layered oxides in the Ag matrix, the oxides are uniformly dispersed. When the contact is about to curve due to the thermal cycle described above, the uniformly dispersed oxide acts as a core in response to the thermal stress, and the inside of the contact receives arc heat or Joule heat. By generating minute cracks, these will absorb the tensile and compressive stress (thermal strain) caused by expansion and contraction due to the thermal cycle of heating and cooling in various places, thereby preventing the peeling and wear and tear phenomenon of the contacts. That is.

[0006] Therefore, the present invention consists of an oxide of Sb containing Ag as a main component and an oxide of Sb containing 0.1 to 6.2 Wt%, and an oxide of Cd containing 0.1 to 20.0 Wt% of Cd. 0.05 to 4.2 Wt% of Sn, In, and Zn
It is characterized by dispersing oxides of Sn, In, and Zn, and oxides of Te and Li with Te and Li content of 0.01 to 2.0 wt%. (powder metallurgy method) or internal oxidation method (melting method), and the latter is suitable from the viewpoint of production cost. In the case of this internal oxidation method, Ag has Sb, C
By making a silver alloy containing d, Sn, In, Zn, and both Te and Li as a solid solution and keeping it at high temperature in an oxidizing atmosphere, oxygen can enter from the surface and selectively remove the above metals. By continuing the oxidation for a long time while oxidizing and producing fine grains of the oxides in the Ag matrix, the oxides of the various metals mentioned above are dispersed throughout the material. On the other hand, in the case of the sintering method, fine powder of Ag and powder of the above metals are mixed, the sintered product is oxidized after pressure forming, and then sintered, or a well-mixed oxide powder of the above metals is processed. By pressure firing, a silver-oxide electrical contact material in which the oxide is dispersed in Ag can be manufactured. However, in any of the above methods, Sb
The oxide has a metal component Sb of 0.1 to 6.2W.
Must be t%. Here, the reason why the upper limit of the amount of Sb added to Ag was set at 6.2 Wt% is that Ag-Sb
The maximum solid solubility limit of Sb in the α solid solution of the alloy is 6.2 Wt% at 300°C, and if Sb is added in excess of this amount, cold workability will be significantly inhibited, making it difficult to use electrical contact materials. This is because mass production will become impossible. Also,
Even when manufactured by a sintering method, the bonding force between particles is weak, resulting in a large amount of arc consumption, making it impossible to obtain desirable properties as a contact material. On the other hand, if the amount added is less than 0.1 wt%, the effect of addition as described below cannot be obtained and the purpose cannot be achieved.

[0007] Furthermore, Cd oxides with Cd of 0.1 to 20
．． The reason for limiting it to 0 Wt% is that if it is less than 0.1 Wt%, it will not be possible to maintain the castability characteristic of Ag-Cd alloys, and furthermore, the cleaning effect due to the arc generated when opening and closing the contacts cannot be expected. and 20.0 Wt%
The reason why this is set as the upper limit is that if the amount added exceeds this amount, the oxide will condense and become coarse, and the amount of consumption and scattering caused by the arc will increase. Furthermore, in the present invention, it is necessary to disperse the Sn oxide in a range of 0.05 to 4.2 wt% Sn. The reason for setting these upper and lower limits is that when Sn is added to an alloy, when it is internally oxidized, the oxide takes on a acicular shape, but when it is added in excess of 5.0 Wt%, the oxide aggregates internally. However, this is because subsequent internal oxidation treatment becomes difficult and embrittlement increases even after oxidation. Furthermore, if the content is less than 0.01 Wt%, the effect of adding Sn will not be apparent. Next, as with Sn above, when an alloy containing In is internally oxidized, In becomes an acicular oxide, but in alloys that are combined with Sb and other elements, In exceeds 5.0 Wt%. When added, a dense oxide film is formed on the surface during internal oxidation, making it difficult for oxygen to penetrate, so the upper limit must be 4.2 Wt% and less than 0.05 Wt%. This is because the effect of addition does not appear when . Next, when Zn is added, Zn oxide has a lower vapor pressure than Sb oxide at temperatures below 1500°C, and together with In, it has the property of suppressing the performance of Sb oxide, and the volatilization of these oxides due to arcing etc. It has the effect of suppressing wear and tear. The reason why the upper limit of Zn addition was set at 4.2 Wt% is that if the amount added exceeds this, the oxide will aggregate during internal oxidation treatment, which will not only make subsequent internal oxidation difficult. This is because the Zn becomes extremely brittle, and if the Zn content is less than 0.05 Wt%, the effect of adding Zn will not be apparent. In this way, Sb
In addition, by adding Cd, Sn, In, and Zn in combination, a synergistic effect that cannot be obtained by adding them alone can be obtained, and each can exert an effect of suppressing volatilization loss.

Furthermore, in the present invention, both Te and Li are added, and as mentioned above, the effect of this addition is that the thermal strain caused by thermal cycles is absorbed by the fine cracks formed by these oxides, resulting in contact separation and The reason why the upper limit was set at 5.0 Wt% was to prevent the contact characteristics from deteriorating due to excessive microcracks, and the lower limit of 0.0 Wt% was set. 0
This is because if the amount is less than 1 wt%, the effect of the addition will not appear. Further, by adding low melting point metals such as Te and Li as described above, the castability of the multi-component alloy of the present application is improved. Furthermore, in addition to the above invention contents, the metal component is 0.
．． It is characterized by dispersing oxides of one or both of Ni and Fe in an amount of 01 to 1.0 wt% in Ag, which is the main component. Here, the reason for adding Ni and Fe is to refine the crystal grains and arrange the oxide particles.
In this case, the upper limit of 1.0 Wt% was set because even if added in excess of this, alloying would be extremely difficult by the melting method, and the lower limit of 0.01 Wt% would reduce the effect of grain refinement. It means the minimum that can be achieved.

[0009]

[Examples] Examples of the present invention will be described below. Examples are shown in Table 1. A metal material having a purity of 99.5 Wt% or more is used as a raw material and is melted in a non-oxidizing atmosphere to produce an ingot having an alloy composition as shown in Examples (1) to (10). After cutting the surface of the ingot, a thin pure silver plate is thermocompression bonded to one surface to form a silver layer for brazing. Next, the material is cold-rolled into a plate with a thickness of 2 mm, then punched into a disk shape with a diameter of 5 mm using a press machine, and placed in an internal oxidation furnace for 70 minutes while introducing oxygen into the furnace.
Heating at 0°C for 180 hours, Sb, Cd, Sn, In, Z
The alloy of the present invention was produced by selectively oxidizing n, Te, and Li.

0010

[Table 1]

[0011] For the above-mentioned Examples (1) to (10), the silver layer formed on the back side of the alloy and the pedestal for holding the contact were soldered with silver to prepare a sample for the contact test. Using a contact tester (AC100V, 20A) and an arc consumption tester (AC200V, 10A), we selected test conditions for each item listed in Table 2 while comparing with typical electrical contact materials that are commonly used in the past. , each contact material was tested under the same conditions.

0012

[Table 2]

[0013]

According to the present invention described in detail above, as shown in Table 2, Sb, Cd, Sn, In, Zn, and T
By dispersing Li oxide in Ag in an amount within a predetermined range, it has properties that are approximately the same as those of Ag-CdO alloys, and the amount of consumption can be significantly reduced. It becomes possible to significantly reduce the number of times of welding. In addition, an improvement effect was obtained in terms of exfoliation wear and tear caused by the above-mentioned thermal cycle, and it became possible to reduce the amount of Cd added as a pollution control measure.Furthermore, by adding Ni and Fe oxides, oxide particles could be reduced. This made it possible to promote improvements in the number of welds.

Claims (2)

[Claims] Claim 1: An oxide of Sb containing Ag as a main component, with a metal content of 0.1 to 6.2 Wt%, an oxide of Cd containing 0.1 to 20.0 Wt% of a metal content, and Sn with a metal component of 0.05 to 4.2 Wt%,
Each oxide of In and Zn and the metal component are 0.01 to 2.0
A silver-oxide electrical contact material characterized by dispersing Te and Li oxides in an amount of Wt%. [Claim 2] An oxide of Sb containing Ag as a main component and having a metal content of 0.1 to 6.2 Wt%, an oxide of Cd having a metal content of 0.1 to 20.0 Wt%, and Sn with a metal component of 0.05 to 4.2 Wt%,
Each oxide of In and Zn and the metal component are 0.01 to 2.0
Wt% of Te and Li oxides and metal components of 0.
A silver-oxide electrical contact material characterized in that 01 to 1.0 Wt% of oxides of one or both of Ni and Fe are dispersed therein.