Використання електротехнічного комплексу для отримання нано- і мікропорошків металів
Abstract
USE OF ELECTRICAL ENGINEERING COMPLEX FOR NANO - AND MIKROMATERIALIV IN TECHNOLOGICAL PROCESSES
A.V. Zhiltsov, V.V. Korobskyy, S.O Lapshin, V.V. Olishevskyy
Abstract. The review of technological operations for obtaining nano- and micropowders of metals is given. To produce these materials, technological solutions are used, one of which is underwater volumetric-spark treatment of materials. The traditional ways of obtaining powder materials, namely physical and chemical, have some drawbacks, one of which is the lack of broad technological capabilities.
The aim of the work is to create a technological installation of volumetric underwater electric spark disperse for the production of nano- and micropowders of metals.
Materials and methods of research. The investigation of the electrospark synthesis of products of dispersion of metal granules was carried out on the technological complex, the main element of which is a discharge pulse generator, the power part of which is built on a thyristor element base. As a storage device, capacitors of 50 ... 600 μF are used. The charging voltage of the capacitor was 110 ... 190 V, the frequency of the discharge pulses was 0.025 ... 0.5 kHz.
Processing of the research results is carried out using mathematical statistics using the "Statistika" software package (version 10.0).
Conclusions and prospects. The results of the study show that the highest concentration of colloidal fraction is achieved at instantaneous values of voltage 160 V and frequency 0,1 kHz.
Key words: electrotechnological complex, volumetric-electrospark processing of materials, powder dispersion, colloid fraction, nanocomposites.
Introduction. The development of modern industrial technologies is on the brink of the sixth technological process (technological revolution). Today's paradigm of material use involves not only reducing the cost of materials, but also providing a number of its specific properties.
Analysis of recent researches and publications. The most simple in technological execution is the mechanical grinding of matter. The dispersion of the powder thus achieved is limited due to the peculiarities of the process.
One method for obtaining powder materials is the method of an electrical explosion of a conductor (EЕС ). By its nature ЕЕС, as a method for obtaining microparticles, combines physical phenomena such as explosive melting of the conductor and evaporation under the action of electric current. Implementation of this method leads to the complication of further collection of the final product in the volume of the explosive chamber. This method of production does not allow to synthesize a solid phase in industrial volumes.
One of the most productive methods of obtaining should be noted plasmochimic synthesis, which is based on the process of plasmoid formation with the help of electric arc plasma torches. The peculiarity of this method is that particles formed, which are not a metallic phase, but mainly metal oxides.
In addition, for the above-mentioned methods, in most cases, after the formation of micro-and nanofractions, their natural consolidation occurs, which complicates their application. Consequently, to solve this problem it is necessary to foresee the formation of a disperse-isolated state (possibly due to passivation of the surface), for example due to the dispersion medium.
Purpose - the creation of a technological complex of volumetric submersible electrosurgical dispersion for the production of nanoscale and microfractional materials.
Materials and methods of research. The research objects used were the following model metals: aluminum, copper, iron, and methodological research was carried out by recording oscillograms of current and voltage.
Investigation of electrosurgical synthesis of products of dispersion of aluminum granules was carried out on a technological complex, the main element of which is a generator of discharge pulses. The power part of the complex is built on thyristors of type TB-320. As a power storage device capacitors of 50 ... 600 μF type K75-17 were used. The pulse current was fed to electrodes of discharge chambers, which are made of aluminum, and the working space is filled with a conductive layer of aluminum granules. The process of obtaining involves volumetric electrospray dispersion of granules in a low-conductivity aqueous medium.
The processing of the results of the study was carried out using methods of mathematical statistics using the package of applications "Statistics" (version 10.0).
Results. In order to combine various physical phenomena into one technological process, it was proposed to use underwater electroscope dispersion to obtain a colloid metal form.
The essence of the volume spark dispersion consists in the formation of simultaneously existing multichannel fast-moving microcircuit discharges in a layer of metal granules between the electrodes. Electroscreen synthesis of products of dispersion of aluminum granules was carried out on a technological complex.
Feeding to the electrodes of one powerful discharge pulse causes simultaneous sparking between many pellets.
Irradiation leads to the electric erosion of the granule material and the formation of a micro and nanostructured powder, which, due to the hydrodynamic component of the process, or the forced mechanical activation of the discharge zone, is carried out from a layer of granules. The number of discharges, their power, duration and frequency of repetition affect the productivity of the formation of powder and its dispersion.
As a result of the processing and analysis of experimental data, the following fact can be stated: the appearance of the surface of the response indicates that the greatest concentration of colloidal fraction was achieved at instantaneous voltage values U = 160V. The length of the processing of granules naturally increased the value, but the determining factor is the voltage U on the electrodes of the discharge chamber, which is described by the regression equation.
Discussion
The results of the study show that the highest concentration of colloidal fraction is achieved at instantaneous values of voltage 160 V and frequency 0,1 kHz.
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