JPS5884939A - Electrical contact material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

In particular, the purpose is to improve the properties of Ag-We alloys. Ag''WO alloys have been widely used as contacts in equipment such as air circuit breakers and switches due to their resistance to arcing and welding.

However, recently, devices such as no-fuse breakers and other air circuit breakers and switches have become smaller and more sophisticated, and as a result, the load on contact materials has become severer, and there has been a strong demand for improved contact performance. It is requested. In addition, as devices become smaller, there is a trend toward smaller contact dimensions and lower contact pressure, which increases wear and tear that occurs when current is interrupted, causes welding of contacts, deterioration of equipment insulation, and increases temperature when switching at the rated current. The problem is that it is easy for this to occur.

One of the ways to respond to such requests for improved characteristics is A.
A contact made by adding graphite (Gr) to g-WO alloy was developed. In this contact, heat generated during opening and closing turns Gr into a reducing gas, preventing oxidation of WC, suppressing temperature rise, and increasing welding resistance due to the lubricity of Gr. However, the addition of Gr causes converse depletion and
There was a drawback that the insulation properties deteriorated. For this reason, in small, high-performance circuit breakers and switches, it has been necessary to use a combination of an Ag-WO contact for the movable contact and an Ag-WO-Gr contact for the fixed contact. However, changing and combining materials for the movable part and the fixed part makes parts management extremely troublesome. Furthermore, even when using such a combination, the contact pressure is small in recent small and high-performance equipment, and the arc heat generated during opening and closing often causes abnormal temperature rises, wear, insulation deterioration, and welding, and it is necessary to improve contact resistance. It is requested.

The present invention has been made in view of the above points, and provides a contact alloy that has excellent adhesion resistance, wear resistance, and insulation resistance, and is highly practical with low temperature rise. .

Furthermore, the alloy of the present invention provides an inexpensive contact alloy that can be used as a contact even when the amount of expensive silver is considerably reduced.

The alloy according to the present invention contains iron group metal and silver;
Carbide of group a metal, IVa%Va%VIa%■a1■a
Group metal nitrides, IVa% V'% Vla%■a
This is an electrical contact material characterized by containing iron group metals and graphite dispersed therein, and in which some or all of carbides, nitrides, and metals are dispersed in iron group metals.

The inventors previously conducted various studies on alloys in which iron group metals and various carbides were added to silver, and found that an alloy in which some or all of the carbides were dissolved in the iron group metal was generated when the current was turned on and off. We have found that consumption and scattering due to arc heat are extremely low, and it has the effect of reducing insulation deterioration and welding of equipment.0 Iron group metals and carbides have poor oxidation resistance and are oxidized by arc heat generated during opening and closing. This has the drawback of increasing contact resistance and increasing the temperature of the equipment. Therefore, when Qr, which has excellent reducing properties, is added to the above contact alloy to prevent the oxidation of iron group metals and carbides, Gr decomposes with the heat of electrical switching and generates reducing gas, preventing the oxidation of iron group metals and carbides. It was found that the contact resistance was kept low, the temperature rise of the equipment was reduced, and the welding resistance was increased due to the lubricity of ()r.Additionally, if nitride was further added to this system, It has been found that during sintering at high temperatures, these nitrides react with carbides via 'Fe group metals, making the carbides finer and further improving arc wear resistance.

In other words, carbides and nitrides are dispersed in the chain of iron group metals, which have excellent mechanical strength and bonding strength at high temperatures, to improve wear resistance and welding resistance. By adding Gr, conventional Ag-WC system and Ag-W
It was possible to obtain an alloy that has high performance welding resistance, wear resistance, insulation resistance, and temperature rise characteristics that could not be expected from O-Gr type contacts.

As a result of further research, the inventors of the present invention discovered that by further adding a group metal to this system, these metals became Gr during sintering at a temperature higher than the melting point of silver.
Carbide is formed on the surface of the powder anti-Mar particles, which greatly improves the wettability of the Ag and Gr interface, improves sinterability, and improves contact performance, especially wear resistance and insulation resistance. It has been found that this can be further improved, leading to the present invention.

Iron group metals are Fe, Co5N1, etc., 5-40% by weight
and preferably io-so weight %.

At less than 5% by weight, iron group metals are dispersed in the chains.

Solid solution of carbides does not occur and wear resistance does not improve. 60 again
If it exceeds the weight percentage, even if Gr is added, the contact resistance will not decrease and there will be no effect of improving the temperature rise characteristics.

The amount is preferably 3 to 70% by weight, particularly 20 to 50% by weight.
Weight % has good characteristics. If the carbide content is less than S weight%, the amount of carbide in Ag is too small and the welding resistance is insufficient, and the
If Gr is added in an amount greater than % by weight, the contact resistance does not decrease and no improvement in temperature rise characteristics is observed.

Nitrides include Ti, Zr, Nb5Or, MO%M
ZI.

? e etc. IVa % Va s VIa %■aS■a
Group metal nitrides are effective, and the amount is 0.1~
It is preferably 30% by weight, and particularly 0.5 to 20% by weight has good properties.

These nitrides react with Gr dispersed by the arc heat during opening and closing to form carbides, and this reaction is an endothermic reaction and releases N 2 gas, which has an arc extinguishing effect. The figure shows the free energy change for this reaction. 0
．． This is because if it is less than 1% by weight, the effect of wear resistance is small, and if it is more than 30% by weight, even if Gr is added, the contact resistance increases and the temperature increase property is adversely reduced.

Metals include WSMo, Ta, Nb, Ti, OrS
I%'&%VaSVIaN■a group metals such as Mn and V are effective, and the amount thereof is 0. / −, weight%
is preferable, and 00S-2% by weight has particularly good characteristics. 0.
If it is less than 1% by weight, the amount of reaction with Gr is small and the effect of improving wear resistance is small, and if it is more than 3% by weight, unreacted metal with Gr remains, and this metal is oxidized during opening and closing, increasing contact resistance. This is because the temperature increase characteristics are adversely reduced.

Next, the effective range of Gr is 1 to 1% by weight, preferably 3 to 7% by weight. If it is less than 1% by weight, no improvement in temperature rise characteristics is observed even if the iron group metal, carbide, nitride, or metal is within the above range, and if it is more than 1% by weight, it is difficult to manufacture the alloy and it is not practical. .

It should be noted that about 0.7% by weight of A45 does not impair the purpose of the present invention.
Si, Se, To, Bi, ZnXCd, In, Sn.

There is no problem even if metal elements such as Oa and Na are included.

Next, the characteristics of the contact alloy according to the present invention will be specifically explained using examples.

Example 1 Each powder was blended in the proportions shown in Tables 1, 2, 3, and 9. After mixing, a reed-shaped body was made, and the molded body was heated at a temperature of Lc/10OC in a hydrogen atmosphere. Sintered.

This sintered body was pressurized again to produce an alloy with almost zero porosity. Alloy inner cylinder q Table shows alloys prepared in Example 19 as comparative materials, M/, B/, 0/, and comparative materials! Movable contacts made from alloys of l/% Dco, D3, DII.

After cutting the fixed contact gXtXa to the dimensions of II x 7 x C, it was bonded to the base metal using resistance brazing, and this was assembled into an SOA rated circuit breaker, and the contact performance was evaluated under the test conditions shown below. As a result, Table 6 was obtained.

Test conditions: Overload test heat 0 here OV, λ00kPf 30 times durability test s AO-120vs jl:)APf, 3'
One-time temperature rise test: MU 0 Coco QV% soA CoH short circuit test Low AO Coco OV, 7.5KA Pf
Q, 3/PO-00, Kopo-o.

Table 6 As shown in Table 6, the alloy of the present invention was found to have 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, carbides, nitrides, and metals, and can significantly reduce the amount of expensive silver, so it has great industrial value. It's expensive.

[Brief explanation of the drawing]

Figure C is a diagram showing free energy changes when producing carbide from nitride and graphite.

Claims (1)

[Claims] (1) IVa, Va, vI of the periodic table of elements
5 to 70% by weight of group A metal carbides, 7 to 70% graphite
77% by weight, iron group metals 5 to 0% by weight, IVa, v
a, Via. ■a1■ Nitride of group a metal is o, i ~ 30% by weight, ■a
\■a\Vla %■a group metals θ, /-5% by weight balance silver, carbides, nitrides and C■a, va. ■a1■ An electrical contact material characterized in that a group a metal is dispersed in an iron group metal and in a chain. (c) Carbide is tungsten, molybdenum, tantalum,
The electrical contact material according to claim (1), characterized in that it is a carbide of at least one of niobium, titanium, and chromium. (Claim (1) characterized in that the iron group metal is at least one of nickel, iron, and cobalt)
Electrical contact materials as described in section. ←) Nitride is titanium, zirconium, niobium, chromium,
The electrical contact material according to claim (1), which is a nitride of at least one of molybdenum, manganese, iron, vanadium, and tantalum. (!6rVa
The electrical contact material according to claim (1), characterized in that it is at least seven metals selected from among chromium, manganese, and vanadium.