KR20210081165A - Method for manufacturing contact material - Google Patents

Abstract

Provided is a method for manufacturing a contact material having excellent physical properties and outstanding deposition performance. The method for manufacturing a contact material in accordance with the present invention comprises: a step (a) of mixing silver (Ag) powder, nickel (Ni) powder, and graphite powder to prepare mixed powder; a step (b) of sintering the mixed powder to form a sinter; a step (c) of extruding the sinter to form a primarily processed wire rod having a shape of a wire rod; a step (d) of heating the primarily processed wire rod under an oxygen atmosphere to form a secondarily processed wire rod composed of a core layer including carbons and a decarburized layer having no carbons in the surface, which surrounds the core layer; a step (e) of removing the decarburized layer on any one among the surfaces of the secondarily processed wire rod to form a contact surface; and a step (f) of cutting the secondarily processed wire rod subjected to removal of the decarburized layer to form a contact material.

Description

Method for manufacturing contact material

The present invention relates to a method for manufacturing a contact material, and more particularly, to a method for manufacturing a contact material having excellent physical properties and excellent welding performance.

In general, a switching element for controlling to connect or block a circuit is used in an electric device or an electric equipment. Since the switching element performs a switching operation while the contact is physically contacted or separated, the contact may be physically damaged due to the repeated switching operation. Contacts of switching elements are not only physically abraded, but also arcs occur during opening and closing operations, causing problems such as welding of contacts and inability to open and close operations. In order to solve problems such as diversifying materials, development is in progress.

Tungsten-based and silver-oxide-based contact materials are commonly used as contact materials, and among them, silver-cadmium oxide (Ag-CdO)-based contact materials with excellent physical properties such as high electrical conductivity and abrasion resistance are typically used. . In addition, as a contact point of a switching element, a contact material with excellent physical properties is bonded and used in multiple layers.

On the other hand, recently, by adding nickel (Ni) and graphite to silver (Ag) to reduce the contact resistance to reduce the arc generation, the development of a contact material to reduce the occurrence of welding between the contacts is being made. However, problems such as poor weldability with copper (Cu) terminals occurred due to the addition of graphite, and it was necessary to solve the problems.

Republic of Korea Patent No. 10-1491932, (2015.02.03)

The technical problem to be achieved by the present invention is to solve such a problem, and to provide a method of manufacturing a contact material having excellent physical properties and excellent welding performance.

The technical problems of the present invention are not limited to the above-mentioned problems, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

The method for manufacturing a contact material according to the present invention comprises a step (a) of mixing silver (Ag) powder, nickel (Ni) powder, and graphite powder to form a mixed powder, and sintering the mixed powder. (b) to form a sintered body, (c) for extruding the sintered body to form a primary overhead wire in the form of a wire rod, and heating the primary overhead wire in an oxygen atmosphere, a core containing carbon (d) forming a secondary overhead wire member comprising a decarburized layer surrounding the core layer by removing carbon from the layer and the surface, and removing the decarburized layer on any one surface of the secondary overhead wire member to form a contact surface (e) of forming a, and (f) of forming a contact material by cutting the secondary overhead wire from which the decarburized layer has been removed.

The thickness of the decarburized layer may be 5 to 15% of the thickness of the contact material.

The decarburized layer is a contact material manufacturing method in which residual carbon is 0.1% or less based on the total weight of the decarburized layer.

The step (d) may be heated to 600 to 800 degrees in an oxygen atmosphere in a pressure range of 3 to 7 kg/cm 2 .

The silver powder, the nickel powder, and the graphite powder may be comprised of 92 to 96 wt%, 1 to 3 wt%, and 3 to 5 wt%, respectively.

In step (e), the decarburized layer may be removed by wet grinding the secondary overhead wire.

The method for manufacturing a contact material according to the present invention has high electrical conductivity and excellent abrasion resistance, and it is possible to manufacture a contact material excellent in welding resistance due to low arc generation.

In addition, according to the present invention, a contact material having very excellent welding performance can be formed, which is very advantageous for manufacturing a switching element.

1 is a perspective view of a contact material manufactured according to an embodiment of the present invention.
2 is a photograph of a contact material manufactured according to an embodiment of the present invention.
3 is a cross-sectional photograph of the contact material of FIG. 2 .
4 and 5 are photographs magnified 500 times and 1000 times, respectively, of the cross-section of the contact material of FIG. 2 .
6 to 10 are views for explaining a manufacturing process according to a method for manufacturing a contact material according to an embodiment of the present invention.

Advantages and features of the present invention, and methods for achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in a variety of different forms, and only these embodiments allow the disclosure of the present invention to be complete and those of ordinary skill in the art to which the present invention pertains. It is provided to fully inform the person of the scope of the invention, and the present invention is only defined by the claims. Like reference numerals refer to like elements throughout.

A contact material manufactured according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 5 . 1 is a perspective view of a contact material manufactured according to an embodiment of the present invention, FIG. 2 is a photograph of a contact material manufactured according to an embodiment of the present invention, FIG. 3 is a cross-sectional photograph of the contact material of FIG. 2, and FIG. and FIG. 5 are photographs magnified by 500 times and 1000 times, respectively, of the cross-section of the contact material of FIG. 2 .

First, referring to FIG. 1 , the contact material 1 manufactured according to an embodiment of the present invention includes a core layer 10 in the center and a decarburized layer 11 surrounding the core layer 10 . At this time, one side of the contact material 1 is polished to form the contact surface 12 on which the core layer 10 is exposed. Since the contact surface 12 has excellent electrical conductivity, the possibility of arc generation is low, and the welding resistance is excellent, thereby increasing the lifespan of the switching element. Hereinafter, each structure is demonstrated concretely.

In the center of the contact material 1, a core layer 10 having excellent electrical conductivity and excellent welding resistance is formed. The core layer 10 is made of silver (Ag), nickel (Ni), and graphite. Silver (Ag), nickel (Ni), and graphite constituting the core layer 10 are mixed in powder form and hardened through a sintering process. Silver (Ag) has excellent electrical conductivity and low contact resistance, so it has excellent performance as an electrical contact material. Such silver (Ag) occupies 92 to 96 wt % based on the total component of the core layer 10 . Nickel (Ni) and graphite are uniformly dispersed in silver (Ag).

Nickel (Ni) exists in the form of a solid solution in silver (Ag) and improves the welding resistance of the contact material. In addition, nickel (Ni) serves to enhance the durability of the contact material by reinforcing the strength of relatively weak silver (Ag) to improve abrasion resistance. That is, nickel (Ni) improves abrasion resistance and welding resistance, so that it is possible to prevent the contact materials from being melted together or from not performing a switching operation due to mechanical damage. Nickel (Ni) may be included in an amount of 1 to 3 wt% based on the total component of the core layer 10 .

Graphite may serve to prevent a decrease in electrical conductivity that may occur by adding nickel (Ni) to silver (Ag). Graphite, as a carbon (C)-based additive, has excellent electrical conductivity and serves to prevent arcing in the contact material 1 . Such graphite may be included in an amount of 3 to 5 wt % based on the total component of the core layer 10 .

Meanwhile, a decarburized layer 11 surrounds the outer core layer 10 . The decarburized layer 11 is a layer from which carbon (C) is removed from the core layer 10 and may be formed to surround the core layer 10 on the remaining surfaces except for the contact surface 12 where the core layer 10 is exposed. have.

The decarburized layer 11 is a layer made of silver (Ag) and nickel (Ni), and carbon (C) is removed to improve welding performance of the contact material. The decarburized layer 11 is formed in a high-temperature furnace in an oxygen atmosphere, and residual carbon may be present in an amount of 0.1% or less based on the weight of the secondary overhead wire 300 or the core layer 10 .

The decarburized layer 11 is a part that is welded to the base material, and is formed with concave-convex grooves as shown in the photo of FIG. 2 so that it can be distinguished from the core layer in appearance. In the decarburized layer 11 , not only oxygen is removed by oxygen, but also silver (Ag) and nickel (Ni) may exist in an oxide state.

Referring to FIGS. 3 to 5 , the core layer 10 and the decarburized layer 11 are divided according to the presence or absence of graphite, so that the boundary is also distinguished with the naked eye. Since the core layer 10 contains graphite, a relatively large amount of black tissue is distributed on the cut surface, and the decarburized layer 11 has a smaller amount of black tissue than the core layer 10 . The thickness of the decarburized layer 11 may be 5 to 15% of the thickness of the contact material 1 . In the decarburized layer 11 , it is preferable that residual carbon is maintained at 0.1% or less of the total weight of the decarburized layer 11 by oxygen in the decarburization process to be described later.

Hereinafter, a method for manufacturing a contact material according to an embodiment of the present invention will be described in detail with reference to FIGS. 6 to 10 . 6 to 10 are views for explaining a manufacturing process according to a method for manufacturing a contact material according to an embodiment of the present invention.

First, referring to FIG. 6 , silver (Ag) powder, nickel (Ni) powder, and graphite powder are mixed to form a mixing powder, and the mixing powder is sintered to form a sintered body 100 . Mixing powder refers to a powder in which silver (Ag) powder, nickel (Ni) powder, and graphite powder are uniformly mixed, and the components are silver powder 92 to 96 weight %, nickel powder 1 to 3 weight %, graphite It may consist of 3 to 5% by weight of the powder.

When the mixing powder is pressurized at a high pressure and heated to a temperature close to the melting point of silver (Ag), the respective powders are combined with each other to form the sintered body 100 in the form of an alloy. The sintered body 100 may be formed in a columnar shape to perform an extrusion process thereafter.

Then, referring to FIG. 7 , the previously prepared sintered body 100 is extruded to form the primary overhead wire 200 in the form of a wire rod. The primary overhead wire has the same internal components as the sintered body 100, but may be formed to be slightly thicker than the thickness of the contact material 1 for actual manufacture. The primary overhead wire 200 is made of the sintered body 100 through an extrusion process, and may have an increased density than the sintered body 100 .

Next, referring to FIG. 8 , the primary overhead wire 200 is heated in an oxygen atmosphere to form the secondary overhead wire 300 on which the decarburized layer 11 is formed. The secondary overhead wire 300 includes a core layer 10 containing carbon (C) and a decarburized layer 11 surrounding the outside of the core layer 10 . The decarburized layer 11 means a layer in which carbon is removed from the surface of the primary overhead wire 200 by oxygen, and by heating at a high temperature in a high-pressure oxygen atmosphere, carbon is removed from the sintered primary overhead wire. can do.

The thickness of the decarburized layer 11 can be controlled by oxygen pressure, heating temperature, and process time. For example, when the oxygen pressure is increased, the oxygen permeation rate can be increased, so that the formation of the decarburized layer 11 can be rapidly progressed, and when the temperature is high, the reaction rate is increased and the formation rate of the decarburized layer 11 is also increased. In addition, if the process time is lengthened, the thickness of the entire decarburized layer 11 can be increased while the depth of decarburization is increased.

In order to precisely control the thickness of the decarburized layer 11, it is preferable to adjust the oxygen pressure to 3 to 7 kg/cm 2 , to set the temperature to 600 to 800 degrees relatively low, and to adjust the process time.

Next, referring to FIG. 9 , a contact surface 12 is formed by removing the decarburized layer 11 on any one surface of the secondary overhead wire 300 .

The decarburized layer 11 has to be removed to expose the core layer 10 because carbon is removed to improve weldability, but performance as a contact material may be deteriorated. The decarburized layer 11 is removed by wet polishing in order to prevent the surface from being denatured by friction during the polishing process. That is, one surface of the secondary overhead wire 300 is wet-polished to expose the core layer 10 to the outside to form the contact surface 12 . The contact surface 12 may be composed of a core layer 10 in the central portion and a decarburized layer 11 on the outside, but the ratio of the actual core layer 10 constitutes the majority, so that the characteristics of the contact material 1 can be maintained. have.

Next, referring to FIG. 10 , the contact material 1 is formed by cutting the secondary overhead wire 300 from which the decarburized layer 11 is removed. The contact material 1 may be formed by cutting the secondary overhead wire 300 to a required size, and thereafter, concavo-convex processing may be added to the welding surface to distinguish the contact surface 12 from the welding surface.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those of ordinary skill in the art to which the present invention pertains will realize that the present invention may be implemented in other specific forms without changing the technical spirit or essential features thereof. You will understand. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

1: contact material
10: core layer
11: decarburized layer
12: contact surface
100: sintered body
200: primary overhead wire rod
300: secondary overhead wire rod

Claims (6)

(a) forming a mixing powder by mixing silver (Ag) powder, nickel (Ni) powder, and graphite powder;
(b) forming a sintered body by sintering the mixed powder;
(c) extruding the sintered body to form a primary overhead wire in the form of a wire rod;
(d) heating the primary overhead wire in an oxygen atmosphere to form a secondary overhead wire including a core layer containing carbon and a decarburized layer surrounding the core layer by removing carbon on the surface;
(e) forming a contact surface by removing the decarburized layer on one of the surfaces of the secondary overhead wire;
and (f) forming a contact material by cutting the secondary overhead wire material from which the decarburized layer has been removed. According to claim 1,
The thickness of the decarburized layer is a contact material manufacturing method of 5 to 15% of the thickness of the contact material. According to claim 1,
The decarburized layer is a contact material manufacturing method in which residual carbon is 0.1% or less based on the total weight of the decarburized layer. According to claim 1,
The step (d) is a contact material manufacturing method of heating at 600 to 800 degrees in an oxygen atmosphere in a pressure range of 3 to 7 kg/cm2. According to claim 1,
The silver powder, the nickel powder, and the graphite powder are each 92 to 96 wt%, 1 to 3 wt%, 3 to 5 wt% of the contact material manufacturing method. According to claim 1,
The step (e) is a contact material manufacturing method of removing the decarburized layer by wet grinding the secondary overhead wire.

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