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  • Counter-current flows in rotating helium II

    The paper discusses the flow induced by centrifugal forces in helium II on the outside of the rotating cylinder. The analysis was carried out in the framework of Landau's two-fluid theory, in the approximation of a plane incompressible fluid. A two-parameter family of solutions of the equations of motion is revealed, in which the centrifugal forces for the normal component are fully compensated by counter-current (normal and super-fluid components) flows. According to preliminary estimates, the most stable of them is the flow, in which the pressure forces in the superconducting part are also compensated, The results show that in the analysis of helium II rotations it is necessary to take into account countercurrent instabilities.

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

  • Investigation of the physico-chemical properties of promoted catalysts based on Co-Al2O3 / SiO2

    The physical and chemical properties of cobalt catalysts for the Fischer-Tropsch synthesis prepared by the method of impregnating a silicate carrier have been studied. The influence of oxide promoters on the specific surface, volume and pore sizes, the degree of reduction of metallic cobalt on the surface of Co-Al2O3 / SiO2 catalyst has been studied.

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

  • Effect of Al2O3 carrier modification on the properties of cobalt Fischer-Tropsch synthesis catalysts

    The parameters of the porous structure and the outer surface of cobalt catalysts for the Fischer-Tropsch synthesis prepared by the water-impregnation method were studied. The effect of the polymorphous modification of the support on the physico-chemical properties of the Co / Al2O3 catalyst was studied.

    Keywords: Fischer-Tropsch synthesis, synthetic motor fuel, catalyst, carrier, promoter, polymorphic Al2O3 modifications, elemental analysis, specific surface, porous structure

  • The technique of calculating the matrix elements of spectroscopic quantities for complex atomic configurations

    The paper presents an overview of the existing calculation schemes and the technique for obtaining the angular parts of the matrix elements of the spectroscopic quantities operators with the discussion of cases of complex electron configurations containing nonequivalent electrons. Using the example of a configuration with four unfilled electronic shells, the high efficiency of the technique for constructing wave functions of arbitrary electronic configurations is shown, based on a combination of Slater's determinant approach and the procedure for sequential coupling of orbital and spin moments on the basis of the Clebsch-Gordan coefficients in the LS coupling approximation.

    Keywords: Slater determinant, Clebsch-Gordan coefficient, orbital angular momentum, spin moment, 3j-symbol, coefficients of fractional parentage, LS-coupling

  • Development of metal-ceramic composite material for the friction unit of the absorbing apparatus of the railway car

    The absorbing apparatus serves to extinguish the impact when the wagons cohere and move. Most of the energy, about 80%, in this system is absorbed by a friction unit consisting of a friction wedge and a fixed plate. Absorption of energy in this system occurs due to the work of frictional forces arising during longitudinal motion of the pressure wedge with respect to the friction plate. Due to the large shock-frictional loads, intensive wear and destruction of the cermet cake occurs, which adversely affects the energy capacity of the absorbing apparatus. To eliminate these shortcomings, studies were conducted to create a new material. After numerous experiments, a composition was obtained with the optimum content of components, which maximally satisfies the working conditions of the friction unit and the requirements imposed on these devices.

    Keywords: absorbing apparatus, friction unit, cermet, wear resistance, friction plate, powder material, sintering technology

  • Electron beam surface modification of multi-component glasses for microsystems

    The questions of desorption of the elemental composition of glass during processing with an electron beam is discussed. Sample silicate glasses prepared by standard technology were studied after polishing by electron beam processing (EBP). Calculated estimates showed that the depth of the surface depletion layer of weakly alkaline elements reaches 20-50 nm. Herewith the temperature front reaches the machining depth of 50 µm.

    Keywords: electron-beam, glass, diffusion, desorption, microsystems

  • Effect of lithium cation on Raman spectra in melts of the LiNO3-LiClO4 system

    Concentration changes in the frequencies of Raman spectra in binary salt molten alkali metal systems with a common cation Li / ClO4, NO3 are shown. An antibiotic change in the frequencies of stretching vibrations is noted.

    Keywords: Concentration changes in the frequencies of Raman spectra in binary salt molten alkali metal systems with a common cation Li / ClO4, NO3 are shown. An antibiotic change in the frequencies of stretching vibrations is noted

  • Flicker noise in a simulated time dependences of amperage in polarization of the ferroelectric

    The main maintenance of a diversification of production as activity of subjects of managing is considered. being shown in purchase of the operating enterprises, theIn this work, we carried out computer simulations of the equilibrium polarization in the ferroelectric noise within the two-dimensional model Ishibashi in the case of deposits and intra-parietal areas. We considered different configurations influence of thermal noise. The analysis revealed flicker noise in the simulated time dependence of the current strength.

    Keywords: simulation, polarization current, domain walls, the noise, Ishibashi model, intra-region, parietal region

  • Polarization noise in ferroelectrics. computer simulation

    In the Landau theory of phase transitions taking into account thermal fluctuations of the computer modeling of ferroelectric polarization noise. Based on the spectral analysis, thermal and polarization noise are investigated. The presence of 1 / f noise in the polarization spectrum is detected.

    Keywords: ferroelectric, modeling, polarization noise, thermal noise, Fourier transform.

  • Investigation of the influence of synthesis methods on the properties of materials used in LTCC products

    To produce controlled radio frequency and microwave devices such as phased antenna arrays, delay lines, an affordable and inexpensive way of manufacturing varactors in large quantities should be found. One of the promising ways to produce such varactors is based on the use of a BST-paste with a low firing temperature, which allows it to be integrated into a substrate of low-temperature co-fired ceramics (LTCC).

    Keywords: semiconductor, ferroelectric, BST-paste, ferroelectric condenser, LTCC technology

  • The investigation of the optical properties of cobalt octaephylporphyrin

    The investigation provides the complex approach for optical properties study of the cobalt octaephylporphyrin. The complex shows the magnetic moment of the central ions. The strength and sign of anisotropy and optical transparency within the visible range can be changed by variation of an environment of the central metal atom (the ligand field) or its replacement. As a result, these materials can be used as stable qubits and nanoelements for spintronics and quantum computing. It is well-known that devices for spintronics and quantum computing require materials with femtosecond time resolution. The insights into the relations between geometry structure and optical and magnetic properties allow to design the tailor-made materials. In this work, we have investigated the optical properties of the cobalt octaephylporphyrin. We have calculated the theoretical spectra of the extinction coefficient, refraction index, and absorption index. These spectra provide us the additional information about optical transitions within the visible range. The design of the stable nanoelements with femtosecond time resolution is hardly-probable without understanding the nature of processes.

    Keywords: Molecular magnets, cobalt octaethylporphyrines, optical properties, dielectric function, femtosecond time resolution

  • Investigation of the structural parameters of promoted Co catalysts on a silicate carrier

    The parameters of the porous structure and the active surface of cobalt catalysts for the synthesis of liquid and solid hydrocarbons (Fischer-Tropsch synthesis) prepared by the method of impregnating a silicate carrier were studied. The effect of additives of oxide promoters on the specific surface, the volume and size of pores, the dispersion and size of crystallites of metallic cobalt on the surface of the Co / SiO2 catalyst was studied.

    Keywords: Fischer-Tropsch synthesis, motor fuel, synthetic hydrocarbons, catalyst, promoter, carrier, specific surface, porous structure, catalytic activity, selectivity

  • A new class of magnetodielectric materials based on manganites

    A new class of materials is proposed that change their dielectric permittivity as a function of the magnetic field strength. Such materials are two-phase composites of composition La0.7Sr0.3MnO3 / I, where I is the isolating phase, Li4P2O7 or GeO2. The ratio of components is close to the percolation threshold: from 10% to 20% by weight. Dielectric properties have been studied in the frequency range of the measuring field from 1 kHz to 1 MHz in magnetic fields from 0 to 15 kOe. Samples have an inductive impedance, their permittivity is negative. In a magnetic field, the permittivity increases in absolute value and at room temperature the values of the magnetodielectric coefficient reach 28%.

    Keywords: lanthanum strontium manganite, composite material, ceramics, one-step synthesis, magnetoresistance, percolation threshold, dielectric constant, barrier layer, tunneling, spin polarization

  • Generation of materials with managed voids rating in process of forming of biological polymer of NA-sodium carboxymethyl cellulose with fine particles of AlOOH for production of functional coatings

    New highly-porous film materials were created based on NA-sodium carboxymethyl cellulose, modifyed by particles of AlOOH. Forming of covers happen as a result of relatively not high temperatures (for about 55 degrees of centigrades). A regression model was suggested which described interrelation between sizes of forming porouses in the film cover with its composition. The ability was shown to manage physical specification of the cover which named surface porosity by changing containing of AlOOH in the composition. It was shown up that porouses were formed sizes between 300 mircometers and 2500 mircometers in proccess of curing of the cover while containing of boehmite in the composition. It was discovered that the general surface porosity was 65%, and the depth of cover was 600 mircometers. The ability was shown to create covers with sliding properties as exemplified in closing of pores by solid lubrication MoS2. It was discovered that it was observable down drag by 30-50% in response to application of covers on steel faces adding down of frictional force.

    Keywords: Porosity, NA-sodium carboxymethyl cellulose, AlOOH, ntifriction material, MoS2, friction

  • Influence of ultrafine modifiers on friction properties of composite coatings

    The conditions, which must be met by modifying additives into electrolyte for receiving of the effective composite Ni-P coatings with anti-friction properties, and the possibility of choice of the effective modificators were discussed. The efficiently of the ultra-dispersion powders of oxides with the corunde and rutile structures, the carbon and boron nitride with diamond-like structures, and powders of the some W and Mg type structures was examined.

    Keywords: structural phase disordering, nanostructures, compositional coatings, nano-diamond, anti-friction properties,modifiers

  • Investigation of coatings with antifriction properties based on the hydroxide film Al(OH)3 on aluminum with a solid-lubricant coating MoS2

    The article discusses the technological capabilities of application of vibratory mechanical hard lubricant coatings on the basis of MоS2 to improve the surface quality and operational properties of parts made of aluminum with an oxide coating.

    Keywords: vibration treatment, the vibration mechano-chemical coating of solid lubricant, combined methods of treatment

  • Features of the dielectric hysteresis of ferroelectrics-relaxors in a sinusoidally changing electric field

    The loops of the dielectric hysteresis of a soft ceramics based on PZT with Curie temperature TC=210℃ are investigated. The studies were carried out at a frequency of 50 Hz in two modes. In the first of them, the field was switched on by 0.07 seconds, in the second - it operated continuously. The amplitude of the field E_m varied from 2.5 to 25 kV / cm and switched stepwise with an interval of 15 minutes. The coercive field EC and the switchable polarization P_m were determined. The switching polarity in the saturation region turns out to be no more, in contrast to BaTiO3 and other materials, but less than the corresponding values obtained with short-term switching.

    Keywords: piezoceramics, piezoelectric material, hot pressing, dielectric hysteresis

  • Influence of the dielectric properties of the medium on the optical properties of enclosed gold nanoparticles

    In this paper, samples containing gold nanoparticles (NPs) distributed in different optically transparent media have been synthesized and characterized. A liquid (aqueous) and a solid (porous silicate glass and polymer (polyvinylpyrrolidone)) media were used. The samples obtained were characterized by optical spectroscopy and electron microscopy. The position of plasmon resonance band was analyzed depending on the dielectric constant of the medium.

    Keywords: gold nanoparticles, colloidal solution, polymer, porous glass

  • Physical properties of light-emitting sold solutions, isoperiodic gallium antimonide

    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: thermomigration, solid solutions, gradient epitaxy, diode with fine mes, gallium antimonide, fundamental transition, photoluminescence spectra

  • On the possibility of using boron-containing diffusion coatings on cutting tools of high speed steels

    Improving the performance of tools by improving their structural condition by method of boriding and heat treatment will ensure the rational use of expensive high alloy materials for the manufacture of cutting tools with working part having a high mechanical and operational properties, which, of course, is an urgent task for the modern machine-building production.

    Keywords: cutting tools, chemical-heat treatment, method of boriding

  • Influence of barrier substances on magneto-resistive properties of composites based on strontium lanthanum manganite

    Based on our own, as well as literary experimental data, the analysis of the Influence of a barrier material used to create heterogeneous composites based on La0.7Sr0.3MnO3 on their magnetoresistive properties is carried out. Such composites differ in existence of an isotropic negative magnitorezistivnost (MR) connected from backs - dependent tunneling of carriers in magnetic field. The largest value MR up to 15% in the field of 15 kOe are shown when using glass-like GeO2 oxide at a percolation ratio of components.

    Keywords: lanthanum strontium manganite, composite material, ceramics, one-step synthesis, magnetoresistance, percolation threshold, dielectric constant, barrier layer, tunneling, spin polarization

  • Problems of interpartial merging and way of their decision when forming structure of powder steel 110G13P

    Stages of receiving samples of high-austenitic powder steel 110G13P a method of dynamic hot pressing are presented. Processes of formation of structure and properties of steklosoderzhashchy powder steel 110G13P are considered. Significant positive effect on formation of structure of powder steel 110G13P with application glass components is defined.

    Keywords: high-austenitic powder steel, method of dynamic hot pressing, agglomeration, mechanical activation of furnace charge, oxidic films

  • Research of the possibility of reducing resistance of the graphite coating in the solid tantalum capacitor

    In recent years, the most widely used semiconductor oxide-tantalum capacitors in high frequency circuits acquired, which causes the need to reduce resistance of the contact and the semiconductor layers. One solution to this problem and at the same time, promising way of improving solid-state tantalum capacitors is to modify process technology for applying the semiconductor layer and heat treatment resistive coating of colloidal graphite. Contact carbon layer according to conventional technology is applied by impregnating the tantalum capacitor sections in an aqueous suspension of colloidal graphite (usually imported), and then produce exposure to air and heat treatment at an elevated temperature. This article presents the results of studies of the effect of conditions of application of the contact layer of colloidal graphite on the electrical characteristics of sections of tantalum oxide-semiconductor capacitor, in particular in the equivalent series resistance, the technique of applying aquadag. Described in detail the design of solid-state tantalum capacitor, the role of the contact carbon layer and its contribution to the ESR of the capacitor.

    Keywords: oxide-semiconductor capacitors, colloidal graphite, resistance of the capacitor, the cathode coating, suspension, immittance, aquadag

  • Using of manganese-vanadium concentrate for intensification of vanadium-containing converter slag roasting

    A manganese-vanadium concentrate precipitate containing V2O5 and MnO2 is formed on the stage of wastewater ozone treatment in sodium technology of vanadium-containing converter metallurgical slag processing. Vanadium content of the slag changes between 4 and 15 % wt and manganese content changes between 62 and 75,5 % wt. The article examines influence of concentrate with 14,33 % wt V2O5 and 65,44 MnO2 % addition in slag-with-soda furnace feed to determine positive effect on the result of roasting. Vanadium content of the slag is 22,34 % wt expressed as V2O5. Roasting temperature is 850 °C, Na2O/V2O5 molar ratio is 0,5:1, the concentrate is added as 0,25; 0,5; 1,0 mass ratio on the content of soda in starting furnace feed. Degree of vanadium conversion in water- and acid-soluble compounds is increased. The most effect is provided on the process of interaction between vanadium oxides and spinels with sodium compounds with formation of water-soluble vanadium forms. The optimal addition of concentrate is 0,25-0,5 mass ratio on the content of soda. Increasing of concentrate content is not effective. Both manganese and vanadium contained in concentrate give positive effect. Concentrate addition can be recommended for existing industry regardless of type of alkali addition on the stage of roasting.

    Keywords: vanadium-containing slag, oxidating roasting with sodium, manganese-vanadium concentrate, increasing of vanadium yield, soluble compounds of vanadium and manganese

  • The effect of the phase composition of titanium dioxide on the photocatalytic degradation of organic dyes

    In the present work, a study was made of the properties of a photocatalyst-adsorbent based on metal oxide, which was titanium dioxide (TiO2). The photodegradation activity of two organic dyes under the action of light was analyzed. The effect of the phase composition of the photocatalyst was compared on the example of three modifications of TiO2 - rutile, anatase and their mixture.

    Keywords: TiO2, photocatalysis, metal oxide, dyes