Table of contents

Preface

The IX Republican Scientific Technical Conference "Low-temperature plasma during the deposition of functional coatings" took place from 5 to 8 November 2017 at the Academy of Sciences of the Republic of Tatarstan and the Kazan Federal University. The conference was chaired by a Member of the Academy of Sciences of the Republic of Tatarstan Nail Kashapov – Professor, Doctor of Technical Sciences– a member of the Scientific and Technical Council of the Ministry of Economy of the Republic of Tatarstan.

At the conference, the participants discussed a wide range of issues affecting the theoretical and computational aspects of research problems in the physics and technology of low-temperature plasma. A series of works were devoted to the study of thin films obtained by low-temperature plasma. This year work dedicated to the related field of heat mass transfer in multiphase media and low-temperature plasma was also presented. Of special interest were reports on the exploration of gas discharges with liquid electrolytic electrodes and the study of dusty plasmas.

Kashapov Nail, D.Sc., Professor (Kazan Federal University)

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

The influence of the initial sizes of two bubbles on their dynamics is studied under the action of a plane ultrasonic wave travelling along a straight line passing through the centers of the bubbles. The bubbles are filled with air, the liquid is water in room conditions. Initially the total volume of the two bubbles is equal to two volumes of a 5 μm bubble, the distance between the bubble centers is 30 μm. The wavelength is 5 mm, its amplitude is 0.3 bar. A mathematical model used is of fourth order of accuracy in terms of the ratio of the radii of bubbles to the distance between them. It allows for the small non-sphericity of the bubbles, the liquid viscosity and compressibility, the surface tension. It is shown that under the considered conditions three scenarios of the interaction of bubbles are possible: their collision, their divergence, and destruction of one of them due to large deformations of its surface. The ranges of a parameter characterizing the ratio of the initial radii of bubbles in which these scenarios are realized are revealed. The interaction scenarios are shown to depend on the arrangement of the bubbles.

The results of study on hydrogen and deuterium trapping and retention in MPG-8 grade graphite and boron carbide coating under consecutive irradiation by deuterium and hydrogen plasma in varying hydrogen irradiation conditions are presented in this paper. It is shown that deuterium content decreases both in graphite and boron carbide under irradiation by hydrogen plasma. It is also shown that the main mechanism of deuterium removal is sputtering for graphite, and isotope exchange for boron carbide.

In the article the characteristics of basalt fibers and threads are given, their advantages over other mineral fibers are considered. Materials and methods of research are described. The results of a study of the properties of filaments, such as the breaking load force of a basalt thread before and after its treatment in a low-temperature plasma are presented. The regime of plasma treatment is revealed at which the strength of the fibers of the basalt thread increases, it established that modification of low-temperature plasma allows increases the characteristics strength of basalt filaments and transforming the structure of their surfaces.

Magnetite anodes were manufactured by plasma spray coating of titanium with the iron oxide powder. The powder was obtained by plasma-electrolytic atomization of carbon steel. Porosity, adhesion, specific resistivity of these coatings were measured in relation to size distribution and chemical composition of the powder used for spray coating.

The effect of coatings deposited from a vacuum-arc plasma on the high-temperature corrosion resistance of martensitic steel in ultrafine-grained and coarse-grained state is studied. It is proved that coatings obtained from a vacuum-arc discharge plasma increase the high-temperature corrosion resistance of martensitic steel. The analysis of high-temperature corrosion resistance was carried out using the method of accelerated cyclic tests developed by the All-Russian Institute of Aviation Materials

Anti-adhesive coatings based on Zr nitrides and oxides deposited form the vacuum-arc plasma were developed. Laboratory tests that determine tribotechnical properties were conducted. Proved, that coatings based on nitrides and carbides increase the anti-adhesive properties

The use of low-temperature plasma for drawing a hydrophobic coating among argon-acetylene (70:30) on polyether textile materials is investigated in work. As a result of the modification, a granular coating with a thickness of 5–10 μm is formed. This hydrophobic covering has allowed to increase values of a contact angle of wetting to 138 degrees.

Formation of dust particles and their agglomerates with sizes ranging from tenths to hundreds of microns is observed in many modern plasma facilities. Dust accumulation can significantly affect discharge parameters in future thermonuclear facilities and lead to the accumulation of dangerously high amounts of tritium. Experiments on the generation of tungsten and tungsten-aluminium dust made of flakes formed during exfoliation of coating deposited on chamber walls from tungsten and aluminium targets sputtered by ions are described in this paper. A comparative analysis of the behavior of such dust and dust (figure 1), formed by crystal particles with simple geometric shapes ("crystal particles") in electric field, their degassing and change occurring in temperatures of up to 2000 K is conducted.

In this paper, the study results of the surface of samples after their purification using a vapor-gas discharge are presented.

A two-dimensional model of glow discharge positive column in gas flow has been suggested in this paper. It is considered that the discharge maintained between the permeable mesh electrodes installed in the initial and end sections of the plane channel. In general case the channel width changing along the stream is accounted. The positive column in gas flow is described by integro-differential system of equations with an approximation of constant gas flow density. The border conditions for gas ionization degree and temperature in the initial section of channel are given by any functions. An analytical solution of that system was obtained and special cases of the boundary conditions analyzed.

The calculation of a temperature field of gas flow with an internal heat source is generalized in case of a non-uniform axisymmetric heat distribution. The distribution is approximated by a set of segments of various lengths. The source function in each segment is considered constant, in the axial direction, while its radial profile is specific only to that segment. Thus, gas flow sequentially moves through n+2 areas: input z < 0, output z > 1 and the area of the internal heat source 0 ≤Z ≤l, presented by n segments. The obtained analytical solutions provide us with a straightforward way to calculate the heat balance for a wide class of complex problems related to describing air flow in the presence of non-uniform heat source distribution in the axial direction.

Acceleration of hydrogen isotope trapping and desorption has been observed in the experiments with stainless steel (Activated Surface Penetration - ASP) under irradiation by hydrogen atoms and hydrogen plasma ions with oxygen impurity. ASP is considered in this paper for a method of low-temperature hydrogen isotope removal from tungsten and aluminum-coated tungsten under irradiation by hydrogen plasma ions with oxygen impurity. It is shown that periodic irradiation by hydrogen plasma ions with oxygen impurity allows preventing accumulation of implanted deuterium ions in tungsten.

A technology was developed for the formation of a multilayer composite coating obtained by the sub – and supersonic plasma spraying method based on Al, Ti, Ni, and Mo. The results of the investigation of a coating of Al-Ti-Ni-Mo powder are deposited by subsonic plasma deposition on a steel substrate followed by the application of an anticorrosion coating from a paint coating material (PCM) of the CINEP brand, which is protected by the supersonic spraying powder Al-Ti-Ni-Mo. This coating layer is designed to protect the anticorrosive layers of the main multicomponent coating of products, which can be subjected to external mechanical stress during operation. It is shown that the resulting composite coating is sufficiently strong and withstands strains in the zone of elastic deformation of the matrix. Carried out corrosion tests showed a high resistance of these coatings.

The article shows the possibility of processing and involving in production of a powder, made from wastes of the VT-22 alloy ingots mechanical processing. These powders are applied as protective coatings by plasma spraying method. From VT-22 powder there were obtained protective coatings on a steel substrate by plasma spraying method. Coating samples were tested for adhesion with the substrate by the three-point bending method and on the corrosion resistance in a salt mist chamber (combined coatings: metallic + paintwork material). When tested in a salt mist chamber, pitting corrosion was quickly detected on the combined coatings, which indicates low protective properties. Three-point bending tests showed that coatings have a good adhesion to the substrate. After the work on the application of plasma coatings, a powder passed through the argon plasma was collected to study the effect of the plasma-forming gas on the properties of the VT-22 powder. Research have shown that even after passing through the plasma, the powder practically does not change physical-processing properties, chemical composition, or morphology of the particles. Based on the data obtained, it can be concluded that it is possible to reuse the powder.

The paper presents the results of Mössbauer effect studies of thin iron films obtained by ion-assisted deposition technique. It was found that the films obtained consist of several phases and have a perpendicular magnetic anisotropy. Magnetization direction can be changed by external magnetic field in sample plane.

We present results of the differential photoinduced absorption spectra investigation of the molybdenum disulfide nanogranular thin films. The films were produced by means of a sulfurization of pre-deposited by magnetron sputtering thin molybdenum films. It has been shown that photoexcitation with the light quanta with the energy higher than the bandgap leads to a modification of the absorption spectra in the visible range. Possible nature of the photoinduced absorption spectra will be discussed.

The paper presents experimental study results of the disperse admixtures in a flame plasma influence on the polymethylmethacrylate combustion rate change under the action of an electric field in a model hybrid rocket engine. It is shown that increase of disperse admixtures concentration in flame leads to the influence of the field on combustion intensification. An explanation of the results obtained on the basis of the ion-wind mechanism is proposed.

Article presents a model for the realization of a glow discharge at low pressures due to the organization of supersonic gas flow in a limited region of discharge chamber. A model of flow regime of a supersonic flow in a vacuum chamber is described. Results of experiments on realization of a glow discharge at low pressures due to the organization of a transverse supersonic gas flow are showen.

The design and operation of the six-jet plasmatron are considered. Experiments using a six-jet electric arc plasmatron are described and their results are shown.

In this work devices to study the electrical and amplifying properties of the plasma of gas mixtures corresponding to carbon dioxide lasers were designs. The devices to a vacuum system that allows them to be pumped out and filled with a working gas mixture are connected. Experiments to study the current-voltage characteristics of the discharge at various pressures of the gas mixture and the diameters of the discharge gaps were carried. The discharge voltage decreases with increasing discharge current, which is characteristic of a discharge with a longitudinal positive column. Large number of experiments to study the enhancement of the emission of carbon dioxide laser in the discharge of various gas mixture were carried: CO₂, CO₂ : N₂, CO₂ : N₂ : He. The obtained dependences have a maximum at a certain pressure. The three-component mixture has the greatest amplification. The results of the studies were used when replacing the active gas mixture of a carbon dioxide laser, as well as in the educational process when studying the amplifying properties of plasma.

In this work an expression for the dynamic resistance of a glow discharge in long tubes was obtained and analyzed. The expression describes the physical processes taking place in the positive column of a glow discharge. The analysis of the frequency dependences of the active and reactive constituents, as well as the dynamic resistance module for discharge conditions corresponding to glow discharge lasers, was performed. On the basis of the expressions obtained a computer program for modeling the dynamic resistance of discharge was developed. The program allows you to calculate and display the plots of the frequency dependences of the active and reactive constituents, as well as the module of the dynamic resistance of the discharge gaps of lasers. Also, the program provides a function for constructing hodographs of dynamic resistance.

Description of the designed impulse plasma torch with localized exploding wire generating high-energy plasma flows are considered. Electrical characteristics of capillary discharge for the two modes of energy input were experimentally studied. In capacitive storage was stored ∼ 4 kJ, the charging voltage was ∼ 3 kV. The reached peak power exceeded 165 MW at a maximum current of 65 kA and the efficiency of energy transfer to the load is about 80%.

Artificial materials that used in the manufacture of textile industry products have increased static characteristic and electrical resistivity. The large electrical charge accumulated by them negatively affects the human body. The use of natural collagen containing polymer materials is the safest way to avoid unacceptable risk to human health. With the help of nonequilibrium low temperature plasma (NLTP) treatment of collagen materials under reduced pressure it is possible to achieve an additional reduction of the electric potential by scattering charges on the surface of genuine leather. Under certain conditions the main reason for the generation and accumulation of static electricity is the high hygroscopicity of the material. Hydrophobization of the surface of collagen containing materials is achieved through the use of a hydrophobizator and volumetric NLTP treatment. Plasma treatment of collagen containing polymer materials also increases their biological compatibility and antimicrobial properties, improving mechanical characteristics by changing the internal structure of the material.

Brief review of the fine-dispersed powders production technologies for additive laser technologies is presented in the paper. Non-stationary mathematical model of DC plasma torch operation and stationary model of the reactor operation for powder spheroidization have been developed. Air is used as the plasma-forming gas. The influence of the transporting flow and compressing gases on the characteristics of the plasma flow is analyzed. Verification of the non-stationary mathematical model of DC plasma torch operation is based on experimental studies. Radial temperature distributions obtained from the results of numerical simulation and spectral diagnostics of the plasma torch PN-V1 are presented. The results of the experimental study describing plasma flow behavior for given parameters of the fine-dispersed powders spheroidization process are presented in the paper.

In this work modeling of atmospheric pressure barrier discharge in argon for saw-tooth voltage signal applied to the electrodes was conducted. The model included balance equations for the densities of charged (electrons, ions) and the excited particles, the electron energy density, and the Poisson equation for the electric potential. The fluxes of charged and excited particles (electrons, ions) and electron energy were given in the drift-diffusion form. Distributions of spatiotemporal parameters of the discharge for different forms of saw-tooth voltage signal were obtained. Numerical experiments have shown that, depending on the growth rate of the external voltage, the one-dimensional model gives three forms of discharge, two of which are slightly different types of Townsend discharge, and one form is a glow discharge.

The dielectric or metal targets isolated from the ground and being irradiated by an electron beam accumulate the electric charge on their surfaces. The amount of a charge is determined not only by the parameters of an e-beam and material of the target and sort and pressure of the gas in which the target is placed but also by the existence or absence of plasma around the target. The paper presents the experimental results about influence of the barrier discharge (BD) plasma on a spectrum of the radiation arising at a surface of a quartz plate irradiated by an electron beam with energy up to 25 keV. The high-current e-beam was generated by the pulsed open discharge in strongly overvoltage regime. The BD-plasma did not influence a shape of the Dα line radiated from the near-surface area of a target that proves a weak impact of the BD plasma on the charge of a target and electric field around the target.

The experimental results on properties of a strongly overvoltage open pulsing discharge being formed in a short gap (3 mm) filled with deuterium at low pressure (P=0.5-2 Torr) are presented. This discharge generates a high-current pulsed-periodical e-beam of 35 mm in diameter with a frequency up to 1.5 kHz and energy up to 25 keV. The repetition frequency influence on the reproducibility of e-beam generation was studied. It was found out that the high-current cathode spots being formed after the transition of the high-voltage regime into low-voltage regime restrict the maximum repetition frequency of a strongly overvoltage open pulsing discharge.

Experimental data of the wood combustion in a high-enthalpy flow in the presence of an electrostatic field with a potential difference of 5 kV research are given. Considering the field effect combustion laws are obtained for birch, used as a solid fuel component in a hybrid rocket engine.

The transformation of dust structures under changes of discharge current in neon dc discharge at a pressure of 20 Pa and the discharge tube temperature of 77 K has been studied. A nonmonotonic dependence of radial and axial sizes of the dust formations on the discharge current have been detected and analyzed. It has been found that dust clouds consisted of a mixture of dust particles and clusters formed from dust particles. The first and second-order phase transitions in dust structures and the mesomorphic state of dusty plasma have been found. The transformation of the dust structure to spherical form has been detected.

The main falling of the discharge tension accounts for the cathode region where the main streams of charged particles are concentrated. The research of this region is important for receiving various coverings and processing of surfaces with gas discharge. Authors have presented results of the experimental electric and optics research of the cathode regions of the glow discharge in nitrogen. The research of the potential distribution in the cathode region is conducted; distribution functions of the various electron energy groups are measured; the research of the ions energy distribution near the cathode is executed. The model of formation of the ions energy distribution near the cathode is offered. Criteria for formation of the potential hole for electrons and its influence on a power range of electrons are experimentally defined. The theoretical analysis of the received results is carried out. Nonlocal theoretical model of the cathode region of the glow discharge is offered. Comparison of the received results to an overall picture of a luminescence of the discharge is executed. The agreement of experimental data with theoretical is shown.

In this paper a version of the extraction of neutral particles from a gas discharge using a gas-distributing disk is proposed, which allows creating a pressure drop between the source volume and the working zone of the vacuum chamber.

The gas distributor ensures a uniform supply of gas to the ionization zone and resonant charge exchange, which will make it possible to achieve uniform combustion of the discharge in the entire volume of the source. Also the gas distributor allows to increase the speed of gas flow, due to pressure drop.

An increase in the rate of gas flow in the volume of the source makes it possible to increase the number of ionization events per unit of time. Consequently, it makes it possible to increase the number of ions generated in the gas discharge, that is, the ionization coefficient of the working gas increases. In turn, an increase in the number of ions generated in the discharge leads to an increase in the number of neutral atoms in the output beam.

this article deals with results of experimental research such as volt-ampere characteristics, electric arc traverse speed and end plasmotron operation performance index for cleaning the oil-pipes and melting of side-wall layer of asphalt, resin and paraffin deposits.

This article deals with temperature calculation results on inner surface of oil pipes and melting of asphalt, resin and paraffin deposits side-wall layer.

The modeling of the formation processes and further transformations of active particles in atmospheric pressure discharge plasma with a sodium chloride solution used as a cathode is performed. Experimental data on the composition of the gas phase and the physical parameters of plasma were used in the numerical simulation. It is determined that electron collisions with water molecules leads to a change in the form of the electron energy distribution function. As a result, the rates of the processes occurring under the action of the electron impact are altering. In addition, the transfer of water molecules to the gas phase leads to the appearance of new active particles, such as OH·, HO₂·, H₂O₂. It has been established that the products of the transfer of solutes influence on the balance of charged particles thus the electric field strength are reduced. This results in changing of the rate constants of the processes occurring in the plasma.

This work shows the possibility of a significant effect on the characteristics of the plasma torch by changing the diameter of the arc chamber along its length.

The composition of the gas formed during the decomposition of polyethylene and polyethylene terephthalate in steam-water plasma was calculated. The database includes thermodynamic information of 32 individual substances that can be formed from carbon, hydrogen and oxygen atoms. The calculated temperature range was chosen from 1000 to 2250 K. The conditions for achieving optimal regimes for the conversion of polymers into synthesis gas was analyzed.

A gas discharge between an aqueous solution of sodium chloride and a copper electrode – anode in air at atmospheric pressure was studied. It was been shown that the electrical conductivity of a gas discharge plasma with a water-solution cathode is predominantly ionic.

A gas discharge in the air between two solid-state electrodes, one of which is in a stream of water and serves as a cathode, has been studied. Two variants are considered. In the first version, the working end of the cathode protruded from the water, and in the second version it was completely immersed in water. Electric and spectral characteristics of discharges obtained under the same conditions of electric power are presented. As the cathode, aluminum, copper, titanium and graphite rods were used. The discharge current was in the range of 13-15 A.

Results of experimental researches on modification of textile polypropylene fibrous materials by a solution of silver nanoparticles with application of plasma processing are presented. Processing of fibrous materials by a current of nonequilibrium low-temperature plasma allows to apply effectively on materials antibacterial preparation and to fix nanoparticles of silver in a superficial layer of a material.

The paper presents a technique for calculating a composition as well as thermodynamic and transport properties of plasma which is used both in plasma technologies and in arc chambers of electrical apparatuses. Examples of calculations are given.

This paper presents a step down converter with a high speed rectifier and filter for Argon plasma torches. Buck circuit with a high frequency pulse width modulation control and very fast MOSFET transistor were used for switching. For Argon (Ar) gas Plasma Torches, and by increasing the pulse width, the average output voltage has modified from 80 V up to 100 V. The frequency of the designed step down converter was steady at 20 KHz.

Influence of the effect of electric arc titanium spraying on the inner surfaces of ceramic molds used for casting titanium was observed. Casting surface and cross-section were examined by electron microscopy with a probe microanalysis system and X-ray photoelectron spectroscopy. It was observed there is an "alpha case" on the casting surface. Its thickness and elemental composition varies through the casting surface.

The efficiency of the UNO- and TVD-modifications of the Godunov method in computing one and two-dimensional linear waves in an elastic body is numerically studied. The body is simulated by an isotropic linear-elastic semi-space. Riemann problem of cylindrical discontinuity in hydrostatic pressure in a body and a problem of propagation of waves caused by the impulsive action on the free surface of a metal body are considered. It is shown that in all the cases both modifications resolve the waves in the body significantly better than the classic Godunov method. At that, in the case of presence of the pronounced extrema in the solution, the UNO- modification appears more preferable because the TVD- modification "cuts" the extrema to implement the TVD-property.

An algorithm of simulation of kinetic movement of electrons in alternating-current field of radio-frequency capacitively coupled discharge is presented in the paper. The results of solving of modelling problems are presented also.

Nonlinear oscillations of gas in an open and closed tube were researched experimentally. Dependencies of the of the pressure oscillation amplitude were obtained at the resonance frequencies of the gas excitation at a fixed amplitude of the tube displacement.

Nanostructured coatings demonstrate lower porousness by an order of magnitude, a far higher tenacity to wear, corrosion and erosion. The article presents the investigations of new method of nanostructured coatings application consisting in plasma spraying of material supplied into plasma jet and nanoparticles in suspension or solution followed by coating surface melting by air plasma jet.

In this article the calculations on the strength of the coupling halves of the CV joint by the finite element method in the system of APM FEM. This calculation method is a method of creating a mathematical model and method of investigation. The assigned technological parameters of plasma spraying, namely, the estimated capacity of the plasma generator is 50 kW, and reach air temperature at the output of 3000 K, and the corresponding enthalpy of 3.8·106 j/kgK. Based on the analysis of the wear of the contact surfaces of the coupling halves, and also carried out strength calculations, was chosen as the material for plasma spraying – tungsten carbide. Developed mathematical model to determine the temperature of the powder particles and their velocities in a plasma jet. Based on the earlier dependence of the kinematic regimes of plasma spraying, the resulting system of equations for the kinematic modes that enable you to organize control of the kinematics of the deposition process details with the internal spherical surface.

Electron microscopy is widely used in biological and medical research, enabling to obtain images of the investigated objects with nanometer resolution. Exposure of biological objects under electron beam during the visualization can, however, cause their damage. Destructive effect of the electron beam can be significantly decreased by formation of metal coating on the surface of the objects to be studied. In the present study, an approach for the formation of ultra-thin metal coatings on the surface of protein-containing structures is proposed. Magnetron sputtering in argon plasma in DC mode was employed to form 8 Å-thick tungsten films on the surface of model protein-containing objects— tobacco mosaic virus particles — for their subsequent visualization by electron microscopy.

The diffusion-drift model of positive column of glow discharge in neon have been used to study the effect of molecular ions in the interaction of plasma with dust particles of micron size. Simulations have been carried out at a pressure of 20 – 100 Pa and gas temperature of 77 K. The electric field of the discharge, the concentrations of discharge components, including metastable atoms and molecular ions, and the charge of dust particles have been simulated.

The article is devoted to an experimental study of transient processes in a glow discharge (GD). The longitudinal GD was ignited in a stream of air in a cylindrical discharge chamber (DC). Copper hollow electrodes were located at a distance of a = (2 – 8) cm from each other along the axis of the DC. The gas pressure P, its flow rate G, discharge current I and its voltage U varied accordingly in the ranges: P = (4.7 – 26) kPa, G = (0 – 0.05) g / s, I = (20 –100) mA, U = (1. 5 – 4. 2) kV. The current-voltage characteristics of the discharge were measured. The voltage decreased with increasing current, which is typical for a given type of discharge. The oscillations of the discharge voltage were registered by an oscilloscope; the current-voltage characteristic of the discharge was recorded by a two-coordinate recorder. Low-frequency (f ∼ 300 Hz) and high-frequency (f ∼ 100 kHz) oscillations of the discharge voltage were observed. The influence of the gas flow on the current-voltage characteristics of the discharge, its shape and the frequency of the detected oscillations is shown.

According to classical concepts, a cylindrical positive column (PC) of the glow discharge (GD) is a luminous volume of ionized gas that fills up the whole space in the discharge chamber (DC) and which parameters are indiscrete, i.e. they do not vary along the axis of the chamber. In this case, the heat balance of the PC is that the electric power released in the discharge is expended on the heat flux to the wall of the discharge chamber (DC) due to heat transfer; also, a certain fraction of energy is carried away due to heat transfer by radiation. In case of an open system when gas flows through the area of the PC, it is possible to change the discharge parameters along its axis, and it is necessary to take into account heat transfer by convection in the energy balance. It is important to have knowledge of heat balance and its components both for gas discharge physics and for any DC designed for various applications. This paper is devoted to a comprehensive experimental study of the distribution of potential, electric field intensity, and gas temperature in the longitudinal GD. The gas pressure P, its flow rate G, the discharge current I and its voltage U varied accordingly in the following ranges: P = (2 – 9) kPa, G = (0 – 0.05) g/s, I = (30 – 80) mA, U= (1 – 2) kV. The obtained distribution of potential, electric field intensity, and gas temperature make it possible to calculate all the heat fluxes in the plasma of the discharge PC.

In this paper we investigated the flow of an elastic fluid, represented by the rheological constitutive relation FENE-P in a typical planar T-shaped channel as a part of microfluidic device. This model succeeds to predict necessary rheological properties of many real fluids. Distributions of the main flow characteristics for different sections were obtained for constant values of the simulation parameters (Reynolds number Re = 0.01, Weissenberg number We = 0.6, retardation coefficient ß = 0.1 and degree of unraveling of the flexible particle L² = 50). The isolines and main flow quantities distributions are drawn, comparison of the results of the elastic and Newtonian fluids is provided, areas of increased stresses are considered.

We present the results of the experimental study of high-voltage nanosecond repetitively pulsed discharge and of its afterglow in ethane, dimethyl ether and their mixtures with oxygen. The measurements were made for room temperature and pressures from 2 to 6 Torr. The measured specific deposited energy and mean discharge current varied with the number of voltage pulses monotonously in ethane and dimethyl ether and nonmonotonously in the hydrocarbon:oxygen mixtures. A microwave interferometer was used for time-resolved electron density measurements in the discharge afterglow. The effective recombination coefficients were obtained from the analysis of the measured data. These coefficients varied with the number of voltage pulses monotonously in ethane and peaked in pure dimethyl ether and its mixture with oxygen. Possible mechanisms of the nonmonotonous behavior of the discharge characteristics were discussed.

The problem of oblique incidence of an acoustic wave from pure air to the boundary of a vapor-gas mixture with droplets of liquid and solid particles is considered. Dependencies of the reflection coefficient of an acoustic wave on the volume content of inclusions and the angle of incidence of a wave are given. The influence of phase transitions is studied.

The mathematical model that determines reflection and transmission of sound waves through a medium containing two-fractional bubbly liquid is presented. For the model of media with three layer the wave reflection and transmission coefficients are calculated. The influence of the volume content of bubbles on the investigated coefficients is shown.

The particle drift in the standing wave taking into account the acoustic flow in the 2D resonator is investigated. Streamlines of acoustic flow and particle trajectories for different entrainment coefficients are calculated. It is shown that the entrainment coefficient has a great influence on deviation of the particle trajectory from the acoustic streamlines.

Based on the numerical solution of polydisperse gas suspension dynamics system of equations, the process of powder spraying on a plane surface in an electric field is described. The model includes motion equations of the carrier medium and disperse phase fractions under aerodynamic friction and Coulomb forces action taking into account interfacial exchange of pulse and energy. The system solves by an explicit predictor-corrector method with splitting on the spatial directions and the non-linear correction scheme. The numerical model is applied to gas suspension speed and density fields receiving in interelectrode space and on target electrode surface. The system of equations was written in the generalized curvilinear coordinates: the physical region of a current in variables (x, y) was written in a canonical computational region in variables (ξ,η) and was solved by an explicit second-order Mac-Cormack method. The Poisson equation for the electric field potential was written in the generalized coordinates and was solved by finite difference method with the use of the iterative Seidel scheme on a gas-dynamic computational mesh.

One of methods of increase in efficiency of the heat exchange equipment is timely detection of a sludge formation and scum on heat exchange surfaces. Deposits of salts and products of corrosion from technical water on the surface of heating of heat exchange devices reduce coefficient of a heat transfer and efficiency of heat exchange that leads to a considerable overexpenditure of energy carriers, overheating of surfaces of heating of coppers, decrease in service life, increase in costs of service and repair of the heat exchange equipment. Reliable methods and control devices of intensity of formation of deposits in the heat exchange equipment don't exist now. In work the method the express of control of thickness of deposits on heat exchange surfaces allowing to make control of a thermal condition of heat exchange surfaces is offered and in due time to carry out washing of devices.

In modern power engineering, there is a problem of rational and efficient use of hydrocarbon fuels variable composition. The composition of the fuel can vary in time and from different sources. These changes lead to combustion optimum regime shift in thermal power plants. Previously, an algorithm of combustion optimizing of a hydrocarbon fuel variable composition in thermal power plants was developed. According to the algorithm, the fuel and air flows are regulated depending on the outlet temperature of the heat carrier. In this paper, a diagram of the implementation of this algorithm is presented.

At present, known methods of direct conversion of the chemical energy of gaseous fuels to electrical energy are not so effective. This work is directed to developing the setup for experimental study of the gas ionization processes in the pulsating mode of combustion. This problem being solve for the first time. As result, schematic diagram and methodological recommendations will be developed which will be subsequently used for experimental studies.

The need for measuring the thermal conductivity of various materials exists in different fields of science and industry. First of all, it relate to constructing and power engineering. Thermal control allows evaluating the thermal insulation properties of the structure, identifying problem areas and assessing the energy efficiency of the pipeline. The paper assesses the transporting heat losses taking into account the actual operating conditions of the pipelines and the heterogeneity of the thermal insulation properties. A number of experiments were carried out. Experiments have shown that the destruction of insulation properties depends on such factors as the surface temperature of the pipe, the humidity of the environment, the service life.

Calculations of the distribution of temperature in the mold based on magnesite oxide, when casting products from titanium alloys, are presented. It is shown that in the mold based on magnesite oxide it cools down exponentially to ambient temperature.

In this work investigate the chemical processes occurring during the manufacture of magnesium oxide-based mold and casting titanium products to prevent the formation of alpha case. When molten titanium is poured into the mold due to low thermal conductivity the mold is heated unevenly. The resulting carbon dioxide and active metal compounds migrate to the more heated regions adjacent to the surface of the casting. The increased concentration on the surface of the O, Si, Ca, Na forms promotes the reactions to form active metal titanates.

The comparison of the results of calculating the shock wave in a two-dimensional acoustic resonator based on the 1D Lagrange approach with experimental, analytical and numerical results of other authors obtained on the basis of 2D simulation is presented. The shock wave, which arises at frequencies close to the first resonant one, is investigated. It's shown that the 1D Lagrange approach gives a satisfactory agreement with the results of 2D simulations of other authors as well as with results obtained using CFD-package Fluent in this work. It's shown that Lagrange's approach due to exact formulation of the boundary condition, high calculation speed and minimum memory requirements can be effectively used to solve a number of two-dimensional problems, as well as to verify the reliability of other numerical methods.

Plasma Electrolytic Oxidation (PEO) is one of advanced methods of obtaining thin layer oxide ceramic coatings on machine elements of different functional purpose providing considerable increase their resource. The work is devoted to the investigation of coating thickness formed by Plasma Electrolytic Oxidation on different aluminium alloys in electrolyte of type «КOH-H3BO3». Plasma Electrolytic Oxidation is recommended to be implemented at different engineering and repair and technical enterprises, dealing with production, restoration and hardening of elements.

The results of numerical simulation of the structure of a two-phase flow of a gas– liquid bubble mixture in a vertical ascending flow in a pipe are presented. The mathematical model is based on the use of the Eulerian description of the mass and momentum conservation for the liquid and gas phases, recorded within the framework of the theory of interacting continua. To describe the bubble-size distribution, the equations of particle-number conservation for individual groups of bubbles with different constant sizes are used for each fraction, taking the processes of breakage and coalescence into account. Comparison of the results of numerical simulation with experimental data has shown that the proposed approach enables the simulation of bubble turbulent polydisperse flows in a wide range of gas concentrations.

The influence of the mutual arrangement of initially identical spherical equidistant gas bubbles in liquid on their dynamics at the antinode pressure of an ultrasonic standing wave is studied. A mathematical model is used, in which small deformations of bubbles are taken into account. Two configurations of their relative position are considered: linear and planar. The first configuration is composed from three bubbles with their centers on one straight line, the second configuration is composed from five bubbles with their centers on two mutually orthogonal straight lines. It is shown that the magnitude of the deformations of the central bubbles in the linear and planar configurations is approximately the same.

Strong compression of the medium in cavitation bubbles in water, acetone and benzol realizing in the final stage of their collapse in the initially motionless liquid at a temperature of 293 K is considered. At the beginning of the collapse, the radius of the bubbles is 500 μm, the vapor in the bubbles is in its saturation state at the temperature of the surrounding liquid. The pressure of water and benzol is varied in the range 1 ≤ p₀ ≤ 100 bar to determine its values at which the degree of compression of the medium inside the cavitation bubbles in these liquids is close to that achieved inside the cavitation bubble in acetone at the pressure p₀ = 15 bar. It is shown that in the case of the bubble in benzol such a degree of the vapor compression can be achieved at p₀ = 4 bar, whereas in the case of the bubble in water, even p₀ = 100 bar is not enough.

The axisymmetric dynamics of a cavitation bubble in a liquid near a flat solid wall is studied. The liquid is considered to be ideal, incompressible, its flow is potential, the gas in the bubble is homobaric. The Euler method is used for determining the position of the bubble surface and the velocity potential on it at every time moment and the boundary elements method is applied for determining the normal velocity component. The possibility of transforming an initially one-connected bubble into a toroidal one is taken into account. The process of expansion and subsequent contraction of a bubble in water under the influence of the excessive internal pressure in it under room conditions is considered. The shape of the bubble surface, the velocity and pressure fields in the surrounding liquid are determined. The results of calculations are given for the case when the ratio of the initial distance from the center of the bubble to the wall to the bubble maximum radius is 0.6, and also the results of comparing the calculations with known experimental data are given.

The influence of a thin layer of water wetting a wall on the impact of a water jet is studied. The jet velocity is 250 m/s. The end of the jet is somewhat blunter than the hemispherical one. The thickness of the wetting layer is 4% of the jet radius so that the level of the pressure on the wall in the center of the impact area is approximately equal to that arising when hitting a dry wall. A numerical technique based on the approach without explicit separation of the interphase boundary is applied. The CUP-CUP method is used for integrating the Euler equations. An adaptive soroban-grid is utilized. It is shown that the presence of the wetting layer mainly manifests itself in a significant decrease of the pressure peaks realized in the narrow peripheral area of the impact zone on the wall.

The paper presents the results of studies on silicon nanotubes production in an arc discharge. The features of the experiments, the description of the experimental setup are given. A description of the obtained nanostructures studied on an electron microscope is presented. It is unequivocal to assert that the obtained silicon nanotubes are single-walled, it is not yet possible. But the fact of obtaining silicon nanotubes is indisputable.

This article theoretically investigates the acoustic waves propagation in bubbly liquids in the presence of diffusion mass transfer. Numerical calculations of the dynamics of pressure pulse in bubbly liquids are performed for different values of the vapor concentration. An increase the vapor concentration in the bubbles leads to a decrease in the propagation velocity of the low-frequency harmonics that make up the pulse and to an increase their attenuation due to the nature of the dependence of the phase velocity and attenuation coefficient on the vapor content in the gas bubbles.

The results of an experimental study of the static action of liquids on polymer-powder coatings obtained in the electrostatic field of the corona discharge are presented. Epoxy, epoxy-polyester, polyester, polyurethane and silicone powder materials have been studied. It has been shown experimentally that epoxy-polyester coating EP111095G is resistant, while epoxy EX611434SG, polyester PD810119G, polyester PD510226G and polyurethane PD010186G coatings are relatively resistant.

The paper presents the results of a study of the physicomechanical properties of oxide-ceramic coatings formed by plasma electrolytic oxidation on various aluminum alloys. It has been found that filling the pores of an oxide-ceramic coating with oil or applying a copper layer to its surface with a friction-mechanical method increases the wear resistance of movable joints of machine parts by 1.7 times and 4.5 times, respectively. Based on the complex of studies carried out, combined methods are proposed that significantly increase the life of reinforced parts of machines in operation.

The results of the investigation of the physical and mechanical properties of diamond-like coatings of the DLCPateks type (a-C: H / a-SiOCN) obtained on friction surfaces by transporting the atomic and molecular flux of vapor particles of liquid chemical compounds by a plasma jet of an arc plasma torch of atmospheric pressure are presented. The layer formed on the working surfaces is a non-metallic amorphous multilayer coating with a low coefficient of friction, increased microhardness, chemical inertness, hydrophilicity, high heat resistance and dielectric characteristics. To minimize the possible defectiveness of the main material, it is proposed to apply thin-film coatings to them at the final stage of manufacturing fuel equipment parts.

In this work modeling of atmospheric pressure barrier discharge in argon for rf-voltage signal applied to the electrodes was conducted. The model included balance equations for the densities of charged (electrons, ions) and the excited particles, the electron energy density, and the Poisson equation for the electric potential. The fluxes of charged and excited particles (electrons, ions) and electron energy were given in the drift-diffusion form. Distributions of spatiotemporal parameters of the discharge were obtained.

Nanocrystalline ZnO thin films with a thickness of ∼ 235 nm were synthesized by ion beam-assisted deposition (IBAD) technique using a metal target of zinc and oxygen (O₂) as a reactive gas. The near-surface region of the synthesized films was subsequently implanted with 30 keV Ag⁺ ions in the fluence range of (0.25-1)×10¹⁷ ion/cm² at high ion current density of 12 μA/cm². The structure parameters and morphology of as-deposited and subsequently implanted with silver ions ZnO films were investigated by X-ray diffraction and scanning electron microscopy techniques. It was found that the as-deposited ZnO films have inhomogeneous structure, which consists of nanocrystallites and disordered amorphous phase. The nanocrystallites of the obtained ZnO thin films have values of lattice parameters higher than for a bulk ZnO. Subsequent implantation with silver ions leads to a significant radiation heating and microstress relaxation of the film as well as to an increase in the size of nanocrystallites due to the amorphous phase.