JPS59226138A - Manufacture of electrical contact material - Google Patents

Abstract

PURPOSE:To obtain an electrical contact material with improved welding resistance by press-molding a powdered mixture having a specified composition consisting of Ag, Ni, Si and Cu oxide and by sintering the molded body in a reducing atmosphere. CONSTITUTION:Powdered starting materials are uniformly mixed so as to provide a composition consisting of 10-30% Ni, 0.5-4.5% Si, 1.7-10% (expressed in terms of Cu) Cu oxide and the balance essentially Ag. The powdered mixture is press-molded and sintered in a reducing atmosphere. During the sintering, at least a part of the Cu oxide is reduced and forms a solid solution in Ag and Ni in the form of metal. By this method a contact material with improved welding resistance can be manufactured inexpensively. This contact material is comparable or superior to a conventional Ag-CdO type electrical contact material in contact performance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an electrical contact material, and in particular to a method for producing a harmless sintered material for electrical contacts with excellent welding resistance.

Conventionally, A g Cd O-based sintered materials, which have been widely used as electrical contact materials in the medium load range, have excellent contact performance, but because they are made of harmful Cd, there are problems during their manufacturing process and use. There is a risk that it may become dust containing Cd and cause pollution), and it also has the disadvantage of being high in cost due to the high Ag content.

On the other hand, Ag is used as a harmless electrical contact material that does not contain Cd.
Although Ni-based sintered materials have been put into practical use, this AgNi-based sintered material has a problem in that it is inferior in welding resistance compared to AgCd0-based materials.

The present invention aims to improve the welding resistance, which is a drawback of conventional AgNi-based sintered materials, and to make it possible to manufacture inexpensive electrical contact materials that have contact performance equivalent to or better than AgCClO-based electrical contact materials. This is the purpose.

The gist of the invention is that N1 10-30%, 810.5-4
．． After pressure-molding a mixed powder consisting of 5% Cu oxide, 1.7 to 10% Cu oxide, and the remainder substantially Ag, it is sintered in a reducing atmosphere, and at least a portion of the oxide is removed. A method for producing an electrical contact material, characterized by reducing the material and forming a solid solution in AB and Ni in the form of a metal.

To explain the reason why the composition of the sintered key material for electrical contacts according to the present invention is limited as described above, Ni is added to improve wear resistance, but if Ni is less than 10%, the effect is However, if it exceeds 30%, the processability deteriorates, so it was set at 10 to 30%. In addition, Si is added to improve welding resistance, and if the amount added is less than 0.5%, the effect of addition will not be fully achieved, and if it exceeds 4.5%, wear resistance will decrease. However, since the processability deteriorates, the content was set at 0.5 to 4.5%. Cu oxide is added to improve contact resistance and Ni dispersibility, and if the amount added is less than 1.7% in terms of metal Cu, no improvement in Ni dispersibility will be observed; If it exceeds 1.7% to 10%, the welding resistance deteriorates.

The electrical contact material according to the method of the present invention having the above-mentioned composition has greatly improved adhesion resistance compared to conventional AFiNi-based sintered materials, and exhibits adhesion resistance equivalent to that of AgCd0-based sintered materials.

In addition, in terms of contact resistance and abrasion resistance, they are equivalent to those of the AHNi type, and are slightly inferior to those of the AgCd0 type, but the difference is not so great as to cause a practical problem. Furthermore, the electrical contact material according to the method of the present invention can be manufactured at a low cost because it can reduce the Ag content compared to AgCd0-based sintered materials, and it does not contain harmful Cd, which can cause pollution. There is no.

According to the present invention, the electrical contact material contains Ag as a raw material.
, Ni, Si, and Cu oxide fine powders are mixed in a predetermined ratio, and after pressure molding, the mixture is heated at 700 to 800°C in a reducing atmosphere such as decomposed ammonia gas (N2+H2).
This is because at least a portion of the oxides are reduced during the sintering process, and the Ni This is because it is difficult to obtain finer Ni alloy particles dispersed in the Ag matrix because the Ni alloy particles are solid-dissolved in the Ag matrix and processed to make them finer. In addition,
A part of the reduced Cu also dissolves in Ag and slightly increases the resistance compared to pure Ag, but this does not pose any particular problem as an electrical contact material. Further, after sintering, it is preferable to subject the obtained sintered body to reprocessing such as sizing and coining.

As the raw material powder, powders having a particle diameter of 0.1 to 103 μm, preferably 0.5 to 20 μm can be used, and commercially available powders may be used as they are.

Examples of the present invention will be described below.

Example raw material powder was Ag (average particle size: 1.08μ) 70% by weight
, Ni (average particle size: 2.2μ) 20% by weight, Si (average particle size: 5.17) 2.5% by weight, Cu20 (average particle size: 5μ) 7.5% by weight (Cu conversion) Mixed uniformly in a ball mill, the mixed powder was mixed at 4t/c.
The molded body was formed into a diameter of 20 mm and a length of 30 nm under a pressure of +n2, and the resulting molded body was placed in a reducing gas atmosphere (N2 + H2
) and sintered by heating at 750° C. for 2 hours to obtain a sintered body for electrical contacts. This sintered body is heated to 700 to soo'c,
After molding into a rod-shaped body with a diameter of 6 mm using an extruder, the contact point obtained by processing with a wire drawing header was assembled into a relay to prepare a test product.

Comparative Example 1 Using the A and CdO powders used in Examples as raw materials, a sintered body made of Ag-12%CdO was obtained in the same manner as in Examples, used as a contact, and incorporated into a relay to make a sample. And so.

Comparative Example 2 Using 1 to 1 g and Ni powders used in Examples as raw materials, these were mixed at a weight ratio of 70% Ag and 30% Ni, and an AgNi-based sintered body was obtained in the same manner as in Examples. This was used as a contact, and this was incorporated into a relay and used as a sample.

Comparative Example 3 The raw material powders Ag, Ni and Sl used in the examples were replaced with metal C.
Along with u, Ag 70%, Ni2O%, Si2.5%,
Cu metal powder (average particle size: 5/7) was mixed at a weight ratio of 7.5%, and a sintered body was obtained in the same manner as in the example to form a contact, which was incorporated into a relay to form a test sample.

The contact resistance, abrasion resistance, and welding properties of the samples obtained in each of the Examples and Comparative Examples described above were measured under the following conditions. The results are shown in the table. The wear resistance is expressed as the number of relays whose contact force was 5 g or less after 350,000 opening and closing operations.

[Test conditions] Sample: 5 relays (2C) each x Pressure: AC220V Current: 4A Load: Resistance load contact crab Initial 20-30g Opening/closing frequency: 30 times/min [Table Monthly contact resistance Wear resistance Pre-welding bend (mΩ) (pcs) (distance) Example ~65 2 49 Comparative Example 1 ~
40 1 45 Comparative example 2 ~70 2
38 Comparative Example 3 ~? '02 46 As is clear from the results shown in Table 1, the electrical contact material according to the present invention has significantly improved welding resistance compared to those of Comparative Example 2 and Comparative Example 3, and the welding resistance of the electrical contact material of the present invention is significantly improved compared to that of Comparative Example 1. It shows equivalent characteristics. Regarding contact resistance and wear resistance, Comparative Example 1
It can be seen that although the difference is slightly inferior to that of

Claims (1)

[Claims] (1) Ni 10-30%, Si 0.5-4.
After press-molding a mixed powder consisting of 5% Cu oxide and 1.7-10% (Cu equivalent) and the remainder substantially Ag, it is sintered in a reducing atmosphere, and at least a portion of the oxide is 1. A method for producing an electrical contact material, which comprises reducing Ag and Ni to form a solid solution in the form of a metal.