JPS60181249A - Electrical contact material made of oxidized and sintered ag-sn-pb alloy - Google Patents

Abstract

PURPOSE:To obtain an electrical contact material having superior welding resistance and stable contact resistance by internally oxidizing an Ag alloy contg. specified amounts of Sn and Pb and by sintering it. CONSTITUTION:An Ag alloy contg. essentially 2-12wt% Sn and 0.01-10wt% Pb is internally oxidized and sintered. To the alloy may be added one or more kinds of elements selected among Cd, Cu, Zn, Sb, In, Bi, Mn, alkaline earth metals and Fe group metals or the oxides of the elements by <=50wt% of the total amount of Sn and Pb.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has excellent sinterability, improves the fire resistance of the contact material, and provides the contact material with excellent adhesion resistance.Sn is completely roasted and oxidized, and there is no debridement zone. Therefore, the present invention provides a composite electrical contact material in which an Ag-Sn-Pb alloy having stable contact resistance is oxidized and sintered.

That is, this silver thread composite electrical contact material has a metal component of 2 to 1
2% by weight of Sn oxide and 0.01 to 10 in metal component
The silver thread composite material contains at least % by weight of Pb oxide.

A metal component that has the effect of imparting fire resistance to Ag-based contact materials.
Pb is added to a composite electrical contact material containing more than % by weight of Sn oxide (the upper limit is 12% by weight of the metal component, considering the processability and the fact that it must be near the solid solubility limit for silver).
It has been found that by adding Sn oxide to the resulting composite material, there is no depletion zone of Sn oxide, the welding resistance is improved, and the contact resistance is significantly stabilized.

Materials produced by such a powder sintering method using PbO powder or Ag-3n02 and Ag-PbO powder are already known.

For example, US Pat. No. 3,205,565 describes a material obtained by sintering copper, silver, etc. powders and PbO powder or a PbO-based mixture powder, such as a mixture powder in which 5n02 powder is added to PbO powder. , and US January patent No. 33
In No. 85677, Ag-Cd, Ag-5njii is A
A silver thread electrical contact material is disclosed by a powder metallurgy method in which g-Pb alloy is internally oxidized and then powdered and graphite powder is sintered.

The present invention differs from such known materials. That is, in the present invention, Pb as a single element oxide
O powder and or 5n02 powder are not used, and binary alloys with Ag, such as Ag-Cd, Ag-5n or A
It does not use a g-Pb alloy that has been internally oxidized and then powdered, but instead uses an alloy of Sn and Pb with Ag, and roasts and sinters this alloy powder.

This is due to the following reasons. That is, Ag-5n
As can be seen from the phase diagrams of the metal alloys 5n-Pb, 5n-Pb, and Ag-Pb, Sn has a solid solubility at room temperature of about 1092% compared to Ag, but Pb has a solid solubility of about 1092% compared to Ag. The solid solubility of Sn at room temperature is extremely small, and the solid solubility of Sn is only a few percent at high temperatures.

Therefore, when the Ag-3n-Pb molten alloy is rapidly cooled,
At that time, the excess amount of Pb atoms (almost all of Pb) is A
Uniformly dispersed and precipitated in g-5n solid phase 7, during internal oxidation or roasting)! ! Under high temperatures, the precipitated atoms either diffuse into the Ag-5n alloy and create lattice defects, or remain as they are at the dispersed and precipitated positions in the silver casting, becoming defects in the solid phase and causing Sn liquefaction precipitation. The core.

As a result, the tendency of the precipitated tin oxide particles to enlarge as they go deeper into the alloy decreases, and since a reliable oxidation mechanism operates even at the surface of the alloy, a fine and uniform oxidized precipitate structure is obtained.

In order to confirm such an effect, we repeated tests and found that if the amount of Pb added is less than 0.01% by weight, the effect described in l- does not occur, and in order to perform oxidation sintering completely, Pb must be added. It has been found that the range is preferably up to 10% by weight.

Cd, Cu, Zn in electrical contact materials related to uninvented
.

Of course, one or more elements selected from Sb, In, Bi, Mn, alkaline earth metals, iron group elements, etc., or one or more oxides thereof may be added.

In addition, the object of the present invention (Ag-based composite electrical contact material,
Considering that Sn oxide and Pb oxide are included as main components and 17), the amount of the other elements or oxides mentioned above is 50% or less of the total oxide.

The present invention will be further explained below with reference to Examples.

Example 1 (1) Ag-Sn7%-Pb5% (2) Ag-Sn7%-Pb2%-Cd3%r3) Ag
-Sn5%-Pb3%-Zn2% (4)Ag-Sn8%
-Pb3%-Cd2% (5)Ag-3n3%-〇d13
%” - (1) to (4) of the indicated composition (% is total weight %)
(5) is for comparison.

Each of the above molten alloys (1) to (5) was sprayed in N2 gas, quenched, passed through a 100 mesh sieve, and the powder that passed through this sieve was used.

Each of these alloy powders was first heated to 700°C.

Internal oxidation was carried out in 02 gas at 3 atm for 2 hours. Thereafter, this alloy powder was ground in a vibrating mill for 10 hours, sieved through a 200-mesh sieve, and the powder that passed through this sieve was crushed into a powder lined with 0.5 mm thick pure silver at a pressure of 5 mm/cmz. It was formed into a thin plate with a length of 3 mm and a length and width of 100 mm each. Next, change this to 850'0 in 02 flow.
for 2 hours, after which it was reshaped at a pressure of 73'/am2. Then, this was further cut to obtain a contact having a length and width of 6 cm and a thickness of 3 mm.

The contact materials (1) to (5) thus obtained were each used in four 30A type 3P breakers, and tested for welding resistance and average insulation resistance between terminals.

The test conditions are as follows.

1F 220V, 2.5KA, pf=0.8,0. C0
3F 220V, 2.5KA, pf=0.8,0. C0
The test results are shown in Table 1.

(Margin below) Table 1 Example 2 (1') Ag-Sn7%-Pb5% (2') Ag-Sn7%-Pb2%-Cd3% (3')
Ag-Sn5%-Pb3%-Zn2% (4') Ag
-3n8%-Pb3%-Cd2% (5')Ag-Sn3
%-〇d13% l-(1') to (4) of the logged cutting portion (all percentages are Toho%)
') is according to the present invention, and (5') is for comparison.

Similarly to Example 1, notes (l') to (51)
) in N2 gas by spraying the molten alloy.
The powder passed through a 00 mesh sieve was used.

This powder was applied to a thickness of 0.5 with a pressure of 53'/cm2.
It was preformed into a thin plate with a thickness of 3 mm and a length and width of 100 mm each lined with mm-sized pure silver. This preform was embedded in alumina powder in a stainless steel container and sintered at 750° C. for 2 hours in a N2 gas atmosphere. Next, this sintered thin plate was 719/cm"
After being remolded at 700° C. and 1 Oatm, internal oxidation was performed in 02 for 20 hours. Then, this was further cut to obtain a contact having a length and width of 6 mm and a thickness of 3III11.

The contact materials (1') to (5') thus obtained were tested in the same manner as in Example 1 above. The results were as shown in Table 2.

(Margin below) 0 Table 2 11 be able to.

As is clear from the above, the electrical contact material according to the present invention has excellent welding resistance and extremely stable contact resistance.

Incidentally, since the electrical contact material according to the present invention is produced by a powder sintering method, it is inevitable that the w'L weave thereof will be somewhat rough.

Therefore, for this purpose, the breaker contact support metal,
For example, when welding to a Cu plate, the Cu plate is placed on a base metal that also serves as one electrode, and the electrical contact piece according to the present invention is placed at a desired location on this Cu plate, and the contact piece is covered with the Cu plate. A punch that presses the electrode is made of, for example, WC, and this is used as the other electrode.

Then, a contact piece is pressed against the Cu plate between this alloy/one electrode and the punch/other electrode, and a
If a current of 0-10000 amperes is applied for 2-3 seconds, the resulting resistance heat generation (960-1000°C
), the pure silver at the bottom of the contact piece melts and welds to the Cu support metal, and at the same time, the structure of the contact piece becomes even denser. 2 Patent Applicant: Chugai Electric Industry Co., Ltd. 3

Claims (4)

[Claims] (1) An electrical contact material formed by internally oxidizing and sintering an Ag alloy containing at least 2 to 12% by weight of Sn as a metal component and 0.01 to 10% by weight of Pb as a metal component. (2) An electrical contact material obtained by internally oxidizing and sintering a pulverized Ag alloy containing at least 2 to 12% by weight of Sn as a metal component and 0.01 to 10% by weight of PB as a metal component. (3) An electrical contact material obtained by internally oxidizing a pulverized and sintered Ag alloy containing at least 2 to 12% by weight of Sn as a metal component and 0.01 to 10% by weight of Pb as a metal component. (4) Cd, Cu, Zn, Sb,
In, B i. Mn, an alkaline earth metal, is formed by adding a plurality of elements or their oxides in an amount of 50% by weight or less based on the total weight of the components other than Ag. Electrical contact material made of sintered Sn-Pb alloy.