RU2301771C1 - Method and device for mixing nano-particles - Google Patents

Abstract

FIELD: production of nano-powder materials; processes of forming nano-composite materials.

SUBSTANCE: proposed method includes forming electrical charges of opposite polarity in nano-particles. Mixing the nano-particles is performed in gel-like or liquid non-conducting medium which is chemically neutral to materials of nano-particles. Mixing is performed in several stages: ionization of nano-particles, main mixing due to attraction of oppositely charged particles, additional mixing due to motion of charged particles and nano-particles under action of electromagnetic field and molding of nano-composite. Device proposed for mixing the nano-particles has two chambers for charging the nano-particles, main mixing chamber, additional mixing chamber in form of flat disk and molding chamber in form of cylinders provided with pistons.

EFFECT: enhanced smoothness of mixing of micro-and nano-powders.

8 cl, 9 dwg

Description

The inventive object relates to methods of mixing nanopowder materials and can be used in technologies for the formation of nanocomposite materials.

The formation of composite materials is prevented by the adhesion of nanoparticles, which does not allow the formation of spatially uniform composite mixtures for pressing powder nanocomposites.

Known methods of mixing nanopowders:

1) mechanical mixing using various chambers and mixing blades [patent of the Russian Federation 96116150/25 applicant Nordakhl G. dated November 3, 1994, patent of the Russian Federation 96103013/14 applicant Dobronravov PN Declared February 16, 1996];

2) the formation of agglomerates through electrical interactions [patent of the Russian Federation 2002115298/02 applicant INDIGO TECHNOLOGIES GROUP PTI LTD of November 10, 2000];

3) obtaining a nanocomposite as a result of chemical reactions and self-organization [patent of the Russian Federation 2003136856/15 applicant Balikhin I.L., Berestenko V.I. and others. Declared December 23, 2003].

The disadvantage of the first method for producing a nanocomposite is the formation of agglomerates (large stable associations) of nanoparticles of the same substance, which impede the mixing of a mixture of nanoparticles. The advantage of the method lies in the large selection of existing mechanical mixing devices.

The second method is quite simple to implement, but supersaturation with an electric charge leads to the destruction of nanoparticles, and insufficient electrification leads to poor mixing of the nanocomposite.

The advantage of the third method is ease of implementation, and the disadvantage is insufficiently uniform mixing and the need for an individual chemical reaction for each type of agglomerate of nanoparticles.

Closest to the claimed technical solution adopted for the prototype is a method of particle agglomeration [patent of the Russian Federation 2002115298/02 applicant INDIGO TECHNOLOGIES GROUP PTI LTD of November 10, 2000]. A mixture of particles in a gas stream is ionized by an ion generator designed to create electrical charges of opposite polarity for particles in a gas stream. The physical characteristics of the gas stream are then changed by means of a structure placed in the direction of flow to mix the oppositely charged particles and thereby facilitate particle agglomeration.

In this method of mixing nanoparticles, the mixing process is implemented in a gas stream, and this leads to the formation of agglomerates of nanoparticles of one material and a decrease in the quality of the mixed mixture. The proposed method solves this problem by the fact that mixing is carried out in a mixing medium. As the mixing medium, a gel-like or liquid electrically non-conductive substance is selected that does not enter into chemical reactions with nanoparticle materials, for example, distilled water. Polyisobutylene may be selected as a gel mixing medium.

Known devices for the agglomeration of nanoparticles and mixing of powder mixtures (see above), based on the mechanical method of mixing and the method of electrical interactions. The mixing of the nanoparticles is carried out in the chambers using the mixing blades or through electromagnetic interactions. The disadvantage of these devices is the formation of stable associations of nanoparticles that impede the process of obtaining a homogeneous mixture.

Closest to the invention, the technical solution is a device for particle agglomeration [patent of the Russian Federation 2002115298/02 applicant INDIGO TECHNOLOGIES GROUP PTI LTD of November 10, 2000]. A device for agglomeration of particles in a gas stream contains an ion generator designed to create electric charges of opposite polarity for particles in a gas stream and a structure located downstream of the ion generator designed to change the physical characteristics of the gas stream to mix oppositely charged particles and facilitate agglomeration particles.

This device has a mixing chamber, a matrix of electrodes, contains an acoustic excitation device designed to excite the particles contained in the gas stream in the chamber. In addition, in the mixing chamber there are ledges and pointed protrusions, forming vortex flows for better mixing of the particles.

The task of the claimed invention is to increase the uniformity of mixing of micro and nanopowders.

The problem is solved in that the mixing is carried out in a mixing medium in the primary and secondary mixing chambers. Nanoparticles of one material charge positively, and the other negatively. Under the action of a piston in the main mixing chamber and electromagnetic forces, the nanoparticles are mixed and fed into an additional mixing chamber. In the additional chamber, mixing is carried out by the movement of charged microbodies in a mixture of nanoparticles and a mixing medium under the influence of an electromagnetic field. The mixed composite is fed into the pressing chamber to remove the mixing medium and pressing the nanocomposite.

The problem is also solved by the fact that the device for mixing nanoparticles includes an ion generator and consists of 2 nanoparticle charging chambers, a main mixing chamber equipped with a piston, and an additional mixing chamber made in the form of a disk in which the electrodes are arranged along a cylindrical surface in the form regular hexagon. The polarities of the electrodes alternate, and between them there are dielectric layers, while in the chamber there are charged microbodies. After mixing, the nanocomposite is pressed in a pressing chamber.

The technical result consists in obtaining a homogeneous nanocomposite.

The drawing (Figure 1) shows a device for mixing nanoparticles. The device consists of two cylindrical chambers for charging nanoparticles 1, the main mixing chamber 2, an additional mixing chamber 3 and a pressing chamber 4.

The main mixing chamber is a vertically arranged cylinder with a section along the axis of the cylinder (Figure 2) and a section perpendicular to the axis of the cylinder (Figure 3). A bottom view of the main mixing chamber is shown in FIG. 4. The mixture of nanoparticles and the mixing medium enters through the valves 5. Additionally, the piston 6 can be equipped with mixing blades 7 and move along a helical spiral 8 deposited on the inner cylindrical surface, while performing a rotational-translational motion. The mixture enters the additional mixing chamber through valve 9.

An additional mixing chamber is depicted in: Figure 5 is a section perpendicular to the axis; 6 is a top view; 7 is a side view; Fig. 8 is a bottom view. An additional mixing chamber is made in the form of a disk, in which the electrodes 10 are located between the outer 11 and inner 12 cylindrical surfaces, in the form of a regular hexagon. The polarities of the electrodes alternate, and dielectric layers 13 are located between them. The mixture of nanoparticles is fed into the chamber through the valve 14, and the charged microbodies 15 through the valve 16. The mixture is fed into the pressing chamber through the valve 17.

The pressing chamber is a horizontally arranged cylinder (Fig. 9). The mixture of nanoparticles is fed into the chamber through the valve 18. Between the piston 19 and the inner cylindrical surface of the chamber there are small gaps 20. The pressing chamber is equipped with a tube 21 and a valve 22.

The method is implemented as follows: the device for mixing is filled with a gel or liquid electrically non-conductive substance that does not enter into chemical reactions with nanoparticle materials, for example, distilled water. This substance is a medium mixing nanoparticles. Polyisobutylene can be used as a gel-like mixing medium. Nanoparticles of one material charge positively and the other negatively (stage I) to increase the repulsive forces between the particles of one material and prevent their adhesion. In the main mixing chamber, due to the attraction of oppositely charged particles to each other, the nanoparticles are mixed (stage II) and fed into the additional mixing chamber.

Additionally, the piston in the main mixing chamber can be equipped with mixing blades made in the form of elongated triangular prisms and located to each other at an angle of 120 degrees (Figure 3). Under the action of the translational-rotational motion of the piston, more intensive mixing of the nanoparticles is performed.

Charged microbodies, for example, fullerenes, are placed in an additional mixing chamber. They apply voltage to two electrodes located on opposite sides of a regular hexagon. Thus, the movement of charged microbodies from the same charged electrode to the oppositely charged occurs. By moving the microbodies, the mixture of nanoparticles is mixed (step III). After a certain period of time, voltage is applied to the other two opposite electrodes and stirring is repeated. After obtaining a homogeneous mixture of nanoparticles and a mixing medium, the mixture solution is fed into the pressing chamber. The voltage supply to the electrodes does not stop. Thus, microbodies are concentrated near one of the electrodes and do not enter the pressing chamber. In the pressing chamber (step IV), the mixing medium is removed from the mixture of nanoparticles and the nanocomposite is pressed.

The device operates as follows: at the initial stage, the valves 5 are open, and 9, 14, 16, 17, 18 are closed, the piston of the main mixing chamber 6 is lowered, the piston of the pressing chamber 19 is in the extreme right position, charged through the valve 16 are introduced microbodies, voltage is applied to two opposite electrodes. Using the piston 6 (upward movement of the piston), the mixture of nanoparticles enters through the valves 5 into the main mixing chamber. Then, the valves 5 are closed, and 9 and 14 open, and under the pressure of the piston 6 (the piston moves downward), the mixture of nanoparticles from the main mixing chamber enters the additional mixing chamber. Valves 14 and 17 are closed, voltage is applied to two electrodes opposite to each other in the additional mixing chamber. Then the voltage is applied to other oppositely located electrodes. After some time, the valves 9, 14, 17 and 18 open and the mixed mixture of nanoparticles is squeezed out by the next portion of the mixture into the pressing chamber. The valve 18 closes and under the pressure of the piston 19, the mixing medium is removed from the mixture of nanoparticles through leaks 20 between the piston and the inner cylindrical wall of the chamber. By means of a valve, a pressed uniformly mixed nanocomposite is supplied for further operation.

Claims (8)

1. The method of mixing nanoparticles, including the creation of nanoparticles of electric charges of opposite polarity, characterized in that the mixing of the nanoparticles is carried out in a gel or liquid electrically non-conductive mixing medium, chemically neutral with the materials of the nanoparticles, and mixing is carried out in several stages: ionization of the nanoparticles, the main mixing due to the attraction of oppositely charged nanoparticles to each other, additional mixing due to the movement of charged micro ate medium stirring mixture and nanoparticles under the action of electromagnetic field, compacting the nanocomposite. 2. The method of mixing nanoparticles according to claim 1, characterized in that distilled water acts as a medium for mixing the nanoparticles. 3. The method of mixing nanoparticles according to claim 1, characterized in that the mixing of the nanoparticles is carried out additionally due to the rotational movement of the mixing blades. 4. The method of mixing nanoparticles according to claim 1, characterized in that fullerenes are used as microbodies. 5. A device for mixing nanoparticles, including an ion generator, designed to create particles in the gas stream of electric charges of opposite polarity, characterized in that it consists of 2 chambers for charging nanoparticles, a main mixing chamber equipped with a piston, an additional mixing chamber made in the form of a disk in which the electrodes are located along a cylindrical surface in the form of a regular hexagon, the polarities of the electrodes alternate, and between them are the dielectric layer and, while in the chamber are charged microbodies, and pressing chambers. 6. The device for mixing nanoparticles according to claim 5, characterized in that the lower part of the piston in the main mixing chamber is equipped with mixing blades and the piston moves in a helical spiral deposited on the inner cylindrical surface of the main mixing chamber. 7. The device for mixing nanoparticles according to claim 6, characterized in that the lower part of the piston in the main mixing chamber is equipped with three mixing blades made in the form of elongated triangular prisms and located to each other at an angle of 120 °. 8. The device for mixing nanoparticles according to claim 5, characterized in that the matrix of electrodes in the additional mixing chamber is made in the form of a regular n-gon.

Images