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We present a study of structural features of diamond coatings prepared by chemical vapor deposition from a hydrogen/methane mixture activated by a microwave discharge using a high-speed jet to transport the mixture to molybdenum substrates heated up to 525 °C, 690 °C, and 1000 °C. The influence of the substrate temperature on morphology, composition, and structure of diamond coatings are studied by scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and near edge X-ray absorption fine structure. The diamond crystals enlarge in size, their density on the substrate increases, while the quality and the crystal surface purity are enhanced as a result of temperature increase.

The gas-jet method of the deposition of diamond-like structures using super-high-frequency (SHF) discharge for activating gases is considered. Direct statistical simulation is applied to analyze the gasdynamic processes occurring in the conditions of the gas-jet deposition of diamond structures. An activated gas flow in a nozzle is investigated and a considerable influence of the processes in the compressed layer formed near the substrate on the rate of synthesis of diamond structures is established. The regimes of flow of mixture components activated in the discharge chamber toward the substrate are determined and a considerable deceleration of heavy components in the compressed layer is found to exist. It is shown that with increase in the pressure in the deposition chamber from 10 to 80 Torr the crystal growth rate increases fourfold at the expense of an increase in the specific flux of the activated components toward the substrate.

A method of gas-phase deposition of diamond structures with the use of high-velocity jets for transporting gases activated in a microwave plasma to the substrate is developed. The diamond structures are synthesized from a hydrogen–methane mixture with the methane concentration of 1%. The influence of the gas mixture flow rate on the synthesis of the diamond structures with an unchanged composition of the mixture, pressure in the deposition chamber, and substrate temperature is studied. It is found that an increase in the flow rate leads to an increase in the polycrystalline film density and in the size of the diamond crystals forming the film. The composition of the mixture at the discharge chamber exit is numerically analyzed for different flow rates of the gas mixture. A correlation of the mixture composition with the growth rate and quality of the diamond structures is demonstrated.

A new method of gas-phase diamond deposition with a high-velocity jet used to transport gases activated in microwave plasma to a substrate is developed. Diamond was synthesized from a mixture of hydrogen with the addition of 1% methane. The deposition rate (78 μm/h) was more than an order of magnitude higher than that achieved earlier in experiments with activation of similar initial mixtures in microwave plasma.

Results of studying the growth of diamond structures on steel specimens with the use of intermediate layers of molybdenum or tungsten carbide cemented by cobalt are reported. The interlayers are deposited by means of detonation spraying. Subsequent deposition of diamond films onto the clad steel specimens is formed by the gas jet method and a special thermocatalytic reactor with extended activating surfaces. The nucleation process on the interlayer surfaces is intensified by preliminary seeding of the specimens in a colloid solution containing nanodiamonds. Information about the phase and structural composition of the resultant specimens and about the film surface morphology is obtained by scanning electron microscopy, Raman spectroscopy, and X-ray diffraction analysis. The tribology of the specimens is studied with the use of hardness nansensors and by the Rockwell hardness indentation method.

According to the experimental results, a comparison of sizes of child-droplets after micro-explosion of drop based on water and diesel has been made. Convective, conductive, or radiative heat exchange has been dominated. The temperature of the medium and the relative volume concentration of the flammable liquid have been varied in ranges: 100-450 С, 10-90 vol. %. The ratios of the sizes of the formed drops to the initial ones have been established. The conditions, which make it possible to increase the total evaporation surface area of a liquid by tens of times, are shown.

According to experimental results, a comparison of sizes of child droplets after micro-explosion fragmentation of water–Diesel droplets is conducted. Convective, conductive, or radiative heat exchange dominated in each experiment. The temperature of the medium and the relative volume concentration of the flammable liquid are varied in the ranges from 100–450°С and from 10–90 vol %. The ratios of the sizes of the droplets formed to the sizes of the original ones are established. The conditions are shown under which it is possible to increase the total surface area of evaporation of a liquid by tenfold or more using the micro-explosion of droplets.

The influence of the dimensionless angular and linear parameters of interaction of water droplets shaped as a sphere, an ellipsoid, and a conventionally liquid disk on the characteristics (regimes) of their collisions in air (bouncing, coalescence, separation, or disruption) is studied by using a system of high-speed video recording. Conditions of sustainable implementation of this interaction are determined. Maps of the corresponding regimes are constructed and compared with available data. The characteristic sizes, the number of liquid fragments formed in collisions, and the total areas of the evaporation surface are calculated. It is demonstrated that the liquid surface area in the case of collisions of conventionally liquid disks is significantly (by several times) greater than that in the case of spherical droplets.

A comparative analysis of experimental results obtained by different researchers using two different experimental approaches is presented: phenomenological (registration of conditions, characteristics and modes of interaction between a drop of a shell and a target drop) and statistical (analysis of collisions of tens and even hundreds of drops of liquids as part of an aerosol). The ranges of Weber criterion values (the basic parameter used for analyzing the effects of collisions of droplets in a gaseous medium) are established, corresponding to bounce, coalescence, reflexive and stretching separation, disruption, according to the results of all considered experimental research. The bounce of droplets upon collision can be observed under the conditions We = 0.35–0.5; the probability of droplet coalescence is maximum in the range We = 1–7.5; it is possible to reliably predict spreading at We = 15–50; splitting of droplets most often occurs at values We > 50. The probability of occurrence of other scenarios in the selected We ranges is not zero. The conclusion about the need to combine experimental techniques to obtain the most reliable data and their further use in the development of prognostic models is formulated.

A comparative analysis of experimental results obtained by various investigators using two different experimental approaches is presented: the phenomenological approach (the detection of conditions, characteristics, and modes of interaction between a projectile droplet and a target droplet) and the statistical approach (the analysis of collisions of tens and even hundreds of liquid droplets as a part of an aerosol). The ranges of values of the Weber criterion (the basic parameter used for analyzing the effects of collisions of droplets in a gaseous medium), which correspond to recoil, coagulation, expansion, and fragmentation are established according to the results of all experimental works considered.

In this paper, we determined the main regularities of suppression of combustion and thermal decomposition of typical forest combustible materials (leaves and needles as an example) when they are exposed to droplet aerosol with a variable specific water consumption. The conditions for suppressing the thermal decomposition in the material layer were controlled using low-inertia thermocouples. The size and concentration of water droplets in the aerosol were determined by using the cross-correlation complex and optical recording methods while the density of irrigation was calculated. The typical suppression times of combustion and thermal decomposition of the materials under study are determined. For the dependence of the suppression times on the specific water consumption, two typical ranges illustrating the necessary and sufficient conditions for effective combustion suppression are established. Based on an analysis of the experimental data, we formulated a hypothesis on the dominant heat and mass exchange in the suppression of combustion and the thermal decomposition of typical forest combustible materials with water.

The diamond synthesis from vapor (gas) phase is realized under complex influence of nonequilibrium transfer processes in activated gas mixtures by formation of carbon structures on a nascent diamond surface. The microwave plasma generates an active gas mixture and fragments of building material are transported

Diamond films are advanced engineering materials for various industrial applications requiring a coating material with extremely high thermal conductivity and low electrical conductivity. An approach for the synthesis of diamond films via high-speed jet deposition of thermally activated gas has been applied. In this method, spatially separated high-speed flows of methane and hydrogen were thermally activated, and methyl and hydrogen radicals were deposited on heated molybdenum substrates. The morphology and structure of three diamond films were studied, which were synthesized at a heating power of 900, 1700, or 1800 W, methane flow rate of 10 or 30 sccm, hydrogen flow rate of 1500 or 3500 sccm, and duration of the synthesis from 1.5 to 3 h.The morphology and electronic state of the carbon on the surface and in the bulk of the obtained films were analyzed by scanning electron microscopy, Raman scattering, X-ray photoelectron, and near-edge X-ray absorption fine structure spectroscopies. The diamond micro-crystals with a thick oxidized amorphous sp2-carbon coating were grown at a heating power of 900 W and a hydrogen flow rate of 1500 sccm. The quality of the crystals was improved, and the growth rate of the diamond film was increased seven times when the heating power was 1700&ndash, 1800 W and the methane and hydrogen flow rates were 30 and 3500 sccm, respectively. Defective octahedral diamond crystals of 30 &mu, m in size with a thin sp2-carbon surface layer were synthesized on a Mo substrate heated at 1273 K for 1.5 h. When the synthesis duration was doubled, and the substrate temperature was decreased to 1073 K, the denser film with rhombic-dodecahedron diamond crystals was grown. In this case, the thinnest hydrogenated sp2-carbon coating was detected on the surface of the diamond crystals.

The paper describes synthesis of diamonds by the method of gas-jet deposition with microwave activation of precursor gases. This method involves the use of a supersonic jet for delivering the components activated in the discharge chamber to the substrate located in the deposition chamber. A series of experiments was carried out with different amounts of methane supplied at a hydrogen flow rate of 8000 sccm. The obtained samples of diamond coatings were studied by scanning electron microscopy and Raman spectroscopy. The temperature of the mixture and the intensities of H, CH, and C2 lines in the plasma of the discharge chamber were measured by optical emission spectroscopy. The values of pressure and temperature in the discharge chamber were used to estimate the composition of the mixture. Thus, the numerical dependences of the molar concentrations of CH3, CH, C2 and C2H2 on the initial concentration of methane have been obtained. These dependences are in qualitative agreement with the dependences of the intensities of H, CH, and С2 lines. The numerical-experimental study performed allows us to conclude that the optimal value of methane concentration in the supplied mixture for the gas-jet deposition method in the considered range of parameters is about 1%.

The spectral study results of a supersonic clustered argon flow stimulated emission in the region of particle excitation (on an electron beam) and downstream are presented. Anomalies in the luminescence of the traditional spindle-shaped jet and the flow of heavy clusters (“wake”) are discussed. Possible causes of the observed anomalous phenomena are presented on the basis of the given comparisons of the results obtained.

This paper presents an original design of a high-vacuum steam jet pump in which a heater made of a heating cable is immersed in a working fluid located in a stainless steel boiler. At the same time, the boiler itself is vacuum isolated from the pump housing. There is also a heater made of a heating cable in a stainless steel shell, made in the form of a spiral and immersed in a working fluid. Such an arrangement of the heater is possible only when a liquid with a homogeneous chemical composition and a low saturated vapor pressure is used as a working fluid in high-vacuum pumps.

The flow of a hydrogen–methane mixture through heated coaxial cylindrical tungsten channels with a built-in tungsten wire is studied by the Direct Simulation Monte Carlo method. The purpose of the study is further development of the gas-phase method of deposition of diamond structures. The axial distributions of the concentrations of the components of the hydrogen–carbon mixture are calculated by means of solving a system of chemical kinetics equations. A series of experiments on deposition of diamond structures from various flows of the hydrogen–methane mixture is performed. The calculated results are compared with the experimental data. Based on these comparisons, it is concluded that numerical optimization of operation modes of gas-dynamic reactors can be used for deposition of diamond structures.

A method for obtaining diamond films using gas jet deposition with activation on extended surfaces made of tungsten heated up to high temperatures is considered in the article. The original reactor had been designed for activation of carbonaceous gas mixtures. A distinguishing feature of this method is to provide an extended interaction of hydrogen, methane, and its fragments with a heated tungsten surface. It is proposed to implement the increase of catalytic thermal dissociation of hydrogen molecules by providing multiple collisions during passage through the heated tungsten channels. In the researches carried out the effect of thermo-gas-dynamic parameters on resulting carbon structures had been studied. During the film deposition on the molybdenum surface, a strong dependence of the film morphology on the temperature of the tungsten surface was observed in the range of 2000–2150 °C. As a result of conducted research next objectives has obtained: the optimal substrate temperature, the value of the pressure in the reaction zone, ways of minimizing the carburization of the activation surfaces were found.

We present new approaches to gas phase deposition of diamond and diamond-like structures, films, and crystals. They are based on the activation of initial gases on hot expanded surfaces due to multiple collisions of molecules. The possibility of realizing the diamond synthesis at a very wide range of regime parameters is a distinctive feature of the method. The success of the research is due to the computer modeling of gas dynamic processes which allows us to predict and analyze the results of experiments. We dealt with a mixture of hydrogen and methane. Some results were obtained by using a separate or joint delivery of components to activating surfaces. The vitality of this new method is proved. The development and optimization of the method led to the creation of an energy saving system.

We have reported on the results of experiments on the gas-jet synthesis of diamond from methane and hydrogen flows for various mixing conditions. An original method of separate feed of gas jet has been proposed, which makes it possible to attain a high growth rate for the diamond phase. The synthesis of diamond structures in gas-jet deposition has been studied for separate feeds of two flows (hydrogen and the mixture of hydrogen with methane) in two versions, i.e., with a lateral feed of the methane-containing mixture and axisymmetric feed. Experiments were performed under the following conditions: the temperature of the surface (activating hydrogen) 2400 K, a substrate temperature of 900–1300 K, pressure in the deposition chamber 2 × 102 Pa, gas mixture fluxes (relative to hydrogen) 1500 ncm3/min, CH4 concentration in H2 of 0.1–0.7%, and the distance from the substrate to the reactor 10 mm. In the case of a separate feed of the methanecontaining gas and hydrogen, a deposition rate of 20 μm/h was attained. In the case of an axisymmetric separate feed of the gases, a single crystal with a mass of 0.6 mg was grown, which corresponded to the deposition rate of approximately 200 μm/h.

Diamond coatings on a molybdenum substrate were obtained by gas-phase deposition from a high-speed jet of activated gases. In the most common case, diamond film is formed as a result of the appearance of discrete nuclei on the substrate, their growing and competing. We observed the formation of coatings consisting of separate isometric aggregates with different types of packaging (111) or (100) plates depending on the process parameters (gas flow, the H2/CH4 ratio, the substrate temperature). The study of coating morphology using optical and electron scanning microscopy suggests that the particles were in the gas phase for a long time and increased to the size of tens of microns, and then deposited on the substrate. This process can be explained by the charged state of the particles, according to the charged cluster model of Hwang (1996). The study of the structure and phase composition by XRD and Raman spectroscopy revealed amorphous carbon, disordered and crystalline graphite, molybdenum carbide with the dominant contribution of diamond). The broadband luminescence of the coating under UV excitation is related to amorphous carbon, whereas 532 nm excitation causes the glow of vacancy centers such as (NV−) and (SiV−).

A flow with physical and chemical reactions on hot surfaces is investigated. On the basis of physical experiments, determining the hydrogen-dissociation degree in rarefied gas and calculation of the flow by the method of direct simulation Monte Carlo (DSMC), it is possible to specify certain unknown constants of interaction of molecules and atoms with a tungsten surface. By the example of the hydrogen flow in a hightemperature tungsten cylindrical channel, the role of dissociation, sorption, and recombination processes is shown in a wide range of flow regimes from free-molecular to continuum.

Annotation. The visualization of gas flows expanding from supersonic nozzles into flooded space under the cluster formation conditions is considered. The technique of exciting the supersonic flow by a well-focused high-voltage electron beam is applied in conjunction with the scanning equipment for the gas objects. The reasons for the secondary cluster jet formation in a flow of easily condensing gases are discussed. A comparison is made between the formation of a traditional spindle-shaped jet and a secondary cluster one. The measurement results of the diameters of the traditional and cluster jets in maximum sections, obtained by the photometry method, are presented. It is shown that for the characteristic sizes of cluster jets of condensing gases, the dependence on parameters proposed by Sherman and Ashkenas is applicable in the entire range of the studied stagnation and background pressures. The similarity of the formation processes of traditional monomeric jets and secondary cluster jets under the conditions of developed condensation of the initial supersonic flow is supposed.

The effect of pressure decrease on the degree of dissociation of hydrogen flowing inside a hot tube was studied. The experimental data were analysed using the previously developed thermal model of the reactor. The heat exchange of gas with the tube wall was estimated based on the direct Monte Carlo simulation. It was shown that decreasing the pressure from 20 mm Hg down to 1 mm Hg leads to a slight increase in the degree of hydrogen dissociation, from 11% up to 13%.

The present work is devoted to a numerical and experimental investigation of the effect of conditions of methane decomposition on the growth of diamond structures during gasjet deposition. The results of experiments on the diamond gas-jet synthesis from methane and hydrogen mixture flows are presented. The direct simulation Monte Carlo method in cylindrical geometry for numerical analysis of these experiments is applied. A one-dimensional approach based on the solution of equilibrium chemical kinetics equations is used to analyze gas-phase methane decomposition. The conducted research has shown that at a decrease in methane decomposition time in the absence of high temperatures of the fed mixture it is possible to receive higher rates of growth of diamond structures. The obtained results can be useful for optimization of gas-dynamic sources of activated gas diamond synthesis.

Thin films of amorphous silicon with inclusions of a nanocrystalline silicon phase have been obtained by the method of gas-phase chemical deposition with hot-wire activation of the precursor. The influence of the gas pressure and of the hydrogen–monosilane ratio on the rate of growth and the degree of crystallinity of the deposited silicon has been investigated. Characteristic values of the synthesis parameters for obtaining silicon films of various degrees of crystallinity have been established.

The presented study is the original analysis of hydrogen flow in channels with heterogeneous physical-chemical reactions. It provides the possibility to evaluate, calculate and predict unknown constants of heterogeneous reactions, using experimental data on dissociation at low pressures. It can be the base of conclusive data for computational modelling of CVD, using high velocity gas mixture flows. Till now there was no way to calculate the flow of hydrogen in tungsten channels in regimes of diamond deposition. The presented research allows formulate the problem of studies the heterogeneous reactions not only for diamond deposition. In the result of precise measurements of fragment fluxes behind heat-resistant capillaries from refractory metals or ceramics at low pressure and direct statistical simulation of gas mixture flows one can determine collisional constants for simple molecules. Such approach is more preferential than expensive and sophisticated molecular beam methods. So possibilities of CVD can be extended. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The presented study is based on the idea of the activation of a gas-precursor high velocity flow by hot wire. The wire forms the channel for flow before expansion to substrate. The construction allows change of the specific flow rate, velocity, composition and temperature of a gas mixture by studying the film synthesis in conditions from free molecular to continuum flow at velocities from hundreds to thousands of m/s. At a high pressure, the film has typical and unusual hexagonal incorporations for diamond tetragonal particles. Raman spectrum with the pronounced diamond peak is typical for diamond-like film. X-ray diffraction points in the presence of lonsdaleite. Conditions of deposition were simulated by Monte Carlo method. Collisions with hot surfaces and chemical transformations were taken into consideration as well.

Algorithm of the direct simulation Monte Carlo method for the flow of hydrogen and methane mixture in a cylindrical channel is developed. Heterogeneous reactions on tungsten channel surfaces are included into the model. Their effects on flows are analyzed. A one-dimensional approach based on the solution of equilibrium chemical kinetics equations is used to analyze gas-phase methane decomposition. The obtained results may be useful for optimization of gas-dynamic sources of activated gas diamond synthesis.

The gas jet deposition of metal-polymer composites is studied. A detailed description of the method is followed by results of studying the properties of the coatings. In particular, optical and antibacterial properties of the obtained samples are presented.

Synthesis of diamond-like coatings from a high-velocity flow of gas mixtures in flow regimes from free-molecular to continuum with flow velocities from hundreds to thousands meters per second at different specific flow rates and temperatures in the case of activation of gases on hot surfaces is studied experimentally. Deposition of carbon films at low (less than 0.15 Pa) and high (2600 Pa) pressures from a mixture of hydrogen and methane is considered. The hydrogen flow is computed by the Direct Simulation Monte Carlo (DSMC) method in accordance with test conditions with given surface temperatures and chemical transformations on the surfaces. It is found that coatings obtained at the high pressure contain particles typical for diamonds and unusual inclusions shaped as prisms with a hexagonal cross section.

For the purpose of simulation of diamond-growth processes, the comparison of reacting gas flows modelled in a heated cylindrical channel has been performed by two different approaches: DSMC method and solution of Navier-Stokes equations. The impact of the channel length on the degree of hydrogen and methane dissociation in the gas mixture has been analyzed. The obtained data were compared with the experimental data.

The gas-jet diamond deposition with the activation of H2 + CH4 mixture by microwave discharge has been implemented. The maximum crystal size was observed at the substrate temperature of 850°C. The dependence of a film structure on the substrate temperature has been established. Diamond coating was received at a low substrate temperature (524°C).

The direct simulation Monte Carlo method is used to study a plane-parallel supersonic gas flow through a grid formed by a series of parallel infinite cylinders. Characteristic features of the shock disturbance formation during the interaction of a supersonic flow with a permeable grid and the effect of this disturbance on the flow parameters behind the grid are revealed. The boundaries of the domain of supersonic flow breakup ahead of the grid and the laws of the total momentum loss on the grid are obtained. Kinetic and energetic characteristics of the flow behind the grid are determined.

Silver nanoparticles possess antibacterial effect for various bacteria; however mechanisms of the interaction between Ag-NPs and bacterial cells remain unclear. The aim of our study was to obtain direct evidence of Ag-NPs penetration into cells of Gram-negative bacterium S. typhimurium and Gram-positive bacterium S. aureus, and to study cell responses to Ag-NPs. The Ag-NPs (most 8-10 nm) were obtained by gas-jet method. S. typhimurium (7.81 × 10⁷ CFU), or S. aureus (8.96 × 10⁷ CFU) were treated by Ag-NPs (0.05 mg/l of silver) in orbital shaker at 190 rpm, 37 °C. Bacteria were sampled at 0.5, 1, 1.5, 2, 5 and 23 h of the incubation for transmission electron microscopy of ultrathin sections. The Ag-NPs adsorbed on outer membrane of S. typhimurium and cell wall of S. auereus; penetrated and accumulated in cells without aggregation and damaging of neighboring cytoplasm. In cells of S. aureus Ag-NPs bound with DNA fibers. Cell responses to Ag-NPs differed morphologically in S. typhimurium and S. aureus, and mainly were presented by damage of cell structures. The cytoplasm of S. aureus became amorphous, while S. typhimurium showed lumping and lysis of cytoplasm which led to formation of "empty" cells. Other difference was fast change of cell shape in S. typhimurium, and late deformation of S. aureus cells. The obtained results showed how different could be responses induced by the same NPs in relatively simple prokaryotic cells. Evidently, Ag-NPs directly interact with macromolecular structures of living cells and are exert an active influence on their metabolism.

In contrast to the widespread deposition method of carbon films with the activation of gas mixtures on a hot wire, activation (dissociation of hydrogen and methane) is performed in a high-temperature channel formed by a tungsten coil in this study. From this channel, the gas is expanded to the substrate where deposition occurs. A film containing diamond crystals and hexagonal crystals having characteristic features of lonsdaleite is deposited at the channel temperature of 2100°C and the surrounding pressure of 20 mmHg. The diamond-like film is deposited from a high-velocity high-temperature un-ionized flow for the first time.

This paper presents a new method of deposition of diamond and diamond like structures by using the original reactor for activation of carbonaceous gas mixtures. One of the important characteristics of the described reactor is the power efficiency owing to low heat losses. The new method of gas flow formation opens new possibilities to get important trade-offs (wide range of background conditions and others). The principal possibility of diamond deposition is proved by experiments with the flow of hydrogen and methane mixture in tungsten resistively heating cylindrical channels. Electron microphotographs and Raman spectrum of deposited structures prove the fact that deposited samples are diamond structures. Numerical study of the mixture flow through the reactor was carried for optimization of gas flow conducted to a substrate.

The analysis of influence of heterogeneous reactions in rarefied gas flows with dissociation and recombination is carried on for the first time, at least for hydrogen and methane flows. The flow in channels with heterogeneous reaction can be equilibrium and non-equilibrium, depending on a flow rate. Non-equilibrium effects are pronounced as a rule in the space between channel exit and substrate, where the activated gas flow to the surface of diamond deposition is formed. The gas dynamic analysis of gas jet deposition of diamond facilitates the optimization of experiments and their analysis.

An algorithm of the direct simulation Monte Carlo (DSMC) method of the flow of the hydrogen and methane mixture in a cylindrical channel is developed. The heterogeneous reactions on the tungsten channel surface are included into the model. Based on the elaborated algorithm, analysis of the background gas pressure effect on the flow gas-dynamics and interaction of the flow particles with the substrate has been performed. The obtained results can be useful for optimization of gas-dynamic sources of activated gas in technologies of diamond synthesis.

The gas-jet deposition of carbon and diamond-like films on a substrate with precursor gas activation by a hot wire mesh has been studied experimentally. Several designs of the wire activator for depositing films from a gaseous mixture of CH4, H2, and Ar have been tested. The carbon structure of obtained films was determined by Raman spectroscopy.

In this paper the results of a study of the deposition of silver nanoparticles with characteristic particle sizes from several nanometers to tens of nanometers obtained by gas-jet deposition from a specially developed thermal source are presented. The characteristics of the thermal source are given as dependences of nanoparticle size values on the source temperature and pressure. Flow regions responsible for the formation of metal clusters have been detected.

A new method of gas-jet deposition of metal-polymer composites with simultaneous deposition of polymer matrices and silver clusters from two gas-dynamic sources is presented. Specific features of cluster deposition and the properties of composite films are described. Results on the antibacterial effect of silver-polymer composites on stock cultures of various bacteria are reported.

The Direct Simulation Monte Carlo (DSMC) method is used to simulate the hydrogen–methane mixtures flowing through a heated cylindrical tungsten tube and expanding into a low-pressure chamber in the substrate holder direction. The DSMC method takes into account heterogeneous reactions in the tube and on the substrate surface. The results of DSMC simulation are used for the chemical kinetics calculations, i.e., axial distributions of species concentrations in various H/C mixtures. The effects of various parameters (reactor configuration, flow rate, initial concentration of methane in the mixture with hydrogen, and pressure in the chamber) on species fluxes to the substrate, the degree of hydrogen dissociation, the degree of methane decomposition, and further conversion of CxHy components up to atomic carbon C are numerically studied. The developed method provides a possibility of solving similar problems for nonequilibrium flows.

Transformation of energy and composition of gas mixtures in a convergent flow from a strip source on a cylindrical surface toward the axis is systematically studied with the use of the direct simulation Monte Carlo method. Information on the influence of gas-flow rarefaction and system geometry on the temperature and concentration of the heavy gas in a dense cloud formed on the axis is obtained. The use of convergent supersonic flows is demonstrated to offer new possibilities for research in the field of physical gas dynamics.