Method for production of nanodispersed metals in liquid phase

FIELD: metallurgy.

SUBSTANCE: invention relates to production of nanodisperesed metals in a liquid phase. One provides for passage of alternating current between electrodes immersed in a liquid phase and particles of metal being dispersed introduced into the interelectrode space. Ratio of the electrode length to the width of the spacing between the electrodes is equal to 20÷200:1. The electric current voltage and frequency are maintained at the level of 1.5-5.5 kV and 0.25-0.8 MHz accordingly. Additionally an inert gas is injected into the liquid phase in the form of bubbles sized 0.1-0.5 mm. The liquid phase is agitated due to continuous circulation of the liquid phase, particles of metal being dispersed and the inert gas within a looped circuit including the interelectrode space.

EFFECT: provision for extension of the functional capabilities of the method for production of nanodispersed metals in a liquid phase, its simplification, performance enhancement and improvement of working conditions.

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The present invention relates to a method for producing nanosized metals (BAT) in the liquid phase (water, organic solvents and other). BAT in the liquid phase (dispersion) are widely used to create different catalytic systems for the modification of polymeric fibrous and plastic materials to make them, in particular, antibacterial properties. Textile materials made of fibrous materials, modified nanosized metals, can be used as an effective screen for protection against electromagnetic radiation.

There are various methods of obtaining nanosized metals in the liquid phase. For example, a method of obtaining BAT, consisting of two stages: the preparation of a mixture of the agent and surface modifier and subsequent mechanical grinding agent [U.S. Patent No. 5543133, IPC A61K 49/00].

A method of obtaining BAT with the help of laser melting of larger particles [U.S. Patent No. 5585020, IPC B23K 26/00].

Known chemical method for deposition of the inorganic particles in the emulsion with subsequent concentration by using a filtration membrane [U.S. Patent No. 5879750, IPC H01B 1/08].

Another method based on the catalytic reduction of metal particles from the respective ions [U.S. Patent No. 6540495, IPC B29C 31/08].

All listed IU the odes economically inefficient for large-scale industrial production of dispersions BAT. In addition, when using chemical methods variance inevitably contaminated source reagents.

A method of obtaining silver dispersions with particle sizes from 2 to 9 nm on the high-voltage electrolytic installing AC HVAC [http://www.csprosystems.com/]. The process is carried out at a voltage of 10 kV between the silver electrodes in the water. The obtained particles have antimicrobial properties; reducing the particle size of the suspension increases its stability in relation to the processes of agglomeration of the particles and increased antimicrobial action of the suspension. However, the efficiency of the electrolytic method for large-scale production of a dispersion of doubt.

A method of obtaining BAT in the liquid phase [RF Patent №2170647, IPC B22F 9/22]. The method includes chemical precipitation of metal hydroxide solution of alkali with the formation of the dispersion, diafiltration obtained dispersion by separating solution of a metal hydroxide, dehydration, preheating the metal hydroxide and restoration production of metal powder and subsequent passivation of the specified powder. Simultaneously with diafiltrate perform sorption purification of the dispersion and restoration of the hydroxide of the metal and passivation of the metal powder is carried out with active stirring of the material the material. The invention allows to obtain ultrafine metal powder with particles structure, with low distortion and lack of extended defects, as well as high-purity metal powder consisting of particles of monodisperse state while maintaining a narrow fractional composition and a given morphology, and provides the ability to control dispersion at all stages of the process.

The known method and device for obtaining a BAT in a dense plasma substances [U.S. Patent No. 7128816, IPC B01J 9/08]. This method and device are used to obtain dispersions of nanoparticles of conductive materials (metals). The dispersion formed in the reactor with a dense plasma substances. The reactor includes at least one static and one rotating electrodes immersed in a highly Mixable fluid, mainly water. Optimally, when one of the electrodes is flat, and the other consists of rods, arranged in a spiral, perpendicular to the plane of the first electrode. Between the electrodes there multiple electrical discharges initiated permanent or alternating current. Plasma discharges produced the smallest particles of matter are made electrodes. The optimum speed of rotation of the electrode about 2000 rpm, which creates cavitation the cavity, of great importance for the efficiency of formation of nanoparticles. The potential difference between the electrodes regulate in the range from 100 to 800 C. the Optimal values of DC voltage from 100 to 200 at a current of from 0.1 to 4 A. This corresponds to the power consumption from 10 to 1000 watts. Due to the rotation of the electrodes discharges occur at different points in the plasma zone, preventing the concentration of thermal energy, so the formation of particles of the suspension affects rather the flow of electrons, and not the heat energy discharge. The patent describes methods of using the particles obtained by the proposed method. In particular it is shown that the dispersion of silver have a high bactericidal action.

There is also known a method of obtaining a BAT and a device for its implementation [USSR Author's certificate No. 117562, IPC B01J 3/00]. Getting BAT carry out complex effects, the components of the electrohydraulic shock at the appearance of the latter in the environment of the liquid between the particles dispersible material. Method implemented in a vessel of various forms, which placed a layer of particulate dispersible metal, with which contact two electrodes attached to the poles of the discharge circuit. Practical implementation of this method consists in the following. At the bottom of the tub, through which pass water or organic liquid, asyout layer of coarsely ground metal, subject to dispersion. The contacts connect the high-voltage oscillating circuit by a power of 10 W at a voltage of 45 kV with capacity equal to 2000, during the hour of the bath can be obtained several tens of grams of air-dried powder was extracted by evaporating the obtained dispersed solution. It is noted that more easily form colloidal solutions soft metals: tin, lead, aluminum, and somewhat more difficult - solid metals and alloys: steel, chromium, osmium and other

The closest technical solution of the problem is the method of obtaining colloidal solutions of metal nanoparticles in the liquid phase [Patent of Ukraine # 24391, IPC B01J 13/00], selected as a prototype.

The method is based on the sputtering surface of the metal granules and the electrodes as a result of erosion under the action of electric discharges in water. The water in the reactor has a conductivity of not more than 0.1 μs/cm, and water with a suspension of nanoparticles, with, usually, dimensions less than 100 nm, repeatedly sent to the reactor, preventing an increase in the concentration of ions in solution. In a reactor charged nanoparticles in the field of electric discharge with a large potential gradient. The process is carried out in the vibration mode for mixing the reaction medium.

This method is energy-intensive, does not allow realizou the th process in the most productive flow reactor, as well as the noise from the vibration worsens working conditions.

Common features of the prototype and the proposed technical solutions are passing an electric current between electrodes immersed in the liquid phase, and particles dispersible metal introduced into the interelectrode space, with stirring of the liquid phase.

The task to be solved by the invention is to enhance the functionality of the method of obtaining nanosized metals in the liquid phase, it is a simplification, increase productivity and improve working conditions.

To solve this problem the method of obtaining nanosized metals in the liquid phase is carried out by passing an alternating electric current between electrodes immersed in the liquid phase, and particles dispersible metal introduced into the interelectrode space, with stirring of the liquid phase, and passing an alternating electric current is conducted between the electrodes, the ratio of the length to the distance between them is 20÷200:1 when the voltage of the electric current 1.5 to 5.5 kV and a frequency of 0.25 to 0.8 MHz, optionally in the liquid phase of the injected inert gas in the form of bubbles with a size of 0.1-0.5 mm, and stirring is carried out by continuous circulation the liquid phase, the particles dispersible metal and inert g is in a closed circuit, including the interelectrode space.

In the private version as inert gas is used, for example, argon or nitrogen.

In another private option exercise passing an alternating electric current between the electrodes and the particles dispersible metal with a particle size of 10-100 microns.

In another private embodiment, the process is conducted continuously.

The use of three-phase systems (large metal particles, liquid phase and gas phase) for mixing greatly simplifies the process, eliminating the need for direct entry of large particles of metal in the interelectrode space.

The presence of an external closed circulation path passing through the interelectrode space, allows you to adjust the mixing speed in the zone receiving the BAT and makes a continuous process due to external dosing of large particles of metal.

Studies have found that the electric discharge when implementing electroconducting the method of obtaining the BAT (electrical discharge between the electrodes in the liquid phase) occurs much easier if in the liquid phase contains gas bubbles. Therefore, the proposed method includes a process in the presence of micro bubbles of gas.

The invention is illustrated by the following figures and table is Izumi.

Figure 1 presents a schematic diagram of obtaining nanosized metals in the liquid phase.

Figure 2 presents electron micrographs of samples Zola copper obtained electroconduction method.

Figure 3 presents the spectra of the characteristic energy losses of electrons:

(a) for pure copper (tabular data);

b) for the original Zola.

4 shows electron micrographs of copper nanoparticles, stabilized 1-dodecanthiol.

Figure 5 presents the absorption spectrum in the visible region of organosol copper nanoparticles, stabilized 1-dodecanthiol, in heptane.

Figure 6 presents the micrograph and histogram of size distribution of silver nanoparticles, stabilized 1-dodecanthiol, in heptane.

Figure 7 presents the absorption spectrum in the visible region of organosol of silver nanoparticles, stabilized 1-dodecanthiol, in heptane.

On Fig presents the picture of electron diffraction on the silver nanoparticles.

Figure 9 presents the micrograph obtained by applying azaconazole of silver nanoparticles on a carbon grid.

Figure 10 presents the absorption spectrum in the visible region of organosol of silver nanoparticles in acetone.

Figure 11 presents the absorption spectrum in the visible region of aquazole of silver nanoparticles, stabilizirovannykh-600.

On Fig presents the micrograph, a histogram of the size distribution and electron diffraction of silver nanoparticles stabilized by PEG-600 in the water.

On Fig presents the micrograph, a histogram of the size distribution and electron diffraction of gold nanoparticles, stabilized 1-dodecanthiol.

On Fig presents XPS spectrum of gold nanoparticles, stabilized 1-dodecanthiol.

Table 1.

Comparison of x-ray scattering data for pure copper and its oxides and experimental data, calculated on the basis of electron microdiffraction

Table 2.

The results of the experiments for obtaining highly dispersed metals in the liquid phase electroconduction method.

The scheme of obtaining nanosized metals in the liquid phase, is presented in figure 1, includes 1 - reactor, 2 - line electrodes, 3 - interelectrode space, 4 - circulation pump, 5 - valve input and dosage large particles dispersible metal, 6 - gate input and dosage of the liquid phase, 7 - gate input and dosage of the gas phase, 8 - circulating circuit 9 - gate output Zola nanosized metals.

The method is illustrated by the following examples.

Example 1.

Using the corresponding gate input and dosage of the liquid phase 6 in a closed circulation circuit 8 is injected idku the phase (ethanol + water) in an amount of 2.1 liters Include the circulation pump 4 and is pumped liquid phase along a closed circulation path through the reactor 1. Through the valve input and the dosage of the gas phase 7 in a closed circulation loop enter the gas phase (argon). The size of the gas bubbles is 0.1-0.5 mm (achieved by using a special ceramic dies). Then through the valve input and dosage large particles dispersible metal 5 in a closed circulation loop impose large metal particles (copper) in the amount of 10.6, the large Size of the metal particles is 50 to 60 microns. Then connected to a generator (not shown in figure 1) electrodes 2 with the following parameters of electrical current: voltage of 2.5 kV, a frequency of 0.4 MHz. The process is carried out at a ratio of length of the electrodes to the distance between the electrodes is equal to 50:1. In the course of the process in the interelectrode space 3 occurs in the electric discharge, the volume of the three-phase system pass nanosized metal particles obtained electroconduction method. Selection Zola nanodispersed metal passes through the valve output 9. Analysis Zola metal carried out by electron microscopy and x-ray analysis by standard methods. Micrographs of the samples receive a transmission electron microscope LEO 912 AB OMEGA (Carl Zeiss, Germany) with a working speed up the named voltage of 100 kV. Samples are prepared by applying 1-2 ál Zola coated formarum copper grid (d=3,05 mm), which is then air-dried. The distribution of the nanoparticles size is calculated on the basis of the obtained micrographs using Femtoscan Online v.2.2.91 (advanced technologies Center, Russia), Figure 2 and Figure 3.

Comparison of the maximum energy loss of electrons at 940 eV for the original Zola with tabular data for pure copper indicate that the dispersed particles are composed of copper atoms. Microdiffraction with individual sections of the sample is obtained is different. For areas where there are large particles (10 to 100 nm), resulting in a diffraction pattern with point reflexes. In the case when there are no large particles, and are only related in the agglomerates of particles, get a diffraction pattern in the form of rings, which also indicates the crystal lattice of the sample. Microdiffraction for nanoparticles (size from 1.2 nm to 3 nm) is amorphous halo.

As a standard for calculating diffraction patterns using the diffraction pattern gold Sol obtained in a similar way. Accuracy ±0.05 A.

Analytical studies have shown:

1. The process of dispersion leads to polydisperse sample. The bulk of substances presented as aggregated about what asomani with small inclusions of spherical shape with a wide size distribution of particles from 1.2 nm to 100 nm. The proportion of small particles is small.

2. According to the spectroscopy of the characteristic energy losses of electrons in the spectrum of energy losses of electrons to the obtained sample of copper found a clear peak loss at 940 eV. Comparison with table data for copper showed that the obtained sample is a copper nanoparticles.

3. The diffraction pattern obtained from three areas:

- when there is a key material is observed diffraction ring;

- when they appear on the background of the main material of large spherical structures - there are additional point reflexes;

- there are only nano-sized particles from 1.2 nm to 3.0 nm - watched amorphous halo.

Example 2.

The process is conducted as in example 1. Table 2 shows the main parameters of the process.

The result of the experiment obtained organosol copper nanoparticles in heptane. According to transmission electron microscopy particle diameter is in the range 2-37 nm, Figure 4.

For recording absorption spectra in the visible region using a spectrometer SPECORD UV-VIS (Carl Zeiss - Jena, Germany). Spectra were normalized, taking 0,0 for the intensity of the absorption at 700 nm, and 1.0 is the maximum of the absorption band.

Analysis of the absorption spectrum in the visible region showed that organosol has the plasmon absorption band of the cut is the mission with a maximum at 550 nm, that corresponds to the absorption of copper nanoparticles, Figure 5.

Example 3.

Getting organosol silver particles, stabilized 1 dodecanthiol, in heptane.

According to transmission electron microscopy the size distribution of the obtained nanoparticles is in the range of 2-6 nm, 6.

Registration absorption spectra in the visible region showed the presence of the characteristic peak of the surface plasmon resonance with a maximum at a wavelength of 460 nm, which corresponds to the absorption of organosols of silver nanoparticles stabilized organo-sulfur modifiers, Fig.7.

Pattern analysis of electronic microdiffraction (here and in subsequent examples 4, 5, 6, 7, 8 and 9 with silver and gold) showed the presence of reflexes with the distances between the diffraction rings corresponding to the diffraction pattern on the sample with a face-centered cubic lattice, which is evidence of crystallinity of the obtained silver nanoparticles, Fig.

Example 4.

Obtained in acetone silver nanoparticles were analyzed similar to the previous described example. According to electron microscopy the size of silver nanoparticles was in the range of 2-8 nm, Figure 9 and Figure 10.

Example 5.

Aqueous dispersions of silver nanoparticles stabilized with polyethylene glycol (MM=600 g/mol) (PEG-600), had a characteristically the peak absorption in the visible region, due to the phenomenon of surface plasma resonance, 11 and Fig.

Example 6.

It is known that hydro - organosol highly dispersed metals most easily and reproducibly possible to obtain in the case of gold. Indeed, in the present example was synthesized organosol gold nanoparticles, the size distribution of which was kept in the range of 1-6 nm. According to electron diffraction determined that the obtained gold nanoparticles (as silver) are crystalline education (face-centered cubic lattice), Fig.

Analysis of x-ray photoelectron spectra showed the presence of two characteristic peaks corresponding to electronic transitions 4f5/2and 4f7/2with the respective energy values of 87 and 83 eV, respectively, Fig.

Examples 7, 8 and 9.

The process is conducted as in example 1. The main results of the process in these examples are shown in table 2.

Thus, the present invention can significantly simplify the method of obtaining nanosized metals in the liquid phase, to improve its performance, reduce energy intensity and improve working conditions.

Table 1
Literature data, x-rayThe electron diffraction experiment
CuOCu2OCuSol copper obtained electroconduction way
d, AndId, AndId, AndId, And
2.511.003.000.032.081.002.92
2.311.002.451.001.810.532.22
1.850.202.120.311.2770.331.96
1.700.081.510.44 1.0890.331.74
1.570.081.2830.311.0430.091.41
1500.151.2280.050.9050.031.23
1.4080.201.0650.031.05
1.3700.200.9770.05
1.2980.05
1.2580.1
1.1590.05
1.0860.05

1. The method of obtaining nanosized metals in the liquid phase by passing an alternating electric current between electrodes immersed in the liquid phase, and particles dispersible metal introduced into the interelectrode space, with stirring of the liquid phase, characterized in that the transmission of an alternating electric current is conducted between the electrodes, the ratio of the length to the distance between them is 20÷200:1 when the voltage of the electric current 1.5 to 5.5 kV and a frequency of 0.25 to 0.8 MHz, optionally in the liquid phase of the injected inert gas in the form of bubbles with a size of 0.1-0.5 mm, and stirring is carried out by continuous circulation of the liquid phase particles dispersible metal and inert gas in the closed circuit including the interelectrode space.

2. The method according to claim 1, characterized in that an inert gas is used, for example, rgon or nitrogen.

3. The method according to claim 1, characterized in that exercise passing an alternating electric current between the electrodes and the particles dispersible metal with a particle size of 10-100 microns.

4. The method according to claim 1, characterized in that the process of obtaining nanosized metals are continuously.



 

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5 cl, 4 ex

FIELD: technological processes.

SUBSTANCE: invention pertains to plasma technology, and specifically to methods of obtaining metal powder. The method involves igniting a discharge between two electrodes, one of which is an anode, made from the spray material, with diameter of 10-40 mm. The cathode is in form of an electrolyte. The process is carried out under the following parameters: voltage between electrodes - 800 - 1600 V, discharge current - 750-1500 mA, distance between the anode and the electrolyte - 2-10 mm. According to the alternative method, the spray material is the anode, and the cathode is the electrolyte. The process takes place under the following parameters: voltage between electrodes - 500-650 V, discharge current - 1.5-3 A, distance between the cathode and electrolyte - 2-10 mm. The technical outcome is the increased efficiency of obtaining metal powder.

EFFECT: increased efficiency of obtaining metal powder.

2 cl, 8 dwg

FIELD: metallurgy.

SUBSTANCE: invention relates to powder metallurgy, in particular, to production of powder materials with particle sizes below 0.2 mcm used in manufacturing cermet and composite materials, as well as those intended for use as fuel for thermite and pyro compositions. An aluminum wire is exploded in a gaseous chemically inert atmosphere. The aluminum powder thus produced is wetted with a solution of boric acid in ethanol with a 0,5 mole/l concentration, the powder being separated from solution in no less than an hour after wetting.

EFFECT: increase in thermal stability of aluminum powder to 580 °C.

2 tbl, 1 ex

FIELD: inorganic protective coatings.

SUBSTANCE: invention provides preparation of chemically homogeneous powder suitable for thermal spraying. Zirconium dioxide is first subjected to electric fusion using up to 60% by weight of oxide appropriate to stabilize zirconium dioxide in tetragonal phase followed by sharp cooling of thus obtained stabilized zirconium dioxide and heat treatment to form mainly spherical hollow particles of stabilized zirconium dioxide 200 μm or less in size. Powder suitable for applying thermal barrier-forming coating onto a substrate contains morphologically and chemically uniform stabilized zirconium dioxide including spheroidized hollow particles.

EFFECT: optimized preparation process.

7 cl, 5 dwg, 1 tbl

FIELD: processes for preparing finely and ultra-dispersed powders of metals and alloys.

SUBSTANCE: process comprises steps of electric erosion dispersing metals in working liquid; using as working liquid low electrically conducting electrolytes containing alloying components in the form of solutions of their compounds.

EFFECT: simplified manufacturing process, improved ecological condition of said process, lowered power consumption.

2 dwg, 2 ex

FIELD: production of powders by electric explosion of wire.

SUBSTANCE: installation includes reactor for electric explosion of wire with high-voltage and low-voltage electrodes that are connected to pulse current sources; mechanism for feeding wire to reactor; gas and powder circulation system; unit for separating gas and accumulating powder. According to invention gas and powder circulation system is in the form of tubular gas discharging pipes communicated by their one ends with reactor in front of inter-electrode gap and by their other ends - with unit for separating gas and accumulating powder. Said unit is in the form of successively connected through branch pipes expanders. Each expander is provided with powder accumulator at providing relation Si/Si+1 ≥ 1.43 where i = 1, 2…, Si - total surface area of effective cross section of tubular gas discharging pipes; S2, S3 - surface area of connection branch pipes.

EFFECT: enhanced quality of product due to lowered agglomeration of powder.

2 dwg, 2 tbl

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