KR20160136884A - Method for Preparing of Ag-Ni-Carbon based Electrical Contact material for Switch and electrical contacts prepared thereby - Google Patents

Abstract

According to the present invention, a method to manufacture a Ag-Ni-carbon based electrical contact material for a switch and an electrical contact manufactured thereby, comprising the following steps: (i) mixing Ag powder, Ni powder, and carbon based powder to manufacture mixed powder; (ii) pressing the mixed powder to manufacture a preliminary formed body; (iii) sintering the preliminary formed body to form Ag-Ni-carbon based billet; (iv) forming the billet into a plate material through hot processing; and (v) processing the plate material through hot rolling. The content of added elements is less restricted in comparison with manufacture of an existing Ag-carbon based sintered contact material, so the content of Ag, which is a mother material, can be reduced. Moreover, added Ni and carbon have excellent electrical conductivity and strength, so a high quality electrical contact can be provided.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a silver-nickel-carbon based electrical contact material for a switchgear and an electrical contact prepared therefrom,

The present invention relates to a method for manufacturing a silver-nickel-carbon based electrical contact material for switchgear having enhanced wear resistance, wear resistance and electrical conductivity and an electrical contact material produced therefrom.

Generally, the electrical contact material is an electrical contact element that is used in electrical apparatuses such as circuit breakers, switches, switches, and the like, and mechanically actuates the circuit opening or closing. Such electrical contact materials need to prevent the occurrence of accidents such as abnormal consumption, welding, entanglement and the like in an environment of high pressure and high temperature due to an arc generated when an electric circuit is opened or closed, have. As a result, the electrical contact material has a low contact resistance, a high melting point, a high sublimation point, a high hardness associated with abrasion resistance, and excellent electrical life.

The electrical contact material is classified into a heavy load contact, a heavy load contact, and a light load contact according to its operating current range and characteristics, Cadmium (Ag-CdO), silver-tungsten, and silver-graphite electrical contact materials.

Since the silver-cadmium oxide (Ag-CdO) contact material has a property of absorbing latent heat generated at the time of arc generation and dispersing heat into the atmosphere owing to the sublimation property at a specific temperature or higher, And improving the resistance to arc, and has been used as a typical electrical contact material. Recently, however, since the cadmium (Cd) component of Ag-CdO is harmful to the human body, its use is limited not only in the overseas but also in the domestic. In order to solve this problem, an oxide-based electrical contact such as tin (Sn) or indium (In) or a sintered contact using nickel (Ni), carbon (C) or tungsten (W) is used instead of cadmium have. The silver-tungsten electrical contact material has a relatively low electrical conductivity as compared with other contact materials and has a high contact resistance. In addition, since the wettability between silver and tungsten is poor, sintering is not performed well during the manufacturing process, and bubbles are generated in the electrical contact material, resulting in a problem that the hardness is lowered. In addition, if the content of graphite in the silver-graphite electrical contact material can not be controlled properly, there is a problem in that the surface of the electrical contact material formed by sintering tends to be peeled off and the workability and density are lowered.

SUMMARY OF THE INVENTION The present invention has been conceived to solve the above-mentioned problems, and it is an object of the present invention to provide a method of manufacturing an electric contact using silver (Ag), nickel (Ni) and carbon (C) Nickel-carbon based electrical contact material having improved chemical resistance, abrasion resistance and electrical conductivity by controlling the surface roughness of the base material.

It is another object of the present invention to provide a silver-nickel-carbon based electrical contact material produced by the above-described manufacturing method.

In order to achieve the above object, the present invention provides a method for manufacturing a silver-nickel-carbon based electrical contact material for use in a switchgear, the method comprising: (i) mixing powder, nickel powder and carbon- ; (ii) pressurizing the mixed powder to produce a preform; (iii) sintering the preform to form a silver-nickel-carbon billet; (iv) forming a plate through hot working the billet; And (v) cold-rolling the plate material. The present invention also provides a method of manufacturing a silver-nickel-carbon-based electrical contact material for a switch.

According to a preferred embodiment of the present invention, in the step (i), the particle size of each powder may be adjusted in the range of 10 to 200 mu m.

Also, in the step (i), the mixed powder may contain 60 to 65% by weight of silver (Ag) based on 100% by weight of the total mixture; 30 to 35% by weight of nickel (Ni); And 0.2 to 2% by weight of carbon (C), wherein the carbon-based powder is selected from the group consisting of graphite, carbon nanotube (CNT), graphene, nano diamond, and activated carbon have.

In addition, the present invention provides a silver-nickel-carbon based electrical contact material for a switch fabricated by the above-described method.

Here, it is preferable that nickel and carbon powder are uniformly dispersed in the silver matrix of the electrical contact material, the electric conductivity is in the range of 50 to 60% IACS, and the hardness is in the range of 100 to 130 Hv.

In the present invention, a silver-nickel-carbon based electrical contact material improved in electrical conductivity and wear resistance can be produced by mixing silver, nickel, and carbon-based powder.

Further, when manufacturing the silver-nickel-carbon based electrical contacts, by controlling the content of nickel and carbon powder and the average particle size thereof to a specific range, it is possible to reduce the amount of silver (Ag) and increase the cost competitiveness.

FIG. 1 is a flowchart illustrating a manufacturing process of a silver-nickel-carbon (Ag-Ni-C) type electrical contact material according to an embodiment of the present invention.
FIG. 2A is an FE-SEM image of the silver-nickel-carbon mixed powder prepared in Example 1, and FIG. 2B is an FE-SEM image of the silver-carbon mixed powder prepared in Comparative Example 1. FIG.
3A is an FE-SEM image of the silver-nickel-carbon based electrical contact material manufactured in Example 1, and FIG. 3B is an FE-SEM image of the silver-carbon based electrical contact material produced in Comparative Example 1.
4 is a graph showing the hardness and electrical conductivity of the electrical contact material produced in Example 1 and Comparative Example 1. FIG.

Hereinafter, the present invention will be described in detail.

In the present invention, silver (Ag), nickel (Ni) and carbon-based powder are mixed and used as components constituting the material of an electrical contact to manufacture an electrical contact material for switchgear having excellent hardness and electrical conductivity. (Composition ratio) and an average particle size.

In the present invention, by appropriately adjusting the content of elements added to the material of the electrical contact, for example, nickel and carbon, the surface hardness, density and workability of the electrical contact material formed by sintering can be increased and the electrical conductivity can be improved. In addition, by adjusting the average particle size of the above-mentioned powders, it is possible to increase the uniformity in the mixed powder and enhance the durability of the final electrical contact material.

In addition, since the amount of silver (Ag) to be used can be reduced owing to the amount of the added element, the cost competitiveness can be increased.

In addition, in the present invention, a high-density silver-nickel-carbon sintered body is manufactured by preliminarily molding and heat-treating a mixed powder in which three-component powders constituting an electrical contact are uniformly mixed with each other. Then, in order to secure a high density, And then cold rolling is carried out sequentially.

More specifically, in the present invention, silver (Ag), nickel (Ni), and nickel (Ni) are used as constituents of an electrical contact material in order to solve the surface squeezing of a sintered contact point such as AgNi, AgC, ) And a carbon-based powder are mixed, and then a method such as compression and extrusion is added. In the case of a contact containing Ni, the extrusion process is not easy because it is relatively strong and has a higher stress than Ag. Therefore, in the present invention, by adjusting the composition ratio of the three components described above, But also a contact material in which the above-mentioned components are uniformly distributed can be produced. By controlling the manufacturing method, process conditions, composition of the contact material, and the like, it is possible to further improve the resistance to wear, abrasion resistance and electrical conductivity of the electrical contact material.

<Manufacturing Method of Silver-Nickel-Carbon Type Electrical Contact Material>

Hereinafter, a method of manufacturing a silver-nickel-carbon based electrical contact material according to the present invention will be described. However, the present invention is not limited to the following production methods, and the steps of each process may be modified or optionally mixed as required.

In one preferred embodiment for producing the silver-nickel-carbon based electrical contact material, (i) mixing powder, nickel powder and carbon powder to prepare a mixed powder (step S10 '); (ii) pressurizing the mixed powder to produce a preform ('S20' step); (iii) sintering the preform to form a silver-nickel-carbon billet (step S30 '); (iv) forming a plate material by hot working the billet (step S40 '); And (v) cold rolling the plate material (step S50 ').

1 is a whole process diagram for explaining a process method for manufacturing a silver-nickel-carbon based electrical contact material according to the present invention.

Hereinafter, the manufacturing method will be described separately for each step with reference to FIG.

(i) powder, nickel powder and carbon powder are mixed to prepare a mixed powder (hereinafter referred to as step S10).

The silver (Ag), which is the main component of the electrical contact material of the present invention, has an advantage of low contact resistance because of high electric conductivity and small temperature rise at the contact portion even at a large current. The nickel (Ni) and carbon (C) powders have an advantage of high electrical conductivity and high hardness.

The average particle size of the silver, nickel, and carbon-based powders is not particularly limited, but is preferably adjusted to be in the range of 10 to 200 μm in order to uniformly disperse the powder to improve the durability of the electrical contact material, 10 to 100 mu m.

In the above step S10, the silver and nickel powders can be used without limitation as those known in the art. The carbonaceous powder may be any of conventional carbonaceous materials known to those skilled in the art. For example, graphite, carbon nanotube (CNT), graphene, activated carbon, or a mixture of at least one thereof . Preferably, carbon nanotubes (CNTs) are used. Such carbon nanotubes (CNTs) are excellent in electrical conductivity and strength and are strong in elasticity, and can be easily subjected to subsequent processes such as extrusion and rolling.

The silver (Ag) powder is a main component constituting the material of the electrical contact of the present invention, and its content is preferably 60 to 65% by weight based on 100% by weight of the total mixed powder.

The content of the nickel (Ni) powder is preferably 30 to 35% by weight based on 100% by weight of the total mixed powder. At this time, when the content of the nickel powder satisfies the above-mentioned range, it is possible to improve the wear resistance of the electrical contact material and to exhibit excellent contact resistance and workability of the produced electrical contact material.

The content of the carbon-based powder is preferably 0.2 to 2% by weight based on 100% by weight of the mixed powder. If the content of the carbon-based powder is less than 0.2% by weight, it may be difficult to improve the electrical conductivity and hardness of the prepared electrical contact material. If the content is more than 2% by weight, the contact resistance of the produced electrical contact material increases, Can be degraded.

In step S10, the silver powder, the nickel powder, and the carbon powder may be mixed according to a conventional method known in the art. For example, a ball mill or a planetary mill, It may be mechanically mixed using a bead mill or the like. At this time, the conditions in the mixing step are not particularly limited and can be appropriately adjusted within the range known in the art.

(ii) A preform is produced using the mixed powder (hereinafter referred to as step S20).

In steps S20 and S30, the preliminary molding and sintering are performed using the mixed powder to secure the density.

As a preferable example of step S20, the produced mixed powder is put into a hydraulic press and pressurized to produce a preform.

The conditions for applying the mixed powder to the hydraulic press are not particularly limited. For example, the pressure is in a range of 80 to 150 MPa, the temperature is room temperature (RT), and the time is preferably about 1 to 10 minutes. By preliminarily manufacturing the preform as described above, it is possible to increase the density of the formed article to be produced later.

(iii) The preform is sintered to produce a high-density molded article (hereinafter referred to as step S30).

In the step S30, the preform may be sintered by any conventional method known to those skilled in the art. For example, a high temperature heat treatment may be applied.

At this time, the temperature for sintering the preform is not particularly limited, but is preferably in the range of 600 to 900 占 폚. If the sintering temperature is lower than 600 ° C, sintering between the silver powder and the nickel or carbon powder may not be smoothly performed. If the sintering temperature exceeds 900 ° C, the formed body is melted or deformed, Can be lowered. The sintering time is not particularly limited, but is preferably 2 to 9 hours, for example.

The sintered compact as described above can ensure a high density, wherein the relative density of the compact is preferably 90% or more.

(iv) The sintered body is hot-pressed and hot extruded to produce a high-density plate (hereinafter referred to as step S40).

In step S40, a silver-nickel-carbon billet sintered in step S30 is hot-worked to form a high-density plate.

The hot working may be carried out without limitation to a conventional post-processing known in the art, for example, hot pressing, hot extrusion, or both. In this case, it is preferable to sequentially perform hot compression and hot extrusion in order to produce a high-density plate through hot extrusion after ensuring the density by performing hot compression first.

How to hot pressing to the sintered body is not particularly limited, and heat-treated at a temperature of 600 ~ 900 ℃ for example prepared by adding to about 150 ~ 170 Kg / cm ² pressure and, after 5 minutes to 2 hours, preferably 10 Min to 30 min. Compressors produced through such hot compression may exhibit a high density of at least 95%.

Through the above-described heat treatment, foreign materials formed on the surface of the molded body can be removed in the course of sintering the preformed body, and the material can be loosened to facilitate the subsequent extrusion process.

Also, the hot extrusion conditions are not particularly limited, but a pressure of about 170 to 220 kg / cm ² is applied, for example, at a temperature of about 550 to 850 ° C for 5 minutes to 2 hours, preferably 10 to 30 minutes And the hot extrusion is easily carried out.

The relative density of the extruded material produced through the above process is 99% Or more.

In the present invention, a heat treatment step may be further included between steps S40 and S50, or after step S50, if necessary. In this case, the heat treatment is preferably performed at a temperature of 400 to 600 ° C for 1 to 3 hours, but is not particularly limited thereto.

(v) cold-rolling the produced extruded material (hereinafter referred to as step S50).

The cold rolling process in the step S50 may be performed by any conventional cold rolling process known in the art without limitation. Through such cold rolling, the hardness and density can be secured.

<Silver-nickel-carbon electrical contact material>

On the other hand, the present invention provides a silver-nickel-carbon based electrical contact material for a switchgear manufactured by the above manufacturing method.

The silver-nickel-carbon based electrical contact material may be a structure in which nickel and carbon powder are uniformly dispersed in a silver matrix. It is also preferable that the electrical conductivity thereof is in the range of 50 to 60% IACS and the hardness is in the range of 100 to 130 Hv.

Since the material of the electrical contact exhibits excellent hardness and electrical conductivity, it is preferably used in a technical field requiring wear resistance and adhesive strength, for example, an electric appliance such as a circuit breaker, a switch, a switch, or an electric appliance. However, the present invention is not particularly limited thereto, and is applicable to all applications to which the material of the above-described configuration can be applied.

Hereinafter, the present invention will be described concretely with reference to Examples. However, the following Examples are intended to illustrate one embodiment of the present invention, but the scope of the present invention is not limited by the following Examples.

[Example 1]

About 63 wt% of silver (Ag), about 35 wt% of nickel (Ni) and about 2 wt% of carbon (CN) (carbon system), each having an average particle size of D After that, mixed powder was obtained by using a ball mill. The FE-SEM photograph of the mixed powder is shown in FIG. 2A. Then, the mixed powder was held at 90 MPa pressure for 1 minute by using a compression press to produce a molded article. The sintered body was maintained in a vacuum atmosphere at about 850 ° C for about 6 hours to obtain a sintered body having a relative density of about 90% or more. The obtained sintered body was hot-pressed. At this time, the billet was maintained at 750 ° C. for 10 minutes, and a compression material having a relative density of about 95% or more was obtained at a compression pressure of about 150 kg / cm ² . Thereafter, the extruded product was subjected to hot extrusion. The extruded product was extruded in the form of a tape at an extrusion pressure of 210 kg / cm ² while maintaining the extrudate at about 750 ° C. for 10 minutes. The produced extruded material was subjected to heat treatment at about 500 ° C for 2 hours, and cold rolling was performed to produce a silver-nickel-carbon based electrical contact.

FIG. 3A shows an FE-SEM photograph of the silver-nickel-carbon based electrical contact prepared above. As can be seen from FIG. 3A, Ni and C were uniformly dispersed in the Ag matrix.

[Comparative Example 1]

As a comparative example, a silver-carbon based electrical contact including a carbon system was prepared.

More specifically, 97 wt% of silver and 3 wt% of diamond powder of about 100 to 300 nm were charged together and mixed through a ball mill process.

The mixed powder was subjected to a pressure of about 20 MPa through a hydraulic press to produce a preform. The preform thus produced was subjected to high-temperature pressure molding (SPS). At this time, the sintering temperature of the hot press molding (SPS) was 750 ° C. and the pressure was 20 MPa. In order to remove the foreign substances on the surface after the sintering process, the foreign substances were removed through atmospheric heat treatment at about 500 ° C., .

The FE-SEM image of the silver-nano diamond mixed powder is shown in FIG. 2B. In the case of the mixed powder of Comparative Example 1, it was found that the nano diamond powder used as the additive element in the silver (Ag) powder as the base material was mixed and uniformly distributed in the particles.

3B is a cross-sectional FE-SEM image of the silver-carbon sintered contact material prepared in Comparative Example 1. FIG. At this time, black particles on the surface indicate that the surface of the silver-carbon sintered contact is torn.

[Experimental Example 1] Evaluation of hardness and electrical conductivity of electrical contact materials

The electrical contact materials prepared in Example 1 and Comparative Example 1 were used, and their hardness and electrical conductivity were evaluated as follows.

Here, the hardness was measured with a Vickers hardness tester at a load of 300 g for 10 seconds. The electrical conductivity was also expressed as% IACS through unit conversion after measuring resistivity.

As a result of the experiment, the silver-nickel-carbon based electrical contact material prepared in Example 1 of the present invention showed 128 Hv, whereas the silver-carbon based electrical contact material of Comparative Example 1 had a hardness of 87 Hv. The electrical conductivity of Comparative Example 1 was 30% IACS, but the electrical conductivity of Example 1 was 52% IACS.

Therefore, it has been confirmed that the silver-nickel-carbon based electrical contact material of the present invention can be effectively used as an electrical contact material having improved hardness and excellent electrical conductivity and improved wear resistance and wear resistance.

Claims (14)

(i) mixing powders, nickel powders and carbon-based powders to prepare mixed powders;
(ii) pressurizing the mixed powder to produce a preform;
(iii) sintering the preform to form a silver-nickel-carbon billet;
(iv) forming a plate through hot working the billet; And
(v) cold rolling the sheet material
Nickel-carbon based electrical contact material for a switch. The method according to claim 1,
In the step (i), the particle size of each powder is controlled in the range of 10 to 200 mu m. The method according to claim 1,
In the step (i), the mixed powder contains, based on 100% by weight of the total,
60 to 65% by weight of silver (Ag); 30 to 35% by weight of nickel (Ni); And carbon (C) in an amount of 0.2 to 2% by weight based on the total weight of the silver-nickel-carbon based electrical contact material. The method according to claim 1,
Wherein the carbon-based powder of step (i) is selected from the group consisting of graphite, carbon nanotube (CNT), graphene, and activated carbon. The method according to claim 1,
The method of manufacturing a silver-nickel-carbon based electrical contact material according to claim 1, wherein the mixing step is performed by a ball mill method, a planetary mill method, or a bead mill method. The method according to claim 1,
Wherein the step (ii) pressurizes the mixed powder to a range of 80 to 150 MPa through a hydraulic press. The method according to claim 1,
Wherein the step (iii) comprises sintering the preform at 600 to 900 DEG C for 2 to 9 hours. The method according to claim 1,
Wherein the relative density of the sintered body produced in the step (iii) is 90% or more. The method according to claim 1,
The method for manufacturing a silver-nickel-carbon based electrical contact material according to claim 1, wherein the hot working in the step (iv) is performed by hot compression and hot extrusion. 10. The method of claim 9,
Nickel-carbon system billet is maintained at a temperature of 600 to 900 DEG C for 10 to 30 minutes and then is performed at a pressure of 150 to 170 kg / cm &lt; ² &gt;. The silver- A method for manufacturing a carbon-based electrical contact material. 11. The method of claim 10,
The hot extrusion of the step (iv) is performed by maintaining the silver-nickel-carbon-based billet at a temperature of 550 to 850 캜 for 10 to 30 minutes and then at a pressure of 170 to 220 kg / cm ² . - Manufacturing method of carbon-based electrical contact material. The method according to claim 1,
Further comprising a step of performing heat treatment at a temperature of 400 to 600 ° C for 1 to 3 hours between the steps (iv) and (v) or after the step (v) Method of manufacturing contact material. A silver-nickel-carbon based electrical contact material for a switch fabricated by the method of any one of claims 1 to 12. 14. The method of claim 13,
Wherein the material of the electrical contact has a uniform distribution of nickel and carbon powder in an Ag matrix and has an electrical conductivity of 50 to 60% IACS and a hardness of 100 to 130 Hv. Nickel-carbon electrical contact material.

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