JPS6376838A - Electric contact material and its production - Google Patents

Abstract

PURPOSE:To improve consumption resistance, low contact characteristic, deposition resistance, and arc extinction characteristic, by specifying a graphite grain size and also by uniformly dispersing the graphite grains in a contact material composed of a copper-silicide-graphite alloy with a specific composition. CONSTITUTION:A copper powder, a powder of silicide of the group IVa, Va, and VIa metals of the periodic table, and a graphite powder are mixed in the ratio of copper to the above silicide to graphite of 50-97pts.wt. to 3-50pts.wt. to 0.1-10pts.wt. by mechanical alloying. In this way, the silicide powder and the graphite powder can be inlayed in the copper powder, so that a powder mixture in which grain size of graphite is regulated to <=3mu and the graphite grains are uniformly dispersed can be obtained. When the above graphite grain size exceeds 3mu, gasificating reaction in which graphite is reacted with O2 in the air by arc heat at the time of making and breaking a contact into CO is liable to occur to a further extent than is required and, as a result, arc extinction is deteriorated. Moreover, deposition due to segregation is eliminated because silicides and graphite are uniformly dispersed.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an electrical contact material used in equipment that conducts electricity and switches, and a method for manufacturing the same, and more specifically, a material made of copper-silicate homogeneous graphite having excellent properties. The present invention relates to an electrical contact material and a manufacturing method thereof.

<Problems to be solved by conventional technology and invention> Conventionally,
Copper-graphite alloys, which have low contact resistance and excellent welding resistance, are known as electrical contact materials.

However, this electrical contact material has a drawback in that graphite tends to react with oxygen in the atmosphere due to arc heat when the contact is opened and closed to form carbon monoxide (Co), resulting in a large amount of graphite being consumed.

On the other hand, as an electrical contact material that consumes less graphite, it is also known that silicide is added to the above-mentioned copper-graphite alloy.

However, when this electrical contact material is manufactured by a conventionally known method, the graphite particles in the contact alloy are large;
Moreover, since the graphite particles are connected, the graphite reacts with oxygen in the atmosphere due to the arc heat when the contacts are opened and closed, resulting in carbon monoxide (CC0), which causes more graphite to escape than necessary and decrease the amount of carbon monoxide. Then, as the graphite falls out, bubbles and cracks occur inside the contact alloy, which significantly accelerates graphite consumption, and the CO gasification reaction progresses more than necessary, making arc breakage worse and graphite breaking as opening and closing progresses. There were many problems such as insufficient amount, which in turn caused decomposition and oxidation of the silicide, resulting in an increase in contact resistance.

Furthermore, if the graphite or silicide in the contact alloy is non-uniformly dispersed, welding may occur at the segregation points.
There was a problem that the welding resistance was poor.

<Object of the Invention> The present invention has been made in view of the above-mentioned conventional problems, and provides an electrical contact material with excellent wear resistance, low contact resistance, welding resistance, and arc breakage, and a method for manufacturing the same. The purpose is to

Means and operation for solving the problems> In order to solve the above conventional problems, the electrical contact material of the first invention has the following features:
Copper, Periodic Table of Elements IVa, Va.

Copper: Silicide of the above metal: Graphite - 50-97
An alloy containing 3 to 50 parts by weight: 0.1 to 10 parts by weight, wherein the graphite particles are 3 to 50 parts by weight.
It is not more than μm in size and is uniformly dispersed.

According to the first invention having the above configuration, since the graphite particles are small at 3 μm or less and are uniformly dispersed, the amount of graphite that reacts with oxygen in the atmosphere due to arc heat during opening and closing is minimized. At the same time, the CO gasification reaction does not proceed to the inside, and the wear resistance is significantly improved. Furthermore, since there is no shortage of graphite during the reaction with oxygen, oxidation of the silicide also occurs, resulting in an electrical contact material with low contact resistance. Furthermore, since silicide and graphite are uniformly dispersed, welding due to segregation is eliminated, and welding resistance is significantly improved.

In addition, the second invention regarding the manufacturing method utilizes the excellent characteristics of the copper-silicide-graphite contact material, and
This method improves the drawbacks of the above contact materials, and is made by mechanically alloying copper powder, silicide powder of a metal selected from groups IVa SVa and VIa of the periodic table of elements, and graphite powder, and pressurizing the resulting mixed powder. The above-mentioned conventional problems are solved by a method of manufacturing an electrical contact material in which the sintered crystal is sintered in an inert atmosphere after being molded, and the sintered crystal is pressed again.

According to the second invention having the above configuration, the copper powder, the metal silicide powder and the graphite powder are mixed by mechanical alloying, so that the silicide powder and the graphite powder are inlaid in the copper powder. A mixed powder in which the graphite particles are uniformly dispersed in a predetermined size can be obtained. Further, by processing the mixed powder in a process such as pressure molding or sintering, an electrical contact material in which graphite particles having a specific particle size are uniformly dispersed can be obtained.

The present invention will be explained in detail below.

The electrical contact material of the first invention includes copper, element IVa of the periodic table.
, Va, silicide of a metal selected from group VIa and graphite, copper: silicide of the above metal: graphite - 50 to 97 parts by weight = 3 to 50 fff part by weight: 0.1
It is contained in a ratio of ~10 parts by weight.

Various types of steel can be used, such as hard copper and semi-hard steel. If the Q-ffl content of these coppers is less than the above-mentioned 50 parts by weight, the electrical conductivity and thermal conductivity will be low, and the various properties as an electrical contact material will not be sufficient. Moreover, if it exceeds 97 parts by weight, it becomes difficult to obtain a practical electrical contact material.

The silicides of the above metals are listed in the Periodic Table of Elements IVa.

V a % A silicide of a metal selected from the group consisting of the V'la group, and one or more types are contained in the alloy. Hafnium, thorium, etc. can be used as these silicides, but in addition to reducing contact resistance,
In order to increase wear resistance, titanium, zirconium, chromium, molybdenum, tungsten, vanadium, niobium, and tantalum are preferred.

The metal silicide is preferably contained in an amount of 3 to 50 parts by weight in the alloy. If the metal silicide content is less than 3 parts by weight, wear resistance will not be sufficient, and if it exceeds 50 parts by weight, contact resistance will increase, which is not preferred.

The alloy also contains graphite to improve welding resistance. The above graphite is 0.1 in the alloy.
It contains up to 10 parts by weight, preferably 1 to 5 parts by weight. If the graphite content ff8 is less than 0.1 part by weight, the graphite content will be insufficient, resulting in poor adhesion resistance and increased contact resistance, which is not preferable. Also 1 0
If it exceeds 1 fi part, the graphite content is too high,
As graphite consumption increases, arc cutting also worsens.

Note that graphite here is used to include amorphous carbon.

The graphite has a particle size of 3 μm or less and is uniformly dispersed in the alloy.

If the size of the graphite particles exceeds 3 μm, the CO gasification reaction is more likely to occur than necessary, and arc breakage becomes poor and consumption of graphite increases, resulting in poor practicality.

-1: According to the alloy containing copper, metal silicide, and graphite, unlike conventional contact alloys, graphite particles with large particle diameters do not stand in a row, and the graphite particles are small at 3 μm or less. Moreover, since it is uniformly dispersed in the alloy, the amount of graphite that reacts with oxygen in the atmosphere due to arc heat during opening and closing can be suppressed to the necessary minimum. Furthermore, the CO conversion reaction does not proceed to the inside of the contact alloy, and wear resistance properties are significantly improved. Furthermore, since there is no shortage of graphite during the reaction with oxygen, oxidation of the silicide occurs, resulting in low contact resistance. Furthermore, since silicide and graphite are uniformly dispersed, welding due to segregation is eliminated, and welding resistance is significantly improved.

In addition, the said alloy may contain appropriate amounts of gold, silver, iridium, palladium, etc. used as electrical contact materials, if desired.

The second invention regarding the manufacturing method will be explained below.

The second invention is copper powder, periodic table of elements IVa, VasVl.
A mechanical alloying process of mechanically alloying silicide powder and graphite powder of metals selected from Group A, a pressure forming process of pressure forming the mixed powder obtained by the mechanical alloying process, and an inert atmosphere. The process consists of a sintering process in which the sintered product is sintered, and a pressurizing process in which the sintered product is re-pressed.

In the mechanical alloying process, copper powder, silicide powder of a metal selected from groups IVa, Va, and Via of the periodic table of elements, and graphite powder are mixed while applying mechanical impact to the copper powder. , the metal silicide powder and graphite powder are embedded in an inlay to obtain a mixed powder in which the graphite powder has a particle size of 3 μm or less and is uniformly dispersed. The above copper powder, the periodic table of elements IVa,
The metal silicide powder and graphite powder selected from Va and Via groups are mixed at a ratio of 50 to 97 parts by weight of copper powder: 3 to 50 parts by weight of metal silicide: 0.1 to IO parts by weight of graphite powder. It is preferable to do so. If the amount of the metal silicide and graphite used is outside the above range,
A problem similar to that described in the first invention section arises. Note that the metal silicides mentioned above may be used alone or in combination of two or more.

In addition, as for the above-mentioned copper powder, silicide, and graphite powder, the graphite powder, etc. is crushed in the above-mentioned mechanical alloying process, and the copper powder, etc. is sintered in the sintering process, so it is necessary to use the appropriate size. Can be used. Further, in the mechanical alloying step, a conventionally known mixer such as a ball mill can be used.

The mechanical alloying step is performed by mixing at an appropriate temperature, for example, 0 to 100°C for 1 to 24 hours.

Note that, prior to the mechanical alloying step, a premixing step is preferably employed in order to uniformly mix the copper powder, metal silicide powder, and graphite powder in advance. By employing this premixing step, the metal silicide and graphite can be more uniformly embedded in the copper powder in the mechanical alloying step. This premixing step is performed using a conventionally known blender and mixing for an appropriate time, for example, 10 minutes to 24 hours.

After the mechanical alloying step, the obtained mixed powder is molded into a predetermined shape in a pressure molding step. This pressure molding step is carried out by a conventionally known method, for example, by applying a pressure of 5 to 500 tons. In addition, the above pressure molding process is
If desired, an appropriate temperature, for example, 100 to 1000°C
It can be carried out at a temperature of

Next, after the pressure forming step, a second sintering step is performed.
The obtained molded product is sintered. This sintering step is performed in an inert atmosphere, for example, a reducing atmosphere such as a hydrogen gas atmosphere, or in a vacuum in order to prevent the copper powder, metal silicide, and graphite from being oxidized. The sintering step is performed at an appropriate temperature necessary to sinter the molded product, for example,
The process is kept at a temperature of 700 to 1500°C for a predetermined period of time.

Further, after the sintering step, repressurization is performed to reduce the porosity of the obtained sintered product. This repressurizing step is carried out by pressurizing the sintered product at a pressure of about 1 to 100 tons, and an electrical contact material having a dense structure is obtained.

According to the above method for producing electrical contact materials, silicide powder and graphite powder can be embedded in copper powder in an inlaid manner by mechanical alloying, and the resulting mixed powder has the graphite particles arranged in a predetermined manner. Evenly distributed in size. Therefore, by processing the above mixed powder through processes such as pressure molding and sintering, graphite particles with a specific particle size are uniformly dispersed, resulting in excellent wear resistance, low contact resistance, welding resistance, and arc breakage. An excellent electrical contact material can be obtained.

Since the electrical contact material of the present invention has excellent properties as described above, it can be used for both low-power and high-power applications, and is suitable for high-load, medium-load, and light-load electrical contacts. Suitable as a material.

<Example> Hereinafter, this invention will be explained in more detail based on Examples.

Examples 1 to 8 and Comparative Examples After mixing copper powder, metal silicide, and graphite in the proportions shown in Table 1, mechanical alloying was performed using a ball mill to produce a powder having the above composition. The powder was embossed. Thereafter, the sintered body was sintered in a hydrogen atmosphere at 900°C three times, and the resulting sintered body was repressed to produce an electrical contact material of the present invention having a porosity of 0 (Examples 1 to 3).
8).

In addition, as a comparative example, conventional electrical contact materials were produced in the same manner as in the above examples at the ratios shown in Table 1.

Then, the characteristics of the electrical contact materials of the above examples and comparative examples were as follows:
When investigated under the following conditions, the results shown in Table 1 were obtained.

Test conditions: Testing machine, ASTM contact testing machine Sample dimensions: 5X5X 1.5XR test method, AS
TM test AC220V, 100A.

pi' 0.75. Opening and closing 20,000 times. The evaluation was performed after the sample was attached to a special jig and oxygen was sufficiently removed.

As is clear from Table 1, the graphite particle size of the electrical contact material of the comparative example is large, and the characteristics as an electrical contact material are not sufficient. On the other hand, it was found that the electrical contact materials of Examples 1 to 8 all had graphite particle diameters of 3 μm or less, had low contact resistance, had excellent arc breakage, and had significantly less melting and wear.

In each of the electrical contact materials of Examples 1 to 8, the graphite particles were independently and uniformly dispersed. In addition, in the comparative example, graphite particles were connected.

<Effects of the Invention> As described above, according to the electrical contact material of the first invention, graphite particles having a particle size of 3 μC or less are uniformly contained in the contact alloy containing copper, metal silicide, and graphite. It has excellent wear resistance, low contact resistance, welding resistance, and arc breakage.

Furthermore, according to the second invention, after the graphite is uniformly dispersed by mechanical alloying, it is subjected to treatments such as pressure forming and sintering, so that the graphite particles are reduced to 3 μm or less in the contact alloy. It has the advantage of being able to be uniformly dispersed and providing electrical contact materials with various excellent properties as described above.

Claims (1)

[Claims] 1. Copper, a silicide of a metal selected from groups IVa, Va, and VIa of the periodic table of the elements, and graphite, copper: silicide of the above metal: graphite = 50 to 97 parts by weight: 3 ~50 parts by weight: 0.
An electrical contact material comprising a sintered alloy containing 1 to 10 parts by weight, wherein the graphite particles are 3 μm or less and uniformly dispersed. 2. The metal silicide is a silicide of one or more metals selected from the group consisting of tungsten, molybdenum, tantalum, niobium, titanium, chromium, zirconium, and vanadium. Electrical contact materials listed. 3. Mechanically alloying copper powder, silicide powder of a metal selected from groups IVa, Va, and VIa of the periodic table of elements, and graphite powder, press-molding the resulting mixed powder, and then forming it in an inert atmosphere. A method for producing an electrical contact material, characterized by sintering and repressurizing the sintered product. 4. Copper powder, silicide powder of a metal selected from groups IVa, Va, and VIa of the periodic table of elements, and graphite, copper powder: silicide powder of the above metal: graphite powder = 50 to 97 parts by weight: 3 to The method for producing an electrical contact material according to claim 3, wherein the materials are mixed at a ratio of 50 parts by weight: 0.1 to 10 parts by weight. 5. The electrical contact material according to claim 3, wherein copper powder, silicide powder of a metal selected from groups IVa, Va, and VIa of the periodic table of elements, and graphite powder are mixed in advance and then mechanically alloyed. manufacturing method.