Table of contents

For ex-situ introduction of AlN nanopowder, obtained by azide technology of self-propagating high-temperature synthesis (SHS) or combustion synthesis in the mixture with the flux cryolite: (AlN-35%Na₃AlF₆), into the aluminum melt, an exothermic master powder composite (EMPC) of different composition (AlN-35%Na₃AlF₆) – (Ti + C) – Na₂TiF₆ was first used, leading to the realization of in-situ process of SHS of reinforcing phase TiC in the combustion mode in the aluminum melt. The conditions were found for reliable ignition of the EMPC and fabrication of cast hybrid nanocomposites Al-Al-TiC, including the calculated composition Al-7.7%AlN-19%TiC with an increased content of AlN reinforcing phase.

Publications devoted to the properties and methods of fabrication of particle- reinforced aluminum matrix composites and nanocomposites of Al/TiC were analyzed. The emphasis was on the application of the method of self-propagating high-temperature synthesis (SHS) for preparation of Al/TiC composites. The results of our own studies of fabrication of Al/10wt.%TiC composite using SHS in the aluminum melt in the presence of alloying additives of copper (5 wt.%) and manganese (2 wt.%) were presented. It was shown that the alloying of Al/10wt.%TiC cast composite with copper and manganese leads to a more uniform distribution of the synthesized nano - and ultrafine particles of titanium carbide, as well as to nearly a twofold increase of strength while maintaining a sufficiently high level of ductility.

The results of the study of possibility of using a simple, energy-saving powder technology, based on the process of self-propagating high-temperature synthesis (SHS) or combustion synthesis, for the single-stage preparation of Cu-Ti₃SiC₂ composite from relatively inexpensive powders of its constituent elements are presented. Placing the Cu powder briquette between two adjacent charge briquettes 3Ti + 1,25Si + 2C for the synthesis of MAX-phase of Ti₃SiC₂, it was possible to use a large heat effect of SHS for melting the Cu briquette and infiltration of Ti₃SiC₂ porous skeleton by Cu melt. For the successful realization of this process, it is necessary to ensure the required fluidity of Cu melt and wetting Ti₃SiC₂ through a high temperature of the melt and the alloying of the melt with silicon, as well as to ensure the delay in the transfer of the melt into pores of SHS product.

The paper represents a study of combustion of vanadium oxide with calcium and calcium nitride in nitrogen. The study shows that when 75% of calcium is replaced with its nitride, it is possible to avoid the spread of the reaction mass. When the content of calcium in the green mixture is 1.2 times higher than the stoichiometric ratio and 75% of calcium is added as nitride, the maximum temperatures exceed 2200 °C in the combustion zone. The X-ray study established that single-phase vanadium nitride can be obtained after acid-dissolution of the calcium compounds contained in the product. An increase in the concentration of calcium in the initial mixture leads to the decrease in the size of product particles.

The results of microwave sintering of powder materials in the regimes with high heating rates and zero hold time at maximum temperature are reported. Microwave processing of compacted samples based on Al₂O₃, Y₂O₃, MgAl₂O₄, and Yb:(LaY)₂O₃ ceramics was carried out using a 6 kW/24 GHz gyrotron system. The volumetric absorption of intense microwave radiation resulted in a very rapid densification with the duration of the high-temperature stage of sintering on the order of one to several minutes. In the rapid microwave heating regimes the effective high-frequency conductivity of the materials increased sharply at a certain threshold temperature as a result of the overheating instability, also known as thermal runaway. This suggests that the ultra-rapid sintering occurs via grain-boundary softening and formation of transient liquid phases. The indications of the presence of such phases were observed in the microstructure of the sintered samples. The absorbed microwave power density required for the transition to the ultra-rapid sintering is on the order of 10...100 W/cm³ for a broad class of the materials. The obtained results suggest that ultra-rapid microwave sintering proceeds via essentially the same mechanism as the so-called flash sintering that occurs in the presence of dc or low-frequency ac electric field.

The paper provides a multicomponent one-velocity model for numerical simulation of the behavior of inert and reactive porous mixtures exposed to explosive detonation. A system of equations describing the nonstationary adiabatic motion of both inert and reactive mixture components is presented. The relations for achieving mechanical equilibrium in a multicomponent mixture exposed to explosive detonation are considered within the framework of an elastic-plastic medium. To simulate explosive detonation, the upper part of the ampoule is exposed to pressure in an axial direction and the lateral side of the ampoule is exposed to pressure in a radial direction.

Study is based on the compare characterization of the structure and evaluation of the residual internal stresses in Ti-6Al-4V samples manufactured by the 3D printing (selective laser melting) and in the Ti-6Al-4V samples obtained with using of the severe plastic deformation by screw extrusion. The microstructure and residual stresses were examined by transmission electron microscope and X-ray diffractometer. High tensile internal residual stresses in the 3D printed sample were found. The high compressive residual internal stresses were found in the hot pressed and in the twisted samples. It was shown that arising of the high residual stresses in the studied samples under various technological processes occurred in various ways. The residual stresses in the severe plastic deformed samples arose due to non-uniform volumetric plastic deformation. In 3D printed sample, the residual tensile stresses arose from both phase (martensitic) transformation and thermal deformation.

This paper is short review the main factors affecting the structure and properties of the metals manufactured by additive technology (selective laser melting). A comparative analysis of the structure and properties of Ti6Al4V or CoCrMo alloys obtained by selective laser melting is presented. We describe the capabilities of laser melting method for producing materials with high density and high mechanical properties. The optimized process parameters for 3D printed medicine materials Ti6Al4V and CoCrMo with high density of are discussed.

The dynamics of chemical and structural conversions in mechanocomposites during mechanical treatment is numerically studied. The application area of different modes for the mechanical treatment of a powder mixture is determined depending on the control parameters. Analytic relations are obtained to estimate the parameters of the layered structure of mechanocomposites, and the degree of activation and fraction of a converted substance.

The heat regimes for a Cr-Cu surface alloy formedon Cu substrate using liquid-phase mixing of film (Cr)–substrate (Cu) system with a low-energy, high-current electron beam (LEHCEB) have been studied. The calculations allowed to determine the melting thresholds for Cr and Cu and the optimal parameters of LEHCEB for Cr-Cu surface alloy formation. The calculations demonstrated that the melt thickness on the surface after irradiation with LEHCEB in optimal modes is 3-4 μm, and the lifetime ∼1 μs. Mechanism of defect generation in the Cr particles was suggested. Generation is attributed to the action of tensile stresses owing to a large difference between the thermal expansion coefficients of Cr and Cu.

The phase composition, morphology, and structural parameters of cobalt ferrospinel powders synthesized by spray pyrolysis combined with drop sol-gel combustion are determined. The obtained data are compared with those of the powders synthesized by sol-gel combustion.

The work is aimed at studying the features and conditions of initiation, reaction, gas generation and final phase formation in the energy condensed "metal-teflon" systems with two types of initiation: local heat pulse and shock-wave loading. Approximate thermodynamic calculations were carried out using THERMO program, which took into account three mixtures and samples of them: (Ni + Al + Teflon), (Ti + B + Teflon), (Hf + B + Teflon). The adiabatic combustion temperatures of mixtures, the composition and the amount of condensed products, and the volume of gaseous products are calculated. Gas formation during combustion of mixtures was measured in a spherical ampoule equipped with temperature and pressure sensors. Shock-wave loading of the samples was carried out in a multi-cell matrix by throwing a flat impactor. The acceleration of the impactor was carried out by the detonation products of the explosive. The design of the recovery fixture provided the same loading conditions in all cells. The investigated compositions are capable of an intense exothermic reaction, both at traditional ignition of a heated spiral, and at shock-wave action.

In the present work, the effect of difference between thermal properties of the base material (matrix) and inclusion on the temperature behavior of the target in the regions of inclusion locations has been considered. The calculations were based on the solution of two-dimensional nonlinear nonstationary heat equation. It has been shown that the most strong effect on the temperature field takes the difference between heat conductivities of the matrix and inclusion. The simulations of temperature fields have been carried out on the real systems matrix-inclusion, namely, stainless steel 316 L/manganese sulfide (SS 316L/MnS), TiNi/Ti₂Ni, TiNi/TiC. The results obtained allows suggestion on the origin of microcraters appearing at the irradiated surface as a result of thermocapillary convection in overheated sites of location of inclusions.

Different modes of mechanochemical synthesis of titanium nitride are found based on the developed mathematical model and experimental data. Approximate analytical formulas are obtained for estimating the characteristics of mechanochemical synthesis during its different stages.

Thermal explosion synthesis of previously mechanoactivated Ti-Ni and Nb-Si systems is studied experimentally. Thermal explosion in previously mechanoactivated Ti-Ni and Nb-Si systems is theoretically described at the macroscopic level. Preliminary mechanical activation is found to accelerate the synthesis of the reaction product. The thermokinetic and thermophysical constants of the process are determined by the inverse problem method using experimental data.

The multiscale approach was used for 3D computer simulation of deformation and failure of porous nanostructured ZrB₂-B₄C composites. It was shown strong influence of ZrB₂-B₄C nanocomposites microstructure on dynamic fracture at temperatures (295-473 K). The fracture of ZrB₂-UHTC is caused by nucleation and coalescence of micro cracks. Cracks are formed near voids and in space between the strengthening particles at the mesoscale level. It was shown the transition of brittle to ductile fracture in ZrB₂-B₄C composites depends on strain rates. Thus, the strength threshold of nanostructured ZrB₂-B₄C composites depends on strain rates in temperature range (473-2200 K). The dynamic strength of ZrB₂-B₄C composites sharply decrease at temperature above 1773 K. It was shown that the dependence of normalized strength of ZrB₂-B₄C composites on the logarithm of normalized strain rates can be described by the power law.

The paper presents the results of experimental studies of the powder production by an electric explosion of titanium fibers in argon media. The main features of energy input in the fibers and its phase transformation were established. It was found that spherical titanium particles (with a diameter of 80-170 μm) were produced at energy consumptions varied from 1.15 to 1.25 J/mg. The characteristic times of the energy input were about 60-100 μs. Reached particle purity was 97.32-99.63 % and determined only by a purity of raw fibers. This method can be useful for the production of metallic powders with low oxygen concentration for addictive manufacturing or high temperature synthesis.

The paper represents the results of numerical simulation of fracture of laminate composites under impact loading. The behavior of a composite target that consists of a titanium alloy (Ti-6-4) and a titanium-titanium trialuminide intermetallide (Al₃Ti) layers were studied. A special model is applied to describe the brittle-like fracture of intermetallide. The axisymmetric problem is solved using the finite element method. In the computations, the thickness of the layers was varied. The multilayered composites were compared with monolithic intermetallide and titanium targets.

Four methods such as thermal explosion, reactive sintering, reactive pressing, and explosive welding + sintering are considered for the obtaining of the Ti-TiAl₃ metal-intermetallic laminate composite. The microstructure and phase composition of the samples are studied by the X-ray diffraction, local X-ray spectrum and optical microscopy methods. The study shows that multi-laminate composites can be obtained by all four methods.

Minimum ignition energy (MIE) values for electric spark have been calculated and experimentally evaluated long ago, but for laser ignition significantly higher values were found, as explained, due to shorter duration and smaller size of the laser impact region. The feature of electric breakdown ignition is high energy input rate in the discharge channel. For laser ignition, energy input rate depends on gas spectral absorption. So only a small part of incident laser energy may be deposited in laser spark near breakdown threshold. MIE for certain gas mixture contents and pressure is expected to be independent on the way of energy deposition. There is a mess in published data on laser ignition energies, because authors often do not state whether incident or deposited energy is mentioned. To resolve these discrepancies, minimum pulse energy (MPE) term is suggested for laser impact, and is a more practical one. Although MPE is easy to measure, its value depends a lot on experimental conditions, which are not always properly documented, to reduce this effect, we suggest to consider MPE to laser breakdown energy ratio. We have experimentally evaluated MPE for butane (C₄H₁₀) based fuel mixture of different equivalence ratios (φ∼0.5-1.5) and pressures (p∼1-4 bar) at the impact of 1064 nm radiation of nanosecond laser. Efficiency of laser ignition was evaluated by MPE to breakdown threshold ratio.

The paper shows new possibilities for studying the effects of microheterogeneous combustion by the method of high-speed micro-thermal imaging. On each video frame, the area of the microfocal reaction, where local superadiabatic heating occurs has been identified,. All the discrete regions of heat generation were combined on a common image of the thermal microstructure of the combustion reaction wave. The characteristic size of the foci of combustion in the Ni-Al system was from 150 to 300 μm, which is 5 times larger than the size of the largest powder particles. It was found experimentally that the combustion front propagates only in the local regions of superadiabatic heating and the motion has a discrete step. The thermal microstructure has the form of a quasiperiodic sequence of layers, the spatial direction of which weakly depends on the position of the combustion front with respect to the horizontal. To verify this fact, which contradicts the classical theory of wave stability in the spin combustion mode, the differential chronoscopic analysis of the interframe difference in the motion of the combustion front line was selected. As a result, it was shown that, independently of the geometry of the combustion front, a synchronous and quasi-periodic occurrence of new local combustion sites is observed. The period of thermochemical induction between each discrete step of motion was from 0.1 to 0.2 ms. Thus, the data of the 2D thermal map of differential chronoscopy (DCS) allow visualization of the SHS combustion wave in the form of coherent thermal structures with quasiperiodic parameters.

The model of composite synthesis from powders of titanium and boron is proposed in this paper. Mathematical model takes into account the dependence of effective properties powders mixture on the composition and structure of reaction mixture. The ignition stage, the formation irreversible phases and reaction retardation by reaction product are also considered in the model. The reaction scheme of the composite synthesis process includes the system of four kinetic equations describing the formation of different titanium borides. Results of modeling for non-stoihiometric composition of the reaction mixture are presented and discussed.

The problem of filtrational gas combustion wave stabilization in a porous cylindrical burner with different pore sizes and heat conductivities of porous carcass is numerically investigated. Simulation is carried out within the framework of the conventional one-dimensional diffusion-thermal model of filtrational gas combustion with allowance for radiative heat losses from the external surface of the burner. The data on influence ofthe carcass pore size and the thermal conductivity ofporous material on the radiative efficiency is investigated.

The paper presents the means for measuring the spatial and temporal coherence of temperature in the micro regions of a wave of self-propagating high-temperature synthesis (SHS) and revealing the relationship between the events of ignition of individual foci. The method for determining the parameters of the thermal wave structure of the synthesis is based on the chronographical and topographical representation of micro thermal data in the form of maps that visualize the ergodicity of the SHS process and facilitate the recognition of individual foci of burning on thermal imaging images. The ergodicity of the phenomenon is used in the method to determine the time of induction of the combustion sites, the time of their growth, the growth rate of the foci tangentially to the front of the SHS wave, the size of the foci in the direction of the normal to the front. The error in measuring the velocity of the SHS front of the wave with the pro-posed technique was 0.05%.

The paper studies the effect of acoustic emission (AE) during combustion of Ni and Al powder mixtures as well as Ni and Al twisted wires. The acoustic measurements show that AE occurs at the moment of ignition of the samples and moderates after the combustion is completed. The features of AE signals are low-ordered discrete pulses with duration of (0.5÷4.5) ms and regular vibrations with a frequency of (860÷900) kHz. The possible mechanisms of generation of acoustic vibrations in propagating combustion waves are analyzed.

The aim of this study is to report a new experimental regularity of the change in the propagation velocity of SHS as a function of the adiabatic temperature at the local point of the combustion front. The paper presents the results of measuring the temperature and velocity in the propagation of a combustion wave, obtained using a special television micro-pyrometer (1200×800 pixels) with high spatial (5.85 μm/pixel) and resolution time (1000 fps). High accuracy of temperature measurement was provided by using a new method of spectrally-bright pyrometry (patent RUS 2616937) from 800 to 2000°C with an error of less than 1%. This paper shows the experimental procedure and statistical data on the hysteretic dependence of velocity on temperature.

This paper discusses the phase composition of macroporous Ni-Al alloys obtained by self-propagating high-temperature synthesis. The alloys have been synthesized in a nonstationary combustion mode. The combustion wave consists of super adiabatic foci, and macroporous structure is realized under the action of capillary hydrodynamic effects. The influence of reaction mixture composition of aluminium in the range of 13.5-31.5 wt.% is also discussed. The specific requirements to obtain the single phase B2 NiAl and LI₂ Ni₃Al as well as biphase gas permeable alloys with the average size of structure elements in the range of 1.2-3.15 mm are described in the paper.

The model of the coating synthesis on the substrate is suggested at the conditions of electron beam controlling. The detailed reaction scheme in the treated layer is taken into account. Reaction kinetics is described based on mass action law. Reaction retardation by solid reaction products is taken into consideration. The review of similar models, simple and coupled, is made. Asymptotical solution of the particular coupled problem with summary reaction scheme is obtained. It was found that self sustaining mode is possible when the coating is synthesized on the substrate. The example of maximal temperature establishment is illustrated for the detailed reaction scheme in the Ti-C-Al system when the conversion is initiated by electron beam.

This paper proposes a mathematical model for the synthesis of porous materials from a granular low-calorie gas-free powder mixture, the reaction of which is supported by the filtration combustion of a gas mixture. The dynamics of synthesis is described by the equations that comprise the heat balance in the condensed and gas phases, the motion of the gas phase, the rate of reactions in phases, the conservation of momentum with additional relations. A numerical study was carried out using finite-difference methods. Mechanisms and modes of the propagation of reaction fronts in phases are determined depending on the characteristics of gas flow during co-current and counter filtration, the ratio of the gas-phase and solid-phase reaction constants, and the parameters of interphase heat transfer

This paper presents experimentally studied environmental and radiation parameters of hollow cylindrical burners during operation with LPG-air fuel mixture. Two combustion modes have been examined – an external combustion mode where the flame anchored near the outer surface of the burner, and an internal combustion mode when the combustion takes place in the inner cavity of the burner. The dependences of CO/NOx emissions and radiation efficiency on a firing rate in the range of 160-420 kW/m², air-fuel equivalence ratio in the range of 1.0 - 1.4, as well as the porous structure of a burner have been analyzed. An influence of a flow deflector installed in front of the burner inlet in order to distribute the flow over the inner cavity of the cylindrical burner on environmental characteristics of the burner is discussed. The necessary condition that ensures CO emission below 50 ppm, NOx emission below 20 ppm and radiation efficiency in the range of 45-55 % is described in the paper.

A brief overview of models describing thermal conversion and combustion of coal is presented. Additionally the properties of coal dust were experimentally studied. The main characteristics of brown coal particles, composition of thermal decomposition products and its change with the temperature were measured. The mass loss rate of coal particles and its temperature dependence were studied. Based on the obtained experimental data, an applicability of available in literature models was analysed.

The paper represents a mathematical model for the gasless combustion of a layered composition. The inner layer of the composition consists of an inert low-melting metal. Other layers consist of a highly exothermic gasless mixture. Metal of the inner layer melts during the combustion of adjacent layers. The melt under the influence of surface tension forces spreads in porous combustion products of the gasless mixture to form a composite material. The capillary flow of melt in porous channels is limited by the temperature of the carcass equal to the melting point. The results have shown that the time required for a combustion wave to propagate through an inert layer depends on its thickness and thermal conductivity. The modes of combustion synthesis are determined for layered composite materials. The dynamics of the structure formation of composite materials is considered depending on the thickness of the inner metal layer and the coefficient of external heat exchange.

Thermal, structural and emissive characteristics of the combustion of metal composite Ni-Al fibers in an inert and oxidizing media are studied using high-speed video recording, dynamic spectrometry and Langmuirprobe. The measurements have shown that combustion wave propagates at a velocity of 0.15÷0.3 m/s depending on the pressure and composition of gas media and the maximum process temperature is in the range of 2600÷3720 K. The kinetics of combustion is shown to be controlled by capillary mass transfer in metalmelts. The effects of emission of nonequilibrium gas plasma and the spontaneous electric polarization of reaction wave are found, where the difference in electrical potentials of the condensed and gas-dust phases can exceed (2÷3) 10³V.

In Russia, as in other industrialized countries, is developing new welding technologies, which refers to the main methods of obtaining permanent connections in the manufacture of machine parts and structures. The possibilities of improving the quality of welded joints using the widespread in domestic and foreign production methods of DC arc welding are already largely exhausted. Tonsuring the possibility of controlling the melting capacity of the arc, welding at increased gaps, in various spatial positions, reducing the spraying of the electrode metal, increasing the stability of the arc and its combustion, reducing labor and saving material resources. Thus, there is a situation when it is necessary to conduct additional research in order to optimize the existing technology. The objective of the work: to study the capabilities of modes of pulsed arc welding and surfacing on the structure and properties of permanent joints during manual arc welding and surfacing with coated electrodes.

The aim of the work is to study the structure, physical, mechanical and operational properties of the deposited coatings by pulsed welding methods with modification of molten metal composite powder materials with submicrocrystalline structure. Samples of weld joints of steel 09G2S. Welding was performed with composite electrodes of the power source Feb-315 "Magma" remote "pulse" for the implementation of the pulsed arc process. The influence of modification by dispersed particles and electric arc impact on the structure, physical, mechanical and operational properties of coatings is studied. It was found that the modification of refractory compounds with submicrocrystalline structure allows to increase the dispersion of the structure and the hardness of the coatings.

The paper represents the study of the kinetics of diffusion-induced recrystallization (DIR) and its effect on the disordering and creep resistance of an alloy based on Ni₃Al doped nickel aluminide. Recrystallization was observed in the Ni₃Al-based alloy hardened by the particles of chromium carbides at a temperature of 1573 K due to dissolution of carbides and diffusion of chromium in the volume of grains. Recrystallization leads to a sharp decrease in the creep resistance of the alloy due to the formation of an unordered γ phase. The alloy can be used as a heat-resistant material at a temperature of not more than 1500 K.

The present work aims the characterization of different types of waves generated upon the plastic flow in single-crystal metals and alloys. The propagation of new types of waves is highlighted during the linear work hardening and easy glide stages of flow. As found, the motion velocity of waves is the inverse function of the work hardening coefficient.

In the paper to be submitted the notions of plastic flow localization are outlined. It is shown that a particular kind of localized plasticity pattern corresponds to a given stage of deformation hardening. In the course of plastic flow development a changeover in the types of localization patterns occurs. It is found that the emergent patterns are manifestations of the autowave nature of plastic flow localization process, each pattern corresponding to a definite type of autowave. The most intriguing localization pattern corresponds to a phase autowave which forms at the stage of linear work hardening. The following characteristics of phase autowave have been determined experimentally: propagation velocity and dispersion dependence of wavelength. Moreover, elastic-plastic strain relation is introduced which relates the elastic and plastic properties of the deforming medium. It is shown that the characteristics of autowaves follow from this relation.

"Titanium carbide – a high speed steel (HSS) steel binder" metal matrix composites were synthesized by the wave combustion mode and investigated. Composite powders "TiC + HSS" obtained by crashing of the self-propagating high temperature synthesis (SHS) cakes were used for electron-beam surfacing of the coatings. An microstructure evolution of composite powder granules during of the surfacing is traced. The evolution involves a partial dissolution of the composite granules in the melt of the surfacing bath and subsequent crystallization of dispersed carbide particles in the dendrites form from a liquid metal solution containing titanium and carbon. The microstructure of the deposited coatings correlates with their hardness and abrasive wear resistance. The abrasive wear mechanism of the coatings is discussed.

The paper represents the method for obtaining and evaluating the catalytic properties of metal-ceramic composites based on silicon and titanium nitrides. The optimum conditions of the materials synthesis in the combustion mode are determined. The results have shown that the obtained iron-containing composites in the presence of H₂O₂, H₂C₂O₄, EDTA have a catalytic activity during the degradation of dyes exposed to UV radiation. The addition of TiN to the ceramic matrix is shown to increase the efficiency of photocatalytic generation of hydrogen from carboxylic acids.

A composite ceramic β-sialon-based material is obtained by the SHS method using aluminium ferrosilicon as an initial material. The effect of the addition of aluminium oxide (α-Al₂O₃) and ash microspheres on the synthesis of sialon is studied. The iron-containing sialon-based composite is shown to exhibit a high catalytic activity in the presence of H₂O₂, H₂C₂O₄ during degradation of dyes and phenol under UV radiation.

A mathematical model of the crystallization of a binary metal alloy inoculated with exogenous refractory nanoparticles has been developed. The process of cooling and solidification of an aluminum alloy with a phase diagram of the eutectic type is considered. Equations describing the growth of the solid phase with the continuous cooling of the alloy to the eutectic temperature and subsequent crystallization of the eutectic are given. Verification of the proposed model was carried out by comparing the results of numerical calculation of the crystallization process of the binary Al + Si system with the corresponding data of the physical experiment.

The method of producing of nano-dimensional silicon carbide and experimental results of pyrolysis of a mixture of a silicon-hydrocarbon composition by compressing in a cyclic chemical reactor has been proposed. New structural design solutions and ceramic coatings obtained by applying the technology of microarc oxidation were used in the compression unit of the chemical compression reactor. This allowed us to forego the traditional schemes, to achieve a high compression ratio, and to obtain the pressure and temperature required in the reaction zone for silicon-hydrocarbon composition pyrolysis. The flow-through pyrolysis method in chemical compression reactor is convenient, technological and efficient to be used in the production of high purity silicon carbide nanopowders.

The obtained results show that using an electron beam wire feed process makes it possible to manufacture axially symmetric articles which metal strength is close to this of conventionally made ones. However, it is necessary to optimize the process parameters and thus provide forming the desired microstructure with or without the anisotropy.

This paper presents a brief review of research made by the authors to determine feasibility of using a titanium-based bilayer material in industrial applications. One layer, corrosion preventive, is formed by surface alloying with highly corrosion-resistant doping elements, in particular, Ta, Nb and Zr. These elements have significantly higher corrosion resistance than titanium. Applying them on the titanium substrate allows formation of a coating resistant, in particular, to boiling strong acids. Resistance of obtained coatings in said media is many times higher than that of titanium or stainless steel. The coatings are formed using a high-penetration electron beam ejected to the atmosphere. This article contains references to findings of previous works and offers some new data.

In this paper the deposition of a-C:H:SiO_x films by plasma activated chemical vapour deposition in a mixture of argon and polyphenylmethylsiloxane (PPMS) vapor with the impulse bipolar bias voltage applied to the substrate is presented. The paper discusses the dependence of the physico-mechanical properties of the deposited films on the flow rate of the PPMS precursor. The structure of the deposited films was determined by Fourier transform infrared spectroscopy and Raman spectroscopy. Mechanical properties characterization of a-C:H:SiOx films (hardness and elastic modulus) was made using the nanoindentation method. Hardness and elastic modulus were used to evaluate the endurance capability (H/E) and resistance to plastic deformation (H³/E²). The elastic recovery was calculated based on loading and unloading curves. It is shown that with an increase in the PPMS flow rate in the range of 35-287 μl/min, the films deposition rate increases from 17 to 221 nm/min. At this films mechanical properties, such as hardness, elastic modulus and elastic recovery did not deteriorate. The maximum values of the endurance capability and resistance to plastic deformation are obtained at a flow rate of 175 μl/min and equal to 0.12 and 203 MPa, respectively.

Mo₂FeB₂ based cermets with different Cr and Ni contents were prepared by liquid phase sintering. The effects of Ni and Cr content on the microstructure, hardness and fracture toughness were investigated. The results reveal that alloying of cermet with nickel leads to formation of structure characterized by high austenite volume fraction and low ferrite content. As a consequence Cr predominantly dissolved in Mo₂FeB₂ boride lattice. Synthesized cermets have a superior combination of hardness and fracture toughness.

Methods of optical microscopy, scanning electron microscopy and EBSD analysis have been used to study the structure of ultrafine-grained materials obtained by friction stir processing. The data obtained indicate a complex and inhomogeneous character of the deformation at the processing area. When conducting TEM studies, it was revealed that grains of the a-Al solid solution of the processed material have the zone axis of the type 〈110〉. The main differences in the structure of materials obtained by processing with different types of tool are determined. It was revealed that in addition to the difference in the use of the tool with the presence or absence of the so-called "pin", the shape and arrangement of grooves on the end part of the tool, the so-called "shoulders", are of paramount importance. The influence of the shape of the grooves affects both the depth of the processed layer and the average grain size of the stir zone.

The study of the structural evolution in the specimens of austenitic steel 321 manufactured by an additive method through the melting of a wire material by an electron beam in a vacuum chamber has been carried out using optical metallography, scanning electron microscopy and EBSD analysis. Tensile properties were determined on standard dumbbell specimens. The studies of the structure and properties showed that the 3D-printed samples have a pronounced dendritic structure with a sharp fusion boundary between the substrate and the printed material. The mechanical properties of the specimens are at the level of those cast austenitic steel 321.

Green pigments based on uvarovite Ca₃Cr₂[SiO4]₃ were obtained from cheap silica-containing materials of the Siberian region by high-temperature solid-phase synthesis with the use of mechanical activation of an initial mixture. The chemical composition of quartz sand and marshallit, the main initial components of pigments, is determined using an optical emission spectrometer with inductively coupled plasma (iCAP 6300 Duo, Thermo Scienfitic). The structure and phase composition of initial materials and reaction products were analyzed by X-ray diffraction (DRON-UM1 diffractometer, filtered CuKa-radiation), IR spectroscopy (Nicolet 5700 FTIR spectrometer), and scanning electron microscopy (Philips SEM 515). Calcium carbonate is shown to decompose during mechanochemical activation. The reactions occurring during the synthesis of pigments were studied using a thermal analyzer (SDT Q600) in the temperature range of 25-1200°C at a heating rate of 20 deg/min. Mechanical activation of initial components in a planetary mill M3 with an acceleration of 45 g for 300 s leads to a decrease in the synthesis temperature by 200°C and increases the degree of conversion of the final products.

The products of self-propagating high-temperature synthesis (SHS) in the reaction mixtures of titanium and carbon (carbon black) containing an excess of titanium content with the purpose of obtaining composite "titanium carbide–titanium binder" powders from the synthesis products were studied by X-ray diffraction analysis, optical and scanning electron microscopy. Based on the results of the investigation of the phase and elemental composition of SHS powders synthesized in argon, the formation of non-stoichiometric titanium carbide has been established which led to a decrease in the content of the titanium binder in composite powders in comparison with the target values. The results of the study of the morphology and structure dependencies of the carbide phase in composite powders on the content of titanium in reactive mixtures have been discussed in conjunction with the results of the determination of the thermo-kinetic characteristics of SHS in the wave combustion mode.

This study is devoted to obtaining long-length two-layer corrosion-resistant tube blanks by explosion welding for their subsequent rolling into tubing. The technological scheme of the process was developed, which allowed ensuring high-quality adhesion of the internal corrosion-resistant layer from austenitic stainless steel 08Kh18N10T with a tube blank made of 37G2F hollow structural steel. In the course of study on the experimental production of bimetallic pipes of 2.4 meters in length, the following problems were solved: 1) the choice of optimal collision regimes of the tube elements thrown on each other; 2) the development of the necessary technological equipment to maintain the alignment of the main elements; 3) ensuring full filling of the internal surface of the device with solid-liquid filler without contact with the welding gap (sealing with welded joints); 4) reducing the degree of lateral dispersion of the explosive due to the assembly enhancing in the ground and use a metal formwork; 5) estimation of the relative narrowing of the outer diameter of the bimetallic tube after explosion welding; 6) carrying out ultrasonic control of the continuity of connection of the obtained two-layer pipes in order to reveal the mistreatment zones along the length of the blanks.

This paper presents experimentally studied temperature and radiation parameters of a gas-fired luminous radiant heater based on a conical aluminium recuperator and a cylindrical Ni-Al burner. Two operation modes have been investigated: (i) with air preheating by means of heat recuperation when the air is supplied into the burner through the hollow recuperator, and (ii) without air preheating when the fuel mixture is directly supplied to the burner. The dependences of radiation efficiency on a burner firing rate in the range of 100-340 kW/m² are analyzed. The specific requirements to obtain the radiation efficiency up to 70% are discussed.

The paper represents the method of obtaining and the main physical and chemical and magnetic characteristics of nanosized oxide-based powders. Nanoparticles are found to be nontoxic and can be used as carriers of drugs, sorption and desorption of nucleic acids, proteins and enzymes.

Metal matrix composite powders "TiC-Al binder" were synthesized in the wave combustion mode and investigated. Combustion concentration limits of Ti-Al-C powder mixtures were founded. Phase and elemental composition of self-propagating high temperature synthesis (SHS) products, morphology of composite powders and the dependence of the carbide phase size in the structure of the composite on the reaction mixture composition were investigated. The SHS composite powders have a lumpy, predominantly equiaxed shape, favourable for good flowability. The carbide inclusions size in the aluminium matrix decreases monotonically with a content increase of the of thermally inert aluminium binder.

Phase composition and structure of "TiC-NiCrBSi alloy binder" metal matrix composite powders have been investigated. The composites were synthesized from titanium, black carbon and Ni77Cr15Si3B2 alloy reaction powder mixtures by self-propagating high temperature synthesis (SHS). The composite powders were produced by crushing of SHS cakes. A size of TiC inclusions in NiCrSiB matrix depends on the content of NiCrBSi in the reactive powder mixtures and varies from 7.3 to 1.2 μm.

The aim of this work is to study the influence of electron beam current on the microstructure, structural-phase state and the change in microhardness of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si alloy samples. The samples were fabricated by electron beam melting (EBM) at different beam currents (3-6 mA). The phase composition and microstructure were analyzed by X-ray diffraction and scanning electron microscopy, respectively. The peculiarities of structure and properties change of samples made by electron beam melting from Ti-6.5Al-3.5Mo-1.5Zr-0.3Si powder have been established, depending on the manufacturing parameters.

Magnesium-aluminate spinel was obtained by self-propagating high-temperature synthesis. Magnesium and aluminum oxides were used as initial components, and aluminum (ASD-4) with additives of amorphous boron was used as fuel. The structure and phase composition of the initial substances and reaction products were studied by means of X-ray diffraction, infrared spectroscopy, and scanning electron microscopy. The synthesis products are shown to contain MgAl₂O₄ as a main phase and a small amount of α-Al₂O₃ corundum as an impurity. Partial substitution of Mg²⁺ by Co²⁺ and of Al³⁺ by Cr³⁺ leads to a shift of X-ray diffraction peaks towards smaller angles, increasing a parameter of the crystal lattice of spinel a, which indicates the formation of solid substitutional solutions. The colour of spinels becomes bright-blue and pink, respectively. A small amount of boron used as energetic additive forms boron oxide, low-melting borates, and eutectics in the MgO-B₂O₃, CoO-B₂O₃, Al₂O₃-B₂O₃ systems during combustion, which leads to the appearance of a liquid phase and the formation of skeletal crystals with the size of 1÷10 μm during the high-speed SHS process.

The SHS process of the Ti-Cr-Al-C powder mixture is studied in the paper. The increase in the content of chromium in the mixture is shown to decrease the maximum temperature of the front of combustion wave. If the content of chromium in the mixture is above 20 wt.%, the process proceeds in the nonstationary combustion mode. Nanolaminate phases Ti₂AlC and Ti₃AlC₂ or their mixtures are found to be formed when the content of chromium is not more than 20 wt. %. The addition of chromium increases the oxidation resistance of materials which can be recommended for use under extreme operating conditions, as an example for electrical contacts, bearings, heating elements, heat exchangers, and high-temperature ceramics.

The regularities of the processes occurring during the thermal decomposition of cobalt, chromium, cerium and sucrose nitrates were studied. Nanodimensional oxide ceramic materials based on oxides of cobalt, chromium, cerium, CoCr₂O₄ are obtained. The effect of the composition of the initial mixture, the mass of the sample, and the rate of heating on the formation of the synthesis product, its phase composition was established. It is shown that the process can proceed in the autoignition mode. A sample was prepared containing the catalytic layer on a porous metal-ceramic support. The obtained sample has catalytic activity in the afterburning process of exhaust gases.

Using the method of self-propagating high-temperature synthesis, coatings based on aluminum nickelides were obtained. The processes occurring in the layers of a powder mixture of nickel and aluminum are studied. The influence of the coating thickness and the degree of dilution of the powder mixture with aluminum oxide on the maximum temperature of the combustion wave and the rate of its propagation is established. The coating consists of small crystals of NiAl, Ni₃Al, fused together. The coating has good electrical conductivity and can be used as electric heaters.

It is known that the epsilon phase of iron oxide ε-Fe₂O₃ has the highest value of coercive force among all known simple metal oxides (∼24 kOe) and is characterized by ferromagnetic resonance in the frequency range from 100 to 200 GHz. The noted features determine the possibility of its wide application. However, there is the problem of synthesis and stabilization this crystal structure at room temperature. In this paper, we consider the possibility to obtain ε-Fe₂O₃ by the plasma dynamic method when the system is operating in the frequency (multi-pulse) regime. The influence of the number power supply impulses on the phase composition of the synthesized products was studied using X-ray diffractometry.

This paper shows the possibility to synthesize directly the nanodispersed zinc oxide (ZnO) in a hyper-velocity jet of an electric discharge erosive plasma. The investigation results demonstrate how the increase in the supplied energy W(t) influences the phase composition, structure, and dispersity of the synthesized powdered ZnO. Using the X-ray diffractometry and transmission electron microscopy it is shown that the obtained product contains only hexagonal ZnO. It is experimentally established that when W(t) varies from 13.7 to 22.6 kJ, the average particle size of the resulting product increases in the range from 80 nm to 95 nm.

Large scale ab-initio calculations are carried out to study the charge state transition levels of nitrogen and phosphorus impurity defects in zinc oxide crystals using the DFT-LCAO approximation as implemented into the CRYSTAL computer code. It is shown that at a high concentration of defects (close location of defects) their formation energy is underestimated due to a significant delocalization of the charge within the supercell. After inclusion the energy offset correction and defect-defective interaction, the formation energy is improved, in a comparison with that calculated in a large supercell. The optical transition levels obtained by a direct calculation confirm the experimental observation: nitrogen and phosphorus impurities are deep acceptor centers with large formation energy in a charged state and, therefore, cannot serve as the effective source of hole charge. The obtained results are in good agreement with the previous theoretical work, in which other calculation methods were used, and are capable of qualitatively describing the energy characteristics of the charged defects.

A composite coating was produced using e-beam formation of surface alloy followed by micro-arc oxidation technique. The Al-Steel surface alloy was formed directly on steel substrate in vacuum by alternating processes of Al thin film deposition followed by a pulsed electron-beam mixing of deposited film and a top layer of the substrate with further formation of the MAO coating from the surface alloy. The microstructure of the coatings including surface morphology, phase and element composition was studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The final ceramic coatings have a typical morphology for MAO coatings and consist of Al₂O₃ and some amorphous Al₂O₃ phases.

The effect of the femtosecond laser irradiation on the formation of oxide layers on the surface of a commercially pure titanium VT1-0 was studied. The methods of X-ray analysis, scanning electron and transmission electron microscopies were used to study the structural and phase state of oxide layers. As a result of the femtosecond laser irradiation, the porous multi-phase nanocrystalline oxide coating with a thickness of 50 μm is formed on the titanium surface. The coating consists of titanium oxides: TiO₂ (rutile and anatase), TiO and Ti₃O₅.

The researched manganese-doped mesoporous silica nanopowder (SiO₂-MnO₂ NP) was produced using evaporation caused by a pulsed electron beam in a vacuum. The synthesized material demonstrated high porosity, amorphous structure and magnetic properties increased with the addition of dopant. The evaluation of the sedimentation stability of NP suspensions showed the need for the additional stabilization. It was established that increasing the sonication time, as the way to increase stability, leads to changes in the structure of the NP. PEG stabilized suspensions showed the highest stability. Experimental results indicated that for different drugs individual methods of loading and release are required. Drug loaded NP demonstrated a high drug loading capacity of 0.09 mg Amoxicillin per mg NP, 0.075 mg Doxorubicin per mg NP that is five times higher than loading capacity of chemically synthesized NP.