JPS6147894B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an Ag-Sn oxide electrical contact material.

Conventionally, Ag-CdO alloys have been used as electrical contact materials in a wide variety of fields because they have excellent electrical contact performance, but Cd is harmful to the human body, so it has not been used as an electrical contact material. Use is not recommended.

For this reason, alloys in which Sn oxide is dispersed in Ag have recently been attracting attention as electrical contact materials with electrical contact performance comparable to Ag-CdO alloys. It was difficult to disperse it well. In other words, when an Ag-Sn alloy is internally oxidized, depending on the oxidation conditions, the dispersion state of Sn oxide in Ag may become non-uniform dispersion forming a deposited layer of Sn oxide, or extremely fine precipitation of Sn oxide may occur. becomes. Of these, especially the latter, extremely fine
Precipitation of Sn oxides significantly impairs the plastic workability of Ag alloys and makes them extremely hard.
As a result, it has been difficult to obtain electrical contacts with a predetermined shape. In addition, as mentioned above, it is not possible to uniformly disperse Sn oxide in Ag with an appropriate size.
The electrical contact performance was inferior to that of Ag-CdO alloys.

For this reason, conventionally, Ag-Sn oxide alloy was made by mixing Ag powder and Sn oxide powder and sintering, but depending on the mixing and sintering method of this powder, Sn oxide in Ag It is difficult to disperse Ag−CdO well.
It was not possible to obtain electrical contact performance equivalent to that of the alloys.

The present invention was made in view of the above circumstances, and provides an Ag-Sn oxide electrical contact material that can uniformly disperse Sn oxide in Ag in an appropriate size and soften the hardness of the alloy. The purpose of this invention is to provide a method for manufacturing.

The method for producing the Ag-Sn oxide electrical contact material of the present invention involves internally oxidizing an alloy containing 0.5 to 12% Sn in Ag at 250 to 600°C and then heating it to 940 to 960°C. This is a characteristic feature.

In other words, in the manufacturing method of the present invention, an alloy in which extremely fine Sn oxides are precipitated in Ag by an internal oxidation method is heat-treated at a temperature close to the melting point of Ag.
This improves the dispersion state of Sn oxide in the alloy and softens the hardness of the alloy.

In the production method of the present invention, Sn is added in Ag from 0.5 to
The reason for containing 12% by weight is that if it is less than 0.5% by weight,
The effect of oxide dispersion on Ag is small;
This is because if it exceeds 12% by weight, internal oxidation becomes extremely difficult.

Also, the reason why an alloy containing 0.5 to 12% by weight of Sn in Ag is internally oxidized at 250 to 600°C is that 250°C
If the temperature is below 600°C, the progress of internal oxidation will be slow and productivity will be poor; if it exceeds 600°C, a dense layer of oxide will form on the surface or just below the surface, making it difficult for oxygen to penetrate.
This is because internal oxidation becomes difficult.

Furthermore, the reason why the alloy is heated at 940 to 960°C after internal oxidation is that below 940°C, the dispersion state of Sn oxide in Ag cannot be improved, and when it exceeds 960°C, the dispersion state of Sn oxide in Ag cannot be improved. This is because separation occurs rapidly and a good dispersion state of Sn oxide cannot be obtained.

Next, in order to clarify the effects of the method for producing an Ag-Sn oxide electrical contact material according to the present invention, specific examples will be described.

Example 1 A 1.0 φmm wire made of an 8% by weight Ag-Sn alloy was heated to 450° C. in an oxygen partial pressure of 9 atmospheres and internally oxidized for 200 hours to obtain an Ag-Sn oxide alloy. The hardness at this time is
I couldn't bend it with Hv230. Next, the Ag-Sn oxide alloy after internal oxidation was heated at 945℃ in the air.
Heat for 20 minutes. The hardness at that time was Hv110, and this
A rivet shape with an occipital diameter of 2.0φmm was made by cutting a 1.0φmm wire.

Example 2 Ag-Sn 8% by weight alloy was made into powder of 0.3φmm to 0.01φmm and heated to 450°C in an oxygen partial pressure of 9 atm.
Ag-Sn oxide alloy powder is produced by internal oxidation for a period of time, heated at 950°C to 960°C for 5 minutes, compressed and extruded into a wire rod, and then wire-drawn to obtain a 2.0 It was made into a φmm wire rod. The hardness at that time
Occipital diameter 4.0 when cutting this 2.0φmm wire at Hv90
Made into a rivet shape of φmm.

As can be seen from the above, the method for producing the Ag-Sn oxide electrical contact material of the present invention is a method for producing an Ag-Sn oxide electrical contact material that is hard enough to be obtained by internally oxidizing the Ag-Sn alloy, and which has very fine Sn oxide precipitated. Alloy continues to be 940~
By heating at 960℃, the hardness becomes soft and has excellent plastic workability, and the dispersion state of Sn oxide in Ag is improved, and Sn oxides of appropriate size are uniformly dispersed. Ag-Sn has a dispersion state similar to that of Ag-CdO alloys and has excellent electrical contact performance.
This has the effect that an oxide electrical contact material can be obtained.

Claims (1)

[Claims] 1. A method for producing an Ag-Sn oxide electrical contact material, which comprises internally oxidizing an alloy containing 0.5 to 12% by weight of Sn in Ag at 250 to 600°C, and then heating it to 940 to 960°C. .