JPS6040649B2 - Electrical contacts and their manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrical contact and a method for manufacturing the same.

Conventionally, gold-based contact materials, silver-based contact materials, and platinum-based contact materials have been used for relay and switching contacts.
is being used.

Contacts using gold-based contact materials have excellent corrosion resistance and atmospheric resistance, and when used under light loads (for example, 100 V, 1 skin A), the contact resistance does not increase and is stable even when the number of openings and closings increases. It is. However, due to the relatively low melting point and hardness of gold-based contact materials, they are susceptible to welding, deformation, and adhesion failure when used under heavy loads (eg, 30V, IA). Therefore, there was a problem in using it under heavy loads. Contacts using silver-based contact materials tend to form an insulating film in the atmosphere, and because the melting point and hardness of silver-based contact materials are low, they are prone to welding, deformation, and adhesion failure when used under heavy loads. there were. Furthermore, since the platinum-based contact material has a high melting point and hardness, contacts using platinum-based contact materials do not cause welding, deformation, or adhesion failure even when used under heavy loads. However, when used under light loads, insulating organic matter (brown powder) tends to form on the contact surface, causing poor contact. Therefore, there was a problem in using it under light loads. In this way, conventional contacts operate accurately only under either gentle loads or heavy loads, and none operate accurately under either light or heavy loads. This inventor is
As a result of a series of research on the development of contacts that operate accurately under both light and heavy loads, we found that Au-A
Since g-alloys have higher hardness, melting point, etc., they discovered that they could be used to construct contacts that would not cause welding or deformation even when used under light loads as well as heavy loads.

As a result of further research, it was discovered that dispersing highly hard WC particles in an Au-Ag alloy would provide a contact with even better characteristics when used under heavy loads. completed. That is, the first gist of the present invention is an electrical contact having a contact layer formed by dispersing WC particles in an Au-Ag alloy, and on the Ag-WC layer formed by dispersing WC particles in Ag, Au-WC layers made by dispersing WC particles in Au are stacked, and in that state Ag-
By slowing down the diffusion of the WC layer and the Au-WC layer, A
The second subject matter is a method for manufacturing an electrical contact characterized by forming a contact layer made by dispersing WC in a u-Ag alloy.

Next, this invention will be explained in detail.

The electrical contact of the present invention has a contact layer formed by dispersing WC particles in an Au-Ag alloy which has a higher hardness and melting point than Au and Ag.

That is, this electrical contact operates accurately under both light and heavy loads because WC particles having the following characteristics are dispersed in the Au-Ag alloy for the contact layer, which has high hardness and melting point.

Characteristics of JWC particles {1} Extremely high hardness.

‘2) High melting point.

{3' Stable against various corrosive gases in the atmosphere.

[4' Conductive. {5) High oxidation resistance.

To be more specific, when this electrical contact is used under light loads, the surface of the contact layer made of mostly Au-Ag alloy (WC is dispersed inside the contact layer and is not exposed on the surface). Opening/closing operation is performed with (no).

Therefore, there is almost no formation of brown powder or insulating film as in the conventional example, and the opening/closing operation is accurate. Also,
When used under heavy loads, the contact layer is heated by the arc heat generated by the opening/closing operation, but the Au constituting the contact layer
-Ag alloy has higher hardness and melting point than Au or Ag alone, so it suppresses the occurrence of welding, deformation, and adhesion failure. When the surface portion of the contact layer wears out due to use under heavy loads, WC particles with extremely high hardness and melting point protrude from the surface of the contact layer and participate in opening and closing. becomes longer. In this case, the amount of dispersed WC particles is preferably set within the range of 15 to 45% by weight (hereinafter abbreviated as %) of the total weight. If the amount of dispersion is below this range, the effect will be small, and if the amount of dispersion is above this range, problems will arise in terms of workability of the contact layer. In particular, in the electrical contact of the present invention, if the concentration gradient of Au is increased so that the Au concentration increases at the surface of the contact layer and decreases toward the inside of the contact layer, the contact surface can be used under light loads. The surface part of the contact layer that acts becomes rich in Au, which has excellent corrosion resistance and atmosphere resistance and has low initial resistance.
The amount of Ag that tends to form an insulating film is reduced.

Therefore, when switching at light loads, the contact resistance becomes more stable even as the number of switches increases, and the life of the contacts becomes longer when used at light loads. Such an effect is most noticeable when the surface portion of the contact layer has a concentration of 100% and the concentration gradually decreases toward the inside. When a concentration gradient of Au is provided in the contact layer in this way, it is expected that Ag will precipitate on the surface of the contact layer, thereby forming an insulating film.

That is, this is because Ag is a metal with extremely high permeability. However, in the contact of the present invention, such a problem does not occur because Ag is alloyed to form an Au-Ag solid solution. Next, we will introduce a contact layer that has a contact layer formed by dispersing WC particles in an Au-Ag alloy, and in which the Au concentration increases at the surface portion of the contact layer, and the A concentration decreases toward the inside. An example of a manufacturing method will be described.

That is, Ag+WC particles were first put into a mold, followed by Au and WC particles, and the molding was carried out under a pressure of 4 tons. Next, it was heated to 920q○ in a hydrogen stream.
Heat for 1 hour to sinter. After finishing the drying process, it is again press-molded at a pressure of 1 kg/kg to make it denser. Then, the densified material is cold rolled to a plate thickness of 0.5
Willow will be punched out to the specified dimensions. A side sectional view of the punched body is shown in FIG. In the figure, 1 is Ag, 2 is Au
, 3 are WC particles. That is, this punched body has a two-layer structure, with the lower layer 4 consisting of an Ag-WC particle layer and the upper layer 5 consisting of an Au-WC particle layer. next,
This punched body was subjected to diffusion sintering at 550° C. for 4 hours in a hydrogen stream. As a result, a contact having a contact layer 6 as shown in FIG. 2 is obtained. This contact layer 6 is A
It is composed of a u-Ag alloy 7 and WC particles 3 dispersed therein, and as shown in FIG.
It has a concentration gradient such that the Au concentration decreases toward the bottom surface at uloo%. As described above, according to this manufacturing method, a contact having a contact layer having the above-mentioned Au concentration gradient can be manufactured extremely easily. Next, an example of manufacturing the electrical contact of the present invention will be described.

Production examples 1 to 3 First, put Ag+WC particles into a mold, then Au+WC particles.
Particles were added and pressure molded at a pressure of 4 tons.

At this time, the amount of WC particles used was adjusted as shown in Table 1 below. Next, the press-molded body was heated at 92,000 for 1 hour in a hydrogen stream to cause competitive bonding. This aggregate was press-molded at a pressure of 1 skin n' to make it denser, then rolled between the sleeves and punched into a predetermined size. Next, this punched body was diffusion annealed in a hydrogen stream at 55,000 ℃ for 4 hours to obtain an electrical contact. Reference Example The punched bodies obtained in Production Examples 1 to 3 were used as electrical contacts without being subjected to diffusion hammering.

Heavy load (3
The contact life in use at 0 V, IA) and light load (100 V, 1 A) was measured, respectively.

The results are shown in Table 2. Table 2 In addition, in Table 2, the measurements were performed as follows.

Heavy load test > Under a load of 30V and IA, the reinforcement point is opened and closed at a frequency of 2.8 times per second, and the opening and closing is continued until the contact resistance becomes 40 or more or welding occurs and it becomes impossible to separate. The contact life is expressed by the number of times.

<Light load test> At a load of 100 mV and lmA, the contacts are opened and closed at a frequency of 100 times per second, and when the contact resistance during the opening and closing operation becomes 300 or more, this is detected as a contact error, and this initial contact error occurs. Contact life is expressed as the number of times the contact is opened and closed.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view for explaining the manufacture of the electrical contact of the present invention;
Figure 2 is a side sectional view of the contact layer of the electrical support point of this invention;
The figure is the Au concentration gradient curve diagram. 3...WC particles, 6...contact layer, 7.
...Au-Ag alloy. Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. An electrical contact having a contact layer formed by dispersing WC particles in an Au-Ag alloy. 2. The electrical contact according to claim 1, wherein the Au concentration is high in the surface portion of the contact layer, and the Au concentration decreases and the Ag concentration increases toward the inside of the contact layer. 3 Overlay the Au-WC layer made of WC particles dispersed in Au on top of the Ag-WC layer made of WC particles dispersed in Ag, and then diffuse the Ag-WC layer and Au-WC layer in this state. A method for manufacturing an electrical contact, which comprises forming a contact layer in which WC is dispersed in an Au-Ag alloy by annealing.