JPS5854179B2 - electrical contact materials - Google Patents

Description

[Detailed description of the invention] The present invention relates to improvements in Ag-WC type contact materials.

Because of its excellent arc resistance and welding resistance, Ag-WC alloys are used as contact materials for air circuit breakers including no-fuse breakers, and for various electrical devices.

However, air circuit breakers and switches such as no-fuse breakers are becoming smaller and more sophisticated, and as a result, the load on contact materials is increasing, making it necessary to improve contact performance. desired.

In particular, there is a problem in that miniaturization increases scattering and wear and tear that occur when current is cut off, resulting in significant deterioration of the insulation properties of the equipment, and it is desired to maintain and improve these properties.

The present invention has been made in view of the above points, and provides an Ag=WC-based electrical contact material that is highly practical and has enhanced insulation resistance.

Next, the features of the present invention will be described.

Deterioration of insulation resistance occurs when current is turned on and off (the arc that occurs causes the contact material to scatter, and consumable dust adheres to the inside of the device), but in the case of Ag-WC contacts (this
It was confirmed that this scattered and consumed dust was mainly Ag.

Therefore, the present inventors investigated various alloy systems from the viewpoint of reducing the amount of scattered Ag and improving the insulation properties by increasing the melting temperature of the scattered Ag. It has been found that by adding 0.01 to 5 weights of aluminum, pressing, and sintering, it is possible to obtain an alloy with greatly improved insulation properties.

In addition, 0.00% Fe group element was added to these Ag-WC-Cr alloys.
It has been found that the properties can be further improved by adding 01 to 3%.

Cr has the effect of raising the melting temperature of Ag, and the addition of Cr increases the melting temperature by about 100°C.

In addition, Fe group elements diffuse into the WC particle interface during sintering, and the Ag
It significantly improves the wettability between Ag and WC, making it possible to perform sintering at low operating temperatures.

If Cr is less than 0.01%, the effect of improving the melting point of Ag is small, and it is difficult to obtain a significant improvement in contact characteristics.
Since it has poor arc resistance, it actually deteriorates the contact performance.

Preferably Cr is 0.2 to 2%. In addition, Fe group elements have a remarkable effect on improving wettability when 0.01% or more.
When the amount increases, an intermediate layer is formed due to reaction with WC, and this intermediate layer has poor arc resistance, conversely deteriorating contact characteristics.

Therefore, a penalty of 3 or less is appropriate.

Examples of this invention are as follows.

A mixture of 60% Ag, 1% Cr, and WC remaining is mixed, molded, and sintered in hydrogen at 000 to 11000 C for 1 hour.

The porosity of the obtained alloy is shown in FIG.

In the figure, (1) is the case where sintering is 10,000 times lower than (2).

Also, Ag60%, Cr1%, Fe0.2~4%, balance W
C was blended and molded after mixing.

This is sintered in a hydrogen atmosphere at the sintering temperature shown in (1) in FIG.

The porosity of the obtained alloy is shown in Figure 2.

When Cr exceeds 5φ, the porosity increases when sintered at a low temperature, making it difficult to obtain a sound alloy, but by adding Fe, a sound alloy sintering with zero porosity can be obtained even at low temperatures.

In order to evaluate the wear characteristics and insulation properties of these alloys,
C220V, 3000A, power factor 0.5 circuit, contact size 4.5 x 5 x 1. Opening and closing was performed once to measure the amount of wear and insulation resistance between the iron pieces of the arc chute.

The results are shown in the following table.

As you can see from the table, 60Ag-WC that does not contain chromium is 2oOmI? However, with the addition of chromium 1, the amount was reduced by 45 ■O, and the consumption amount was further reduced by 0.5% of the present invention material.
The one with added Fe has decreased to 30μ.

It can be seen that the addition of Fe not only greatly reduces the consumption amount, but also improves the insulation resistance.

[Brief explanation of the drawing]

The drawing is a diagram explaining the characteristics of the material of the present invention.
The figure shows the porosity of the sintered body when A g -W CIC chromium, which is the base of the present invention, is added.
g WC-Cr G is a diagram showing the porosity of the sintered body according to the present invention when iron is added.

Claims (1)

[Claims] An electrical contact material of IAg-WC system, characterized in that it contains 0101 to 5 weight φ of Cr and further contains 0.01 to 3 weight φ of tCFe.