JPH0142321B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to a method for producing an Ag-oxide contact material obtained by hot extrusion.

[Prior art and its problems]

For example, Ag-CdO, Ag- _SnO2 , Ag- _SnO2-
Ag-based metal oxide alloys (hereinafter abbreviated as Ag-MeO) such as In ₂ O ₃ , Ag-ZnO, and Ag-Bi ₂ O ₃ are often used. Ag-MeO is a useful material that has a relatively well-balanced property of wear resistance, welding resistance, and low contact resistance, which are important properties as a contact material, even though these properties are contradictory to each other. However, as electronic and electrical equipment becomes smaller and has a longer lifespan, contacts tend to be used under even more severe circuit conditions, so improvements in contact materials are being made in various fields. ing. The following two methods are conventionally known as methods for producing Ag-MeO contact materials. One method is mainly based on the melting method, in which an ingot is melted and cast by adding metal elements to Ag in a predetermined ratio and then rolled into a plate shape, which is then hot-rolled with an Ag plate as a backing material. Crimp. Then oxygen partial pressure 1Kg/cm ²
After carrying out internal oxidation treatment by maintaining the plate at a temperature in the range of 300 to 750° C. for several tens to hundreds of hours in the above oxidizing atmosphere, contacts are obtained by punching this plate into a desired shape. Among the above processes, plate-shaped
The reason for hot-pressing the Ag backing material onto the Ag alloy is as follows. The Ag alloy is then subjected to internal oxidation treatment, and the added metal element takes the form of an oxide and becomes Ag-MeO, but in order to use this as a contact, it must be soldered to a base metal such as Cu. It won't happen. However, it is difficult to solder the base metal with Ag-MeO, which has many oxides on the surface, so in order to form a surface that is easy to solder,
An Ag plate is heat-pressed onto one side of the Ag alloy. Since the Ag of this backing material is not oxidized during internal oxidation treatment, it can be easily soldered to the base metal. FIG. 2 shows the material composition of the contact point attached to the base metal in this manner. Ag- with backing material 2 on base metal 1 as shown in Fig. 2
A MeO contact base material 3 is bonded via a brazing material 4 and used as a contact. The Ag-MeO contact made mainly by the above melting method has good contact performance, but on the other hand, it has the following drawbacks. Internal oxidation treatment is extremely difficult in the atmosphere, and high-pressure oxidation must be performed using a high-pressure container. The internal oxidation process takes quite a long time. The adhesion between Ag-MeO and Ag plate is poor, and Ag-MeO falls off due to peeling from the soldered interface due to thermal stress generated during the opening and closing operation of the contact, and cracks in the Ag plate generated due to thermal stress. there is a possibility. On the other hand, there is another manufacturing method for Ag-MeO contact materials different from the above-mentioned method, which is mainly based on a sintering method based on a powder metallurgy method. This method uses mixed powders of Ag and metal oxides, or Ag alloys, which are made into alloy powders by water atomization, etc., and which are internally oxidized.
-The contact is obtained through a process of powder molding using -MeO powder and then sintering. According to the sintering method, an Ag layer can be attached to the contact base material by filling a mold with Ag-MeO powder and an Ag plate serving as a backing material during the molding process to form two layers.
This sintering method has the following advantages over the above-mentioned melting method. Internal oxidation treatment can be simplified. By arbitrarily selecting the composition of the contact material, the properties of the contact can be correspondingly varied. Various contact shapes can be set and there is almost no material loss. However, the sintering method has the disadvantage that the internal structure of the contact is not sufficiently refined and the contact performance is somewhat inferior to that of the melting method. For this purpose, the Ag-MeO contact material obtained by the sintering method is further hot-pressed,
Secondary processing such as hot rolling, hot forging, or hot extrusion is performed to refine the internal structure. Among these methods, hot pressing is effective in increasing the density of the contact material and making the structure finer, but burrs are generated around the periphery of the material and productivity is reduced due to the removal of these burrs, and moreover, material loss is large. Also, in hot rolling and hot forging, the sintered alloy is more porous and has lower strength than the alloy in the melting and rolling process, so defects such as cracks are likely to occur due to the tensile stress acting on the side surfaces of the workpiece. Both of these methods are difficult to adopt as industrial production methods. On the other hand, in hot extrusion, the workpiece is only pushed from the surroundings, no tensile stress is generated on the side surfaces, and defects are less likely to occur during processing, and large deformations can be applied. It is valid. However, this hot extrusion process has traditionally only been applied to contact materials that are made of a single material and that allow direct soldering between the contact and the base metal, such as Ag-Ni alloy wire. . Ag-
The thin rectangular contact material consists of two layers, MeO and backing material Ag, and these have different thicknesses.Ag-MeO
Because Ag contains a hard oxide and Ag is a soft and malleable material, the mechanical strength and deformation resistance of the two are extremely different, and such materials can be uniformly processed by hot extrusion. This is difficult and has rarely been done in the past. However, as mentioned above, the sintering method has advantages not found in the melting method, so it is thought that there is an urgent need to solve the problem of hot extrusion, which is effective in refining the internal structure.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and its purpose is to hot-extrude an Ag-MeO contact material having a two-layer structure of a contact base material and a backing material having different thicknesses and mechanical strengths. Our goal is to provide a manufacturing method that makes it possible.

[Key points of the invention]

In order to bring the mechanical strength of the backing material close to that of the Ag-MeO contact base material without impairing the electrical conductivity or solderability, the present invention uses Ag in an amount of 0.15% by weight or more to 1% by weight.
The following backing material added with Al oxide is used to enable hot extrusion of the base material and backing material in a two-layer sintering method.

[Embodiments of the invention]

The present invention will be explained below based on examples. In order to strengthen the backing material, it is effective to disperse a metal compound in Ag, and the inventor determined that it is easiest to use an oxide as the metal compound in terms of manufacturing method. They first used Li, Al, Mg, and other elements that can be internally oxidized as Ag alloys.
Zr, Cd, Fe, Mn, Si, Bi, and In were considered, but in order to increase the strength and not impair conductivity and solderability, the content as an oxide must be Separate experiments were conducted in order to select an alloying element with as little amount as possible and yet with high strength as a backing material, and as described below ~, it was found that the alloying element suitable for this purpose was A1. Ag-Al oxide alloys have mechanical properties such as hardness that are significantly higher than those of the other elements mentioned above even when the amount of Al added is small, and since the amount added is very small, the solderability does not deteriorate. . Furthermore, the Ag-Al alloy has the characteristic that internal oxidation is possible even when treated in the atmosphere. The contact is bonded to the base metal, and the specified conditions (voltage
440V/AC, current 480A, power factor 0.35, switching frequency
When conducting opening/closing tests in tens of thousands of directions at 300SW/h),
The thermal stress generated at this time may cause cracks in the backing material, causing the contacts to fall off. Cracks are generally more likely to occur if the strength of the backing material is low, especially if the hardness is low. It has been experimentally confirmed that the backing material should have a Bitkers hardness of approximately 80 or higher. Ag-Al oxide alloy satisfies this requirement. The table below shows a comparison of properties when an Ag-oxide alloy that can be internally oxidized in the atmosphere is used as a backing material.

[Table] Furthermore, even with A1 oxide, if the content of A1 oxide exceeds 1%, workability becomes poor and cracks occur, so it was found that the upper limit should be 1%. Furthermore, it has been found that a suitable lower limit is 0.15%; if the amount is less than this, the strength and deformation resistance of the backing material are too low, causing a problem in which only the backing material is extruded first during processing. The Ag-Al alloy used as the backing material was melted and then rolled into a plate shape, cut into the required shape, and internally oxidized in the atmosphere at 800°C to determine its strength. An example of the results is listed in Table 1. Table 1 shows the strength of Ag-Al ₂ O ₃ alloys obtained by changing the amount of Al added, but also shows the strength of conventional Ag for comparison.

[Table] Next, alloy powder made by water atomization was internally oxidized in the air for the Ag-MeO contact base material.
Ag-13.3% _SnO2-5.1 % _{In2O3 ,} Ag-5.7% _SnO2
-2.2% In ₂ O ₃ and Ag - 13% CdO, the first
For example, the combination with the lining material shown in the table can be
I made it like the table.

[Table] In Table 2, No. 1 and No. 2 are those using the backing material according to the present invention, and No. 3 is a conventional contact material for comparison. First, the thickness of the plate cut into the specified shape
After placing a 0.15mm backing material in the mold and filling it with a specified amount of Ag-MeO contact powder, 3Ton/
A pressure of cm ² was applied to form a two-layer compact having a thickness of 10 mm x width of 15 mm x length of 55 mm, and this was sintered in the atmosphere at 800° C. for 2 hours to obtain sintered compacts according to the combinations shown in Table 2.
Next, hot extrusion was carried out at a temperature of 550° C. and an extrusion ratio of 6 in a direction perpendicular to the stacking direction of the sintered body.
As a result, the contact materials No. 1 and No. 2 using the backing material according to the present invention were both able to be extruded uniformly with two layers, whereas the contact materials using the conventional Ag backing material In the case of .3, only the Ag was extruded first, so the required extrusion molding process was impossible. FIG. 1 is a microscopic structure showing the cross section of the two-layer extruded material according to the combination No. 2 in Table 2 at a magnification of 100 times. As can be seen from Figure 1, Ag−
0.72% _{Al2O3 alloy} backing material 5 and Ag−13.3% _SnO2
-5.1% In ₂ O ₃ The adhesion to the contact base material 6 is also good, and the internal structure of the contact is dense. Also, Table 2
In the case of combination No. 1, extrusion processing was also possible, and the cross-sectional structure showed good properties similar to those shown in Fig. 1. It has been confirmed through separate experiments that with the combination of the backing material and contact base material according to the present invention, two-layer extrusion is possible at a hot extrusion temperature of 450 to 700°C and an extrusion ratio of 3 to 7. . The contact material obtained according to the present invention was soldered to a base metal and incorporated into an electromagnetic contactor, and a switching test was conducted 30,000 times under the following electrical load conditions, and the contact performance and peelability between the contact base material and the backing material were evaluated. I looked into it. Voltage 440V, AC current 480A Power factor 0.35 Opening/closing frequency 300 (SW/h) As a result of this test, the wear amount of the Ag-MeO contact according to the present invention after 30,000 openings and closings was equal to or less than that of conventional contacts, and no welding occurred. No phenomenon was observed at all. In addition, no peeling was observed between the backing material and the soldering layer, or between the backing material and the contact base material, and the contacts using the backing material of the present invention were able to withstand thermal stress caused by repeated opening and closing. It has become clear that this is possible.

【Effect of the invention】

As explained in the examples above, the
When manufacturing Ag-MeO based contact base materials by hot extrusion, not only the conventionally used Ag but also
By using a backing material that contains 0.15% to 1% by weight of Al oxide to Ag and has increased mechanical strength to the same level as the base material, extrusion processing is facilitated, and the resulting contact material is dense. structure and strength,
It has excellent electrical conductivity and solderability, so it improves contact performance when used as a contact in an electromagnetic contactor, etc., and can sufficiently withstand the thermal stress caused by opening and closing the contact. This has the great effect of eliminating accidents caused by missing contacts, etc.

[Brief explanation of drawings]

Fig. 1 is a photograph of the metal structure of a cross section of a contact material using a backing material according to the present invention after hot extrusion, viewed under a microscope, and Fig. 2 is a cross-sectional view showing the material composition of a contact attached to a base metal. . 1: base metal, 2, 5: lining material, 3, 6: contact base material, 4: brazing material.

Claims (1)

[Claims] 1. In a method for manufacturing an Ag-metal oxide contact material equipped with a backing material that serves as a soldering part, an Ag plate containing 0.15% by weight or more and 1% by weight or less of A1 oxide is used as the backing material, and the A contact material characterized in that an Ag plate and a raw material powder of an Ag-metal oxide contact material are laminated and pressure-molded to form a two-layer sintered body, and then hot extruded in a direction perpendicular to the lamination direction. manufacturing method.