KR20160107016A - Method for manufacturing electric contact for thermostat and the electric contact for thermostat prepared thereby - Google Patents

Abstract

The present invention relates to a manufacturing method of a thermostat of an electric contact for a thermostat, and an electric contact for a thermostat manufactured thereof. The manufacturing method comprises: (a) a step of casting a first billet by sintering a contact point device including silver (Ag) and a first metal; (b) a step of casting a second billet with nickel (Ni) or a copper-nickel alloy; (c) a step of forming a third billet by cutting and assembling the first billet and the second billet; (d) a step of diffused-bonding the third billet; and (e) a step of extruding and rolling the diffusion-bonded third billet to form a multilayered plate.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method of manufacturing an electrical contact for a thermostat, and an electrical contact for a thermostat,

The present invention relates to a method of manufacturing an electrical contact for a thermostat and an electrical contact for the thermostat produced thereby.

Conventionally, the alloy-based electrical contacts are used by being bonded to various materials (for example, Cu, Ni, bronze, etc.) according to use and use conditions. In particular, electrical contacts used in thermostats are made of copper-nickel alloy (Cu-Ni alloy) or nickel (Ni) because of the difference in heat resistance and thermal expansion coefficient.

In manufacturing such conventional electrical contacts, the silver alloy and the base material are bonded through a cold working method such as heading. Recently, in order to improve the productivity, the contact material is often used in the form of a strip. In this case, it is mainly bonded to the large material by using resistance welding. Such strip-type electrical contacts use the hot atmosphere bonding method in the overseas advanced companies because of the oxidation problems occurring at the interface between the silver alloy and the base material during the bonding process between the silver alloy and the base material. However, it is disadvantageous in that the production cost is expensive due to limitations such as expensive equipment construction.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a silver-copper alloy layer and a silver-copper alloy layer on a bonding interface, It is another object of the present invention to provide a novel manufacturing method for an electrical contact for a thermostat in which formation of a nickel alloy layer is minimized.

It is another object of the present invention to provide a multilayer strip type electrical contact manufactured by the above-described manufacturing method.

(A) casting a first billet by sintering a contact material comprising silver (Ag) and a first metal; (b) casting a second billet with nickel (Ni) or a copper-nickel alloy; (c) cutting and assembling the first billet and the second billet to form a third billet; (d) diffusion bonding the third billet; And (e) extruding and rolling the diffusion bonded third billet to form a multi-layered plate. The present invention also provides a method of manufacturing an electrical contact for a thermostat.

According to an example, the manufacturing method may further include, before the step (d), canning the third billet.

According to another example, the manufacturing method may further include shaping the multilayer plate formed in the step (e).

The first metal may be at least one selected from the group consisting of nickel (Ni), cadmium (Cd), tin (Sn), and indium (In), wherein the content of the first metal By weight based on the total weight of the composition.

The step (d) may be carried out at a temperature of 700 to 850 ° C. and a pressure of 40 to 130 MPa for 1 to 10 hours to effect the bonding through diffusion between the nickel layer or the copper-nickel alloy layer and the silver alloy layer interface have.

On the other hand, the present invention provides an electrical contact for a thermostat manufactured by the above-described manufacturing method.

The present invention relates to a nickel-containing or copper-nickel alloy-containing billet and a nickel-containing or copper-nickel alloy-containing billet by directly joining them by utilizing a diffusion bonding method when bonding silver- It is possible to manufacture an electrical contact for a thermostat in which the formation of a silver-copper alloy layer or a silver-nickel alloy layer is minimized at the bonding interface between the billets.

Further, in the present invention, it is possible to manufacture a strip-type electrical contact having a multi-layer by utilizing the diffusion bonding method described above. As described above, the electrical contact material of the present invention has excellent durability and reliability, and thus can be usefully used as a contact material in various fields.

Fig. 1 is an FE-SEM photograph and an EDS mapping photograph showing a joint surface of the electrical contact prepared in Example 1, wherein (a) to (d) and (g) are FE-SEM photographs, ) Is an EDS Mapping photograph.
2 is an FE-SEM photograph showing a cross section of the electrical contact prepared in Example 1. Fig.

Hereinafter, the present invention will be described.

In the present invention, instead of using a heading junction or a brazing junction, a silver diffusion bonding method is used to directly connect a nickel layer or a copper-nickel alloy layer to a silver (Ag) alloy layer in manufacturing an electrical contact for a thermostat .

That is, when different kinds of objects are brought into contact with each other, diffusion occurs in which atom of each object moves to a relative object lower than its own concentration according to time and temperature. In particular, since metals have a high melting point, when pressure, temperature, and spacing are controlled artificially, diffusion of atoms occurs in a dissimilar metal material, which is called diffusion bonding.

When the diffusion bonding is applied as described above, not only the formation of an impurity layer (for example, a silver-copper alloy layer or a silver-nickel alloy layer) on the bonding interface is minimized, but also an oxide layer For example, a nickel oxide layer or a copper-nickel alloy oxide layer) can be controlled to improve the service life of the electrical contact.

Hereinafter, a method of manufacturing an electrical contact 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 step may be modified or optionally mixed as necessary.

In one preferred embodiment of the method for manufacturing the electrical contact for the thermostat, (a) a step of sintering a contact material comprising silver (Ag) and a first metal to cast a first billet; (b) casting a second billet with nickel (Ni) or a copper-nickel alloy; (c) cutting and assembling the first billet and the second billet to form a third billet; (d) diffusion bonding the third billet; And (e) extruding and rolling the diffusion bonded third billet to form a multilayer plate.

Hereinafter, the manufacturing method will be described separately for each process step as follows.

(a) First Billet  casting

First, a contact material including silver (Ag) and a first metal is sintered to form a first billet (hereinafter referred to as step S100).

Specifically, a composition of a contact material containing silver (Ag) as a main component and containing a first metal is designed, and then the mixture is introduced into a melting furnace and sintered to cast the first billet. At this time, the casting conditions of the first billet can be appropriately adjusted within the conventional range known in the art.

Here, the casting means that the molten material is made into a billet, which is a metal ingot in a form that can be easily extruded later. At this time, the billet may have a rectangular cross section of 160 mm or less and a cross section of 25,600 mm 2 or less.

The first metal is not particularly limited as long as it is a contact material capable of forming silver and an alloy in the art. For example, the first metal may be a metal such as Ni, Cd, Sn, and In. It is preferable to use at least one kind selected. The content of the first metal is not particularly limited, but may be 10 wt% or more, preferably about 8 to 12 wt% based on the total weight of the first billet.

(b) the second Billet  casting

Nickel (Ni) or a copper-nickel alloy (hereinafter referred to as " S200 step ").

The casting condition of the second billet is not particularly limited and can be appropriately adjusted within the conventional range known in the art. For example, a nickel or copper-nickel alloy may be cast into a circular mold and subjected to a pressure of about 160 to 180 kgf / cm ² . In another example, a nickel or copper-nickel alloy may be cast into a circular mold and then cast in a vacuum atmosphere.

(c) Third Billet  formation

The first billet obtained in the step S100 and the second billet obtained in the step S200 are cut in accordance with the sectional area ratio and then assembled to form a third billet (hereinafter referred to as 'step S300').

The above assembling method can be carried out by processing the thicknesses of the first billet and the second billet, and then stacking the second billet on the first billet. In the laminating method, the second billet is laminated on the first billet to obtain the second billet of the second layer, or the first billet - the second billet - the first billet are stacked in this order to obtain the third billet of the third layer Or the first billet - the second billet - the first billet - the second billet ... Are stacked in this order to obtain a second billet having two or more layers.

Alternatively, at the time of forming the third billet, a silver (Ag) layer may be separately inserted by inserting a silver (Ag) plate if necessary.

Alternatively, a canning process may be performed on the third billet obtained in step S300, or a degassing process may be performed to prevent gas remaining in the can from affecting the junction before step S400. can do.

(d) Third Billet  Diffusion bonding

In step S300, a nickel layer or a copper-nickel alloy layer is bonded to a silver (Ag) alloy layer through an isotropic diffusion bonding in a vacuum state (hereinafter referred to as 'S400 step').

The method and condition for the diffusion bonding can be appropriately adjusted within the range known in the art. As a preferred example of the step S400, the third billet is maintained at a temperature of about 780 to 850 DEG C and a pressure of about 40 to 130 MPa (preferably about 50 to 110 MPa) for about 1 to 10 hours, Layer and the nickel layer interface or between the silver alloy layer and the copper-nickel alloy layer interface.

Specifically, when the above-mentioned conditions are maintained for the third billet, wetting by the alloy liquid phase occurs over the entire surface of the third billet, so that a full bonding is formed. That is, the bonding is performed through diffusion between the silver alloy layer and the nickel layer or the copper-nickel alloy layer interface. At this time, if it is lower than the above-mentioned condition, a local alloy layer is formed only at the interface, so that the electrical contact can be peeled off at the time of use, and if it is higher than the above condition, the settling of the contact becomes large.

The diffusion layer formed by the diffusion bonding is made of silver and nickel or consists of silver, nickel and copper, depending on the components of the second billet. Since such a diffusion layer has a higher melting point and a higher temperature strength as compared with the silver-containing layer used in conventional bonding, it is also difficult to peel off the temperature rise due to energization of a large current. In addition, the bonding strength can be equivalent to the contact strength by soldering.

In addition, since the thickness of the diffusion layer can be controlled by heating temperature, heating time, pressure, etc., it is possible to control the diffusion layer thickness to a desired value according to the characteristics of the bonding portion.

The third billet subjected to the diffusion bonding as described above may further be further improved in bonding strength through a process such as hot pressing.

(e) Formation of a multilayer plate

The third billet diffusion-bonded in step S400 is then extruded and rolled to form a multi-layered plate (hereinafter, referred to as step S500).

As a preferable example of the method for forming the multilayered plate, the third billet is put into a mold of a strip shape, and then hot extruded at a pressure of about 170 to 210 kgf / cm 2 at a temperature of about 600 to 700 ° C. .

In this step S500, the extrusion is a step of manufacturing the diffusion bonded third billet in a form to press-contact. Such extrusion may result in surface roughening, foreign matter, and oxides depending on the mold, and if necessary, the surface may be ground through a brush or acid treatment process.

The contact material in the form of a strip or plate contact can be produced by the extrusion process. Therefore, since the possibility of occurrence of cracks and defects in the base material is small, the durability and the reliability of the product can be expected to be improved.

Thereafter, the contact material is rolled to a desired thickness to match the desired thickness.

In this case, the rolling may be performed by conventional hot rolling, cold rolling or both, which are known in the art, and more specifically, the hot rolling of the multilayered plate at a temperature of about 300 to 450 DEG C, Can be manufactured in the dimensioned dimensions. Further, it can be manufactured by cutting to a desired width through a slitting process.

(f) Machining of multi-layered plates

Alternatively, the nickel layer or the copper-nickel alloy layer of the multilayer plate obtained in the step S500 may be shaped. By performing this step, the welding strength of the electrical contact can be improved.

The shape processing method is not particularly limited and can be carried out by a method known in the art. At this time, an example of the shape may be a pattern such as a line or a W shape.

(g) brush  And Slitting

Thereafter, the burr and the foreign substance on the surface of the electrical contact material to be bonded are removed and a brushing process and a leveling process are performed according to a conventional method known in the art to obtain a good surface roughness, and then a slitting process is performed.

At this time, depending on the surface condition required by the user, it is possible to adjust the degree of processing of the surface.

The present invention also provides an electrical contact for a thermostat produced by the above-described method.

The electrical contact for the thermostat of the present invention is a form in which two or more multi-layer heterogeneous materials including a silver-alloy layer, a nickel layer, a silver alloy layer and a copper-nickel layer are bonded to each other. In the case of such an electrical contact, the silver-alloy layer and the nickel layer are directly bonded through the diffusion bonding, or the silver alloy layer and the copper-nickel alloy layer are directly bonded, so that the bonding strength between the interfaces is higher than that of the conventional electrical contact for the thermostat Therefore, the life of the electrical contact can be improved.

Specifically, the electrical contact for a thermostat of the present invention comprises: (a) a silver alloy layer in which silver (Ag) and a first metal are mixed; (b) a diffusion layer containing silver and nickel; (c) - nickel alloy layer.

The electrical contact for the thermostat may have a structure of two to four layers, and may be formed by inserting another heterogeneous material as necessary.

Hereinafter, the present invention will be described in more detail 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  One]

90 wt% of silver (Ag) and 10 wt% of nickel (Ni) powder were mixed and charged into a mold and sintered at 800 ° C for 12 hours to prepare a circular first billet. On the other hand, nickel (Ni) was vacuum cast to produce a second billet. Then, the first billet and the second billet were cut at a ratio of 1: 1, respectively, and then assembled to prepare a third billet. The third billet was canned and degassed while being held at 800 DEG C and 98 MPa for 4 hours for diffusion bonding. Thereafter, the third billet was indirectly extruded at 190 kgf / cm 2 after induction heating at 800 ° C, and rolled to a thickness of 0.6 mm to form a silver alloy nickel-nickel multilayer plate. Then, after cutting to a width of 3.5 mm, a nickel surface having a protrusion shape and a silver alloy surface having a round shape were formed to prepare an electrical contact for a thermostat composed of a silver alloy layer and a nickel layer.

[ Comparative Example  One]

90 wt% of silver (Ag) and 10 wt% of nickel (Ni) powder were mixed, and the mixture was charged into a mold and sintered to form a circular first billet. On the other hand, 100 wt% of nickel (Ni) powder was put into a mold and then sintered to cast a circular second billet. Thereafter, the first billet and the second billet were cut at a ratio of 1: 1, respectively, and then assembled to prepare a third billet. Subsequently, the third billet was indirectly extruded at 190 kgf / cm 2 after induction heating at 800 ° C, but the bonding process was peeled off and the subsequent process could not proceed.

[ Experimental Example  One]

The bonding surfaces of the electrical contacts prepared in Example 1 were confirmed by FE-SEM, and the components of the electrical contacts were analyzed by EDX. The results are shown in Fig. The cross-section of the electrical contact prepared in Example 1 was confirmed by FE-SEM, and the result is shown in Fig.

Claims (7)

(a) sintering a contact material comprising silver (Ag) and a first metal to cast a first billet;
(b) casting a second billet with nickel (Ni) or a copper-nickel alloy;
(c) cutting and assembling the first billet and the second billet to form a third billet;
(d) diffusion bonding the third billet; And
(e) extruding and rolling the diffusion bonded third billet to form a multilayer plate
Wherein the thermostat is a thermostat. The method according to claim 1,
Further comprising the step of canning the third billet prior to step (d). ≪ RTI ID = 0.0 > 11. < / RTI > The method according to claim 1,
Further comprising the step of shaping the multilayer plate formed in the step (e). The method according to claim 1,
Wherein the first metal is at least one selected from the group consisting of Ni, Cd, Sn, and In. The method according to claim 1,
Wherein the content of the first metal is in the range of 8 to 12 wt% based on the total weight of the first billet. The method according to claim 1,
The step (d) may be carried out at a temperature of 700 to 850 ° C. and a pressure of 40 to 130 MPa for 1 to 10 hours to effect bonding by diffusion between the nickel layer or the copper-nickel alloy layer and the silver alloy layer interface Wherein the method comprises the steps of: An electrical contact for a thermostat produced by the manufacturing method according to any one of claims 1 to 6.

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