Nano-particle producing process

FIELD: powder metallurgy, namely processes for producing metallic and oxide nano-particles.

SUBSTANCE: process comprises steps of placing electrodes in chamber with dielectric liquid; realizing pulse electric discharge between them for generating electric arc; measuring spacing between electrodes for fixing its value; creating flow-through motion of dielectric liquid in chamber; measuring temperature of dielectric liquid at inlet and at outlet of chamber; providing preset temperature range of dielectric liquid at inlet and at outlet of chamber due to changing flow rate of said liquid passing through chamber. Temperature difference of dielectric liquid at inlet and outlet of chamber is no more than 7°C. Invention provides increased quantity of nano-particles with fraction size 5 -50 nm.

EFFECT: enhanced quality of nano-particles.

4 cl, 1 dwg, 1 tbl

 

The invention relates to the technology of metal or oxide nanoparticles.

Currently, nanoparticles of metals (with sizes ranging from 5 to 50 nm) are widely used in electronic and chemical industry, medicine and other industries.

A method of producing nanoparticles, in which the pieces of metal wire with a diameter of 7.5 to 25 microns is placed in the chamber and passed through the electric current from the pulse generator with a working current of 450 kA and duration of a single pulse 100 NS. There is an explosion of the wire piece, in which nanoparticles are formed, see R. Sen and others, "Preparation of Cu, Ag, Fe and Al nanoparticles by the exploding wire technique", Proc. Indian Sci (Chem. Sci Vol.115, Nos 5&6, October-December 2003, p.p.499-508, Indian Academy of Sciences (reference copy attached).

The disadvantage of this method is unacceptably large variation of particle sizes: nanoparticles (1-100 nm), individual pieces of wire (10 μm, and more). In addition, the implementation of the method requires a very durable camera, powerful special generator; given the extremely high level of operating currents (hundreds of ka), the process is extremely difficult to automate in the continuous mode.

A method of producing nanoparticles, in which the camera with a dielectric liquid is placed electrodes and carry between them pulsed electric RA is a number with the formation of the arc, see W.H.Lee and others, "Electro-discharge method to manufacture superparamagnetic iron oxide nanoparticles". International Journal of Nanoscience, Vol 2, Nos 4&5 (2003), p.p.271-282 (reference copy attached).

This solution is taken as the prototype of the present invention.

When implementing this method, the temperature of the dielectric liquid uncontrolled changes within very wide limits. This leads to the fact that the conditions of discharge also vary within a wide range of values. As a result, the nanoparticles have a size of from 5 to 300 nm, while the nanoparticles show a specific, necessary for their practical use, properties in size from 5 to 50 nm.

In addition, the quality of the obtained nanoparticles is affected by the variability of the distance between the electrodes, which also dramatically changes the parameters of the discharge; the camera collects the products of erosion of the electrodes, ions and particles, which in turn negatively affect the conditions of discharge and, accordingly, the parameters of the product (nanoparticles).

The present invention laid the task of improving the quality of the nanoparticles by increasing the proportion of nanoparticles with a size of 5-50 nm in the total mass of the obtained nanoparticles.

According to the invention this problem is solved by a method for producing nanoparticles, in which the camera with a dielectric liquid is placed electrodes and implement settled between them pulsed electrical discharge with the formation of the arc, measure the distance between the electrodes and his constant support, carry out the flowing movement of the dielectric liquid through the chamber, commonly used to measure the temperature of the dielectric fluid inlet and outlet chambers and support within the specified limits of temperature values on the input and at the output of the camera, changing the flow of the dielectric fluid passing through the chamber, while providing the temperature difference between the dielectric liquid at the outlet from the chamber and at the inlet into the chamber is not more than 7°C; the temperature of the dielectric liquid can be maintained in the range of 5 to 50°; dielectric the liquid may submit an inert gas; in the dielectric fluid may submit the oxygen.

The applicant has not identified the sources containing information about technical solutions, identical to the present invention, which allows to make a conclusion about its compliance with the criterion of "novelty".

Thanks to the implementation of the distinguishing features of the invention is achieved a very important result, which is a significant increase in the share of the nanoparticles with a size of 5-50 nm, to the greatest extent exhibiting specific properties.

The applicant has not found any sources of information containing data about the impact of an alleged distinguishing signs on achievable due to their implementing the technical result. This, according to the applicant demonstrates compliance with this technical solution, the criterion of "inventive step".

The invention is illustrated in the drawing, which shows the diagram of an installation for implementing the method.

In the chamber 1 made of a solid dielectric material, in particular polycarbonate, posted by metal electrodes 2 and 3. The electrode 2 is provided with actuator 4, which provides its movement to maintain a given constant value of the interelectrode distance. The control of this distance by using the optical sensor 5, which is connected with the controller 6. When changing the interelectrode distance sensor 5 supplies a corresponding signal to the controller 6, which controls the actuator 4 of the electrode 2. The electrodes 2, 3 are connected to a generator 7 high-voltage pulses (open circuit voltage 50 kV, current 20 A). The dielectric liquid, such as deionized water, is fed in line 8 and then by means of a pump 9 through the input part 10, the camera goes inside the camera. The pump 9 is controlled by the actuator 11 connected with the controller 6. In the camera 1 are the sensor 12 (output) and the sensor 13 (inlet) temperature of the liquid in the chamber connected with the controller 6. In the output part 14 of the camera 1 set the separator 15 from which the pipe 16 after separation act the produced nanoparticles. The water and particles are removed through pipe 17.

When periodic electrical discharges between the electrodes 2 and 3 is erosion, which resulted in the formed nanoparticles and ions and particles. When the temperature of the dielectric fluid signals from sensors 12 and 13 are received in the controller 6, which controls the actuator 11 of the pump 9. The flow of dielectric fluid through the chamber 1 increases, and the temperature of the liquid at the outlet of the cell is reduced, while remaining within the specified limits, almost no higher than 50°C. maintaining the temperature of the dielectric liquid in the chamber 1 below 5°inappropriate because it does not lead to noticeable improvement in the quality of the product, but unsustainable increases the flow of dielectric fluid. At temperatures above 50°With sharply reduced the share of the nanoparticles with the desired dimensions. In addition, the controller 6 provides the temperature difference between the inlet and the outlet of the chamber 1 is not more than 7°because when this value is exceeded, the emission from the dielectric liquid with the formation of bubbles, which negatively affects the conditions of discharge and, consequently, on the quality of the nanoparticles.

If necessary, obtain mainly metal nanoparticles in dielectric fluid serves inert gas, for example the EP argon.

If necessary, obtain mainly of oxide nanoparticles in a dielectric fluid serves oxygen.

The results of the test method given in the table. Were used electrodes made of copper.

Thus, it was found a significant increase in the share of the nanoparticles with a size of 5-50 nm when implementing the inventive method in comparison with the method of the prototype.

To implement the method used certain equipment and materials, which makes the invention according to the criterion of "industrial applicability".

1. Method for the production of nanoparticles, in which the camera with a dielectric liquid is placed electrodes and carry between them pulsed electrical discharge with the formation of the arc, characterized in that the measured distance between the electrodes and his constant support, carry out the flowing movement of the dielectric liquid through the chamber, commonly used to measure the temperature of the dielectric fluid inlet and outlet chambers and support within the specified limits of temperature values on the input and at the output of the camera, changing the flow of the dielectric fluid passing through the chamber, while providing the temperature difference between the dielectric liquid at the outlet from the chamber and the inlet chamber no more than 7°C.

2. The method according to claim 1 characterized in, to maintain the temperature of the dielectric liquid in the range of 5 to 50°C.

3. The method according to claim 1, characterized in that the dielectric fluid serves inert gas.

4. The method according to claim 1, characterized in that the dielectric fluid serves oxygen.



 

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