JPS61288033A - Electrical contact point material - Google Patents

Abstract

PURPOSE:To provide an electrical contact point material having low contact resistance and excellent resistance to consumption and melt sticking by compounding a metallic compd. such as metallic boride having a specific Vickers hardness, m.p. and specific electric resistance as well as Ag and Ni. CONSTITUTION:The electrical contact point material is produced from the metallic compd. of at least one kind selected from the metallic boride (TiB2, etc.), metallic nitride (TiN, etc.) and metallic carbide (TaC, etc.) having >=1,500 Vickers hardness >=2,000 deg.C m.p. and <=3X10<-5>OMEGA.cm specific electric resistance as well as Ag and Ni. The compounding ratio thereof is 5-30wt% Ni, 0.05-10wt% metallic compd. and the balance Ag which are made into a sintered alloy. Electrolytic Ag powder of about <=200 mesh is used for the Ag, carbonyl Ni powder of about 290 mesh for the Ni and the powder having the grain size approximately equal to the grain sizes of the Ag powder and Ni powder for the metallic compd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to contact materials used for contacts of switches, relays, etc.

[Background technology]

Conventionally, electrical contact materials made of Ag-Ni sintered alloy (Ag
-Ni-based electrical contact materials) are known to have lower contact resistance and superior wear resistance than internally oxidized electrical contact materials. However, Ag-Ni-based electrical contact materials have drawbacks in welding resistance in medium to large current ranges.
Initial welding was likely to occur. Therefore, there has been a need for electrical contact materials that have low contact resistance, excellent wear resistance, and excellent welding resistance.

[Purpose of the invention]

An object of the present invention is to provide an electrical contact material that has low contact resistance, excellent wear resistance, and also excellent welding resistance.

[Disclosure of the invention]

The inventors focused on Ag-Ni electrical contact material and attempted to achieve the above object by improving this electrical contact material. As a result, at least one selected from metal borides (hereinafter referred to as rMBJ), metal nitrides (hereinafter referred to as MNJ), and metal carbides (hereinafter referred to as rMcJ), with a Vickers hardness of 1500 or more. , melting point is 2000℃ or higher, and electrical resistivity is 3×10'''5
Ω・Metal compounds under the mouth (hereinafter referred to as MB, MN and MC)
(hereinafter referred to as a "metal compound") powder is added to a mixed powder of Ag powder and Ni powder, and this is sintered to form a sintered alloy, which is used as an electrical contact material to improve the welding resistance. They discovered that it was possible to do so and completed this invention.

Therefore, the present invention provides at least one kind selected from metal borides, metal nitrides, and metal carbides, which has a Biwakaas hardness of 1500 or more and a melting point of 2000.
The gist of the invention is an electrical contact material characterized by containing a metal compound, Ag, and Ni with a resistivity of 3×10'Ω·1 or less and a resistivity of 3×10′Ω·1 or less.

This invention will be explained in detail below.

As mentioned above, the electrical contact material according to the present invention has MB
, MN and MC, and has a Vickers hardness of 1500 (kgf/n+m2).
) or above, melting point is 2000℃ or above, and electrical resistivity is 3
Since it contains a metal compound under the mouth, the contact resistance is low and it has excellent abrasion resistance.In addition, it improves the welding resistance by improving the shortcoming of the low welding resistance of Ag Ni-based electrical contact materials. It is excellent.

As MB, TiB2, ZrB2, LaB6, Y
B6, HfB2, VB2, CrB
2, W2, B5, etc. As an MN,
Examples include TiN and ZrN. Examples of MC include TaC. As mentioned above, two or more kinds of such metal compounds may be used in combination.

The inventors created various electrical contact materials by adjusting the proportions of Ag, Ni, and the metal compound, and as a result of their investigation, the proportions of Aj, Ni, and the metal compound were found to be 3.
If the total amount of Ni is 5% by weight or more and 30% by weight or less, the metallization or compound is 0.05% by weight or more and 10% by weight or less, and the balance is Ag, the improvement effect will be significant. found that it was high. Therefore, it is preferable to use the three in such proportions. .

When the proportion of Ni is less than 5% by weight, A due to the addition of Ni
The welding resistance improvement effect of g tends to decrease, and conversely,
If it exceeds 30% by weight, contact resistance increases (electrical conductivity decreases), wear resistance decreases, and contact resistance tends to increase.

If the proportion of the metal compound is less than 0.055% by weight, the effect of improving welding resistance by adding the metal compound tends to decrease, and if it exceeds 10% by weight, the abrasion resistance decreases significantly, and the contact becomes difficult to open and close. Extreme deformation is likely to occur,
Contact resistance also tends to increase.

Note that the electrical contact material according to the present invention may contain additives other than Ni, metal compounds, and Ag for the purpose of improving performance.

The electrical contact material according to the present invention is usually manufactured as follows. That is, Ag powder.

It is manufactured by mixing Ni powder and metal compound powder in a predetermined ratio, compression molding this mixture, and then sintering it. To explain in more detail, an electrolytic Ag powder of 200 mesh or less is usually used as the -Ag powder, and a carbonyl Ni powder of 290 mesh is used as the Ni powder. The particle size of the metal compound powder is A.
Φ equivalent to or lower than g powder and Ni powder
It is preferable to use Such Ag powder, Ni powder, and metal compound powder were mixed for 20 hours in a type mixer to form a mixed powder, and then heated in a vacuum (10-3T).
Ag-Ni-(MB, MC
, MN) type electrical contact material. When producing electrical contact materials in this way, powdered materials are used as Ag, Ni, and metal compound raw materials, so
A sintered alloy in which the metal compound is uniformly dispersed can be obtained simply by sufficiently mixing the powders.

The metal compound powder has a Vickers hardness of 1500.
Because it has a high hardness as described above and a melting point of 2000°C or higher, it is thermally stable, so it does not react with Ag powder and Ni powder during sintering, and when mixed into the sintered body. Similarly, it is evenly dispersed. In this case, as mentioned above, the particle size of the metal compound powder is Ag powder, N
If the particle size is equal to or smaller than that of the i powder, the dispersion state will hardly be impaired by sintering.

In the electrical contact material manufactured in this way, metal compound particles with high hardness and high thermal stability are uniformly dispersed in the Ag base, so the heat resistance of the low melting point Ag base is improved overall. In addition to being uniformly improved, the overall hardness is uniformly improved as a whole, and the welding resistance and abrasion resistance (abrasion resistance) are excellent, and there is almost no occurrence of initial welding. Furthermore, the electrical resistivity of metal compound particles is 3×
Since it has sufficient electrical conductivity of 10-5 Ω·■ or less, there is almost no increase in resistance value due to addition, and there is no practical problem at all. Furthermore, the contact resistance is uniformly low throughout. Furthermore, this electrical contact material is easy to manufacture because it does not require a process such as internal oxidation.

Next, an example and a conventional example will be described. The electrical contact materials of Examples 1 to 6 and the conventional example were composed of Ag powder, Ni powder,
It was manufactured by mixing metal compound powder, compression molding, and firing. However, all metal compound powders must have a Vickers hardness of 1500 or higher, a melting point of 2000°C or higher, and
The electrical specific resistance was 3×10 −5 Ω·value or less.

Table 1 shows the results of measuring the number of times of welding, the amount of wear, and the contact resistance of the contacts made of the electrical contact materials of Examples 1 to 6 and the conventional example. However, the measurement was performed using an ASTM type testing machine, and the contacts were opened and closed 500 times. Also,
Measurement conditions were ACIooV, 40A, R load, and opening force 3.
40 g, and the contact force was 200 g.

From Table 1, it can be seen that the electrical contact materials of Examples 1 to 6 have the same wear resistance and contact resistance as the conventional examples, but have very good welding resistance.

〔Effect of the invention〕

The electrical contact material according to the present invention is at least one selected from metal borides, metal nitrides, and metal carbides, has a Vickers hardness of 1500 or more, a melting point of 2000°C or more, and has an electrical specific resistance. is 3×10″5Ω・
Contains metal compounds, Ag, and Ni below the value,
It has low contact resistance, excellent wear resistance, and excellent welding resistance.

Claims (6)

[Claims] (1) At least one selected from metal borides, metal nitrides, and metal carbides, with a Vickers hardness of 1500 or more, a melting point of 2000°C or more, and an electrical resistivity of 3 x 10^- Metal compounds below ＾5Ω・cm,
An electrical contact material containing Ag and Ni. (2) Metal borides include TiB_2, ZrB_2, La
B_6, YB_6, HfB_2, VB_2, CrB_2
The electrical contact material according to claim 1, which is at least one member selected from the group consisting of and W_2B_5. (3) The electrical contact material according to claim 1 or 2, wherein the metal nitride is either TiN or ZrN. (4) The electrical contact material according to any one of claims 1 to 3, wherein the metal carbide is TaC. (5) The blending ratio of the metal compound, Ag and Ni is 5% by weight or more and 30% by weight or less of Ni with respect to the total amount of the three,
The electrical contact material according to any one of claims 1 to 4, wherein the metal compound is 0.05% by weight or more and 10% by weight or less, and the balance is Ag. (6) The electrical contact material according to any one of claims 1 to 5, wherein the metal compound, Ag, and Ni are a sintered alloy.