JPS5941429A - Electric contact material - Google Patents

Abstract

PURPOSE:To obtain the electric contact material having a short arc-welding time, by forming said material by dispersing the carbide, boride or nitride of a metallic element belonging to Group- I A or IIA in silver. CONSTITUTION:Silver, e.g. electrolytic silver of 250 meshes or less, is mixed with 0.1-5wt% (esp. 0.5-3wt%) the carbide, boride or nitride of a metallic element belonging to Group- I A or IIA having a particle size of 100-200 meshes. The mixture is agglomerated into a predetermined shape by high-pressure forming, sintered at a high temp., hot-extruded and then rolled to obtain the electric contact material. As the carbide, boride or nitride of the Group- I A or IIA element, barium carbide, beryllium carbide, lithium boride, calcium nitride, strontium boride, magnesium nitride, etc. are used. In addition, carbonyl nickel powder of 350 meshes or less may be added to said mixture.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an electrical contact material, particularly an electrical contact material having excellent arc properties.

(Background technology) Conventional molds include cadmium oxide, silver and tin oxide.

Silver-nickel solid solutions are used for contacts in various electrical devices such as electromagnetic contactors and relays, and silver-cadmium oxide or silver-tin oxide systems have low welding wear and tear in terms of performance.
The silver-nickel system is known as a material with low wear and tear and excellent workability in manufacturing.

However, when these contact materials are used in the contacts of a type of breaker that limits the current by running an arc using electromagnetic force during a short circuit and dividing it with a grid, the short circuit breaking performance is poor due to the lack of arc running properties. In other words, the contacts of such electrical equipment are required to have good running performance, which determines the length of time it takes for an arc to enter the grid.

(Disclosure of the Invention) The present invention was made against the background of the above-mentioned facts, and it is an object of the present invention to provide a contact material having a short so-called arc sticking time, in which the time that an arc remains between the contacts is short.

This invention will be explained in detail below. The present invention is an electrical contact material in which carbide, octide, or carbide of a metal element belonging to Group 11 or Group 11A is dispersed in the chain. Here I
Group A, ■ Carbide of Group A elements.

Nitride and boride include barium carbide, beryllium carbide,
Various compounds such as lithium 111], calcium nitride, strontium boride, magnesium nitride, barium 5III, and lithium nitride are used. When these carbides, nitrides, and borides are dispersed and included in the chain, the arc sticking time is shortened, but no improvement in welding resistance or abrasion resistance is observed. The amount of dispersion is suitably 0.1 to 5% by weight, preferably 0.5 to 3.0% by weight.

As mentioned above, an electrical contact material composed of silver and a carbide, nitride, or boride of an element belonging to Group A or Group IA maintains arc properties, including shortening of arc sticking time, and is resistant to welding. In order to improve wear resistance, it is effective to further add nickel to the composition of the above components. That is, when nickel coexists with carbides, nitrides, or borides as described above in the chain, arc characteristics, welding resistance, and abrasion resistance are all improved. In this case, the amount of nickel is 2-20
Weight % is appropriate. That is, if it is less than 2% by weight, no effect of improving wear resistance or welding resistance can be obtained, and if it exceeds 20% by weight, the electrical conductivity decreases and the welding resistance is affected. The carbides, nitrides, and borides coexisting with nickel are suitably contained in an amount of 0.1 to 5% by weight, showing the same tendency as in the first invention.

That is, if it is less than 0.1% by weight, no effect on shortening the arc sticking time will be observed, and if it exceeds 5% by weight, the welding resistance and wear resistance improved by nickel will be inhibited.

These electrical contact materials are obtained by mixing their constituent substances, agglomerating them into a certain shape by high-pressure molding, sintering the agglomerates at high temperatures, and then hot extruding and rolling.

Examples of the present invention will be described below in terms of performance for each constituent component, and will be compared with a comparative example of a silver-nickel contact material to demonstrate the effects of the present invention.

Incidentally, the following manufacturing conditions are common to all embodiments.

As for silver, electrolytic silver powder of 250 mesh or less was used.

Powders of 100 to 200 mesh were used for carbides, borides, and nitrides.

As the nickel, carponyl nickel powder with a mesh size of 350 mesh or less was used.

Then, these constituent materials were thoroughly mixed in a type mixer, agglomerated under high pressure of 4 torrents, sintered at 800℃ for 2 hours, and then subjected to hot extrusion, rolling, and punching processes to form a sample. And so.

By the way, the thickness was reduced to 1mm by rolling.

In addition, to explain the test conditions for each performance, the quality of the arc characteristics was judged based on the arc sticking time. This is done by applying it to the contacts of a current-limiting breaker, performing a short circuit test, and measuring the arc sticking time. More specifically, the arc sticking time is an index of short-circuit breaking performance, and a contact was formed using a test piece as a breaker contact material, and changes in arc voltage that occur with a short-circuit were captured.

To explain specifically the arc stagnation time, it is the time during which the arc generated between the contacts stagnates without fluctuation, and electromagnetic force is generated along with the generated arc, and this electromagnetic force causes the arc to move. Therefore, the short-circuit breaking performance is improved by shortening the arc sticking time.

Note that the short circuit current is 5.2 KA.

The quality of welding resistance and abrasion resistance is determined by A, which is typical in this type of test.
It was conducted based on the STM test method (B182-49).

The specific conditions were set as follows.

Load 100V 40A with two AC single phase Contact shape: φ
-5mm, flat (fixed contact).

φ-5 cabinet, 12R (movable contact) Number of opening and closing times: 50,000 times, contact force 200P.

Disassociation force 340 Test number: 3 The consumption amount in the following table is shown as an average value, and the number of welding L3
It is expressed as the total number of welds that occurred in each individual. The superiority or inferiority of a material as a contact material is judged by the decrease in wear and number of welding.

[Results]

Here, () indicates overlapping percentage.

The above measurement results prove that nitrides, carbides, or borides of lithium belonging to Group IA, barium beryllium, strontium, magnesium, etc. belonging to Group A are effective in shortening the arc sticking time. Furthermore, the coexistence of nickel is effective in improving welding resistance and abrasion resistance.

patent applicant Matsushita Electric Works Co., Ltd. Representative Patent Attorney Toshimaru Takemoto (2 idiots)

Claims (2)

[Claims] (1) An electrical contact material characterized in that a carbide, boride, or nitride of a metal element belonging to Group IA or Group A is dispersed in the chain. (2) An electrical contact material characterized in that a carbide, boride or nitride of a metal element belonging to Group IA or Group I[A] is dispersed in the chain, and nickel is further dispersed therein.