In this paper, we present a review of the use of colloidal solutions in the preparation of inorganic composites and ceramics. Sol-gel direction in the technology of ceramics and inorganic composites, which is the formation of materials from solutions using sol-gel processes, has been intensively developed in recent years. One of the main types of raw materials in these processes are colloidal solutions - sols of oxides of various metals. The most important factors characterizing the perfection of the process of synthesis of sols are aggregative stability, the maximum attainable concentration, monodispersity of the sol. In the presented review, methods for obtaining metal oxide sols. The most common methods of obtaining sols are dialysis and electro dialysis, ion exchange, peptization of gels, hydrolysis and electrolysis of metal compounds. The influence of various factors on the stability of sols. The most important characteristics of sols that determine their behavior are chemical composition, particle size, their size distribution, concentration, pH value, viscosity. Based on the analysis of various literature data, we have shown the possibilities of using sols for the preparation of inorganic composites and ceramics.
Keywords: colloidal solutions, sols of metal oxides, stability of sols, inorganic composites, ceramics
Installation for the preparation of emulsions and suspensions refers to devices intended for the preparation of disperse systems. It can be used in the synthesis of polyhydric alcohols and other organic and organometallic compounds, where the immiscible liquids interact. The installation comprises a hydraulic jet mixer pump connected to the outlet of a hydromechanical dispersion pump. The installation comprises one or more components of the dispensing systems, each of which consists of a supply container and the dispenser. Technical result of the installation is created by intensifying the process of mixing and improving the quality of the final products.
Keywords: technological installation; emulsion; suspension; preparation of emulsions and suspensions; intensification of heterophase processes
This article presents the results of an experimental study of the deep cooling of natural gas combustion products in a condensation heat exchanger of a waste heat exchanger in a boiler house No. 12 at the Federal State Budgetary Educational Institution of Higher Education "National Research Ogarev Mordovia State University". The heat scheme of the boiler house with the flue gas heat exchanger provides the maximum continuous cooling mode. The study identified the factors that have the greatest impact on the efficiency of the heat exchanger-utilizer.With short-term operation of the boiler in the spring and autumn periods, the efficiency is more than 3%.
Keywords: burner, combustion mode optimization, heat utilizer, boiler room thermal circuit, boiler unit, flue gases, condensation, heat exchanger, cogeneration mode, cooled gases
The electrical properties of composites based on La0.7Sr0.3MnO3 (LSMO) synthesized at the percolation threshold have been studied: LSMO / Li4P2O7, LSMO / Sb2O3, LSMO / GeO2. The activation energies of these compounds have been determined. New ceramic materials with silver interlayers between LSMO manganite crystallites have been synthesized. The current-voltage characteristics for the LSMO / GeO2 series are given. The nonlinearity of the characteristics is most pronounced for compositions near the percolation threshold, 85% LSMO / 15GeO2.
Keywords: lanthanum strontium manganite, composite material, ceramics, one-step synthesis, magnetoresistance, percolation threshold, dielectric constant, barrier layer, tunneling, spin polarization
The article describes optimal mechanisms of wideband transmitter and receiver (150-600 kHz) for information transfer and for researching of thin structure of ionosphere in different helio-geophysical conditions. The proposed schemes give an opportunity to receiving with division of beams and to use the energy of all waves for increasing interference immunity.
Keywords: wideband, frequency of sounding, synchronization, antenna, reference generator, processor, band-pass filter, interference immunity, multipath propagation, phase, program
The article describes the correlation between the signal edge amount of sounding pulse and small irregularities detection in environments with dispersion. The analysis of experimental data on effective bandwidth of decameter waves spreading on the route Moscow-Ekaterinburg and results of wideband ground-penetrating radar sounding in natural environments with high dispersion gives the opportunity to experiment on surface, vertical and backward-inclined sounding. It is reported that the use of wideband electromagnetic pulses is perspective trend of progress in sounding of natural environments.
Keywords: electromagnetic sounding, decameter waves, electromagnetic pulses, small irregularities, permittivity, ground-penetrating radar sounding, dispersion, natural environment, vertical sounding, spectral form, ionosphere
TThe processes of creating a composite metal-thermal fuel, obtained on the basis of domestic mineral resources of the Batken region is investigated in this article. The bauxites of the Kadamzhai deposit in the Batken region were studied and the percentages of chemical elements in bauxite were determined. It is shown that the researched bauxite consists of mainly from aluminum (61.2%) and iron (30.2%). We obtained ferroalloy and other secondary substances in the process of metallothermic reactions and composite metal-thermal fuel was obtained according to the following scheme: the raw materials were dried to constant weight; grinded to a powder and fractionated through a sieve (50-250 mm) in size; weighed the composite mass composition in percent; ferromanganese alloys and secondary substances were obtained through the metallothermic method; The physicochemical analysis on the content of manganese and iron from the composition of the ferromanganese was studied by the potentiometric method. Ferroalloy (ferromanganese) and by-products (potassium glycerate, aluminum nitrate) based on bauxite of the Kadamzhai deposit in the Batken region were obtained. It is shown that the percentage of manganese in the composition of ferromanganese is 69.2%. To study the content of manganese from the alloy (Ferromanganese), the universal ion meter EV-74 was used equipped with glass and calomel electrodes (chlorine-silver).
Keywords: Thermal effect, optimization, composite, conditions, of the mettalothermic reaction, composition fraction, drying, oxide, fuel, ferroalloy ferromanganese, spectrograph, photographic plate, photometer, ionomer, calibration
An experimental assessment of the dependence of the normal flame velocity of methane-hydrogen fuel with air using the Gouy-Michelson method has been carried out. The concentration of hydrogen varied from 0% to 70% by volume.
Keywords: burning rate, normal flame propagation speed, flame front, methane-hydrogen fuel, Gouy-Michelson method
The paper deals with the theoretical substantiation of the directional properties of the antenna arrays of a parametric profilograph intended for installation on an underwater uninhabited apparatus. A feature of such systems is the structural limitations of the overall dimensions of the carrier, which do not allow the antenna system to be implemented on the principles of linear hydroacoustics in the radiation mode. To solve this problem, we simulated the directional properties of the antenna arrays of the pump converter of a parametric profilograph. The directivity characteristics calculated for the center frequency of pumping in the diametral and traverse planes make it possible to take into account the expansion of the directivity of the radiating antenna when compensating for specified angles. The obtained values of the estimation of the change in the directivity characteristic by the level of 0,7 make it possible to ensure the necessary axial concentration ratio of the radiating antenna of the profilograph for each of the working frequencies.
Keywords: parametric profilograph, bottom survey, pumping antenna, directional characteristic, scanning, side-lobe level
The paper deals with the optimization of characteristics and justification of the directional properties of the receiving antenna of a parametric profilograph. A feature of such systems is their performance in the form of a separate receiving channel, providing high sensitivity, the possibility of matching with the receiving-amplifier path and the best signal-to-noise ratio. In addition, the receiving antenna must provide for the required overall limitations the required angular resolution in the entire sector of the review. In solving these problems, the simulation was performed on the directional properties of the antenna receiving antenna. The issues of optimizing the layout of the antenna system and the use of cylinders on the transverse piezoelectric effect as elements of the receiving antenna are considered. The question of eliminating the influence of the thickness of the fill of the receiving antenna on the transparency coefficient is considered, which allows to ensure the necessary sensitivity of the receiving antenna.
Keywords: Kirichenko I. A.
Hot stamping of porous billets (GSPZ) is considered. Structural steels obtained with the use of GSPZ technology are significantly inferior in terms of machinability by cutting similar in chemical composition to cast and hot-rolled steels. Various alloying elements are considered to improve the machinability of structural powder steels by cutting and their effect on physical and mechanical properties.
Keywords: powder metallurgy hot stamping of porous billets, GSPS, machinability, alloying elements
The parameters of the porous structure and the active surface of cobalt catalysts for Fischer-Tropsch synthesis (SFT) prepared by the impregnation method have been studied. Characteristics of composition and porous structure were studied using elemental analysis and the Brunauer-Emmett-Taylor method (BET). The effect of the addition of oxide promoters on the specific surface area, pore volume and pore size of the Co / SiO2 catalyst has been studied.
Keywords: Fischer-Tropsch synthesis, heterogeneous catalyst, promoter, carrier, specific surface area, porous structure, selectivity, activity, dipping method
Electrocatalytic systems based on platinum and tin oxides with different composition and microstructure characteristics were prepared via sequential electrochemical dispersion of tin and platinum electrodes under the action of an alternating pulsed current. The complex of physicochemical methods investigated the effect of electrolyte on the composition and structure obtained in the first stage of the synthesis of tin oxides.It is shown that the presence of tin oxide in a Pt-containing catalytic system generally has a promoting effect on the oxidation of ethanol on platinum. However, neither the composition nor the microstructure of the oxide affects the electrocatalytic properties of the Pt-containing catalyst.
Keywords: Pt/C, tin oxide, tin dioxide, ethanol, platinum nanoparticles, electrocatalysis, alternating current, metals electrooxidation, electrochemical dispersion, fuel cell
The parameters of the porous structure and the outer surface of cobalt catalysts for the synthesis of Fischer-Tropsch, promoted by magnesium, prepared by the impregnation method according to moisture capacity, were studied. The effect of polymorphic modification (γ, θ, α) of the carrier on the physicochemical properties of the catalyst Co-Mg / Al2O3 was studied.
Keywords: Fischer-Tropsch synthesis, polymorphic modifications of Al2O3, synthetic motor fuel, catalyst, carrier, elemental analysis, BET method, specific surface, porous structure
This paper contains an analysis of the modeling results of the electrophysical parameters of light-emitting GaInAsSb / GaSb solid solutions. The model takes into account three types of current - drift, thermionic emission and tunneling through potential barriers. In the work, graphs of radiation power versus current strength and current-voltage characteristic (IVC) of the LED device are plotted. Modeling indicators based on the features of the band structure of semiconductor systems have been built. Experimental results were discussed, which showed satisfactory agreement with the data obtained on the basis of calculations.
Keywords: solid solutions, Sim Windows 1,5, radiating structures, currents limited by space charge, electrophysical parameters
Developed approaches to measure the structural organization of systems. The concept of entropy expands and acts as an asymmetric criterion for the systems complexity. The necessity of a nonequilibrium approach to describing the interaction of physical structures and the possibility of interpreting entropy as a measure of the structural diversity of systems is shown. The validity of this approach is confirmed by a number of examples of the evolution of different systems, the structural distributions of the elements of which play an important role in modeling physical and physicochemical processes. Theoretical aspects are based on the fundamental work of D. Gibbs and L. Boltzman. The information content of the entropy concept correlates with the well-known “complementary” factor - coentropy. In this work, the evolution curves of complex systems are constructed as dependencies on statistical diversity. The symmetry of the functions of the density of entropy and coentropy with respect to the bifurcation points is discussed. It is shown that two-phase systems “liquid – vapor”, “crystal – melt” are characterized by inversion of evolutionary trajectories.
Keywords: entropy, negentropy, koentropy, orderliness measure, structural variety, normal distribution, dissipative systems, asymmetric structure, orthogonal distributions, dependence inversion
The paper presents a systematic review of recent advances in the development of polymer-matrix nanocomposites containing fibrous (sepiolite-palygorskite group) and non-swelling (kaolinite-serpentine group) clay minerals, as well as their modified forms obtained using surface reactions with organic and inorganic substances. An analysis of scientific trends and the current status of research in this area has been carried out, with particular emphasis on the influence of the types and forms of the considered mineral fillers on the properties of nanocomposites for various applications.
Keywords: polymer nanocomposites, clay minerals, kaolinite, halloysite, sepiolite, palygorskite
Modern development of x-ray technology allows to conduct a detailed study of multiphoton processes of absorption and scattering of x-ray photon by deep and subvalent shells of molecular systems in a wide range of energies. The specifics of solving the problem of interaction of an x-ray photon with a multiatomic system requires the use of a single-center approach to the calculation of the electronic States of molecules. The main disadvantage of this approach is a decrease in the accuracy of the calculation of spectroscopic quantities with limited consideration of the terms of the single-center decomposition of the molecular orbital. The paper studies the effect of accounting for higher harmonics of single-center molecular orbital decomposition on the calculation of the energy characteristics of molecular systems. The analysis of the parameters of the single-center decomposition of the functions of the nuclear ligand, depending on its charge. The criteria for inclusion of higher harmonics of single-center decomposition of atomic ligand functions in the molecular orbital are determined. The calculation of energy characteristics is performed on the example of diatomic molecules HF, LiF and BF. The selected series of molecules makes it possible to study the behavior of higher harmonics of the single-center decomposition of the molecular orbital depending on the growth of the atomic ligand charge.
Keywords: molecular orbital, single-center decomposition, higher harmonics, a nuclear ligand, the energy of the electronic state of a diatomic molecule
The paper presents the results of studies on the effect of deposition regimes on the properties of electrochemical copper powders. The obtained ultradispersed powders of copper and application of different regimes of electrolysis. The paper presents data on the possibility of obtaining ultrafine copper powders (UDP) in pulsed mode with the addition of polyvinylpyrrolidone (PVP) as a particle growth stabilizer. The influence of the current amplitude and the cathode-anode time ratio is revealed. It is shown that the parameters determining the current wave determine the size of the deposited copper powder particles.
Keywords: ultradispersed copper powders, particle size distribution, the parameters of the electrolysis of, kinetics of electrocrystallization
The paper presents a theoretical study of spinodal and binodal decomposition of binary solutions. Since there is no thermodynamic barrier in spinodal decomposition, phase decomposition is determined only by diffusion. Thus, at decay many features of phase decomposition can be described by the analytical solution. The equations of spinodal and binodal decomposition in solutions without structural phase transitions are obtained.
Keywords: binary solutions, the spinodal decomposition, a bimodal decay
The article is devoted to the problem of theoretical research and development of perovskite-based solar cells to optimize their design and increase efficiency. The paper presents a numerical simulation of the transfer and accumulation of charge carriers in the planar p – i – n heterostructure of a solar cell. The simulation is based on a stationary physico-topological model based on the diffusion-drift system of semiconductor equations. The efficiency of solar cells for different perovskite film thickness was obtained. It has been established that the maximum efficiency of the optimized design of a solar cell is about 27% with a perovskite film thickness of 500-700 nm and a defect concentration in it of the order of 1012 cm-3.
Keywords: Numerical simulation, solar cell, perovskite, film thickness, defect concentration, current-voltage characteristic
Experimental studies on the formation of nanoscale structures on the surface of gallium arsenide were carried out. To obtain a modified layer on the substrate surface, the method of focused ion beams was used, and the method of plasma-chemical etching was used for the subsequent formation of structures. According to the research results, structures with a width of 90 to 196 nm and a depth of 2 to 9.6 nm were formed. The results of the studies can be applied as structures for the subsequent formation of quantum dots during molecular beam epitaxy.
Keywords: Nanotechnology, focused ion beam, plasma treatment, atomic force microscope, GaAs
The relevance of the study of two-dimensional periodic graphene gratings in the terahertz range is described. The structure under study and the results of calculation of scattering and reflection diagrams of multilayer structures are presented.The relevance of the study of two-dimensional periodic graphene gratings in the terahertz range is described. The structure under study and the results of calculation of scattering and reflection diagrams of multilayer structures are presented.
Keywords: Golovacheva E.V., Ivanova I.N., Gribnikova E.I., Makhno V.V.
The local atomic and electronic structure of PANI / Cu nanocomposite was studied by X-ray absorption spectroscopy. It was found that as a result of the formation of a nanocomposite, the polymer chain is transformed by π electronic subsystem and changes local structure of copper. Polyaniline in composite is partially oxidized and protonated.
Keywords: polyaniline, polymer-inorganic composites, X-ray absorption spectroscopy, electronic structure, conductive polymers