JPS6255252B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of manufacturing an electric contact, and more particularly to a method of joining a contact base and a contact that constitute a contact. There are two methods for joining the contact block and contacts: mechanical methods: caulking method, cladding method, and welding method: brazing method. The former is highly malleable and can withstand plastic deformation because the contact itself undergoes strong mechanical processing.
Ag--Materials such as Ni and Ag are required. This type of material has poor wear resistance and tends to melt at high temperatures, so it is limited to relatively small and small capacity contacts. In addition, in the latter case, the low melting point alloy layer of the brazing material and the base metal generates voids during the process of melting and cooling, and the voids occupy 20 to 30% of the joint area, which not only deteriorates the thermal properties but also causes mechanical problems. lowers the strength of the target and lowers its reliability. In addition, in the welding method, flux,
The brazing filler metal becomes colloidal during use, making it difficult to automate and save labor. Furthermore, pollution caused by evaporated gas of cadmium contained in the brazing filler metal is also an important problem in the production of electrical contacts. On top of that,
Ag-Cd contacts have poor brazing properties, and to improve this, the joint surfaces must be coated with silver in advance, which increases costs. The present invention solves the problems of the above conventional method,
It is an object of the present invention to provide a method for manufacturing an electrical contact that has excellent heat resistance and is inexpensive. In order to achieve this object, the method for manufacturing an electrical contact according to the present invention involves inserting a contact base and a contact point between two electrodes having parallel surfaces facing each other, and inserting the contact base and the contact point between the two electrodes. The contact base and the contact are heated to a temperature that does not exceed the lower of the melting points of the two members by applying electricity between the electrodes while applying pressure to prevent plastic deformation of both members, and then rapidly cooled. The method is characterized in that the two members are joined together. In this method, the contact block and the contact are 0.02
400℃ while applying pressure of Kg/mm ² to 1Kg/mm ²
Preferably, it is heated to 900°C and then rapidly cooled in water. Next, general and specific examples of the method for manufacturing an electric contact according to the present invention will be described with reference to the drawings. First, a general embodiment of the present invention will be described. FIG. 1 is a longitudinal cross-sectional view of a bonding device used for bonding a contact base and a contact. In FIG. 1, a contact base 3 and a contact 4 are inserted between carbon electrodes 1 and 2 under a certain atmosphere (for example, in the atmosphere), and a cylinder 5 is used to push the electrode 2 in the direction of the arrow. Pressure in the range of 0.02 to 1.0 Kg/mm ² on the pressurized surface when moving (less than 0.02 is not sufficient pressure;
If the pressure exceeds 1, the contacts and the contact base will undergo plastic deformation), and at the same time, power is supplied to electrodes 1 and 2 from a power source (not shown) (6000 to 9000 A, either AC or DC is acceptable). As shown in the heating temperature control curve diagram in FIG. After heating to 900℃, it is rapidly cooled in water to complete the bonding. Next, specific examples of the method of the present invention will be described. Example 1 Copper was used as the contact base 3, and silver-cadmium was used as the contact 4, and the two were joined by the method described above. The atmosphere was atmospheric. The pressure applied to the contact block 3 and the contact 4 is applied to the pressurized surface.
It was set to 0.4Kg/ ^mm2 . In addition, the contact base material (copper) and the contact material (silver-cadmium alloy) were heated to 650° C. by applying current (9000 A current) between the electrodes 1 and 2 for 3 seconds without exceeding their melting points. Ordinary tap water (water temperature 15°C) was used as cooling water. FIG. 3 is a micrograph of the cross section of the electrical contact thus obtained, magnified 150 times. In Figure 3, the copper contact block 3
and the silver-cadmium alloy contact 4 are directly joined,
No alloy layer formed by fusion of low heat-resistant brazing filler metal or bonding materials was observed between the two joints, indicating that the joint state was ideal. FIG. 4 is a diagram schematically showing the results of analyzing the above-mentioned joint using an X-ray microanalyzer. In FIG. 4, the characteristic line Cu shows the change in the diffusion concentration of copper, which is a component of the contact base 3, and the characteristic line Ag shows the change in the diffusion concentration of silver, which is the main component of the contact. As is clear from Figure 4, the characteristic line Cu and
The point where the Ag intersects is the bonding interface between both bonding materials, and the copper of contact block 3 diffuses into the silver of contact 4 to a depth of 4.1 μm, and the silver of contact 4 diffuses into the copper of contact block 3. diffuses to a depth of 1.6 μm. Furthermore, due to the sensitivity of the analyzer, etc., the diffusion concentration of each component is
If a region of 30% or more is defined as a diffusion layer, the thickness of this diffusion layer is 1.8 μm as shown in FIG. Since the contact base 3 and the contact 4 are joined by mutual diffusion of both joining members as described above,
Only a diffusion layer is generated at the bonded portion, and an alloy layer that fuses both bonding members is not generated. When a diffusion layer is generated at the joint between the contact base 3 and the contact 4 in this way, the heat resistance temperature of the joint is lower than the melting point of both joining members, unlike when an alloy layer is formed at the joint. It is determined by the melting point, whichever is lower. As in this example, copper contact base and silver
When bonded with a cadmium alloy contact, the melting point of copper (100% by weight) is 1083℃, and the melting point of silver (87%
Since the melting point of the cadmium (13% by weight) alloy is approximately 900°C, the heat resistant temperature of the joint in this case is 900°C. When a copper-silver alloy layer is formed at the joint, the temperature decreases the most to about 780°C. Example 2 Brass was used as the contact base 3, and a sintered product of silver and cadmium oxide was used as the contact 4, and both were joined in the same manner as in Example 1. Figure 5 shows the cross section of the electrical contact obtained in this way after the shear breakage test.
This is a 62x micrograph. From this photograph, it can be seen that in this example as well, as in Example 1, the joining was carried out at a temperature lower than the melting point of both joining members, so no alloy layer was formed at the joint, and mutual diffusion of both joining members occurred. It can be seen that the bonding is performed by . And, despite receiving high heat from the arc during the burnout,
The joint portion serving as the boundary between the contact base 3 and the contact point 4 has no cavity indicating mutual peeling, indicating a stable joint state. Next, the following table shows typical examples of combinations of contact base materials and contact materials that can be joined by the joining method according to the present invention. The mark 〇 indicates that it is possible to join. According to the present invention, the contact base and the contact are placed one on top of the other and pressurized, while making sure that the melting point of both members is not exceeded.

[Table] Since direct diffusion bonding is performed by heating with electricity, the following effects can be obtained. a Flux and brazing filler metal are not required. b) Therefore, there is no need to supply brazing filler metal or flux, so automation, labor saving, and mass production are easy. c. Since an alloy layer is not formed at the joint, heat resistance equivalent to that of the material of the contact base or the contact, whichever has a lower melting point, is obtained, and there is no decrease in heat resistance due to joining. d) Since the bonding members are not melted, no voids are generated in the bonded area, and the entire surface of the bonded area can be bonded uniformly. e Since no brazing filler metal is used, there is no need to treat the vaporized cadmium oxide gas generated when the brazing filler metal is melted. f Since no brazing filler metal is used, even when bonding Ag-Cd contacts, it is possible to bond without silver-plating the bonded area in advance.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a bonding device for carrying out the method of bonding a contact block and a contact according to the present invention, and FIG. 2 is a diagram of a heating temperature control curve in the method of the present invention.
Figure 3 shows a cross section of the joint between the copper contact block and the silver-cadmium alloy contact, which were joined by the method of the present invention.
A 150x micrograph, Figure 4 is a diagram schematically showing the analysis results of the above joint using an X-ray microanalyzer, and Figure 5 shows a brass contact base and a silver-cadmium oxide sintered part joined by the method of the present invention. The cross section of the joint after the shear test of the joint with the solid-state contact
This is a 62x magnification micrograph. 1, 2...electrode, 3...contact stand, 4...contact.

Claims (1)

[Claims] 1. A contact base and a contact are inserted between two electrodes having parallel surfaces facing each other, and the contact base and the contact are inserted between the two electrodes so that both members are plastic. The two members are heated to a temperature that does not exceed the lower of the melting points of the two members by applying current between the electrodes while applying a pressure that does not cause deformation, and then rapidly cooled to join the two members. A method of manufacturing an electric contact. 2. In the method described in claim 1, the contact base and the contacts are heated to 400°C to 900°C while pressurized at a pressure of 0.02Kg/mm ² to 1Kg/mm ² and then rapidly cooled in water. A method of manufacturing an electric contact, characterized by: