INSTITUTE OF PULSE PROCESSES AND TECHNOLOGIES
NATIONAL ACADEMY OF SCIENCE OF UKRAINE
MAIN RESULTS OF SCIENTIFIC ACTIVITIES
in 2013
© 2012 Institute of pulse processes and technologies NAS of Ukraine. All rights reserved.
It is determined for the first time that average equivalent strains of high strength steel DP780, BH240, BH210, HSLA350 subjected to electro-hydraulic forming depend only on the density of strain energy, strain rate and the grade of an alloy. The increase in electrical efficiency of the discharge increases the efficiency of strain processes 1.6 times, leads to 2-4 times higher density of plate strain energy and applied pressure, and the lengthening of the technological channel of the discharge chamber in 2 times increases the efficiency of plastic deformation process 1.4 times. These dependencies allow choosing effective modes of electrohydraulic forming of sheet materials and render a guaranteed opportunity to obtain formed parts with better degree of drawing-out and parts of complex shapes from the new high-strength steels.
Research "To investigate the influence of parameters and schemes of pulse electroplastic deformation on the properties of high strength sheet steels and to develop effective technological methods and schemes for cold forming".
The research is accomplished in compliance with a targeted research program prepared by Institute of Physics and Mathematics of NAS of Ukraine.
Research "Development and implementation of the technological process and equipment for electric-discharge local weakening of soils having different strength and structure."
The work was carried out in compliance with the scientific and technological (innovative) project of NAS of Ukraine.
Key regularities are determined for the high-voltage electrochemical explosion which, unlike conventional explosives, ensures the destruction of natural and artificial non-metal materials with strength over 40 MPa in a precisely predetermined cylindrical volume with no casual crack formation. The maximum energy of such local destruction does not exceed 500 kJ. The small-sized mobile equipment is fabricated which initiates the electrochemical explosion and has ten times smaller mass-dimensional characteristics compared to existing equipment. The method of electrodischarge local weakening and the equipment fabricated can be used, in particular, for destruction of strong soils or construction monoliths.
Research "Study of physico-chemical processes of interaction of aluminum melt with modifiers under pulsed load and the development of effective integrated technological schemes of hypereutectic silumin modification".
The study is carried out in frames of the department's main research topic.
The regularities of dissolution and absorption of P; SiC; Ti and B-based modifiers by the molten hypereutectic silumin A390 under the action of electric current are determined. The optimum parameters are established for a complex treatment that combines introduction of these modifiers into a melt of a specific ratio and DC/pulse electric current treatment, and, in contrast to sole modification, such a treatment guarantees the formation of dispersed molten metal structure with contents of compact crystals of primary Si of size less than 20 µm and modified eutectics with eutectic Si particle size of less than 10 µm.
Research "Study of the influence of the electric field strength on aging of combined dielectric film systems of high-voltage pulse capacitor sections."
The work was carried out in frames of the prospecting topic.
The distribution of the electric field strength in dielectric systems of sections and components of high-voltage pulse capacitors considering the
nonuniform strengthening of boundary elements, and also the influence of increasing total thickness of an impregnated polypropylene-polyethylene
terephthalate combined dielectric on its "stressed volume". The dependences of dielectric strength, resistance and loss tangent of the dielectric film on
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the operating system of the electric field in the range of 110-185 kV / mm and the number of cycles "charge - discharge" (up to 2x10 cycles). A
relationship between these parameters in the aging process of the dielectric. The recommendations on the choice of the working field strength of
dielectric systems of varying thickness to create a high-voltage pulse capacitors with a given resource.
Research "Study of the electric current impact on the formation of intermetallic compounds in multilayer conductors".
The work was carried out in frames of the prospecting topic.
A new method of intensifying the chemical interaction of micron thin layers of Ti and Al foils is proposed, which is based on passing of electric current through the layered package during its reactive sintering. It is established that the growth rate of intermetallic layers is found from the total electric energy introduced into the layered conductor during sintering, and the methods which accelerate heterogeneous chemical reactions is the Joule heating, electromigration and electroplastic effect. Transformation of the original layered package being sintered without current into a monolith with a structure of metal-intermetallic composite lasts 7-8 hours, under pulse current - 5 hours and DC - no more than 3-4 hours. It is proved that electric current reactive sintering of layered metallic systems is a several times less energy intensive process compared to hot isostatic pressing.
Research "Development of methodology of dispersion and activation of superhard and carbon-containing powders and synthesis of composite ultrafine Ti and Fe carbide and boride powders by highly concentrated energy flows".
The study is carried out in frames of the department's main research topic.
The effective circuit designs of the new method of synthesis of superhard composite powders by electric discharge treatment of initial powder mixtures
75 % Fe + 20% Ti + 5% B4C, 80 % Fe +20 % Ti and Fe and Ti powders in kerosene are determined. The regularities of changes in morphometric
characteristics of powders and dispersion kinetics from 1 mm to 0.05-1 µm are established. They depend on the current growth rate, integral energy and
treatment time. Electric discharge treatment additionally provides the formation of strengthening phases, such as Fe C, TiC, FeB, Fe Ti, Fe (B C )
3 2 3 0,7 0,3
and allows to increase carbidization of source powders to almost 55 %. Synthesized powders feature, therefore, a finely dispersed and homogeneous
charge to carbide steels.
Research "Development of methods for producing carbon nanomaterials and integrated electrofiltration of environmentally hazardous industrial emissions using discharge-pulse technologies". The study is carried out in frames of the department's main research topic.
The dependence of a carbon nanomaterial structure on the degree of hybridization of carbon atoms of source organic liquids or carbon-containing gases
exposed to electric discharge treatment is established: nanocomposites of carbon with an onion - like structure can be obtained from liquid alkanes and
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cycloalkanes having sp hybridization of carbon atoms; globular nanoparticles with turbostratic structure are obtained from alkynes with sp-hybridization,
2
and amorphous carbon, carbon nanotubes and nanofibers - from gaseous alkenes having sp - hybridization. It is shown that the onion - like nanocarbon
obtained by electric discharge synthesis is a spectrally pure and structurally stable up to 1,300 °C product suitable for use as high-temperature
wear-resistant additives.
Technological capabilities of the method of electrofiltration of gas emissions, based on the combined action of DC voltage sources which are already
used in the gas treatment system, and additional sources of a multi-level pulse voltage up to 50 kV are expanded. The optimum ratio of the electrical
parameters of the integrated power source are determined, the implementation of which allows to increase the capacity of a streamer corona discharge
and to 1.5-to 1.8-fold increase the different-impedance dust catching ability compared to present industrial gas cleaning systems. In particular, due to the
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action of such a discharge, concentration of harmful sulfur dioxide in gas emissions may decrease to 10 mg/m .
Research "Study of energy conversion processes in the underwater high-voltage electrochemical explosion in limited amounts for intensification of discharge-pulse technologies of material treatment".
The study is carried out in frames of the department's main research topic.
The analysis of existing research results of complex conversion of electric and chemical energy of the underwater high-voltage electrochemical explosion (HVEE) with other types (acoustic, fluid flows) is carried out, and the conditions of the practical use of this phenomenon in different pulse-discharge technologies of material treatment are determned. It is shown that the process of the underwater HVEE in confined and limited amounts is the least studied. The experimental test-bed for physical modeling of the underwater HVEE in limited amounts and for exploring its energy, electric and hydrodynamic characteristics is designed and assembled. The choice of components for the exothermal mix needed for the research is justified.
Research "The search for flow diagrams and parameters of the electrodischarge treatment of ilmenite concentrates and sludge to improve the efficiency of titanium production".
The work was carried out in frames of the prospecting topic.
Using the industrial specimens of the source raw ore and Ti concentrates produced by JSC "Crimean Titan", the parameters of electric discharge treatment are established which provide for reducing sizes of ore agglomerates to the size of 1 mm or smaller and decreasing more than 2.5 times the content of sulfur and chlorine impurities at the same specific energy consumed. The required dispersity of disintegration products is adjusted by varying the discharge pulse generation frequency. The electrodischarge technology allows to significantly reduce energy consumption for the production of titanium and its compounds, to omit some processes of heat treatment of the concentrate and, which is more important, to improve the production cleanness.
Research "Development, fabrication and commissioning of the experimental installation designated for producing nanocarbon from carbonaceous gas."
The work was carried out under the contract.
The new method is developed for the synthesis of nanocarbons with an onion-like structure from hydrocarbon gases (e.g., propane-butane) in the plasma of high-frequency pulse-periodic discharge, which provides for variation of the oscillation frequency of discharge pulses with a voltage of 20 kV in the range 20 to 100 kHz and enables synthesis of nanocarbon with low dispersion in size. On this basis, a compact electrodischarge installation of continuous operation is produced. It allows for obtaining up to 20 g/hour of unalloyed nanoproduct for tribotechnical purposes per1 kW of design capacity of an adjustable high-frequency converter.
