KR101478486B1 - Method for making silver coated copper powder by galvanic displacement reaction - Google Patents

Abstract

The present invention provides a method of coating a surface of a first metal with a second metal having a lower reducing power than the first metal, comprising: preparing a first solution in which a first metal is dispersed in de-ionized water; Preparing a second metal electrolyte in which the second metal ion is dissociated; And a method of coating a surface of a first metal with a second metal having a lower reducing power than the first metal, comprising the step of adding a metal electrolytic solution to the first solution to generate a spontaneous substitution reaction.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for producing silver coated copper powder using a spontaneous substitution reaction,

The present invention overcomes the above-described problems of the prior art, and it is an object of the present invention to eliminate the steps such as electrolytic solution manufacturing and cleaning method, There is provided a method of coating a second metal particle having a reducing power lower than that of a particle.

Alternatively, one object of the present invention is to provide a silver coating process for a copper powder using a spontaneous substitution reaction, a process for removing an oxide film of a copper powder, and a process for preparing a silver coated copper powder will be.

Silver (Ag) powders are mainly used as electromagnetic shielding materials for electronic devices such as mobile phones, notebooks, and tablet PCs, electronic materials, conductive pastes, and screen printing materials in the semiconductor display industry. It is also used as a material for forming a front electrode of a solar cell and a material for forming a circuit in a PCB substrate.

These silver (Ag) powder products have rarely developed in Korea, and most of them have been dependent on imports. Recently, research and development have been done in Korea.

* Due to the problem of rising cost of silver (Ag), a method of coating silver (Cu) with silver (silver coated copper powder) has been developed as a method of reducing the price. This method is advantageous in that cost reduction can be achieved and the excellent conductivity efficiency of silver (Ag) can be obtained.

Silver (Ag) is an expensive raw material and it is important to achieve maximum efficiency in small quantities. It is necessary to maintain excellent ductility, electrical conductivity and thermal / electrical conductivity of silver (Ag). Silver (Ag) is followed by copper (Cu) is the material that shows excellent properties. Copper also has excellent electrical conductivity, but it has a weak oxidation problem. Therefore, studies have been made on the preparation of a silver-coated copper powder having a core-shell structure by overcoming the above problems.

In general, silver (Ag) is coated on copper by electrolytic plating, electroless plating, sputtering, vapor phase reaction, or the like. An electroless plating method using a reducing agent, a complexing agent and other additives is used as an industrially applicable method.

As described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2006-319675), a silver particle-attached silver composite powder using ammonium salt as a complexing agent with silver nitrate, a reducing agent, and ethylenediamine tetraacetic acid as a chelating agent has been prepared .

As in Patent Document 2 (Japanese Patent Application Laid-Open No. 10-2006-0052293), an electroless silver plating method has been disclosed in which an amine compound is used as a reducing agent and a relative concentration is controlled.

However, the silver (Ag) coating method using the electroless plating method has to be complicated in the manufacturing and washing methods of the electrolytic solution to be used, and it has been pointed out the problems of environmental pollution caused by the use of the reducing agent and the complexing agent used basically, It is a good method to apply industrially due to the problem of impurity generation due to excessive reducing agent generated in the manufacturing process and non-uniform coating, but a processing method that can overcome these problems is needed.

Also, since the oxide film of copper powder directly affects the electrical conductivity characteristics of the silver-coated copper powder, it is necessary to study the oxide film removal process and the technology for preventing regeneration.

Patent Document 1: Japanese Patent Application Laid-Open No. 2006-319675

Patent Document 2: Korean Patent Laid-Open No. 10-2006-0052293

The present invention overcomes the above-described problems of the prior art, and it is an object of the present invention to eliminate the steps such as electrolytic solution manufacturing and cleaning method, There is provided a method of coating a second metal particle having a reducing power lower than that of a particle.

Alternatively, one object of the present invention is to provide a silver coating process for a copper powder using a spontaneous substitution reaction, a process for removing an oxide film of a copper powder, and a process for preparing a silver coated copper powder will be.

The present invention provides a method for coating a surface of a first metal with a second metal having a lower reducing power than the first metal.

The method comprises the steps of: preparing a first solution in which a first metal is dispersed in de-ionized water; Preparing a second metal electrolyte in which the second metal ion is dissociated; And adding the metal electrolyte to the first solution to generate a spontaneous substitution reaction.

Preferably, the first metal is copper particles, and the second metal electrolytic solution is an electrolytic solution in which silver ions are dissociated.

More preferably, the second metal electrolytic solution is a metal electrolytic solution selected from silver nitrate (AgNO ₃ ), silver chloride (AgCl), silver sulfate (Ag ₂ SO ₄ ), and silver fluoride (AgF) dissociated into de- Electrolytic solution. More preferably, the second metal electrolytic solution is an electrolytic solution in which silver nitrate (AgNO ₃ ) or silver chloride (AgCl) is dissolved in de-ionized water.

In yet another aspect of the present invention, the second metal electrolyte comprises sodium thiosulfate (Na ₂ S ₂ O ₃ ) to control the rate of spontaneous substitution reaction and to induce a uniform coating.

In another aspect of the present invention, the rate of the spontaneous substitution reaction can be controlled by adjusting the concentration of the second metal electrolyte.

In another aspect of the present invention, the second metal electrolytic solution contains ammonium ions as a decelerating agent for the spontaneous substitution reaction, and may include chloride ions as an accelerator.

In another aspect of the present invention, the step of removing the oxide film on the surface of the first metal is provided prior to the spontaneous substitution reaction.

The oxide film removing step is a step of supporting the first metal in a mixed solution of ammonia water (NH ₃ H ₂ O) and ammonium sulfate ((NH ₄ ) ₂ SO ₄ ).

Alternatively, the present invention provides a coating on a surface of a first metal formed in accordance with the method, wherein the second metal has a lower reductivity than the first metal.

The coating has a core-shell structure.

According to the method of forming the silver coated copper powder according to the embodiments of the present invention, the two most important elements in the process of coating silver (Ag) on the copper (Cu) To improve the process.

First, the oxide film on the surface of the copper powder is removed, and after that, the generation of the natural oxide film in the air is effectively prevented, thereby improving the problem of the decrease in the electrical conductivity due to the conventional copper oxide film. As a result, silver nitrate, silver chloride, and sodium thiosulfate are uniformly coated on the surface of the copper powder used in the electrolytic solution for replacing silver (Ag), thereby preventing generation of impurities and preventing environmental pollution by using no reducing agent, .

Although this process has been attempted to convert the silver (Ag) powder and the silver-coated copper powder into an import-dependent form in domestic development, it has not yet achieved a sufficient efficient production method and a highly effective process method .

The above process and silver coated copper powder can be used for shielding electromagnetic waves of electronic devices such as mobile phones, notebooks, and tablet PCs, and can be used for electronic materials, conductive pastes, and screen printing in the semiconductor display industry, And can be applied to circuit formation on a PCB substrate, and the ripple effect is very large.

1 is a process flow diagram illustrating a process for forming a silver coated copper powder according to an embodiment of the present invention.
2 (a) to 2 (f) are scanning electron microscope (FESEM) photographs showing various structures of copper dendrites and spherical, three-dimensional powders formed according to Example 1 of the present invention.
3 (a) is an X-ray diffraction analysis (XRD) of a copper powder which has undergone an oxide film removing process on the surface of a copper powder, which has not been subjected to an oxide film removing step on the surface of the copper powder, This is the data that distinguishes the difference.
FIG. 4 is a scanning electron microscope (FESEM) photograph showing silver (Ag) coated on a copper powder by a substitution reaction in a mixed solution for the spontaneous substitution reaction of silver nitrate and sodium thiosulfate according to Example 2 of the present invention.
FIG. 5 is a scanning electron microscope (SEM) image of silver (Ag) coated on a copper powder by a substitution reaction in a mixed solution for the spontaneous substitution reaction of silver chloride and sodium thiosulfate according to Example 3 of the present invention.
6 is an X-ray diffraction (XRD) result according to the silver (Ag) content of the silver-coated copper powder.
FIG. 7 is an X-ray diffraction (XRD) result of the copper powder and the silver-coated copper powder which have undergone the oxide film removal and regeneration prevention process on the copper surface.
8 is a scanning electron microscope (FESEM) photograph showing a core-shell structure cross-section of the silver-coated copper powder.
FIG. 9 is a data of the electromagnetic shielding efficiency of the silver-coated copper powder.

Hereinafter, a method for forming a high surface area powder according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The present invention is capable of various modifications and various forms, and specific embodiments are illustrated in the drawings and described in detail in the text. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. Like reference numerals are used for like elements in describing each drawing. In the accompanying drawings, the dimensions of the sheets are enlarged from the actual size for the sake of clarity of the present invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "comprises", "having", and the like are used to specify that a feature, a number, a step, an operation, an element, a part or a combination thereof is described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted as either ideal or overly formal in the sense of the present application Do not.

1 is a flowchart illustrating a method of forming a silver coated copper powder according to an embodiment of the present invention.

A copper powder having a dendritic structure is prepared as a first metal. For the production of the copper powder, refer to Patent Document 3 (domestic patent application 10-2011-0112732). 2 (a-d) are photographs of copper powders produced according to a scanning electron microscope (FESEM).

The dendritic copper powder is formed at a high temperature at room temperature by spontaneous substitution reaction of aluminum having a high reducing power and copper having a relatively low reducing power. The dendritic copper powder may be a dissociated chlorine ion serving as a reaction accelerator in the electrolytic solution. For example, dendritic copper powder can be formed through an electrolytic solution in which copper chloride and sulfuric acid are dissociated into pure water. On the other hand, if copper sulfate, which does not contain chlorine ions, and sulfuric acid are dissolved in pure water, Substitution reaction is difficult to achieve. An active spontaneous substitution reaction can be made by adding sodium chloride (NaCl) containing chlorine ions thereto. Examples of such solutions may include de-ionized water.

In addition to the metal chloride including copper, sodium chloride, ammonium chloride, hydrochloric acid, or a mixture thereof may be used for the electrolytic solution containing the chloride ion. Further, the dendritic copper powder may form various structures through metal growth directional modification and surface modification by adding an additive to the electrolytic solution. In addition, the structure and size of the copper powder can be adjusted according to the concentration of each substance constituting the electrolytic solution.

In addition to the dendritic copper powder according to the embodiment of the present invention, the solid and nanoparticle clustering copper powders are prepared at room temperature by electroless synthesis using a reducing agent and a capping agent, sodium hydroxide, which form a film. (See Fig. 2 (e) (f)). Examples of the solution may include de-ionized water.

The solid and nanoparticle type copper powders through the electroless synthesis method can change the size and shape of the structure by controlling the concentration of each substance constituting the electrolyte.

The mixed solution 1 for removing the surface oxide film and preventing oxidation of the copper powder according to the embodiment of the present invention is prepared. The mixed solution 1 is a mixed solution of ammonia water (NH ₃ H ₂ O) and ammonium sulfate ((NH ₄ ) ₂ SO ₄ ). The concentration of the solution may be varied organically and other additives including it may be added. Examples of such solutions may include de-ionized water.

The mixed solution 1 may be used in place of a solution containing ammonia ions, or may be replaced with a substance containing an amine.

The removal of the oxide film on the copper surface by the mixed solution 1 and the prevention of air regeneration can be a means for solving the problems of electrical conductivity and performance deterioration due to the oxide film, which has been a problem in the preparation of the silver-coated copper powder, Examples 2 and 3 demonstrate this.

After the removal of the copper oxide film and the oxidation prevention process using the first mixed solution, the copper powder may be washed with ethanol or methanol, and further washed with pure water, filtered, and then dried using a vacuum oven. Also, the drying process using the freeze dryer can be performed immediately after the washing process. Alternatively, the drying step may be omitted, and silver powder may be formed by immersing the copper powder in the following mixed solution 2 immediately after the washing process.

In a spontaneous substitution reaction process for coating silver (Ag) on a copper powder according to an embodiment of the present invention, silver nitrate (AgNO) containing silver (Ag) as a second metal having a lower reducing power than copper ₃ ), silver chloride (AgCl), silver sulfate (Ag ₂ SO ₄ ), and silver fluoride (AgF).

In this case, the concentration of the electrolyte of the material containing silver (Ag) is adjusted to the desired concentration by weight calculation of the content of silver (Ag) to be compared with copper. Subsequently, Solution 2 in which sodium hydroxide (Na ₂ S ₂ O ₃ ) capable of controlling the rate of spontaneous substitution reaction was uniformly coated on the copper surface was dissolved in pure water to prepare Solution 2, and Solution 1 was dissolved in Solution 2 And the mixed solution 2 is prepared. Examples of the mixed solution 2 may include de-ionized water.

In addition to the sodium thiosulfate ion, a reaction accelerator using ammonium (NH ₄ ⁺ ) ion and a reaction accelerator using chlorine ion can be used in the mixed solution 2 by controlling the spontaneous substitution reaction rate.

Subsequently, the mixed powder of silver (Ag) for spontaneous substitution reaction is immersed in the copper powder which has undergone the copper surface oxide film removal and regeneration preventing process to produce silver coated copper powder. The first metal and the second metals can utilize all the metals and metal oxides having a difference in reducing power between them, and the structure formed by the spontaneous substitution reaction process is a core-shell structure and an alloy structure or a second structure It is possible to further form.

The silver-coated copper powder prepared by the above process is washed with methanol or ethanol, rinsed again with pure water, filtered, and kept at a constant temperature in a vacuum oven for 5 hours or more. Alternatively, the powder that has undergone the washing process without being subjected to the filtering process is dried using a freeze dryer.

Example 1: Preparation of copper powder

(1) The copper powder used in the preparation of the coated copper powder is formed by two process methods. The copper powder of the dendritic structure is formed by a spontaneous substitution reaction, and aluminum foil and aluminum powder having higher reducing power than copper can be used. 2 (a) is 0.1M copper chloride (CuCl ₂₎ and 1M sulfuric acid (H ₂ SO ₄₎ was prepared in the electrolytic solution is dissociated in pure 2 (b) is 0.1M copper chloride (CuCl ₂₎ and 1M acetic acid (acetic acid) was prepared from an electrolytic solution dissociated to pure water. In addition, FIG. 2 (c) was prepared from 0.1M copper chloride (CuCl ₂₎ and 1M hydrochloric acid (HCl) electrolyte is dissociated in pure water, and Fig. 2 (d) is 0.1M copper chloride (CuCl ₂₎ and the additive hexamethylene bromide A hexadecyltrimethyl ammonium bromide (CTAB) was prepared in an electrolytic solution dissociated in pure water.

All the above electrolytic solution contains a chloride ion to a solution of the reaction accelerator role, and when using the copper materials such as copper sulfate (CuSO ₄₂ O) that does not contain chloride ions, such as copper chloride (CuCl _2), sodium chloride, ammonium chloride , And hydrochloric acid can be used to produce electrolytes.

(2) An aluminum foil having a high reducing power is supported on the electrolytic solutions to generate a spontaneous substitution reaction. Hydrogen droplets are generated very actively during the reaction, and mass transfer limitation phenomenon occurs by the hydrogen release reaction, and dendritic structure formation is possible. The dendritic copper powder produced by the above process is subjected to a drying process using a vacuum oven at 80 ° C. for 10 hours or a freeze dryer after the filtering process.

(3) In addition to the process by the spontaneous substitution reaction using the aluminum foil, the process for forming the solid and nanoparticle clustering copper powder uses the electroless synthesis method using the reducing agent, the capping agent, and the electrolyte dissociated with NaOH. Stereoscopic copper powder 0.1M copper sulfate (CuSO ₄₂ O) in FIG. 2 (e), 0.3M hydrazine: dissociation to pure water _{(Hydrazine N 2 H 4),} 1M sodium citrate (Sodium citrate), 1.25M sodium hydroxide (NaOH) Was prepared at room temperature using the electrolytic solution. Figure 2 (f) nanoparticle aggregation-shaped copper powders 0.1M copper sulfate (CuSO ₄₂ O) a, 0.5M hydrazine (Hydrazine: N2H4), 0.1M sodium citrate (Sodium citrate), 1.25M sodium hydroxide (NaOH) in the pure The dissociated electrolyte was used at room temperature. Each copper powder formed after a certain reaction time passes through a filtering process and then a drying process using a vacuum oven at 80 ° C for 10 hours or a freeze dryer.

Example 2: Preparation of silver (Ag) coated copper (Cu) powder using silver nitrate

1. Removal step of oxide film of copper powder

(1) is a pretreatment process for forming a coated copper powder. In order to remove the oxide film on the copper powder surface prepared according to Example 1, 0.02M ammonia water (NH ₃ H ₂ O) is added to a de- And 0.06 M ammonium sulfate ((NH ₄ ) ₂ SO ₄ ) were prepared.

(2) The copper powder prepared in Example 1 was immersed in the mixed solution 1 for about 5 minutes until the oxide film was removed. At this time, the oxide film was removed and the color of the solution was changed to blue.

(3) After the removal of the copper oxide film, ethanol or methanol was washed three times with water and three times with de-ionized water, and then filtered using a vacuum oven to dry the powder. The drying process was carried out at 80 DEG C for 5 hours or more using a drying process or a freeze dryer. This drying step can be omitted and a spontaneous substitution reaction process of silver (Ag) using the following mixed solution 2 is possible.

2. Silver coating step

(1) In order to coat silver (Ag) on the copper powder subjected to the copper oxide removal and oxidation prevention process using the mixed solution 1, silver nitrate (AgNO ₃ ) Solution 1 dissolving in pure water and solution _{2 in which} sodium thiosulfate (Na ₂ S ₂ O ₃ ) at a concentration of 1/5 of the silver nitrate dissociated in pure water was prepared, solution 1 was added to solution 2 to prepare a mixed solution 2 .

(2) In this Example 2, 0.5627 g silver nitrate (AgNO ₃ ) was added to 2 g copper powder in 100 ml de-ionized water solution to prepare a silver coated copper powder having a content of 10% silver (Ag) And 0.12 g of sodium thiosulfate (Na ₂ S ₂ O ₃ ) were used.

(3) Copper powder was dispersed in a de-ionized water solution through an ultrasonic disperser (Sonicator), and then the mixed solution 2 was added. At this time, silver (Ag) having a lower reducing power than copper causes a galvanic displacement reaction on the copper surface and is gradually coated on the surface of the copper powder. The rate of the spontaneous substitution reaction can be controlled according to the concentration of the mixed solution 2, and the reaction rate can be controlled by using a reducing agent including ammonium ions and an accelerator containing chloride ions.

(4) After the spontaneous substitution reaction of silver on the copper surface in the vessel is completed, the solution remaining after the reaction is removed, and the solution is washed with an alcohol solution such as methanol or ethanol, and then de-ionized water solution The washing process was carried out three times or more. The silver coated copper powder prepared by the above process was filtered and then dried in a vacuum oven at a temperature of 80 ° C for 10 hours or in a freeze dryer.

(5) FIG. 4 is an electron microscope (SEM) photograph of the silver coated copper powder according to the silver content by the above process. 4 (a) and 4 (b) are silver coated copper powders with a silver (Ag) content of 10% and FIG. 4 (c) and (d)

Example 3: Preparation of silver (Ag) coated copper (Cu) powder using silver chloride

Except that silver chloride (AgCl) was used instead of silver nitrate (AgNO ₃ ) in the spontaneous substitution reaction process of preparing silver coated copper powder, unlike the mixed solution 2 in Example 2, 2 and the process thereof.

5 (a) to 5 (d) are SEM photographs of silver coated copper powder prepared according to Example 3 of the present invention and coated on the copper surface according to the content of silver (Ag).

5 (a) and 5 (b) show that silver (Ag) is uniformly coated by a spontaneous substitution reaction while maintaining the structure of the dendritic copper powder as a silver-coated copper powder having a silver (Ag) content of 30% have.

5 (c) and (d) show that silver (Ag) was uniformly coated by the spontaneous substitution reaction while maintaining the structure of the dendritic copper powder as a silver-coated copper powder having a silver content of 50% have. 5 (d), it can be seen that a second structure due to a long-term substitution reaction can be additionally generated.

Experimental Example 1: Analysis of whether or not copper oxide film removal and regeneration prevention process

Is a mixed solution of ammonia water (NH ₃ H ₂ O) and ammonium sulfate ((NH ₄ ) ₂ SO ₄ ) as a process for solving the problem of decrease in electrical conductivity and resistance efficiency caused by copper oxide film, The oxidation peak of copper powder by copper oxide removal and oxidation prevention process using XRD (XRD) was performed.

FIG. 3 (a) shows that a copper oxide film is generated as a result of X-ray diffraction analysis (XRD) of the copper powder which has not undergone the copper oxide film removal and oxidation prevention process.

FIG. 3 (b) shows that the copper oxide film was completely removed as a result of X-ray diffraction analysis (XRD) of the copper powder subjected to the copper oxide film removal and oxidation prevention process.

6 shows X-ray diffraction (XRD) results of the silver-coated copper powder prepared through the copper oxide film removal and oxidation prevention process and the spontaneous substitution reaction, and the silver (Ag) content It can be confirmed that the silver peak is increased.

7 (a) and 7 (b) show the results of X-ray diffraction analysis (XRD) of the copper oxide and the silver-coated copper powder which have undergone the copper oxide removal and oxidation prevention process, In the case of FIG. 7 (c), after about 150 days of the coated copper powder, a slight amount of copper oxide film is formed.

Experimental Example 2: Resistance measurement of silver-coated copper powder and performance analysis of electromagnetic shielding material

In order to measure the resistance of the silver-coated copper powder prepared by the copper oxide removal and oxidation prevention process and the spontaneous substitution reaction of the copper powder, the powders were prepared in a circle size of 1 cm in diameter and analyzed through a 4-point probe .

Table 1 below shows the resistance change depending on the resistance and the silver content of the copper powder depending on the presence or absence of the copper oxide removal and oxidation prevention process.

Sample Resistivity (10 ^-6 Ω m) Copper powder without oxide removal process 184 Copper powder with oxide film removal process 1.44 Ag (10%) coated copper powder 0.979 Ag (30%) coated copper powder 0.95 Ag (50%) coated copper powder 0.168

The resistance of the copper powder after the copper oxide removal and oxidation prevention process showed the greatest resistance value and the resistance of the copper powder after the copper oxide removal and oxidation prevention process was greatly reduced. Also, as the content of silver (Ag) increases, the resistance value decreases, indicating excellent resistance and electrical conductivity efficiency.

In order to analyze the characteristics of the silver-coated copper powder according to the present invention as an electromagnetic wave shielding agent, 3 g of silver-coated copper powder was mixed with a solution of 10 ml of acetone and 1 g of octanoic acid and uniformly dispersed in an ultrasonic disperser Dispersion is carried out. Subsequently, the solution was mixed with 1 g of epoxy and uniformly coated on the PET film by spin coating. The electromagnetic wave shielding performance of a sample in which acetone is vaporized in air is shown in Fig.

Claims (11)

A method of coating a surface of a first metal with a second metal having a lower reducing power than the first metal,
Preparing a first solution in which a first metal is dispersed in de-ionized water;
Preparing a second metal electrolyte in which the second metal ion is dissociated;
Generating a spontaneous substitution reaction by adding the metal electrolyte to the first solution,
Wherein the second metal electrolytic solution contains ammonium ions as a decelerating agent for the spontaneous substitution reaction, and contains chloride ions as an accelerator, and comprises sodium thiosulfate (Na ₂ S ₂ O ₃ )
Wherein the surface of the first metal particle is coated with a second metal having a lower reducing power than the first metal.
The method according to claim 1,
Wherein the first metal is copper particles and the second metal electrolytic solution is an electrolytic solution in which silver ions are dissociated,
Wherein the surface of the first metal particle is coated with a second metal having a lower reducing power than the first metal.
3. The method of claim 2,
Wherein the second metal electrolytic solution is an electrolytic solution in which deionized water is selected from silver nitrate (AgNO ₃ ), silver chloride (AgCl), silver sulfate (Ag ₂ SO ₄ ), and silver fluoride (AgF)
Wherein the surface of the first metal particle is coated with a second metal having a lower reducing power than the first metal.
3. The method of claim 2,
And controlling the rate of the spontaneous substitution reaction by controlling the concentration of the second metal electrolyte,
Wherein the surface of the first metal particle is coated with a second metal having a lower reducing power than the first metal.
The method according to claim 1,
Wherein the step of removing the oxide film on the surface of the first metal is performed prior to the spontaneous substitution reaction.
Wherein the surface of the first metal particle is coated with a second metal having a lower reducing power than the first metal.
6. The method of claim 5,
Wherein the oxide film removing step comprises the step of supporting the first metal on a solution containing ammonia ions and an amine,
Wherein the surface of the first metal particle is coated with a second metal having a lower reducing power than the first metal.
The method according to claim 6,
Wherein the solution containing the ammonia ion and the amine is a mixed solution of ammonia water (NH ₃ H ₂ O) and ammonium sulfate ((NH ₄ ) ₂ SO ₄ )
Wherein the surface of the first metal particle is coated with a second metal having a lower reducing power than the first metal.
A coating material coated on a surface of a first metal formed by the method of claim 1 with a second metal having a lower reducing power than the first metal.
9. The method of claim 8,
Wherein the second metal is coated on the first metal to have a core-shell structure,
And a second metal having a lower reducing power than the first metal is coated on a surface of the first metal.
9. The method of claim 8,
Wherein the first metal has a structure of a type selected from the group consisting of a dendritic structure, a spherical shape, a linear shape, a three-dimensional shape, and a tubular shape.
And a second metal having a lower reducing power than the first metal is coated on a surface of the first metal.
9. The method of claim 8,
Wherein the first metal is copper particles and the second metal electrolytic solution is an electrolytic solution in which silver ions are dissociated,
And a second metal having a lower reducing power than the first metal is coated on a surface of the first metal.

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