JPH06102813B2 - Electric contact material and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an electrical contact material used for a device for energizing and closing electricity, more specifically, a contact material for improving the characteristics of silver-boride-graphite. And a manufacturing method thereof.

(Prior Art) The silver-graphite contact has a low contact resistance and excellent welding resistance, but has a drawback that it consumes much. Wear is reduced by making a contact material with boride added to it.

(Problems to be solved by the invention) However, in the above-mentioned manufacturing method, since the graphite particles in the contact alloy are large or some of them are continuous, the graphite is exposed to the atmosphere due to the arc heat when the contact is opened and closed. Since it reacts with oxygen in the product to form CO gas, which escapes more than necessary and decreases, bubbles and cracks occur inside the contact alloy, significantly increasing wear and causing excessive CO gas reaction and arc breakage. There have been many problems such as a deterioration of contact resistance and an increase in contact resistance due to deterioration of the borate and decomposition and oxidation of boride as the opening and closing progresses.

Further, if the graphite and boride in the contact alloy are not evenly dispersed, the deposition may occur at the segregated silver.

In view of the above, the present invention was developed in order to solve such problems, and is an electrical contact material having excellent wearability, low contact resistance, welding resistance, and arc breakage, and a method for producing the same. Is provided.

(Means for Solving the Problems) That is, the electrical contact material of the present invention has a silver powder weight ratio of 97 to 50%, IV
Grainite particles in the alloy obtained by mechanically alloying by mixing 10 to 0.1% by weight of graphite powder with 50 to 3% by weight of boride of a, Va, VIa group metal and having a size of 3μ or less. Each is characterized by being independent and uniformly dispersed.

Further, the method for producing the above electrical contact material of the present invention, silver powder in a weight ratio of 97 to 50%, element periodic table IVa, Va, VIa group metal tungsten, molybdenum, tantalum, niobium, titanium, chromium, One or two or more boride powders selected from the group consisting of zirconium and vanadium in a weight ratio of 3
10 to 0.1% by weight of graphite powder to 50%
It is characterized in that after mixing and mechanical alloying, the obtained complete powder is pressure-molded, it is sintered in a reducing atmosphere or vacuum, and the sintered product is re-pressurized.

The present invention will be described in detail below.

The inventor mixes silver powder, boride powder, and graphite powder by a mechanical alloying method as a method of utilizing the excellent performance of silver-boride-graphite contact and improving defects.
Graphite particles in the contact alloy are made into 3 by making mixed powder in which boride and graphite are embedded in silver powder in an inlaid form and press-molding, sintering and re-pressurizing the mixed powder.
We succeeded in making independent and evenly distributed contacts with a size of less than μ.

(Function) As a characteristic of the electrical contact made in this way, since the graphite particles are as small as 3 μm or less and are dispersed independently and uniformly, the amount of graphite that reacts with oxygen in the air by the arc heat during opening and closing is Since this reaction is suppressed to the minimum necessary and the reaction does not extend to the inside, the wear resistance is remarkably improved. In addition, since the shortage of graphite is unlikely to occur, boride oxidation is also unlikely to occur and low contact resistance is obtained. Since the graphite and the graphite are uniformly dispersed, it was confirmed that the welding due to the segregation of silver disappeared and the welding resistance was remarkably improved.

The weight percent of boride is in the range of 50 to 3%, and when it exceeds 50%, the contact resistance increases, and when it is less than 3%, the wear resistance is insufficient.

The weight ratio of graphite is 10 to 0.1%, preferably 5 to 1%. When it exceeds 10%, the effect of the present invention is hard to be obtained because the graphite is too much, the wear is large, and the arc breakage is not good. If it is less than 0.1%, the adhesion and contact resistance are not good due to insufficient graphite.

Further, it is desirable that the size of the graphite particles be 3 μm or less, and if it is larger than this, CO reaction occurs more than necessary, arc breakage becomes worse, wear increases, and it is not practical.

(Example) Next, the characteristics of the contact material according to the present invention will be specifically described with reference to Examples.

Example-1. Silver powder, boride powder, and graphite powder were mixed in the proportions shown in Table 1, mechanically alloyed with a ball mill to make powder, and the powder was impressed at a temperature of 900 ° C. in a hydrogen atmosphere.
Then, the sintered body was repressurized to manufacture an alloy having zero porosity.

In order to investigate the characteristics of the electrical contact material of the present invention obtained by the above method, a comparative test was performed with the conventional material under the following conditions.

Test conditions ASTM contact tester, sample size 5 x 5 x 1.5 x R sample was brazed to a special jig and thoroughly pickled before evaluation.

(Effects of the Invention) As described above, according to the contact material of the present invention, it is possible to obtain an electric contact material having excellent wearability, low contact resistance, welding resistance, and arc breakage and excellent practicality.

Further, according to the manufacturing method of the present invention, the size of the Gr particles in the contact alloy can be reduced to 3 μm or less by the mechanical alloying method, and the particles can be dispersed independently and uniformly, so that the excellent electric contact material can be manufactured as described above. .

Claims (3)

[Claims] 1. A silver powder weight ratio of 97 to 50%, an element periodic table IVa, V
a, VIa group metal boride weight ratio of 3 to 50%, graphite powder weight ratio of 10 to 0.1% is mixed and mechanically alloyed to obtain a graphite particle size of 3
An electric contact material characterized in that each of them is independent and uniformly dispersed at a value of μ or less. 2. The boride is one or more boride selected from the group consisting of tungsten, molybdenum, tantalum, niobium, titanium, chromium, zirconium and vanadium. The electrical contact material according to the item. 3. A silver powder in a weight ratio of 97 to 50%, an element periodic table
3 to 50% by weight of one or more boride powders selected from the group consisting of tungsten, molybdenum, tantalum, niobium, titanium, chromium, zirconium and vanadium of IVa, Va and VIa group metals. On the other hand, graphite powder is mixed in a weight ratio of 10-0.1%, mechanically alloyed, and the resulting finished powder is pressure-molded and then sintered in a reducing atmosphere or vacuum, and the sintered product is repressurized. And a method for producing an electric contact material.