KR20090125322A - Method for the preparation of nano-powders by wire explosion in liquid with improved dispersibility - Google Patents

Abstract

PURPOSE: A method for manufacturing a nanopowder is provided to prevent the agglomeration of the nanopowders explosion-generated and to improve dispersion. CONSTITUTION: A method for manufacturing a nanopowder comprises the step of electrically exploding a conductive material by using the pulse power in the chamber filled with liquid to prepare a nanopowder, wherein a dispersant or a surfactant is injected into the liquid filled in the chamber to prevent the agglomeration of nanopowders. The molecular weight of the dispersant or the surfactant is selected according to the size of the nanopowder.

Description

Method for the preparation of nano-powders by wire explosion in liquid with improved dispersibility}

The present invention relates to a method for producing nanopowders by electroexplosion in liquid having improved dispersibility. In particular, in order to prevent agglomeration of nanopowders, a dispersant or a surfactant is introduced into a liquid in a chamber before or after electroexplosion to generate an explosion. The present invention relates to a method for preparing nanopowders by electroexplosion in liquid, which prevents agglomeration of the nanoparticles, thereby facilitating classification, concentration, collection, and redistribution by particle size.

Recently, the development of nanostructured powder materials as a new material has been very important because it can be applied as a foundation technology in a new field including nano devices.

Ultra-fine powder materials can exhibit unusual electromagnetic, mechanical and catalytic properties that cannot be achieved with conventional materials due to the miniaturization of the material structure (less than 100 nm) and the increase in the surface area. Therefore, ultra-high strength parts, magnetic parts, thermoelectrics, Next-generation functional materials, such as sensors, filters and catalysts, must create new demand throughout the industry.

With the development of the high-tech industry, the performance and miniaturization of components and systems are progressing. Currently, component factors having a phenomenological length of micron or submicron, which determine physical / chemical / biological characteristics, are used.

Therefore, the importance of nanotechnology is a technology that can overcome the limitations of the existing technology for high performance and miniaturization of parts and systems, and it is typical and cutting edge of future technology because new performance can be expressed as the phenomenological length decreases. It is an essential element in product development.

At present, there are various methods of manufacturing a material from nano powder, such as a physical method and a chemical method, but among them, the method of manufacturing metal nano powder by the electric explosion method using pulse power is the only physical method. It is known that the production of nano powders is possible, and is still being actively researched.

The nanopowder manufacturing method using such pulse power has a very important significance in terms of industrial applications, and is also very advantageous economically compared to other methods of preparing nanopowders.

Conventional electric explosion methods using pulse power include the air explosion method and the liquid explosion method.

The air explosion method is to produce a nanopowder by feeding a metal wire into a chamber filled with air or an inert gas, electrically exploding the metal wire using pulse power, and then collecting the metal wire.

In addition, the submerged explosion method (applicant filed by the applicant (application number: 10-2005-0078518)) is fed to the metal wire inside the chamber filled with the liquid to some extent, it is electrically exploded using pulse power and collected by It is to prepare a nano powder.

However, the air explosion method, there is a risk that the nano-powder is exposed and oxidized during the collection and handling in the air, or there is a risk of explosion due to dust, the powder is deposited inside the chamber to clean the chamber regularly, and the nano-size There is a disadvantage that it is not easy to classify very much.

In the liquid explosion method, the size of the nanoparticles produced is smaller than that of the air explosion method, and a sample dispersed well in a solution can be obtained. Since the dispersion is dispersed in a liquid, the nanoparticles do not scatter in the air at the time of recovery. Has a safe advantage.

However, in addition to the nano-sized particles are generated during the electro-explosion, a separate process is required to remove them. In addition, due to the nature of the electro-explosion, the particle size distribution is wide, so the classification by size is required for industrial use. Although necessary, there is a problem in that the aggregation of the particles occurs in the conventional concentration or collection step so that the classification of the nanopowder is impossible.

In addition, when the filter is used for classification, the filter may be blocked by agglomeration of nanoparticles and thus may not function properly. In particular, magnetic nanoparticles, such as nickel, depending on the type of metal, the aggregation is accelerated by the magnetic force to further exacerbate this problem.

The present invention prevents agglomeration of nanopowders generated by dispersing a surfactant or a surfactant into a liquid in a chamber before or after electroexplosion to prevent agglomeration of the nanopowders generated by the conventional liquid explosion method. An object of the present invention is to provide a method for producing nanopowders by electroexplosion in a liquid having improved dispersibility that is easy to concentrate, collect and redisperse.

In order to solve the above problems, the present invention provides a method for producing nanopowders by electroexplosion in a liquid which electrically explodes a conductive material using pulse power in a chamber filled with liquid, wherein The manufacturing method of the nanopowder by the electroexplosion in the liquid with improved dispersibility, characterized by preventing the agglomeration of the nanopowder by adding a dispersant or a surfactant to the filled liquid.

In addition, the dispersant or the surfactant is preferably added before or after the electric explosion, and the dispersant or the surfactant is preferably selected according to the size of the nanopowder.

Here, as the dispersant, it is preferable to use a polymer ligand including polyvinylpyrrolidone, or the surfactant may be a thiol or amine system having a hydrocarbon chain.

Moreover, it is preferable to select and use any one of the said liquid, distilled water, aqueous solution, an organic solvent, and an organic solution.

In addition, the nano-powder is classified according to the size by any one method of natural sedimentation method, centrifugation method, plug flow separation method, hydrocyclone method, impactor method and electrophoresis method, or classified by size by filter. .

In addition, the nanopowder is concentrated by removing only the liquid with a vacuum distillation, or by simultaneously removing the liquid and the dispersant or the surfactant by using a tangential flow filter having a nanometer pore. It is preferable.

In addition, the nano-powder, it is preferable to remove the liquid by a method of centrifugal filter, heating drying, vacuum drying or a combination thereof to collect the nano-powder in a solid state.

In addition, the nanopowder may be prepared by using any one of a solution, a slurry, a paste, an alloy, and a composite in which the nanopowder is dispersed by redispersing in any one of distilled water, an aqueous solution, an organic solvent, and an organic solution, depending on the application. .

According to the above-mentioned problem solving means, the present invention, in addition to the effects of the conventional explosion method in the liquid, by improving the dispersibility of the nanopowder in the liquid to prevent aggregation, it is easy to classify, concentrate, collect and redistribute the nanopowder by size In this way, the nanopowder has an economic ripple effect that enables mass production of dispersed solutions, slurries, pastes, alloys and composites.

The present invention relates to a method for producing nanopowders by electroexplosion in a liquid to electrically explode a conductive material using pulse power in a chamber filled with a liquid, wherein a dispersant or a surfactant is added to the liquid. This is to prevent the aggregation of nanopowders.

The conductive material may be any conductive material including a metal wire, and may be formed in various shapes such as strip, rod, and tube, but the conductive material and the non-conductive material are mixed. The use of the prepared material is also possible.

As the liquid used herein, all kinds of liquids having some conductivity, that is, distilled water, aqueous solutions, organic solvents, organic solutions, and the like may be used.

The dispersant or surfactant may be added before or after the electric explosion, the molecular weight may be selected according to the size of the nanopowder produced.

In addition, the dispersant or the surfactant is preferably selected according to the type of the liquid to be filled in the chamber, in particular the dispersing agent is used a polymeric ligand containing polyvinylpyrrolidone (polivinylpyrrolidone), or the surfactant Preference is given to using thiol or amine systems with hydrocarbon chains.

If the nano powder is a metal and the liquid is distilled water, aqueous solution, alcohols such as methanol, ethanol, propanol, butanol, isopropanol, cyclohexanol, glycols such as propylene glycol, polyethylene glycol, acetone, glycerin, triethanolamine In the case of methylene chloride or the like, polyvinylpyrrolidone (PVP) is preferably used as a dispersant, and as a surfactant, a thiol or amine system having a hydrocarbon chain may be used. It is preferable to use.

Here, the molecular weight of polyvinylpyrrolidone can be selected according to the size of the nanoparticles to be produced, and when the particle size is about tens to hundreds of nanometers, polyvinylpyrrolidone K-30 (PVP K-30) is used. do.

When the dispersant or the surfactant is added to the liquid filled in the chamber as described above, the conductive material is fed and pulse power is applied, the conductive material explodes in the liquid to form nanopowders. The related device is a technology filed by the present applicant, and since it is disclosed in detail in the registered patent publication (Registration No.:10-0726713), the detailed description thereof will be omitted here because it may obscure the subject matter of the present invention.

Nanopowders prepared by such electroexplosion can control the size distribution of nanoparticles according to the explosion conditions in various liquids such as pulse power size, liquid type, dispersant, or surfactant type. Particles of size are also mixed.

In order to classify the nanopowder by the size of particles, natural sedimentation, centrifugal separation, plug flow separation, or hydrocyclone method using inertia, which separate the layers by size after natural sedimentation using gravity, Either hydrocyclone, impactor or electrophoresis using electrophoresis is used.

In addition, a filter may be used to classify the nanopowder by size, and the pore size of the filter may be formed in multiple stages according to the size of the nanopowder. When the filter is clogged by large particles, it is possible to minimize the blockage of the filter by using ultrasonic wave, back-flow filtration, and tangential flow filtration.

In addition, the classified nanopowders may be concentrated while removing only the liquid by vacuum distillation, or may be concentrated while simultaneously removing liquid and dispersant or liquid and surfactant using a tangential flow filter having nanometer pores. have.

In addition, the nano-powder may be collected by a centrifugal filter, heating drying, vacuum drying or any combination thereof to collect the liquid as a nano-powder in the solid state, the nano-powder according to the purpose, distilled water, aqueous solution And redispersed in any one of an organic solvent and an organic solution, and may be used as one of a solution, a slurry, a paste, an alloy, and a composite in which the nanopowder is dispersed.

That is, the generated nanopowders may be classified, concentrated, collected, or redispersed for use in various applications.

Hereinafter will be described a preferred embodiment of the present invention.

First, in order to prepare a nanopowder according to the present invention, ethanol was filled in a predetermined chamber, and then polyvinylpyrrolidone K-30 as a dispersant was dissolved in an amount of 0.1 to 10 parts by weight based on the nanopowder to be prepared.

Providing nickel wire of 0.1 ~ 2mm in diameter and 20 ~ 200mm in ethanol in the ethanol, pulse power of 0.1 ~ 100kJ flows to generate electrical explosion, and the nanopowder of nickel wire in the liquid To produce.

The nanopowders thus produced were separated by layer by natural sedimentation or classified by size using a filter and ultrasonic waves.

In addition, as a comparative example of the present invention, when the dispersant is not added to the above embodiment, the layers are separated by a natural sedimentation method or classified by size using a filter and an ultrasonic wave.

FIG. 1 is a SEM photograph showing a state classified by synthesizing nickel nanopowders in ethanol and separating them by natural sedimentation. FIG. 1 (a) illustrates a case where natural sedimentation and sedimentation are performed when a dispersant is not used. b) shows a case where the layers are separated by spontaneous sedimentation when a dispersant is used. Both were allowed to settle for the same time.

As shown, when the dispersant is not used, agglomeration phenomenon occurs between the nanopowders, so that the size of the particles is not uniform, and classification cannot be performed properly by size. Agglomeration is minimized, so that the size of the nano powder is relatively uniform, and classification is possible by size through layer separation.

FIG. 2 is a SEM photograph showing a state in which nickel nanopowders are synthesized in ethanol and classified using a 0.4 μm filter and ultrasonic waves, and FIG. 2 (a) illustrates a case where the dispersant is classified using a filter and ultrasonic waves. 2 (b) shows a case of classifying using a filter and an ultrasonic wave when a dispersant is used.

As shown in the figure, when the dispersant is not used, agglomeration phenomenon between the nanopowders occurs, and the size of the particles is not uniform, and the size of the particles increases, which causes the filter to be clogged, thereby making it difficult to perform the continuous process and classifying properly. Will not be. On the other hand, when the dispersant is added, the size of the particles is relatively uniform, thereby minimizing the clogging of the filter, and thus the classification process can be performed continuously and properly.

3 is a case where nickel nanopowders are synthesized by adding a dispersant, and FIG. 3 (a) is a state before classification, and FIG. 3 (b) is a case where the layers are separated and classified by a natural sedimentation method. It shows the classification status. As shown, the state of the top layer separated by the natural sedimentation method was found that the classification was properly performed because the size of the particles was uniform.

In this way, it can be seen that the result of the dispersing agent is different from the case of adding the dispersant, and thus the filter clogging phenomenon and classification due to the aggregation of the nanopowders in the prior art cannot be properly performed. In order to solve the problem, the present invention facilitates the classification, concentration, capture, and redistribution of nanopowders by size compared to the conventional methods, thereby enabling economic production of mass-produced solutions, slurries, pastes, alloys, and composites in which nanopowders are dispersed. It can be seen that the ripple effect can be obtained.

Figure 1-SEM photograph showing the state classified by synthesizing the nickel nano powder in ethanol layer separated by natural sedimentation ((a) when the dispersant is not used, (b) when the dispersant is used).

FIG. 2-SEM photograph showing a state in which nickel nanopowders were synthesized in ethanol and classified using a 0.4 μm filter and ultrasonic waves ((a) when no dispersant was used and (b) when a dispersant was used).

FIG. 3-SEM photograph showing the case where nickel nanopowder was synthesized by dispersing agent ((a) state before classification, (b) when separated by layer separation by natural sedimentation method).

Claims (9)

In the manufacturing method of the nanopowder by electroexplosion in the liquid to electrically explode the conductive material using a pulse power in the chamber filled with liquid to produce the nanopowder, Dispersing agent or a surfactant in the liquid filled in the chamber to prevent the agglomeration of the nano-powder, characterized in that the nano-powder by the electrical explosion in the liquid with improved dispersibility. The method of claim 1, wherein the dispersant or surfactant, A method for producing nanopowders by electroexplosion in a liquid having improved dispersibility, which is added before or after electroexplosion. The method of claim 1, wherein the dispersant or surfactant, A method for producing nanopowders by electroexplosion in a liquid having improved dispersibility, characterized in that the molecular weight is selected according to the size of the nanopowder. The method of claim 4, wherein the dispersing agent uses a polymer ligand containing polyvinylpyrrolidone (polivinylpyrrolidone), The surfactant is a method for producing nanopowders by electroexplosion in liquid having improved dispersibility, characterized in that using a thiol or amine system having a hydrocarbon chain. The method of claim 1, wherein the liquid, A method for preparing nanopowders by electroexplosion in a liquid having improved dispersibility, characterized in that any one selected from distilled water, an aqueous solution, an organic solvent and an organic solution is used. The nanopowder according to any one of claims 1 to 5, wherein Submerged liquid with improved dispersibility, characterized in that it is classified by size by any one of natural sedimentation method, centrifugal separation method, plug flow separation method, hydrocyclone method, impactor method and electrophoresis method or classified by size by filter Method for preparing nanopowder by electric explosion. The method of claim 6, wherein the nano powder, Concentration while removing only the liquid with a vacuum distillation, or using a tangential flow filter (nanometer-grade pores) to concentrate while simultaneously removing the liquid and dispersant or surfactant Improved method of preparing nanopowder by liquid explosion in liquid. The method of claim 7, wherein the nano powder, Method for producing nanopowders by electroexplosion in liquid having improved dispersibility, characterized in that the liquid is removed by a centrifugal filter, heating drying, vacuum drying or a combination thereof to collect the liquid into a nanoparticle in a solid state. . The method of claim 8, wherein the nano powder, Electroexplosion in liquid with improved dispersibility, characterized in that the nanopowder is prepared by dispersing in any one of distilled water, aqueous solution, organic solvent and organic solution according to the use, any one of the solution, slurry, paste, alloy and composites Method for producing a nano powder by.

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