The solid-state formation of gallium antimonide on Si(111) from a stoichiometric mixture of GaSb in the temperature range of 300 °C–500 °C and thicknesses of 12–40 nm was studied under ultrahigh vacuum conditions. The influence of the preformed GaSb seed islands on the morphology, composition, and structure was studied. It has been found that at 300 °C a strained continuous polycrystalline film is formed, which rupture at 350 °C. It has been shown that a continuous single-crystal GaSb film grows at 400 °C–500 °C if the sample is annealed at a weak antimony flow. This is also facilitated by the preliminary formation of a high density of nanosize GaSb seed islands. As a result, a continuous relaxed film with epitaxial relations GaSb(111)∣∣Si(111) and GaSb[1–10]∣∣Si[1–10] was obtained from a GaSb mixture 40 nm thick at 500 °C. We demonstrate a possibility of direct formation of GaSb on Si(111) without buffer layers of other chemical elements.

На основе стационарного решения уравнения диффузии изучена сепарация наночастиц в прозрачной полидисперсной водной суспензии с различными типами распределений по размерам под действием силы светового давления, возникающей в поле лазерного излучения интенсивностью 0,5 - 500 кВт/см. Установлено, что на дно кюветы преимущественно будут осаждаться частицы радиусом более 100 нм, а концентрация более мелких наночастиц во всем объеме суспензии останется без изменений. В случае симметричного начальное распределения наночастиц по размерам воздействие интенсивного светового пучка на суспензию приводит к нарушению симметрии кривой функции распределения, а также смещению максимума в область меньших размеров частиц на облучаемой поверхности. Если начальное распределение по размерам имеет несимметричный характер, исходное одномодовое распределение частиц по размерам трансформируется в двумодовое. Данная методика может быть использована для выделения наночастиц определенных размеров в зависимости от плотности мощности излучения. On the basis of a stationary solution of a diffusion equation separation of nanoparticles in a transparent polydisperse aqueous suspension with different types of size distributions was studied under the action of the light pressure arising in the laser radiation field with the intensity of 0,5 - 500 kW/cm. It was found that particles with a radius of more than 100 nm will mainly be precipitated at the bottom of the cell, and the concentration of smaller nanoparticles in the entire volume of the suspension will remain unchanged. In the case of a symmetrical initial distribution of nanoparticles size, the effect of a light beam with high intensity on the suspension leads to a violation of the symmetry of the distribution function curve, as well as a shift of the maximum to the region of smaller particle sizes on the irradiated surface. If the initial size distribution is asymmetric, the initial single-mode particle size distribution is transformed into a two-mode one. This technique can be used to isolate nanoparticles of certain sizes depending on the power density of the radiation.

The work is dedicated to the formation of TiAl titanium aluminide coatings with cobalt and nickel additives by means of the method of mechanical alloying with the further maturing at high temperature in vacuum. Coatings were applied with the use of the ball mill of the planetary type upon VT1-0 titanium alloy substrate which were placed in the mill cup filled with metal powders. There is studied growth kinetics, a coating thickness is measured. A specific rate of metal powder sedimentation upon a titanium substrate makes from 4.6 to 11 g/(min•m2). Deposited layers have a mean thickness 70-180 mkm. There are studied thoroughly compositions and microstructure of mechanical-alloyed coatings. For that there were used methods of X-ray diffractometry and raster electronic microscopy. It is defined that the inner structure of coatings is heterogeneous. After deposited layer thermal treatment a metal interpenetration takes place first aluminum into particles of titanium, cobalt or nickel. Coatings are composite material the basis of which makes aluminide of RiAl titanium, and as inclusions there are other inter-metallides, titanium, cobalt or nickel and also aluminum oxide. Mean values of micro-hardness of coatings obtained are 1.2 - 3.4 times higher than of titanium substrate. The highest values of micro-hardness (more than 6.5 GΠa) after thermal treatment in vacuum are observed in TiAl-5%Co and TiAl-10%Co coatings. Micro-hardness of VT1-0 titanium alloy after annealing, vice versa, decreases by 1.3 times.

The photocatalytic activity of heterostructural α-Bi 2 O 3 /Bi compositions obtained by low-temperature pyrolysis of bismuth complexes with sorbite has been investigated. The efficiency of catalysts has been estimated based on the decomposition rate of methylene blue under illumination by visible light. The obtained catalysts are characterized by different contents of metallic Bi and different degrees of imperfection of the α-Bi 2 O 3 lattice, which was obtained by changing the amount of sorbite in the composition of the precursor organomineral bismuth complex and varying the synthesis temperature. It is established that isothermal annealing of the α-Bi 2 O 3 /Bi compositions in air in the range of 400–600°C leads to relaxation of defects and an increase in the α-Bi 2 O 3 lattice volume. An increase in the annealing temperature to 550°C is accompanied by a rise in the α-Bi 2 O 3 /Bi catalytic activity. However, the heterostructure degrades at higher temperatures as a result of metallic bismuth oxidation, while the catalytic activity decreases.

Thick epitaxial Ca2Si(100) films were first grown on Si(111) substrates by forming a sacrificial Mg2Si(111) template and converting it into the Ca2Si template. It was found that a temperature of 250 degrees C is sufficient to transfer it into the Ca2Si template with sufficient uniformity. During Ca and Si co-deposition at 250 degrees C, epitaxial Ca2Si(100) domains with two orientations are formed in a thin (100 nm) film, and increasing the substrate temperature to 300 degrees C leads to a deterioration in the Ca2Si crystalline quality due to a partial violation of its continuity and grain growth of the CaSi phase from Si substrate. An increase in the film thickness to 400 nm at 250 degrees C led to the appearance, in addition to the Ca2Si(100) epitaxial phase, of the second Ca2Si(010) epitaxial phase with both contributing to the LEED pattern. From the transmission and reflection spectra of the grown samples, it was found that Ca2Si film has a first direct interband transition at E-1d = 1.095 +/- 0.15 eV, strong defect adsorption lower 1.0 eV and dispersionless refractive index n(o) <= 3.8. Eight Raman peaks and 6 FIR peaks were first registered and identified, which are in good agreement with theoretical calculations. The absorption coefficients characteristic of FIR peaks was determined, which can be used further in the quick estimation of the thickness of Ca2Si films through an intensity of FIR absorption peaks.

This work is dedicated to a study of the influence of the duration of an electrical discharge on the size of the melting zone formed at a cathode of VT20 titanium alloy. It is found that the melting zone possesses radial symmetry and is surrounded by a ring-shaped zone, whose surface is exposed to electrical erosion. The dependence of the radii of the melting region and the erosion zone, and of the volume of melted metal on the duration of the discharge pulse is determined in the interval from 0.05 ms to 1 ms. A mathematical model is proposed, allowing us to calculate the temperature distribution in a metal plate at different times during the discharge. The parameters of a nonstationary surface heat source arising in the region of the electrical discharge are found from the condition of coincidence of the position of the boundary of the solid–melt phase transition observed in experiments and determined by solving the heat transfer equation.

Приведены результаты автоматизированных измерений каталитической активности висмутовых покрытий в ходе реакции фоторазложения водного раствора модельного загрязнителя.Измерения проведены с помощью разработанной установки, в которой объединены фотореакционные и измерительные ячейки.Эффективность фотокаталитических покрытий -нанопорошков висмутата стронция, нанесенных на керамический носитель в один, четыре и семь слоев, оценивалась по скорости уменьшения концентрации органического красителяметиленового синего -после продолжительного облучения видимым и ультрафиолетовым светом.Показано, что фотокаталитическая активность покрытий на основе висмутатов стронция зависит от кратности их нанесения на

The work is dedicated to the simulation of the processes of erosion and electrode metal transfer at coating formation by an electrospark alloying method. Anode is a cylindrical rod, and cathode – a disk. During discharge pulses the erosion takes place both in anode material, and in cathode material. The anode moves in a spiral along a cathode surface. There are calculated the coefficients of precipitation equal to the probability of metal emitted from the surface of one electrode and falling onto the surface of the opposite electrode. They are constant close to the central cathode axis, but at the anode approach to the cathode end a coefficient of anode metal precipitation on a cathode decreases, a coefficient of cathode metal precipitation on an anode increases. The rates of anode erosion and cathode weight increase when the mass ratio of eroded substance of anode and cathode increases in the course of one discharge. When this ratio is equal to 5, a coefficient of mass transfer achieves 0.8-0.9 it tells of small substance loss during its transfer between electrodes. The model developed is useful for the parameter estimate of mass transfer between cylindrical electrodes at electrospark processing taking into ac-count their dimensions and paths of anode motion.

The composite coatings Ti-Al, Ti-Al-Si-C and Ti-Al-B-C were formed on the Ti6Al4V titanium alloy by a new method of electro-spark deposition from granules. The granules were produced by sintering powders of titanium and aluminum mixed in a ratio of 3 :1, including 15 wt.% additives of silicon carbide and boron carbide. During coating, the frequency of the discharge pulses was 1 kHz, the on-pulse duration was 0.1 ms, and the deposition time was 12 min. The manufactured electro-spark coatings had a thickness of 20-40 µm. The composition of the surface layer formed by the deposition of pure intermetallic Ti3Al coincides with the composition of the initial material of the electrode. The Ti-Al-Si-C coatings are based on TiC, Ti5Si3 and Ti1+xAl1-x. The electrospark coatings formed from Ti-Al-B-C granules contain intermetallic compound Ti3Al, borides TiB and TiB2. Among the investigated samples, the Ti3Al +15%SiC coating has the highest microhardness, which is approximately 4 times higher than that of the titanium substrate from Ti6Al4V. The wear intensity of the titanium alloy during dry friction decreases by more than 19 times if it is coated with Ti3Al or Ti3Al +15%B4C coatings. The coating deposited from Ti3Al granules with 15 wt.% SiC additive has the highest wear resistance, its rate of deterioration is 38 times lower compared to Ti6Al4V. The friction coefficient of the obtained composite coatings is equal to 0.38 – 0.52. The oxidation rate of the titanium alloy during the isothermal heating at a temperature of 900°C can be reduced by 1.9 times if the alloy is coated with Ti3Al, and can be reduced by 2.3 times if the alloy is coated with Ti3Al with the additions of SiC or B4C.

Представлены результаты изучения свойств фотокаталитически активной композиции SrBi 4-у O 7-z / ½у(BiO) 2 СО 3 , где y=1,2…1,7, полученной пиролитическим синтезом из органических прекурсорных комплексов стронция и висмута с сорбитом.Установлено, что синтезированные порошковые материалы поглощают свет видимого диапазона вплоть до 500 нм за счет наличия узкозонного полупроводника SrBi 4 O 7 .Присутствие широкозонного полупроводника (BiO) 2 СО 3 обеспечивает эффективное разделение электронно-дырочных пар.Спектры диффузного отражения композиций имеют отличия от аналогичных спектров механической смеси данных полупроводниковых фаз того же состава, что позволяет предполагать гетероструктурное строение полупроводниковой системы.Каталитические частицы, синтезированные при температуре 500 °С и содержащие 73 мас.% SrBi 4-у O 7-z и 27 мас.% (BiO) 2 СО 3 , обладают наибольшей активностью при фоторазложении метилена синего.Показана возможность управления оптическими свойствами и фотокаталитической активностью композиции за счет совместного формирования фазы висмутата

The results of a cross-correlation analysis of the relationship between the process conditions for obtaining CoNiFeSiB amorphous alloys, their physical and chemical properties and structure are presented. The alloys are obtained by single-roll rapid quenching on a copper wheel at frequencies from 30 to 60 Hz, which corresponds to linear velocities from 22 to 38 m/s, a chamber pressure from 0.05 to 0.6 atm, and a pressure in the crucible from 0.4 to 0.6 atm. Elemental analysis is carried out; the atomic and surface structures, phase-transition parameters upon heating, and the corrosion properties are investigated. Correlations between the structural-ordering parameters and physical and chemical properties are determined. Regression models of the dependence between the structural characteristics, physical and chemical properties, and process conditions of production are formulated. A regression model for the dependence of the average cluster area in the atomic image on the specific energy of structural changes is proposed. The concentrations of nickel, silicon, and boron in cobalt-based alloys are found to play an important role in determining the structural characteristics and properties of the alloys.

FeCrWMoC metallic glass (MG) is synthesized in the form of coatings by electric spark treatment in grain media consisting of individual components. It is demonstrated that the amorphous phase fraction in the composition of the coatings increases with the time of the granule treatment increasing to 100–150 min. The proposed approach offers the potential for the one-stage synthesis of MG in the form of coatings in the automatic mode.

The search for inexpensive and efficient methods of forming thin BaSi2 films as a promising material for photovoltaic is an actual task. The co-deposition of Ba and Si atoms with alloy thickness of 100-120 nm on the silicon substrate at room temperature with following annealing (SPE method) was proposed. Ba-Si alloy compounds then were thermally annealed at different temperatures and three samples were formed: #1 at T = 600 ° C, #2 at T = 700 ° C and #3 at T = 800 ° C. Polycrystalline films with an orthorhombic BaSi2 structure were formed by XRD, UV-VIS, FIR and Raman spectroscopies data. BaSi2 grains in samples #1 and #2 have sizes 62-64 nm and 86 nm in the sample #3 from XRD data calculations by Scherrer formula. Proposed growth method resulted to strong compression of the BaSi2 unit cell volume on 1.78 – 2.70%. The strongest compression was observed after annealing at 800 °C, which was accompanied by desorption of a noticeable amount of barium and a strong decrease in the film thickness in the sample #3. The formation of nanosize Si clusters was confirmed by Raman data for samples #2 and #3, but they did not observed in the sample #3. So, the film, formed at 800 °C, is the most qualitative in terms of structure and single-phase BaSi2, but with strong decrease of initial Ba-Si alloy thickness due to Ba desorption.

Relevance. the titanium alloy Ti6Al4V is widely used in aerospace and medical industries, due to its high specific strength, ductility and corrosion resistance. However, the use of Ti6Al4V alloy in some important structural elements is limited due to its relatively low oxidation resistance and high viscosity during wear. The purpose of the study is to investigate the increase in the oxidation resistance of the titanium alloy Ti6Al4V at high temperatures and dry sliding wear, by applying Ti-Al-Si-C composite protective layers. the coatings obtained by the method of spark deposition using electrodes made in the form of rods by sintering Ti3Al aluminide powders with 5-15 wt% SiC carbide additives are investigated. Materials and methods. the phase composition of the coatings is studied by X-ray diffraction analysis. Corrosion tests of the coatings are presented by a study of oxidation resistance at a temperature of 900 degrees C for similar to 62 hours and potentiodynamic tests in 3.5% NaCl solution. the microhardness of the deposited layers is determined by Vickers indentation at the load of 0.5 N. The wear resistance and coefficient of friction of the coatings are determined in the dry sliding mode versus to high-speed steel R6M5 at a sliding speed of 12 m/s and a load of 25 N. Results and discussion. Electrode materials with addition of Ti3Al intennetallide contained titanium carbide 'tic titanium silicide Ti5Si3 and complex carbide Ti4AlC2. According to the analysis of kinetic mass transfer curves; the optimum deposition time of the spark Ti-Al-Si-C coatings for Ti6Al4V alloy is 4 min/cm(2). It is established that the basis of coatings is composed of intennetallides Ti3Al and TiAl. In addition, it includes TiC carbide and Ti5Si3 titanium silicide, the content of which increases wills increasing the concentration of the SiC additive in the initial composition of the powder mixture. The oxidation resistance of Ti6Al4V alloy With a composite coating obtained from Ti3Al with the addition of 5 wt% silicon carbide Was 2.7 times higher than that without coating. According to the results of potentiodynamic tests, it was concluded that Ti3Al coating wills a 15 wt% SiC additive had the best anticorrosion characteristics. This coating allows decreasing the wear rate of the titanium alloy Ti6Al4V from 1.9.10(-4) to 1.2.10(-6) mm(3)/(Nm). the hardness of coatings was in the range of 10...22 GPa.

This work is devoted to the wear nature of Fe–Ni–Cr–W–Mo–Co–C–B metal glass coatings on steel 1035 substrate via electrospark deposition in various granules mediumcompositions. The microhardness, roughness, and wear resistance of the coatings under dry abrasive and dry sliding wear conditions in the load range of 2.2 to 50 N were studied. During dry abrasive friction, the minimum specific wear rate of the coatings was 1.4 to two times lower than that of steel 1035 in all load ranges. Tests of the Fe33Ni8Cr8W8Mo8Co8C16B11 coating resistance to dry friction against P6M5 steel showed that its wear at 30 km was 1.5 to two times lower than steel 35, but, with a decrease in the normal load, the greatest effect of steel hardening was observed. The results show that the method used in the electrospark deposition of the Fe33Ni8Cr8W8Mo8Co8C16B11 granules mixture can protect the steel substrate from abrasive and sliding wear at low loads and speeds.

Photocatalytic activity, optical properties, thermal stability, phase patterns and morphology of nano-size ТiО2/WO3 compositions obtained from organic precursors through hydrothermal synthesis have been studied. It has been shown that doping of anatase nanoparticles with tungsten W+6 results in particle diameter reduction from 35 to 10 nm; decrease in width of the band gap from 3.15 eV to 2.91 eV and increase in temperature of phase transition of anatase to rutile up to 980оС. Catalytic activity of ТiО2/WO3 (4 mol.%) composition under photochemical methylene blue (MB) oxidation by simulated solar light exceeds that of undoped anatase (obtained in the same way) 6-fold.

The synthesis of nanotubes and faceted nanocrystals of titanium dioxide doped with alkali metals cations has been performed. It has been established that TiO2 nanotubes with lengths of up to 100 nm and thicknesses of 50–500 nm obtained by solvothermal synthesis have an anatase structure in the direction of crystal growth. Faceted TiO2 particles with sizes of 80–150 nm doped with Na and K cations (2–7 at % calculated to a yield of TiO2 yield) preserve the anatase structure, whereas doping with Li induces the formation of a mixture of anatase and rutile. An analysis of the diffuse reflectance spectra showed that dopants had an insignificant effect on optic properties of TiO2 nanoparticles. The high activity of these catalysts is explained by a decrease in the rate of recombination of charge carriers, rather than by the increase of their photo-generation yield.