×

You are using an outdated browser Internet Explorer. It does not support some functions of the site.

Recommend that you install one of the following browsers: Firefox, Opera or Chrome.

Contacts:

+7 961 270-60-01
ivdon3@bk.ru

  • Analysis of structural mechanisms of formation of the low-symmetric spinel phases

    The possibility of formation of a certain set of disordered and partially ordered phases of solid solutions with defective spinel structures is analyzed. The compositions and symmetry of the structures of ordered phases and the nature of the change in residual disordering depending on the degree of deviation from the stoichiometry of the structural type of normal spinel are theoretically determined.

    Keywords: structural-phase disorder, solid solutions, spinalator phase retinopathy phase coating

  • Electrodeposition of a dispersed alloy of iron-nickel in stationary and non-stationary electric modes

    The process of electrodeposition of the iron-nickel alloy in stationary and non-stationary electric modes is studied. The influence of periodic currents of various forms and parameters on the rate of extraction of the alloy components, its composition, and also the current efficiency of the alloy is investigated.

    Keywords: iron-nickel alloy, current density, current efficiency

  • Cathodic processes in intergranular corrosion of nickel-chrome stainless steel

    The nature of cathodic reactions occurring during intergranular corrosion (ICC) on stainless steel 08X18H10T in a solution of 0.5 M H2SO4 + 0.01 M KCNS is considered. Evaluation of the thermodynamic potential of various reactions with components of the solution showed that the ICC process in this system proceeds with mixed oxygen-hydrogen depolarization. When the temperature rises, an intensification of the cathode process occurs, which is associated with a decrease in the overvoltage of the reduction of oxidants. Forced medium movement at low temperatures also facilitates the cathodic process, and at elevated temperatures the effect of convective medium movement decreases. This is due to the decrease in the proportion of oxygen involved in the cathode process, since its concentration in solution increases with increasing temperature.

    Keywords: intergranular corrosion, stainless steel, temperature and hydrodynamic conditions

  • Electrical properties of magnetoresistive composites based on manganites

    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

  • Obtaininq a ferromanqanese alloy by the metallothermal method and determining the content of the elements (Fe, Mn) by the potentiometricSimulation of the design activity diversification of innovative enterprise

    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

  • Investigation of the effect of Zr and Mn promoters on the properties of cobalt catalysts for Fischer-Tropsch synthesis

    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

  • Pt/SnOx-C electrocatalytic systems with different morphology of tin oxide

    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

  • Cobalt Fischer-Tropsch synthesis catalysts supported on Al2O3 of various polymorphic modifications

    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

  • Еntropy analysis of complex systems as a tool of engineering activity

    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

  • Polymer-matrix nanocomposites containing mineral nanoparticles: synthesis, properties, applications

    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

  • Theoretical study of decay in binary systems. Part of the Equation of the spinodal and binary decay of the binary system in the isotropic phase

    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 influence of liquid crystals based lubricants for Me - Me friction pair

    It has been established that the concentration of cholesterol mesogenic esters in lubricants ambiguously affects the microrelief parameters and the tribotechnical characteristics of a steel 45 – steel 45 friction pair. %, the best indicators of friction and wear of metals, on the contrary, are realized with an increase in the concentration of cholesterol esters in lubricating compositions.

    Keywords: lubricant, cholesteric liquid crystal, microrelief on friction surface, coefficient of friction

  • Influence of the method of introducing additives on the composition and porous structure of Co-catalysts for the synthesis of hydrocarbons

    Three batches of Co-MxOy / SiO2 catalysts were prepared with different methods of introducing an oxide additive. Physicochemical studies of catalysts by elemental analysis and Brunauer-Emmett-Taylor (BET) methods have been carried out. The effect of additives of oxide promoters and the method of their introduction on the specific surface, volume and pore sizes for Fischer-Tropsch synthesis catalysts were studied.

    Keywords: Fischer-Tropsch synthesis, carbon-containing resources, catalyst, active component, silicate carrier, Al2O3 and ZrO2 promoters, elemental analysis, BET method, surface area, volume and pore size

  • Influence of the method of introducing a promoter on the properties of the active component Co catalysts for the synthesis of hydrocarbons

    Using the methods of thermo-programmed reduction (TPV) and thermo-programmed hydrogen desorption (TPD H2), physico-chemical studies of Co-MxOy / SiO2 catalysts obtained by various methods of introducing a promoter additive were carried out. The effect of the introduction method and the nature of the promoting oxide additive on the properties of the active component of the Fischer-Tropsch synthesis catalysts was studied.

    Keywords: Fischer-Tropsch synthesis, catalyst, active component, silicate carrier, Al2O3 and ZrO2 promoters, TPV and TPD H2 methods, crystallite size, degree of reduction, dispersity

  • Methods for solving the problem of crystal-chemical design of composite coatings with anti-friction properties

    The interrelation of tribological properties of composite coatings with the properties, structure and distribution of surface phases, as well as the mechanism of formation of surface phases is discussed.

    Keywords: the structure of crystals, structural phase disorder, tribological properties of the surface phases of the composite coating

  • Physical and chemical properties of cobalt catalysts with promoting additives of copper and zirconium

    Physical and chemical properties of cobalt catalysts for Fischer-Tropsch synthesis are investigated. The influence of copper and zirconium oxides on the specific surface area, cobalt concentration, pore volume and size, the degree of reduction of the catalyst Co-Al2O3/SiO2 was studied.

    Keywords: Fischer-Tropsch synthesis, carbonaceous resources, catalyst, active component, silicate carrier, CuO and ZrO2 promoters, elemental analysis, recovery rate, BET method, specific surface area

  • Research of influence of additives on physical and chemical properties of cobalt catalysts of Fischer-Tropsch synthesis

    The study of physical and chemical properties of cobalt catalysts in the synthesis of hydrocarbons by the Fischer-Tropsch method is carried out. The effect of additives promoters NiO, Fe2O3, MnO2, on the specific surface area, pore volume, size of cobalt crystallites, the degree of catalyst reduction is considered

    Keywords: Fischer-Tropsch synthesis, synthetic hydrocarbons, catalyst, promoter, carrier, specific surface area, porous structure, catalytic activity, dispersion, cobalt crystallites

  • Spatial equations of mechanics of composite solid for viscoelasticity models containing in one-dimensional case of two elastic and one viscous element

    For the first time, in the generalization to the spatial case of a one-dimensional viscoe-lasticity model for one viscous and two elastic elements, the stress deviators, deformations, and also the stress and strain rates were used. It is established that the model of a standard viscoelastic body (standard linear solid model) is more universal. The second model cannot be used to solve problems for a weighty body, or dynamic problems, since leads to the solution of an auxiliary physically unjustified boundary or initial-boundary value problem for doubled values of the accelerations. It means that the second model can be applied only to the solution of quasistatic problems for weightless bodies. It is established that the model of a standard viscoelastic body (standard linear solid model) is applicable only to the study of unsteady creep, while the second model is suitable for investigating the steady rheological behavior of a weightless material. Generalization of both models viscoelasticity for composite body was created. The effective Kravchuk-Tarasyuk values of the Poisson ratio, the Young's modulus, and the viscosity of composite material were defined.

    Keywords: deviator of stresses, deviator of strains, deviator of stress rates, deviator of strain rates, viscosity, standard linear solid model

  • A new type of vortex-free flows of helium II in a rotating cylinder

    Within the framework of the two-fluid Landau theory, flows into helium II inside a rotating cylinder are investigated. Special attention is paid to the analysis of excitation by centrifugal forces of counter-current (by super-fluid and normal components) flows. In the approximation of incompressible fluid, an analytical solution of the equations of motion, vortex-free for both components is obtained. The tangential velocities for it are the same as those of a rotating solid body, with the normal and superfluid components moving in opposite directions, with different angular velocities. It's resulting vorticity is compensated by a spiraled counter-current radical movements. Such solution has no axial symmetry and has a tangential gap along the radius. Despite its instability, it is of some interest. First, it can be corrected by stabilizing deformations. In addition, it shows the paths of loss of stability of high-symmetric States. In particular, in our opinion, this type of disturbance are intermediate flow from Landau (superfluid component is at rest) one to the rotation of the Feynman type (in the superfluid part of a system of vortices).

    Keywords: helium II, rotating cylinder, two-fluid theory, counter-current flows, centrifugal forces, vorticity compensation

  • Determination of the yield stress of the material by static indentation

    For the first time, using the simplest model of an elasto-ideally-plastic coating, a relationship between the Meyer hardness and the absolute value of the yield stress of the material under compression was established for all types of indenters used for static hardness testing. The necessity for an accurate determination of the thickness of the layer in the simplest coating model is eliminated, when using the Prandtl bilinear diagram corresponding to an elasto-perfectly-plastic material as the equation of state. If the linear dimension of the test mark of the hardness is equal to 90 percent of the linear dimension of the total contact area, taking into account the elastic deformations, than the Meyer hardness is the absolute value of the compressive yield strength for the material under compression.

    Keywords: surface hardness, Meyer hardness, yield strength, ball indenter, conic indenter, pyramidal indentor

  • The effect of modifying additives on the properties of the supported cobalt catalyst

    The physical and chemical properties of cobalt catalysts for Fischer-Tropsch synthesis have been studied. The effect of copper and iron oxides on the specific surface, pore volume and dimensions, and the degree of reduction of metallic cobalt on the surface of the Co-Al2O3 / SiO2 catalyst have been studied.

    Keywords: Fischer-Tropsch synthesis, synthetic hydrocarbons, catalyst, cobalt, promoter, carrier, specific surface, porous structure, catalytic activity, reduction degree

  • The structure of epitaxial layers of narrow-gap solid solutions and compensation of defects

    The paper contains an analysis of the results of experiments on obtaining radiative structures based on gallium antimonide, formed by the method of thermal melt migration in a semiconductor matrix. The epitaxial process modes within the selected range were optimized for such parameters as the wavelength corresponding to the fundamental transition, a small lattice discrepancy, a small discrepancy in the coefficients of thermal expansion of the growing TP and the matrix. An original effect is described - an increase in the solubility of the Bi content in solid solutions, isoperiodic binary compounds A3B5 under conditions of a gradient temperature field. This effect allows a wide variation in the optical parameters of the element base of instruments based on solid solutions of GaSbBi / GaSb. The mechanisms of the generation of dislocations in a crystallized solid solution and the features of electrophysical and photoelectric parameters are analyzed. A structural solution of a light-emitting diode with strip geometry is proposed.

    Keywords: solid solutions, recrystallization, gradient liquid-phase epitaxy, thermomigration, indium antimonide-bismuthide, melt thickness, temperature gradient, components, growth coordinate, epitaxial layers

  • Physical properties of multicomponent narrow-gap solid solutions with mesostructure authors

    In this paper, the modeling of phase equilibria in multicomponent systems of A3B5 compounds was carried out and the compositions of the liquid phase equilibrated with a given solid solution were calculated. A model of excess thermodynamic functions is used, which takes into account the formation of associates in the melt near the solidus temperatures. The developed algorithm allows solving a direct problem (in which the input parameters are the growth temperature of the layers and the composition of the solid phase corresponding to the expected instrument characteristics) and the inverse problem (the growth temperature and composition of the solid solution are sought for the given liquid phase). The limiting concentrations of the alloying components, arsenic and bismuth, are determined. The structural and electrophysical characteristics of multicomponent semiconductor A3B5 heterosystems are discussed, the solid solutions of which crystallize from the liquid phase in a gradient thermal field. The mechanism for introducing impurities into the lattice of epitaxial layers of multicomponent solid solutions is described for the first time. With an increase in the thickness of the crystallizable film, the thermodynamically equilibrium substitution by antimony bismuth atoms is completed and the introduction of Bi atoms into the interstices takes place. The interaction of neighboring atoms with the valence electron shells of Bi becomes more symmetrical, which causes an increase in concentration. The concentration of film defects near its rear surface also increases. The obtained values of electrophysical parameters make it possible to draw a conclusion about the instrumental suitability of the materials under study.

    Keywords: solid solutions, mesostructure, antimonide, alloying, liquid phase, phase transformations, binary compounds, associates, lattice constant, multicomponent systems

  • Optimization of the reanodization in the production of tantalum oxide-semiconductor capacitors

    A complex of technological operations for the formation of a cathode liner based on manganese dioxide is of particular importance in the production of tantalum oxide-semiconductor capacitors. Electrical characteristics and reliability indicators of capacitors are laid at this stage in their manufacture. In according with the classical technology, the formation of a semiconductor coating of MnO2 on tantalum capacitors is associated with multiple heating of oxidized anodes with the previous impregnation in solutions of manganese nitrate. It has a negative effect on the quality of the Ta2O5-dielectric. To minimize the defect formation in the dielectric, is realized a periodic electrochemical anodization of the tantalum anode in the acetic acid solution by anodic connection of the sections of the capacitors to the direct current source. The authors proposed to modify the process of reanodization of sections of tantalum oxide-semiconductor capacitors by changing the composition of the electrolyte. The results of the investigation of the electrochemical anodizing of a tantalum anode in aqueous solutions of nitric acid and manganese nitrate are presented, the morphology of the obtained coatings, their phase composition, as well as electrical parameters of the sections of capacitors manufactured by the proposed method are analyzed.

    Keywords: Tantalum oxide-semiconductor capacitor, reanodization, manganese nitrate, capacitance, leakage current, dielectric loss tangent, electrolyte

  • Cobalt-nickel catalysts for the synthesis of hydrocarbons on alumina carriers

    The dispersion parameters of the active component of cobalt catalysts promoted by nickel for Fischer-Tropsch synthesis by the temperature-programmed hydrogen desorption method (TPD H2) were studied. The influence of the polymorph (γ, θ, α) of the support on the physicochemical properties of the Co-Ni / Al2O3 catalyst was studied.

    Keywords: Fischer-Tropsch synthesis, biomass, catalyst, support, Ni promoter, polymorphic Al2O3 modifications, TPD H2 method, active surface, dispersity, cobalt crystallites