INSTITUTE  OF  PULSE  PROCESSES  AND  TECHNOLOGIES

NATIONAL  ACADEMY  OF  SCIENCE  OF  UKRAINE
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| Scientific  Achievements | Main results of Scientific activities in 2014     
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MAIN  RESULTS  OF  SCIENTIFIC  ACTIVITIES
in  2014

The mathematical model of sequential energy conversation by a capacitor bank in discharge systems was developed and tested. This model displays for the first time the two-dimensional interaction of electromagnetic, hydrodynamic and elastoplastic processes of pulse deformation of metals. The model chiefly determines the dynamics of pressure fields in a confined technological volume with account of flow-line elastoplastic deformation of a blank, diffraction and interference of waves, and also cavitation of a fluid and its separation from the surface of the part being deformed depending on parameters of electric generating system, environment, configuration and geometry of discharge chambers. It allows forecasting the conditions for effective use of the energy generated by a capacitor bank of pulse electrohydraulic plants for intensifying plastic deformations and facilitating the shape forming of sheet high-strength steels grades DP780, BH240, BH210, HSLA350 during their cold pulse forming
Study the impact of parameters and patterns of pulse electrohydraulic forming on elastic properties of sheet high-strength steels and develop the efficient technological methods and patterns for their cold forming.

The research is being performed under the target program of the Department "Fundamental Problems of Making the Materials with Predetermined Properties, Methods of Their Integration and Treatment" of the Institute of Physics and Mechanics of the NAS of Ukraine
Search for methods of improving the electrode system for implementation of a high-voltage
electrochemical explosion in discharge-pulse technologies of nonmetals destruction.               

Work to the Topic is completed
Basing on the analysis of known principles of electrode system construction and operating experience, assessing the mechanical stress on its elements and the electric field level and configuration, investigating the initiating conditions for the electrochemical explosion with use of various capsules with an exothermal mix, draft designs of electrodes for discharge-pulse technology of nonmetal materials destruction are refurbished. Implementation of refurbished diagrams with use of dielectrics with proven ability to bear thermomechanical stresses allowed, first of all, increasing the electrode system resistance in conditions of a high-voltage electrochemical explosion with working voltages to 25 kV and energy release to 100 kJ, as well as forwarding
their new design concepts with self-cost 3-fold less than of available products due to decreasing the electric field stress in the end-piece insulation area
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from 1.1·10    to 1.7·10    V/m
Exploring physical and chemical processes of aluminum melt interaction with modifiers in conditions of pulse stressing and developing effective complex modifying process methods for hypereutectic silumins

Work to the Topic is completed
Technological bases for complex treatment of hypereutectic piston silumin melts are elaborated, thus enabling production of primary Si particles not exceeding 20 m and eutectic Si inclusions to 10 m in melts. In particular, a complex of steps such as introducing (0.025 wt%) in a melt + pulse electric current out-of-furnace treatment' allowed for increasing the strength threshold by 14% and elongation from 0.8 to 2.8% for alloy 390. Adding one more extra step - electrohydropulse in-furnace treatment of a melt contributes to increasing these indicators by 14% and from 0.8 to 2.8%, respectively. It is established that joint chemical and pulse energy actions on a melt are associated with activated processes of transfer, sorption and dilution, and also cluster structure rearrangement.
Exploring the influence of elevated temperatures on operational properties of electroinsulation penetrating fluids of combined dielectric systems operated in conditions of strong electric fields.

Work to the Topic is completed
The interdependence of the factor change of relative light transmission of permeable liquids and the factor change of destabilization during their heat aging in presence of polymeric combined dielectric systems, inclusive of due to partial dilution of films, is determined by experiments basing on the analysis of indicators characterizing thermal resistance of electroinsulating permeable liquids of such capacitors (within temperature range to 100). This serves to elaborate methods of nondestructive control over operating conditions and service life limits of high-voltage pulse capacitors with film dielectrics. It is established that the polymethylsiloxane fluid and petroleum oils in polypropylene and polyethyleneterephthalate film dielectric systems demonstrate better indicators of thermal stability under continuously increasing temperatures among the materials selected with respect to technical and economic characteristics in model conditions during monitored maintenance of respective stress of electric fields
Study of electric current action on the processes of reactive sintering of the Al - Ti multilayer system.

Work to the Topic is completed

Regularities of structural and phase transformations in a multilayer package of Al - Ti system during thermobarelectrical treatment are obtained. The

influence of current amplitude on each layer and package geometry on the structural and phase state of sintered material is determined. Threshold

parameters of treatment and terms of sintering time reduction are found. It is shown that additional diffusion flows with the same direction as the heat

diffusion arise in a multilayer package during current passing due to temperature gradient induced by Joule heating. Mechanical properties

measurements of obtained Ti-Al  Ti multilayer specimens showed that their hardness and specific destructive energy during a shock correlate with
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indicators of shock-proof materials

Development of the methods of dispersion, activation of superhard and carbon-containing powders and synthesis of composite ultradisperse Ti and Fe carbide and boride powders by high-concentration energy flows.

Work to the Topic is completed

Dependencies of impact of the high-voltage electrodischarge water treatment of diamond micropowders on their morphometric characteristics, mechanical and physical/chemical properties are determined. It is established that the degree of fracturing of diamond microparticles and increase of their specific surface are directly proportional to the electric discharge channel pressure and specific treatment energy. Electrodischarge treatment of 20/14 micropowder, in particular, increases the sorption potential by 15 %, reduces to 3 times the content of unwanted metal additives, reduces more than 2.5 times the specific magnetic sensitivity. The as-treated diamond powders have higher corrosion resistance under higher temperatures and the abrasion resistance that is 15% higher, which in general enhances quality and service life of a cutting tool
Development of methods for carbon nanomaterials obtaining and complex electric filtering of environmentally hazardous industrial emissions by use of the discharge-pulse technologies

Work to the Topic is completed

Physical and technical foundations of a new method of recycling the paint and varnish wastes are established, which includes electrodischarge processing of organic solutions which segregates into carbon nanomaterials (CNM) and hydrogen for two consecutive stages. It is established that CNM output at the first stage when electrodischarge treatment is applied to organic liquid does not depend on accumulated or introduced energy, and it is determined mainly the number of C-C bonds in molecules of hydrocarbons. CNM output at the second stage when electrodischarge treatment is applied to organic gases that are formed due to decomposition of fluids is calculated from the area and catalytic surfaces activity. The features of the reactor design, schematics implementation method and power modes of electrodischarge treatment that ensure effective utilization of waste paints and polichlorpylene biphenyls are determined.

Technological potentials of the electric filtering method of gas emissions are propagated. This method is based on the combined action of DC sources

that are used in gas cleaning systems, and additional sources of multi-pulse voltage of 50 kV. The optimal ratio of electrical parameters of the integrated

power supply which allows increasing 1.5 - 1.8 times the effectiveness of catching the different-impedance dust compared to current industrial gas

cleaning systems, and also implementing plasma chemical processing of harmful oxides (CO, SO, NO) in safe substance. In particular, the action of

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streamer corona discharge can reduce the concentration of sulfur dioxide in gas emissions to 10 mg / m



Development of new discharge-pulse methods for the synthesis of nanodisperse powders of metal carbides.

The work performed by the grant of NAS of Ukraine for young scientists
Work to the Topic is completed

A new discharge-pulse method for the synthesis of nanodisperse powders of metal carbides is developed, which involves obtaining of organic liquids of carbon-containing paste during the electrodischarge treatment, and performing the electric explosion of tungsten and molybdenum conductors in that paste. It was established that the main factor influencing the phase and disperse composition of synthesized nano-size carbide powders is the ratio of stored energy and sublimation metal energy, while the hybridization degree of carbon atoms in the molecules of the paste produces no effect on synthesis products. The most effective mode of carbide synthesis by electrical explosion of conductors dia. 0.3 mm and 50 mm long with repeated continuous current breakdown when stored energy is more than three times greater than sublimation energy
The study of energy conversion processes in underwater high-voltage electrochemical explosion in limited volumes for intensification of discharge-pulse technologies of materials treatment

The dependence of the electrodynamic, hydrodynamic and energy characteristics of high-voltage electrochemical explosion (HVEE) in limited volumes with respect to initial and boundary conditions is determined, which allows finding the weight ratio of the exothermic mixture, the shell in which it is enclosed, and the electrical voltage applied necessary for the effective implementation of an explosion. The baseline data for the development of the algorithm for calculating the parameters of the combined energy source using the HVEE in limited volumes is obtained
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