SU1644240A1 - Composite liquid-metal contact and method of its manufacture - Google Patents

Abstract

The invention can be used to create electrical switching devices. The purpose of the invention is to increase reliability and simplify manufacture. The contact (K) contains a porous frame, which is impregnated on the side of contact with the low-melting metal, and on the side facing the materials from which the contact carrier (CD) is made. Manufacturing method K consists in simultaneously wetting the frame with a low-melting metal and a CD material. Wetting is carried out on opposite sides of the frame in the opposite direction. 2 sp.f-ly, 2 ill. (Ls

Description

The invention relates to electrical apparatus, in particular to the contact nodes of switching devices, and can be used to create high-current switching equipment with composite liquid metal contacts.

The purpose of the invention is to increase reliability and simplify manufacture.

FIG. 1 shows a composite liquid metal contact fixed in the contact holder; in fig. 2 illustrates a method for making composite contact.

The contact (see Fig.1) contains a porous frame 1 made of powder of a refractory metal and impregnated from the contact side with a low-melting metal or alloy

2, and from the side of contact holder 3, material 4, from which the contact holder is made. The finished contact is fixed in the socket of the contact holder 3 by soldering 5.

The contact works as follows.

The contacting part of the contact is impregnated with a low-melting alloy or metal 2, therefore, when contacting with a similar contact, all the advantages of liquid-contact contact (low contact resistance, no welding of contacts, small amount of contact pressing force, etc.) remain. On the other hand, due to the fact that part of the contact facing the contact holder 3 is impregnated

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On the material 4, from which the contact holder is made, it is easy to ensure high-quality fixing of the contact in the contact holder 3, as the welding and soldering technologies for homogeneous metals have been well developed.

Contact example. The framework is made of refractory powder (providing high erosion and chemical resistance) of a metal, for example, tungsten. The gallium-indi- tin alloy is impregnated on the contact side (melting point + 10.5 ° C) and copper on the side of the contact holder. The contact is fixed in the socket of the contact holder by soldering with copper solder.

The method of making the contact is schematically presented in FIG. Initially, the porous frame 1 made of refractory metal is pressed and sintered by powder metallurgy methods. Then, the porous frame 1 is placed in an impregnation bath 6, above which a reservoir 7 is located, equipped with a shutter 8. In the reservoir 7 there is a low-melting alloy 2, and in the bath 6 - metal 4, identical to the metal of the contact holder. The wetting process is carried out either in a vacuum or in a hydrogen furnace (not shown in the drawing) when both of the impregnating materials are in the molten state. Due to the fact that the melting point of the material 4 of the contact holder is always higher than the melting point of the low-melting alloy 2, the latter is maintained until the temperature at which the wetting of the frame starts with the contact-holder material and only after that the valve 8 is removed, the liquid low-melting metal comes into contact with the frame and begins to wet it and impregnate. The wetting and soaking process on the rum framework 1 will simultaneously dry two liquid components from opposite sides towards

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each other and ends at the meeting boundary of these components. By knowing the wetting rate of the porous metal with both liquid components, it is possible to determine in advance the position of the boundary of the meeting of these components.

An example implementation of the method. Ready porous tungsten frame 1 is placed in the bath 6 on the copper plate. In the tank 7 is placed an alloy of gallium-indium-tin. Bath 6 and the tank 7 are placed in a hydrogen furnace. At the melting point of copper (1083 C), the valve 8 is opened. The process of wetting the porous framework with a low-melting alloy and copper occurs simultaneously in the opposite direction. The result is a contact, one side of which is impregnated with a low-melting alloy, and the other side with a contact-holder material.

Claims (2)

1. A composite liquid metal contact containing a porous refractory metal frame is at least partially impregnated with a low-melting metal or alloy, one side of which is intended to be fixed to the contact carrier, which, in order to increase reliability and simplify manufacturing, is porous the frame on the side of attachment to the contact holder is impregnated with the material from which the contact holder is made. 2. A method for manufacturing a composite liquid metal contact, which includes the manufacture of a porous carcass from refractory metal powder followed by impregnation with a low-melting metal or alloy, characterized in that simultaneously with the impregnation with a fusible metal or alloy, the carcass is impregnated with the material from which the contact holder is made, and these operations produced from opposite sides of the frame in the opposite direction. Fy ,eight Fie.2