JPS5884945A - Electrical contact material - Google Patents

Abstract

PURPOSE:To provide superior welding resistance, hardly dissipative property, dielectric strength and temp. rising characteristic to the resulting titled material and to reduce the cost of the material by dispersing the boride and silicide of a IVa, Va or VIa group metal and graphite in an iron group metal and silver. CONSTITUTION:This electrical contact material has a composition consisting of, by weight, 5-70% boride of a IVa, Va or VIa group metal, 1-11% graphite, 5- 60% iron group metal, 0.1-30% silicide of a IVa, Va or VIa group metal, and the balance silver. Said boride, silicide and graphite are dispersed in the iron group metal and silver.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrical contact material used in equipment that conducts current and switches on and off.

It is also aimed at improving the properties of %KAg-Ni-boride alloy. Conventionally, Ag-We alloys have been widely used as contacts in equipment such as air circuit breakers and switches due to their excellent arc resistance and welding resistance.

However, recently, devices such as air circuit breakers and switches, including no-fuse breakers, have become smaller and more sophisticated, and as a result, the load on contact materials has become severer, and there is a strong demand for improved contact performance. has been done. In addition, as devices become smaller, contact dimensions tend to become smaller and contact pressure decreases, which increases wear and tear that occurs when current is cut off, increases the risk of contact welding, insulation deterioration of devices, and increases temperature when switching at the rated current. There are problems that can easily occur. Mug-we
A contact was developed in which Gr was added to the alloy. In this contact, Gr becomes a reducing gas due to the arc heat generated when opening and closing, preventing oxidation of We and suppressing temperature rise.
Moreover, the lubricity of Gr has the effect of increasing welding resistance.

However, Gr was added. For this reason, in small, high-performance circuit breakers and switches, a combination of Ag-We contacts for movable contacts and Ag-We-Gr contacts for fixed contacts has been required.

However, in devices where the movable and fixed parts are made of different materials and combined, the contact pressure is low, and the arc heat generated when opening and closing causes abnormal temperature rises, wear, insulation deterioration, and welding, and further improvements in contact performance are required. It is requested. On the other hand, in response to these requirements, Ag-Ni-boride contacts have been developed, but they have some drawbacks in terms of temperature rise and have the disadvantage of a narrow range of use.The present invention was developed in view of the above points. The present invention provides a contact alloy that has excellent welding resistance, abrasion resistance, and insulation resistance, and has low temperature rise and excellent practicality. Furthermore, the alloy according to the present invention provides an inexpensive contact alloy that can be used as a contact even if the amount of expensive silver is considerably reduced.

This is an electrical contact material containing dispersed borides, silicides, and graphite of VA group metals, and characterized in that the borides and silicides are dispersed in complexes and iron group metals.

The characteristics of the alloy according to the present invention will be explained below.

The inventors previously conducted various studies on alloys made by adding iron group metals and various borides to silver, and found that alloys in which borides are dispersed in the iron group metals are more susceptible to arc heat generated when current is switched on and off. It has been reconfirmed that there is extremely little wear and tear, and that it is effective in reducing insulation deterioration and welding of equipment.

However, iron group metals and borides have the disadvantage of poor oxidation resistance and are oxidized by arc heat generated during switching, forming boron oxide on the contact surface, increasing contact resistance and increasing the temperature of the device. For this reason, when Gr, which has excellent reducing properties, is added to the above contact alloy to prevent oxidation of iron group metals and borides, Gr decomposes with the heat generated during electrical switching and generates reducing gas, causing the oxidation of iron group metals and borides. It has been found that it prevents oxidation, keeps contact resistance low, reduces temperature rise in equipment, and increases welding resistance due to the lubricity of Gr.

As a result of further research, the present inventors found that when silicides of NIL, VA, and LA group metals were further added to this system, these borides,
It was found that silicides are dispersed in iron group metals, borides are made finer, and deformation at high temperatures is reduced. Therefore, it was found that the arc wear resistance was improved, and the present invention was developed. At least wear resistance and
By adding Gr, which improves adhesion and has excellent reducing properties and lubricity, conventional Ag-wc-Gr-based rubber g-Ni
- We were able to obtain an alloy with high performance welding resistance, abrasion resistance, insulation resistance, and temperature rise characteristics that could not be expected from boride-based contacts.

Note that solid solution reactions between iron group metals, borides, and silicides generally occur only at high temperatures, but when silver is present, the steel becomes a liquid phase during sintering, and the reaction is accelerated through the liquid phase between It has been found.

Iron group metals include Fe, Co, Ni, etc., and s ~
If the weight is less than 3% by weight, and preferably X-5O is suitable, the iron group metal will be dispersed in the chain, solid solution of boride will not occur, and wear resistance will not improve. Also 60 weight-
In the above case, even if Gr is added, the contact resistance does not decrease and there is no effect of improving the temperature rise characteristics.0 The borides include W, Mo, Ta, Nb, and Ti.
, Or.

Borides of P/a, Va, and Wa group metals such as Zr and v are effective, and the amount thereof is preferably 3 to 70% by weight, and has good properties in the range of 1 to 30% by weight. If the boride content is less than 5% by weight, the amount of boride in the chain is too small and the welding resistance is insufficient, and if it is more than 70% by weight, the contact resistance does not decrease even if Gr is added, and the temperature rise characteristics cannot be improved. Unacceptable silicides include W, Mo, Ta, Nb, T
i, Or.

Silicides of group metals such as Zr and V, ■a, ■a, %la are effective, and the amount thereof is preferably ai ~ 30 weight-, @ycas ~ J weight- is less than 001 weight-, which has good characteristics. The effect of improving wear resistance is small, and the weight is 30%.
This is because even if Gr is added, the contact resistance increases and the temperature increase characteristics deteriorate.

The effective range of KGr is /-11% by weight, preferably 3 to 7% by weight. Below 01% by weight, even if the iron group metal yarns and silicides are within the above range, the temperature rise characteristics cannot be improved. It is not recognized, and if it exceeds 11% by weight, it is difficult to manufacture the alloy and it is not practical.

In addition, about 1% by weight of α, which does not impair the purpose of the present invention, is 1.8%.
1, 8@, ? @, Bl, Zn, C(1
, In, 8n, (3a.

There is no problem even if metal elements such as M& are included.

-Next, the characteristics of the contact alloy according to the present invention will be specifically explained with reference to Examples.

Example 1 Residue powders were blended in the proportions shown in Table 1, and after mixing, a molded moat body was prepared, and the molded moat body was sintered at a temperature of /100~ in a hydrogen atmosphere. This sintered body was pressurized again to produce an alloy with almost zero porosity.

The alloys prepared as shown in Table 1 above were evaluated for current conduction characteristics and wear characteristics using an A37M tester. As a condition, AC! 100V! OA, pf/, 0,
The contact pressure was 200gr, the opening force was 200gr, and the contact shape was jXjX/, jttl, and -Gallo opening and closing was performed. Table 2 shows the results of voltage variation and wear amount after 20,000 times of opening and closing.
After cutting the fixed contact IXI x 2 to the dimensions of 7 x 28, it was bonded to the base metal with resistance brazing, and this was assembled into a 30 m rated circuit breaker, and the contact performance was evaluated under the test conditions shown below. As a result of the evaluation, Table 3 was obtained.Test conditions: Overload test: AC, 220V, 200kpf 5
0 times durability test: AOJ20V, j (7Apf j
4 (oral temperature rise test: MczzOv, 5oAJ
H short circuit test: Mu c2 OV, 7. jKA pf
(ljlpo-co, 2po-c.

As shown in Table 3, it can be seen that the alloy of the present invention has low wear, low temperature rise, high dielectric strength, and high performance contact characteristics.

The alloy of the present invention not only has excellent contact performance as mentioned above, but also contains large amounts of iron group metals, borides, and silicides, and can significantly reduce the amount of expensive steel, making it a highly desirable industrial product. is 0

Claims (1)

[Claims] α) boride of group metals a, Va, % of the periodic table of elements j to 70% by weight, graphite i, ti by weight,
Iron group metal 3 to 60 weight - 1P/a, Va, ■ A group metal silicide consisting of αl to 30% by weight balance silver, characterized in that the boride silicide is dispersed in the iron group metal and the chain. electrical contact materials. (2) W&, VIL, characterized in that the silicide and boride of the Wa group metal is at least one of tungsten, molybdenum, tantalum, niobium, titanium, chromium zirconium, and vanadium. An electrical contact material according to claim (1). (3) The electrical contact material according to claim (1), wherein the iron group metal is at least one of nickel, iron, and cobalt.