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The reduction of divalent nickel with hydrazine hydrate from alkaline ammonia solutions at elevated temperatures was studied. A procedure to synthesize finely divided nickel powders was proposed. The morphology of the objects obtained under various synthesis conditions was investigated by scanning electron microscopy; it was shown that both needle-like and spherical particles can form. The specific surface area of the synthesized metallic nickel powders was determined by low-temperature nitrogen adsorption to be within the range 5–20 m2/g, depending on the synthesis conditions (the concentration of the initial salt in the solution, the pH, and the temperature). X-ray powder diffraction analysis showed that all the powders are mixtures of two phases: nickel (to 99%) and nickel hydroxide. X-ray photoelectron spectroscopy demonstrated that a particle of the powders consists of a nickel(0) core coated with several atomic layers of nickel hydroxide.

The kinetics of the solid-state reaction between nanolayers of polycrystalline copper and amorphous silicon (a-Si) has been studied in a Cu/a-Si thin-film system by the methods of electron diffraction and simultaneous thermal analysis (STA), including the methods of differential scanning calorimetry (DSC) and thermogravimetry (TG). It has been established that, in the solid-state reaction, two phases are formed in a sequence: Cu + Si → η″-Cu3Si → γ-Cu5Si. It has been shown that the estimated values of the kinetic parameters of the formation processes for the phases η″-Cu3Si and γ-Cu5Si, obtained using electron diffraction, are in good agreement with those obtained by DSC. The formation enthalpy of the phases η″-Cu3Si and γ-Cu5Si has been estimated to be: ΔHη″-Cu3Si = −12.4 ± 0.2 kJ/mol; ΔHγ-Cu5Si = −8.4 ± 0.4 kJ/mol. As a result of the model description of the thermo-analytical data, it has been found that the process of solid-state transformations in the Cu/a-Si thin-film system under study is best described by a four-stage kinetic model R3 → R3 → (Cn-X) → (Cn-X). The kinetic parameters of formation of the η″-Cu3Si phase are the following: Ea = 199.9 kJ/mol, log(A, s−1) = 20.5, n = 1.7; and for the γ-Cu5Si phase: Ea = 149.7 kJ/mol, log(A, s−1) = 10.4, n = 1.3, with the kinetic parameters of formation of the γ-Cu5Si phase being determined for the first time.

A method making it possible to form HTS ceramics of non-superconducting coating consisting of self-organizing CuO crystals, whose sizes are less than the coherence length, i.e., within several tens of nanometers, has been developed. It has been shown that the combination of self-organizing structures in the form of whiskers and nanoparticles which arise as a result of combined sintering of YBa2Cu3O(7–x) powders and electric arc CuO nanopowders results in a significant increase in the current density and appearance of peak effect at high magnetic fields. Very high current density arises from the complex vortex pinning, where whisker defects provide high pinning energy and nanoparticles suppress flux creep. The morphology of such structures can be controlled by a simple change in the concentration of nanodisperse additives. It has been shown that 20 wt % of CuO additive is optimal.

Samples of an electrocontact composite material (CM) based on silver and reinforced with a zinc oxide nanopowder in an amount of 2–10 wt % are prepared by powder metallurgy. The microstructure of the CM samples is studied by electron microscopy and their electrical resistivity is determined. The mathematical simulation of the electrical resistivity was performed using the lattice model of an Ag–ZnO powder CM. To bring the structure of the finite element model to the structure of real electrocontact CM samples, which have with more complex geometry, as close as possible, we developed a program to automate the processes of constructing a finite element model of CM, applying boundary conditions, and solving and displaying results. To verify the generated CM model, we estimated the electrical resistivity of the lattice model CM for various nonconducting-component volumes in comparison with an analytical calculation and experimental results.

Results of experimental study of the temperature field of coatings deposited under different conditions are presented. Revealed in this paper are the basic technical options of the control of the thermal state of coatings and determination of the noncrystalline solidification regimes of melt.

This article presents experimental data on the coefficients of viscosity and thermal and electrical conductivities, as well as the absorption spectra, of suspensions of ultradispersed diamonds. Suspensions of UDA-S and UDP-A detonation nanodiamond particles, as well as UDP-AG diamond–graphite powder, are used in the experiments. The concentration of nanodiamonds in distilled water is varied within a range of 0.5–5 wt %. It is shown that the technology of purification diamond powders from side products of their synthesis substantially affects the physicochemical properties of aqueous suspensions of these powders.

Pb10 – xPrx(GeO4)2 + x(VO4)4 – x (x = 0, 1, 2, 3) apatites have been prepared by solid-state reactions via sequential firing of appropriate oxide mixtures (PbO, Pr2O3, GeO2, and V2O5) in air in the temperature range 773–1073 K. Their unit-cell parameters have been determined as functions of temperature by high-temperature X-ray diffraction measurements, and the linear and volume expansion coefficients of Pb7Pr3(GeO4)5(VO4) have been calculated. The heat capacity of the synthesized Pb10 – xPrx(GeO4)2 + x(VO4)4 – x (x = 0, 1, 2, 3) compounds with the apatite structure has been determined by differential scanning calorimetry in the temperature range 350–1050 K. The cp(T) curves of the samples with x = 1, 2, and 3 have been shown to have extrema (in particular, peaks at 701, 917, and 1018 K for the x = 3 sample) due to phase transitions. The experimental Cp(T) heat capacity data have been used to evaluate the thermodynamic functions of the synthesized apatites.

A new silver-based electrocontact material dispersion-strengthened with nanopowders of zinc, tin, and titanium oxides has been obtained. The microstructure and elemental composition of the phases formed during solid-phase sintering and electroerosive tests have been studied by electron microscopy and energy-dispersive microanalysis. The electroerosive wear is determined during laboratory tests, and the transition resistance is calculated. The developed electrocontact material possesses physicomechanical and operating characteristics that are similar to those of a commercial contact prepared using toxic cadmium oxide.

Specific features of the structure formation in rapidly quenched high-cobalt alloy coatings formed by plasma sputtering have been investigated. The structural state of the investigated coatings has been identified by the X-ray diffraction technique. The sequence and kinetics of structural transformations occurring in the specified time-temperature heating regimes have been examined using differential thermal analysis. It has been established that heat generation and crystallization temperature depend on the conditions of formation of bulk amorphous coatings.

Electrical resistivity of the Fe X Mn 1−X S (0 ≤ X ≤ 0.29) single crystals based on the Mott insulator α-MnS is experimentally studied in the temperature range of 2–300 K at ambient pressure (P = 0) and at high (up to 30 GPa) hydrostatic pressures for x = 0.12. The electron subsystem of Fe X Mn 1−X S undergoes insulator-to-metal transitions indicated by a resistivity drop by a factor of 10 6 with an increase in the chemical pressure (X) due to the cation substitution under ambient conditions and at the hydrostatic pressure (P C = 27 ± 5 GPa) for x = 0.12. The results obtained show that the hydrostatic pressure - and cation-substitution induced insulator-to-metal transitions in the α-MnS-based Mott compounds have similar mechanisms. The dependence of the critical hydrostatic pressure P C on the Fe content in Fe X Mn 1−X S is established.

Fe substitution effect on the magnetic behavior of Mn2−xFexBO4 (x = 0.3, 0.5, 0.7) warwickites has been investigated combining Mossbauer spectroscopy, dc magnetization, ac magnetic susceptibility, and heat capacity measurements. The Fe3+ ions distribution over two crystallographic nonequivalent sites is studied. The Fe introduction breaks a long-range antiferromagnetic order and leads to onset of spin-glass ground state. The antiferromagnetic short-range-order spin correlations persist up to temperatures well above TSG reflecting in increasing deviations from the Curie-Weiss law, the reduced effective magnetic moment and “missing” entropy. The results are interpreted in the terms of the progressive increase of the frustration effect and the formation of spin-correlated regions.

Magnetic resonance characteristics of mixed chalcospinel nanocrystals CuCr2SxSe4−x (x = 0 and 2) and CoxCu1−xCr2S4 (x = 0.1 and 0.2) have been investigated. It has been established based on TEM, SEM and resonance data that all the samples contain both blocks with sizes from 1 to 50 m of compacted nanosized crystallites and individual nanoparticles with sizes from 10 to 30 nm. The studies provide evidence of strong interparticle interaction in all the samples leading to high values of the blocking temperature. Magnetic dipolar field arise in the boundary regions of interacting adjacent nanocrystals below the blocking temperature. This results in inhomogeneous broadening of the magnetic resonance spectrum along with appearance of additional absorption lines. With increase in magnetic anisotropy at low temperatures, a shift of the resonance field along with line broadening are observed for all the studied compounds due to freezing of the moments in the nanoparticles, both in the individual and compacted ones. A gapped characteristic of the resonance spectrum is established below the freezing temperature Tfr, with the energy gap defined by the averaged magnetic anisotropy . Anionic substitution of sulfur by selenium results in a decrease in the magnetic anisotropy. In contrast, cationic substitution of copper by cobalt increases the magnetic anisotropy due to a strong contribution from the latter ion.

The microstructure of the transition zone and powder spacer, the concentration distribution of chemical elements over the width of the diffusion-bonded joint, and microhardness of 45 steel–compacted Ni powder spacer–45 steel layered composites formed by diffusion bonding have been investigated. It has been shown that the relative spacer thickness χ < 0.06 is optimal for obtaining a high-quality joint has been formed under a compacting pressure of 500 MPa. The solid-state diffusion bonding is accompanied by sintering the nickel powder spacer and the formation of the transition zone between the spacer and steel. The transition zone consists of solid solution of nickel in the α-Fe phase and ordered solid solution of iron in nickel (FeNi3).

We have made investigations of the phase formation and microstructure on the ceramics obtained from a starting nanopowder mixture with the weight ratio ZnO : TiO2 = 4 : 1. Ceramic is obtained at different sintering temperatures, namely, 948, 1223 and 1473 ?. Using the characterization methods of electron microscopy, energy dispersive microanalysis and X-ray diffraction phase analysis it has been shown that the ceramics structure is consisted of two dispersed phases of Zn2TiO4 and ZnO with the grain sizes being in range 0,5-1 ?m. It has been found also that, at ceramic`s sintering temperature of 1223 ?, the solid phase interactions are completed with the structure ZnO : Zn2TiO4 ? 1 : 1,5 phase ratio.

A solid-state reaction process in Ag/Al multilayer thin films has been investigated by the methods of in situ electron diffraction, simultaneous thermal analysis, transmission electron microscopy and X-ray diffraction with the aim of studying the phase formation kinetics of intermetallic compounds. The sequence of the phase transformations in the solid-state reaction has been established: Ag+Al→(Ag)+(Al)→(Ag)+δ-Ag2Al→μ-Ag3Al. The process of the solid-state interaction has been shown to consist of two steps; each of them is described by a kinetic model of the nth order reactions with autocatalysis. The kinetic parameters of the autocatalytic process of the phase formation for δ-Ag2Al and µ-Ag3Al, have been determined, in particular, their apparent activation energy: 126 kJ/mol and 106 kJ/mol, respectively.

Fe x Mn1−x S belongs to the group of strong electron correlations compounds MnO. We present here experimental results for the antiferromagnetic iron–manganese sulfide system, based on X-ray and neutron diffraction studies. The neutron diffraction investigations were carried out at ambient conditions and at hydrostatic pressures up to 4.2 GPa in the temperature range from 65 to 300 K. Our results indicate that the Neel temperature of α-MnS increases up to room temperature by applying chemical (x Fe) or weak hydrostatic pressure P. In Fe0.27Mn0.73S, the Neel temperature increases from 205(2) K (P = 0 GPa) to 280(2) K (P = 4.2 GPa) and the magnetization at 100 K decreases by a factor of 2.5 when the hydrostatic pressure increases from 0 to 4.2 GPa.

Samples of a composite electrocontact material based on silver strengthened by the dispersed phases of zinc and titanium oxides have been investigated by the electron microscopy and energy dispersive X-ray spectroscopy. A uniform distribution of the oxide phases containing 2 wt % zinc oxide in the initial charge has been revealed. The increase in the amount of zinc oxide leads to an increase of the size of the oxide phases. It has been shown that at the zinc oxide content of 2 wt %, the minimum wear is observed in the process of electroerosion tests; at 3 wt %, an overheating and welding of the contacts are observed.

The paper deals with the experimental study of nanofluids boiling on cylindrical heater. The studied nanofluids were prepared on the basis of distilled water and nanoparticles of silicon, aluminum and iron oxides as well as diamond. The volume concentration of nanoparticles varied from 0.05 to 1%. The nanoparticles diameter ranged from 10 to 100 nm, the diameter of the heater was varied from 0.1 to 0.3 mm. It is revealed that the use of nanofluids provides a several-fold increase of the critical heat flux. However, critical heat flux in nanofluids depends on the material and size of nanoparticles as well as on the diameter of used cylindrical heater. It is shown that the critical heat flux increases with increasing the nanoparticles size, while it decreases with increasing the heater diameter. It was revealed for the first time that the critical heat flux depends on the boiling process duration.

(Co + Al)-doped ZnO films have been synthesized by the RF magnetron sputtering. Films of this composition have first been obtained in mixed atmosphere of Ar + H2. High hydrogen concentration of 20–50% has been used together with high enough substrate temperature of 450 °C. The used technological conditions affected the morphology, chemical composition, optical, electric, and magnetic properties of the films to an even more than in the case of Co-doped ZnO films synthesized under the same conditions and studied earlier. The films exhibit ferromagnetic behavior at room temperature with much greater magnetization and magneto-optical activity compared to the Co-doped films. At the same time, the hydrogenated films show an increase in electric conductivity in comparison with samples synthesized in the atmosphere of Ar + O2. The magnetic nature of the hydrogenated films has been associated with the defect-related mechanism.

Investigations were carried out into the microstructure and properties of diffusion-welded joints produced through a submicron nickel powder layer deposited on the metallic coating at welding temperatures of (0.4–0.7) Tm. The results show that using the submicron powder as an activating layer produces high quality diffusion-welded joints at 850 °C, which is equal to 0.6Tm.

Nickel oxide nanoparticles were first synthesized by sputtering high-purity nickel in an oxygen plasma of a low-pressure arc discharge. The structure, morphology, and optical and magnetic properties of NiO nanoparticles were studied by XRD, TEM, FTIR, UV-VIS, and VSM. TEM images showed that the obtained NiO nanoparticles have a narrow particle size distribution and an average particle size of 12 nm. The XRD results and the processing of diffractograms by the Rietveld method showed that the obtained nanoparticles have a face-centered cubic lattice with an average particle size of 13 nm. With decreasing temperature, residual stresses increase and peaks corresponding to the superstructure appear. The band gap of NiO was determined from the optical absorption spectrum and amounted to 3.21 eV. Magnetic measurements showed that, at temperatures of 200 and 300 K, NiO nanoparticles, unlike bulk particles, exhibit ferromagnetic behavior, and at 5 K a magnetic hysteresis loop appears. Based on the studies, a dendritic model of the nanoparticle microstructure is proposed.

Nanopowders of zinc and titanium oxides were used to obtain samples of Zn2TiO4–ZnO ceramic. Phase formation as well as the microstructure and elemental composition of the phases formed were studied by means of electron microscopy. The density and porosity were calculated, and the sizes of grains and pores in the ceramic were determined. The temperature at the zinc titanate forms was determined. It was shown that it corresponds to the sintering temperature of electrocontact materials with this composition. It is proposed that zinc titanate and oxide be used as arc-suppressing and dispersion-hardening additional additives in copper-based electrocontact materials.

Nanoclusters and nanocrystals of the room temperature magnetic spinel CuCr2S4 synthesized using a facile solution-based method were examined by magnetic resonance in a wide frequency range 9.6÷80 GHz and at temperatures down to 4.2 K. Decreasing of the resonance field and broadening of the resonance lines are found below ∼ 50 K for both the nanocluster and nanocube samples due to the freezing of magnetic moments of nanocubes and nanocrystalline particles constituting nanoclusters. Additional blocking temperature Tb≅300 K appears in nanoclusters due to the freezing of the magnetic moment of the entire cluster as a whole. Below this temperature, an additional low-field resonance line is found in the resonance spectra of nanoclusters at X-band.

The microstructures of the transition zone and the powder layer, the concentration distribution of chemical elements across a diffusion joint, and the microhardness of the grade 45 steel-Ni powder layer-grade 45 steel layered composite materials fabricated by diffusion welding at various temperatures are studied. It is shown that the deposition of a nickel sublayer on steel and the application of a submicron nickel powder as an activating layer make it possible to form a high-quality diffusion joint at a temperature of 850°C, which is ~0.6 of the melting temperature of nickel (which has the lowest melting temperature in the given composite material). The sintering of a nickel powder and the formation of a transition zone between the nickel layer and steel occur simultaneously in a solid phase during diffusion joining. The transition zone consists of an α-Fe solid solution and the FeNi3 compound.

Solid-state reaction processes in Fe/Si multilayer nanofilms have been studied in situ by the methods of transmission electron microscopy and electron diffraction in the process of heating from room temperature up to 900ºС at a heating rate of 8-10ºС/min. The solid-state reaction between the nanolayers of iron and silicon has been established to begin at 350-450ºС increasing with the thickness of the iron layer.

This paper presents the results of silicon oxide nanoparticles-incorporated drilling fluid filtration through a porous medium with different permeability. A water-based clay suspension was used as a basic model for creating investigated fluid samples. AlN (aluminium nitride) particles were used as a dispersed phase. The concentration of microparticles varied from 0.5 to 4.00 wt%, while the microparticles size varied from 1 to 10 μm. The concentration of SiO2 nanoparticles was changed within the range of 0.25 and 4.00 wt%, while the nanoparticles size varied from 5 to 100 nm. It was shown that filtration of drilling fluids with nanoparticles inclusions depends on their concentration, size and material, the concentration and size of microparticles and the pore sizes of ceramic filters. The addition of the nanoparticles leads to a significant reduction in filtration of a microsuspension and affects the structure and thickness of a cake formed on the surface of a filter. The main novelty of this work lies in the fact that the effect of the addition of nanoparticles on filtration losses depends on the ratio between nano and microparticles. It was shown that the positive effect of nanoparticle additives on filtration losses is determined not only by the properties of nanoparticles (size and concentration), but also by the properties of microparticles contained in the drilling fluid, as well as the characteristics of the rock (pore size).

The physicochemical and technical properties of the R-98 reforming catalyst partially spent on a LK-6Us unit in the Achinsk refinery and changes in these characteristics during operation after four regeneration cycles have been studied. It has been found that during the time on stream of the catalyst, a reduction in the specific surface area, partial phase transformation of the oxide support, and buildup of carbon deposits and metal impurities serving as catalyst poisons take place. The regeneration did not afford complete recovery of the properties. In total, the above irreversible changes in the catalyst characteristics led to gradual degradation of the efficiency upon reforming.

A layered Cu-Cr-S structure composed of single-crystal CuCrS2 layers and thin CuCr2S4 plates embedded in them has been investigated by the magnetic resonance and scanning electron microscopy methods. The Curie temperature and saturation magnetization of the spinel phase of the investigated samples have been determined. The thickness of the CuCr2S4 layers has been estimated. The dependence of the growncrystal topology on synthesis conditions has been established. An interpretation of the anomalous behavior of the magnetostatic oscillation intensity is offered.

The influence of TiO2 nanopowder additive on the microstructure, physicomechanical properties, and performance characteristics of a copper-based composite is studied. The properties of the composites are compared with those of pure copper compacts. The microstructure and state of the composite’s working surface after performance tests are examined. It is shown that, when the amount of TiO2 grows, the hardness of the material rises and the arc quenching effect is enhanced.

Method for microwave liquid-phase synthesis of hydroxyapatite samples was developed. The composition of the synthesis products obtained and natural hydroxyapatite was studied by X-ray phase and X-ray fluorescence microanalysis. IR spectra were measured and the dispersity of hydroxyapatite powders obtained, their solubility in water at 20°C, and structural parameters were determined in comparison with natural hydroxyapatite and that produced by the common (“classical”) liquid-phase technique. The microwave-synthesized hydroxyapatite compares well in its properties with the biological and “classical” hydroxyapatites.

The microstructure and properties of electrocontact silver-zinc oxide nanopowder material have been studied. Scanning and transmission electron microscopy were used to determine the shape and size of initial powder particles and oxide inclusions in sintered electrocontact materials, depending on the concentration of zinc oxide, and to confirm the absence of a diffusion interaction between the components. The density, microhardness, and electrical resistivity have been measured.

Investigation results for electrocontact materials based on silver and copper and modified by nanoparticles are presented. Their optimum compositions; technological production features; and physical, mechanical, and operational properties are determined and the microstructure is studied. It is shown possible to replace the standard, widely applied electrocontact materials and Ag-containing products with copperbased pseudoalloys with nanoparticle additives. Prospects of innovation for the investigative results are considered.

Research objective - an assessment of morphological and element composition various as surfaces of implants, with the diagnosis periimplantitis, subjected to processing by the Er laser; Cr; YSGG wave of 2780 nanometers long in comparison with not subjected. Used implants of three producers: (1 - Nobel Biocare (Sweden), TiUnite surface; 2 - XIVE Dentsplay (Germany), SLA surface; 3 - BioHorizons (USA), RBM surface). Electronic and microscopic methods investigated surfaces of the control (new) implants removed with the diagnosis periimplantit, with the diagnosis periimplantit and processed by the laser. It is revealed that the surface of new sterile implants isn't ideal, on it there are traces of impregnation by inorganic connections, a large amount of foreign chemical elements, especially on a surface of SLA of an implant of XIVE Dentsplay is revealed. The surface of skilled implants with the diagnosis periimplantit is very strongly polluted by carbon (C), phosphorus (P), sulfur (S), silicon (Si), etc., being formed on a surface during an inflammation. After processing of the same surface by the Er laser; Cr; YSGG wave of 2780 nanometers long occurs surface clarification, and the element structure almost completely corresponds to the control.Цель исследования - оценка морфологического и элементного состава различных по типу поверхностей имплантатов, с диагнозом периимплантита, подвергнутых обработке лазером Er;Cr; YSGG длиной волны 2780 нм в сравнении с не подвергнутыми. Использовали имплантаты трех производителей: (1 - 'NobelBiocare' (Швеция), поверхность TiUnite; 2 - 'XIVE Dentsplay' (Германия), поверхность SLA; 3 - 'BioHorizons' (США), поверхность RBM). Электронно-микроскопическими методами исследовали поверхности контрольных (новых) имплантатов, удаленных с диагнозом периимплантита, с диагнозом периимплантита и обработанных лазером. Выявлено, что поверхность новых стерильных имплантатов не идеальна, на ней присутствуют следы импрегнации неорганическими соединениями, выявлено большое количество посторонних химических элементов, особенно на поверхности SLA имплантата XIVE Dentsplay. Поверхность опытных имплантатов с диагнозом периимплантита очень сильно загрязнена углеродом (С), фосфором (Р), серой (S), кремнием (Si) и др. образующимися на поверхности во время воспаления. После обработки этой же поверхности лазером Er; Cr; YSGG длиной волны 2780 нм происходит очищение поверхности, и элементный состав практически полностью соответствует контрольному.

Research objective was a comparative assessment of quality of sealing of root canals, subjected to a standard method of processing, processing by the laser and processing by LAI equipment, with sealer and the gutta-percha. The study included 20 teeth extracted because of chronic periodontitis and divided into four groups. Root canals were processed according to the traditional protocol using as an irrigant 3% NaOCl and 17% EDTA solution, LAI equipment, the Er laser; Cr; YSGG 2780 nm at a power 1W and 1,5W and sealed up using single protocol by means of an epoxy siler of AH+ and gutta-percha by continuous wave by means of the CalamusDual (DentsplayMaillefer) device. Scanning electronic microscopy was used to study the efficiency of sealing depending on a type of processing. The highest sealing of the obturation material to the canal walls was revealed in teeth processed by the laser at a power of 1.5 W confirmed by lack of emptiness between a material and a dentine. Conventional irrigation protocol did not result in an optimal obturation with the extent of empty spaces up to 13 microns. The results of the pilot research are the basis for more extensive studies.Цель исследования — сравнительная оценка качества герметизации корневых каналов, подвергнутых стандартному методу обработки, обработке лазером и обработке техникой LAI, силером и гуттаперчей. Исследовано 20 зубов, удаленных с диагнозом хронический периодонтит и разделенных на четыре группы. Корневые каналы обработаны по традиционному протоколу, используя в качестве ирриганта 3% NaOCl и 17% раствор ЭДТА, техникой LAI, лазером Er;Cr;YSGG 2780 nm на мощности 1 и 1,5 Вт, и запломбированы по одному протоколу с помощью эпоксидного силера АН+ и гуттаперчи по методу непрерывной волны с помощью прибора CalamusD ual (Dentsplay Maillefer). Методами сканирующей электронной микроскопии изучена эффективность пломбирования корней зубов в зависимости от вида обработки. Выявлено, что наиболее высокая плотность обтурации материала к стенкам канала получается при обработке лазером на мощности 1,5 Вт, что подтверждается отсутствием пустот между материалом и дентином. При традиционном протоколе не удалось достигнуть плотного прилегания материала на всем протяжении, размер пустот составлял до 13 мкм. Результаты данного пилотного исследования являются основанием для дальнейших более широких исследований.

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала. Abstract—A copper-based electrical-contact composite material hardened by disperse zinc oxide and zinc titanate is studied by electron microscopy and energy dispersive X-ray macroanalysis. The distribution of oxide phases in the samples containing 2.5 wt % oxide nanopowder mixture in an initial charge is found to be uniform. An increase in the amount of oxides leads to an increase in their sized in sintering. A relation between the sample wear and the sample composition is obtained during laboratory tests. It is shown that the introduction of more than 2.5 wt % oxide mixture results in intense wear of the working surface of the sample and an increase in the running-in period of contacts.

HTSC Bi 1.8 Pb 0.3 Sr 2 Ca 2 Cu 3 O x of low density has been synthesized and its structural and physical properties have been studied. Scanning electron microscopy (SEM) image shows that the material obtained has porous “foam” structure. The levitation force measured for the porous Bi 1.8 Pb 0.3 Sr 2 Ca 2 Cu 3 O x is appeared to be approximately the same as for polycrystalline YBCO of high density. These “foam” structures may be an ideal material for some practical applications of HTSCs in bulk form.

The results of investigations of the transition zone between BrKh08 bronze and copper M1 produced by a diffusion bonding through a nickel–phosphorus interlayer are used to evaluate the quality of the diffusion-bonded joints, to determine the dependence of the distribution of elements in the diffusion zone and also to calculate the coefficient of mutual diffusion of copper and nickel and construct the dependence of the properties on concentration.