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The influence of the conditions of mechanical activation of a mixture of Cu–12 wt. % Sn with different content of the modifier Cu9 Al4 on the structural-phase composition and morphology of the formed composites was studied by the methods of X-ray diffraction analysis, optical and electron microscopy. With the mechanochemical introduction of 10 wt. % of the modifying additive into the matrix of mechanosynthesized tin bronze, the product mainly forms a ternary solid solution of aluminum and tin in copper, Al0.05Cu0.9Sn0.05. In the case of 20 wt. % of the modifying additive, the product contains a solid solution of tin in copper Cu0.9Sn0.1 and an intermetallic compound Cu9 Al4. Studies of the mechanical and tribotechnical characteristics of the material obtained by sintering under pressure showed that the intensity of wear of bronze of the mechanochemically synthesized powder Cu–12 wt. % Sn is slightly less than that of industrial bronze BrTPh10-1, the friction coefficient f decreases by a factor of 1.4, and the range of its values is quite wide f = 0.7–0.9. Modification of mechanically synthesized Cu–12 wt. % Sn bronze with the Cu9 Al4 intermetallic compound makes it possible to reduce wear by a factor of 1.4–1.8 and significantly reduces the friction coefficient (by a factor of 2). A stable value of f = 0.5 is achieved for the MA composition Cu–12 wt. % Sn + 20 wt. % Cu9 Al4. The introduction of an intermetallic compound increases the microhardness of the alloys by a factor of 1.6–2.0 (up to Hμ = 2730 MPa) relative to the bronze alloy BrTPh10-1and mechanically synthesized bronze.

The processes of mechanochemical reduction of oxides of iron, nickel, and copper with aluminum with a stoichio metric ratio of components and in mixtures with a two-, three-, and four-fold excess of the aluminum content over the stoichiometric, as well as in the presence of an excess of oxide-forming metal and solid solutions of aluminum in iron and copper, were studied by the Mössbauer and IR spectroscopy, X-ray diffraction analysis, including the use of synchrotron radiation, and electron microscopy. The conditions for formation of metals modified with aluminum oxide (iron, nickel, copper) and their monoaluminides are determined. High aluminum content aluminides are formed at a three-fold excess of aluminum, and at a four-fold excess, a mechanochemical reduction of oxides does not occur. The preferred method for modifying metals with alumina is the mechanochemical reduction of oxides with a solid solution of aluminum in the oxideforming metal. Mechanochemical interaction in the high-energy Hf–C system in the presence of 20, 30, and 50 wt. % copper leads to the formation of hafnium carbide; and with an increase in the copper content, the crystallite size decreases.

Received: 28.12.2020. Revised: 05.02.2021. Accepted: 05.02.2021. Available online: 08.02.2021. This article belongs to the PCEE-2020 Special Issue. The interaction of a solid inert metal Ru with liquid active metal Ga during mechanical activation in a high-energy planetary ball mill was studied using the X-ray diffraction and the high resolution scanning electron microscopy with energy dispersive X-ray microanalyses. This paper considers mechanical activation effects on formation of intermetallic compounds GaxRuy and their solubility in concentrated acids. Gallium is a surface-active substance with respect to Ruthenium. Under intensive mechanical treatment, liquid Gallium penetrates into grain boundaries of polycrystalline Ruthenium particles and sharply reduces their strength. Because of severe mechanical deformation, an intensive increase of contact surface between solid and liquid metals observed, which a place of rapid formation of intermetallic compounds. This processing leads to high reactive products of mechanical activation of Ga + Ru. Their interaction with a mixed concentrated hydrochloric and nitric acid allows Ruthenium (~37%) to pass into an acidic solution, forming complex compounds of the HxRuCly type (H2RuCl6). The research was carried out within the state assignment to ISSCM SB RAS (project No. 0237-2021-0002).

The interaction between a solid inert metal (Ir) and an active liquid metal (Ga) during mechanical activation in a high-energy planetary mill is studied by X-ray diffraction and scanning electron microscopy with EDS-apparatus for high-resolution energy dispersive X-ray microanalysis. The influence of mechanical activation conditions on the formation of GaxIry intermetallic compounds and GaxIry/Ir composites and on their solubility in various acids is investigated. Being a surfactant for iridium, gallium propagates along the grain boundaries of polycrystalline iridium particles during mechanical activaiton and, hence, sharply decreases their strength. As a result of strong mechanical deformation during activation, the contact surface area between the solid and liquid metals, where the intermetallic compounds form intensely, increases sharply. As a result of treatment of the products of mechanical activaiton by a mixture of concentrated hydrochloric and nitric acids, iridium (>30%) from passes into an acid solution and forms HxIrCly complex compounds, which can interact with bases to form soluble complex salts.

Magnetic abrasive machining is one of the advanced finishing processes that produce a high level of surface quality of any type. The productivity of the finishing process and the quality of the treated surfaces are determined by magnetic and abrasive properties of the working media. To synthesize effective magneto abrasive composites with the size range of 1–100 μm the intensive mechanical treatment of powdered mixtures of chemically inert (Fe:SiC, Fe:B4C and Fe:diamond) and exothermically reacting (Fe2O3:Fe:Me, Me = Al, Zr) systems in high-energy planetary ball mills is performed. It is shown that the formation of composites is the result of intensive processes of grinding and deformation (mechanical alloying) as well as of the mechanically intensified redox reactions (mechanochemical synthesis) leading to the formation of abrasive particles (MexOy) in iron matrix. X-ray diffraction, scanning electron microscopy, Mossbauer spectroscopy and investigations of mechanical properties accompanied by the measurements of the abrasive activity in the finishing process of the surface polishing are used for the characterization of the as-prepared composites. The main parameters and mechanisms of the formation of the optimal structure of composites are revealed. It is demonstrated that the smallest roughness of the machined surface (Ra ~ 1 nm) is achieved in the case of using the mechanically alloyed Fe/diamond composite and the mechanosynthesized Fe/ZrO2 composite.

Inkjet ink based on silver nanoparticles with sizes of 11.1 ± 2.4 nm has been developed. Test images are printed on a laboratory inkjet printer, followed by sintering the printed patterns with a diode laser having a wavelength of 453 nm. The structure and electrical properties of the resulting films are studied depending on the parameters of laser sintering. It is found that under optimal conditions, an electrically conductive film with a low resistivity of 12.2 μΩ· cm can be formed.

The interaction in the Hf–C system during mechanical activation performed in a high-energy planetary ball mill and the irradiation-assisted fabrication of hafnium carbide from an Hf/C mechanocomposite are studied by synchrotron X-ray diffraction (at a quantum energy of 33.7 keV) and high-resolution scanning electron microscopy. The mechanochemical interaction results in the formation of an Hf/C mechanocomposite at the first stage and mechanical activation for ≥8 min forms hafnium carbide. The irradiation of the Hf/C mechanocomposite with a high-energy electron beam (~150 W/mm2) causes melting and spreading of hafnium over the carbon particle surface and the crystallization of hafnium carbide.

Mechanical activation of the natural biopolymer arabinogalactan with organic acids (succinic, aminoacetic) was studied by IR spectroscopy and X-ray phase analysis. Evidence was obtained for the formation of mechanocomposites with a chemical bond between the natural biopolymer and organic acids. The nature of this bond depends on the nature of the acid. The composites obtained by mechanical activation of such mixtures are stable disperse systems with a uniformly distributed active ingrediaent.

IR spectroscopy, X-ray phase analysis, and high-resolution electron microscopy were used to examine the nature of the interaction of organic acids with silicates in their joint mechanical activation for the example of succinic acid. It was found that mechanocomposites with chemically bound components are formed in the course of activation of acid–layered silicate mixtures. It was shown that in the acid/nano-SiO2 composite, monomer molecules of the acid are bound to nano-SiO2 via molecules of adsorbed water, which form rather strong hydrogen bonds with the basic active centers of nano-SiO2 and hydroxy groups of the monomer molecules of the acid.

Silver nanoparticles stabilized by an amino and fatty acid (C12) derivative—n-lauroylsarcosine with the average size of 8.4 nm have been obtained via the reduction of the silver nitrate with hydrazine in o-xylene at room temperature. The synthesized silver nanoparticles were investigated by transmission electron microscopy, powder X-ray diffraction, UV–Vis- and IR-spectroscopy. Thermal decomposition and removal of the capping agent from the surface of the nanoparticles have been studied by thermogravimetric analysis. It was determined that n-lauroylsarcosine is removed from the surface of the nanoparticles in two stages at a temperature range of 110–210 °C. Ink consisting of the silver nanoparticles capped with n-nauroylsarcosine has been prepared in o-xylene. Its physical properties and stability have been studied. Silver layers were formed by spin coating the developed ink on a polyimide substrate. The structure and electrical properties of the conductive films obtained at different curing temperatures have been studied. It was found that, after annealing at various temperatures in the range of 100–250 °C, the deposited layers have the different structures, which determine the electrical properties. In the case of the n-lauroylsarcosine capped silver nanoparticles, low resistivity of the film (

Data on the physicochemical properties (pH, Eh, salinity) and content of U and other trace elements (As, Li, B, Br, I, Sr) are provided for the mineralized lakes of the Kulundinskaya steppe of Altai Krai. The sodic lakes of the region are characterized by higher U238 contents (up to 4 mg/l). The U contents in the lake waters are positively correlated with the sum of carbonate and hydrocarbonate ions and the pH of waters and are negatively correlated with salinity. These data confirm the presence of an economic U-bearing zone of the ground reservoir oxidation located along the eastern slope of the Platovskoe uplift in the northwestern direction along the boundary with Kazakhstan.

The joint mechanical activation of chemically interacting iron and titanium has been studied by X-ray diffraction and atomic force microscopy. It is shown that chemically interacting metals Fe and Ti do not form any intermetallic compounds or solid solutions upon intense mechanical activation in a high-energy planetary mill. The products of mechanical activation are Fe/Ti mechanocomposites, in which titanium is distributed over the iron grain surface. An increase in the mechanical activation time leads to the agglomeration of powders and the formation of particles with a wide size range (5–25 μm). The iron crystallite sizes and the level of microstresses are reduced, indicating a decrease in the particle strength.

IR spectroscopy was used to study the process of a mechanochemical interaction of glucose, sorbite, and cetyl alcohol with natural layered silicates. It was found that mechanocomposites with a chemical bond between the components are formed in the course of activation of the systems. The only exception is the mixture of cetyl alcohol and kaolinite because, being even weaker acids than water, monoatomic alcohols react similarly to water only with alkali and alkaline-earth metals. The data obtained can be used in development of medicinal cosmetic preparations.

Effect of electron irradiation on the structural state of a composite material based on ultrahigh molecular weight polyethylene (UHMWPE) and boron carbide particles (B4C) which is a precursor for functional radiation protection materials has been investigated. Composite powder materials were synthesized from industrially available components by the method of mechanochemical activation under conditions of intense shock-shear deformations. Specimens in the form of 2 mm thick composite powder’s pressed plates were irradiated with 2 MeV electrons in air. Studies of changes in the structural and morphological characteristics of the composite samples were carried out by means of scanning electron microscopy, X-ray diffraction, FTIR spectroscopy and differential scanning calorimetry. Effects of electron irradiation on the structure of the composite as a whole and its components were analysed. The analysis of the obtained data showed the resistance of the composite material with respect to the electron irradiation fluence up to 8·1014 cm–2.

Considering lack of lithium, the authors believe it is advisable to analyze dressability of spodumene concentrates from mine wastes, specifically from tailings of Transbaikal Mining-and-Processing Integrated Works. The analysis includes mineral chemical, and grain-size compositions of raw material, as well as the capacity of spodumene to be separated and recovered. These characteristics make the basis for developing the dressing technology and process flowsheet for the indicated type of technogenic (i.e. resulted from production activities) deposits.

The mechanism of mechanochemical formation of composites consisting of PA-6 polyamide and clay minerals (pyrophyllite, kaolinite) was studied by IR spectroscopy and X-ray diffraction analysis. Composites with chemical bonding between the components are formed by activation of polyamide-pyrophyllite mixtures at polymer content c ≤ 10% and of polyamide-kaolinite mixtures at c ≤ 5%. Increased polymer content of the starting mixture “inhibits” the disordering of the silicate structure in the course of activation. Modification of polymers with mechanochemically formed polyamide/clay mineral composites improves the physicomechanical characteristics of the composite materials obtained.

We have used IR spectroscopy and x-ray diffraction to study "mechanocomposites" obtained by joint mechanical activation of polymers (polyamide, Sevilen, and poly-N-vinylpyrrolidone) with nanosized silicon dioxide in a highenergy ball mill. We have established that for

The combination of mechanochemical activation and self-propagating high-temperature synthesis (SHS) have widened the possibilities for both methods. For metallic systems, the investigation showed that a short-term mechanochemical activation of heterophase SHS products leads to single-phase and ultrafine intermetallides obtained from the elements by mechanical alloying. It was demonstrated that metastable phases, usually obtained by mechanical alloying, can be obtained from the equilibrium intermetallic compounds synthesized by SHS. Besides this, the investigations showed that preliminary mechanical activation, during which layered composites are formed from the initial elements, allows one to extend the concentration limits of SHS processes up to a solid solution region.The preliminary mechanical activation also allows production of single-phase ultrafine complex oxides.

The interaction between a solid inert metal Ir and an active liquid metal Ga during mechanical activation in a high-energy planetary mill is studied by X-ray diffraction and scanning electron microscopy with high-resolution energy dispersive X-ray microanalysis. The effect of mechanical activation on the formation of GaxIry intermetallic compounds and GaxIry/Ir composites and their solubility in acids was investigated. The subsequent extraction of Ga from intermetallic compounds and composites in the mixture of concentrated acids [Formula: see text] makes it possible to produce nanoscale Ir.

Mechanocomposites composed of tungsten and metals interacting with it, such as nickel and iron, have been studied; a composition, structure, density, and strength of samples obtained at the stages of mechanical alloying, compacting, and sintering have been considered.

Mechanochemical interaction between iron and gallium has been investigated. The multistage character and the dynamics of mechanochemical formation of the gallium solid solution in iron have been established. X-ray diffraction, electron microscopy, and atomic force microscopy have been used for studying structural and morphological peculiarities of products formed at various stages of mechanical activation. Mossbauer spectroscopy has been used for the investigation of local variations in the nearest surroundings of iron atoms during phase transformations.

When 25-nm α-Al2O3 powder is injected into an aluminum nitrate solution of ≥0.5 wt %, the kinetics of formation of the stable α phase is significantly accelerated upon subsequent heating of the precursor. The total transformation into α-Al2O3 occurs at temperatures varying from 800 to 930°C in accordance with the amount and the method of seed injection. The resulting powder consists of crystallites 50–60 nm in size. They form porous agglomerates 10–20 μm in size, and their size does not depend on the amount of injected seed. Milling under soft conditions breaks the agglomerates and makes it possible to obtain a nanopowder which sinters into a material of 95–99% density in the range of 1300–1400°C.

The possibility of obtaining nanostructured composites Cu/TiO2 by combining mechanical activation and self-propagating high temperature synthesis was investigated by X-ray diffraction and electron microscopy.

The crystal structure of the complex (N2H5)[Ni(NH2NHCOO)3] · H2O (I) was refined using X-ray diffraction data (obtained on an Apex X8 diffractometer, MoKα radiation, 1830 Fhkl, R = 0.0182). The structure is built of complex anions [Ni(NH2NHCOO)3]−, cations N2H5+, and water molecules and is characterized by strong hydrogen bonds N-H…O, O-H…O, and N-H…N. The N3O3 coordination polyhedron around a Ni atom is a slightly distorted octahedron. The thermal decomposition of complex I was studied in high-boiling organic liquids. The feasibility of preparing non-pyrophoric nickel powders having particle sizes of up to 20 nm is shown.

Analysis of major- and trace-element compositions of water in hypersaline soda closed basin lakes of Northwestern Mongolia and Chuya basin (Gorny Altai) shows high enrichment in 238U (up to 1 mg/l). Proceeding from new data, uranium accumulation in water has been attributed to (i) location of the lakes and their watersheds in potential provinces of U-bearing rocks and (ii) uranium complexing with carbonate in presence of carbonate (bicarbonate) anions. Among the explored hypersaline soda lakes of the area, the greatest uranium resources are stored in Lake Hyargas Nuur (about 6000 ton).

The possibility of producing Cu/ZrO2 composites by combining mechanical activation and self-propagating high-temperature synthesis (SHS) is studied using x-ray diffraction and electron microscopy. It is shown that Cu/ZrO2 composites are formed in SHS using CuO/Cu/Zr mechanocomposite as a precursor.

Atomic force microscopy and scanning electron microscopy were used to study the structure of metallic cements that are formed upon the interaction of Cu/Bi mechanocomposites with liquid gallium at room temperature. It has been established that the intermetallic compound CuGa2, which is the basic component of this metallic cement, is formed as tetragonal crystals 1–4 μm in size with a characteristic layeredspiral growth. The second phase—bismuth—is adsorbed at the growth steps in the form of disperse formations 70–250 nm in size; local bismuth accumulations of micron size are also observed. It is shown that in the metallic cement that is formed at room temperature regions of incompletely reacted Cu/Bi composite are retained.

Interactions in the copper-gallium-tin ternary system are studied. New phase formation involves the step of dissolution of solid copper alloys in a liquid phase. The induction period of tin segregation in an autonomous phase depends on tin concentration in the feed. The formation of solid solution of gallium in tin is suggested.

Composites of mesoporous alumina and Fe- or Co-containing ferromagnetic nanoparticles have been prepared from appropriate aqueous metal chloride solutions by a sol-gel process. The synthesis products were heat-treated at different temperatures in air or vacuum and then characterized by a variety of techniques. The results indicate that the mesoporous structure of the nanostructured composites has a large specific surface area, a narrow, unior bimodal pore size distribution, and high thermal stability. The phase composition of the magnetic particles in the X-ray amorphous oxide matrix strongly depends on the heat-treatment conditions.

The results of experimental studies in the mechanochemical synthesis of organic compounds and composites with their participation published over the last 15 years are described systematically. The key reactions of organic compounds are considered: synthesis of the salts of organic acids, acylation, substitution, dehalogenation, esterification, hydrometallation and other reactions. Primary attention is devoted to systems and compounds that cannot be obtained by traditional chemistry methods.

The phase composition and morphology of the diffusion-hardened compound containing Cu/Bi mechanocomposite with nanoscale metals and liquid gallium were examined by synchrotron radiation X-ray diffraction, as well as by atomic force and electron microscopic techniques.

Three various α-alumina nanopowders have been characterized and their behavior in dry uniaxial pressing followed by pressureless sintering in air investigated. Nearly full dense ceramic material has been obtained at no more than 1300°C and its grain size evaluated by scanning electron microscopy and X-ray line profile analysis as being about 200 nm. The most suitable powder for low temperature sintering was reported to be that consisting of aggregates strong enough to enable their dense packing during the die filling and early period of pressure rise but capable of being destroyed further at final stage of compaction. Several dense samples with grain size on the level of 100 nm and less have been shown to be available at 1150-1200°C if a proper molding technique would be developed.

Mechanical activation of a mixture of silicon oxide and aluminum is studied by methods of infrared spectroscopy, differential thermal analysis, and x-ray diffraction. If a SiO2/Al mechanocomposite is used as a precursor, then a Si/Al2O3 composite with a small grain size and a uniform distribution of the components can be obtained by the method of self-propagating high-temperature synthesis.

The reduction of nickel oxide by aluminum and synthesis of nickel aluminides were studied by IR spectroscopy, x-ray diffraction (including synchrotron radiation), and electron microscopy. Composites consisting of nickel aluminides and aluminum oxide were produced by varying the composition of the initial mixture (nickel oxide+ aluminum + nickel) and by a combination of mechanical activation and self-propagating high-temperature synthesis.

It was found that mechanical activation of a mixture containing iron, aluminum, and oxide iron resulted in mechanochemical reduction of iron oxide and formation of a Fe/Al/Al2O3 nanostructural mechanocomposite. High-temperature self-propagating synthesis (SHS) using this composite as a precursor yielded a FeAl/Al2O3 composite, which retained the morphology and dimensional characteristics of the precursor. During mechanical activation of a mixture of iron, aluminum, and chromium oxide, complete reduction of the latter did not occur but SHS also led to the formation of an intermetallide/oxide nanocomposite, in which chromium atoms were incorporated in the structure of iron aluminide.

The mechanochemical preparation of nickel aluminide/corundum (NixAly/Al2O3) powder nanocomposites is shown to be possible during the mechanochemical aluminum reduction of nickel oxide at various weight proportions of the components.

The process of mechanochemical interaction of solid and liquid metals is examined. It is shown that the mechanochemical formation of solid solutions in all the cases occurs through the stages of the formation of stable intermetallic compounds.

Formation of solid solutions in the copper-gallium system under mechanical activation is considered as an example of a mechanochemical interaction between a solid metal and a liquid metal.

On the basis of data of IR spectroscopy and powder diffraction analysis, an aqueous solution of poly-N-vinylpyrrolidone was shown to interact with hydrated alumina and zirconia synthesized from corresponding metal chlorides by means of sol-gel technology. A change was shown in the nature of polymer interaction with individual components and their binary mixture at different annealing temperatures. Different mechanisms of formation of intermediate substances in the synthesis of alumina and zirconia from hydrosols in the presence of a water-soluble polymer were assumed with respect to the nature of synthesized sols. The phase composition of oxides in the course of crystallization is affected by poly-N-vinylpyrrolidone and its hydrolysis products formed by electrochemical synthesis of metal oxide hydrosols.

Mesoporous alumina with a narrow effective pore diameter distribution has been prepared using poly(N-vinylpyrrolidone)-modified sols of hydrous Al2O3 and Al2O3-ZrO2. We compare the microstructures of nanoporous aluminas prepared from electrochemically produced unmodified and modified sols of hydrous oxides and describe the formation of highly ordered mesoporous structures from a mixture of modified sols of hydrous metal oxides differing in chemical nature. Microstructural studies of uni-and biporous permeable nanosystems during heat treatment demonstrate that the pore diameter distribution in the mesoporous oxides prepared from the modified sols remains unchanged at calcination temperatures of 700°C and lower. The microstructure and phase composition of the oxides depend on the initial properties of the sols.

We have synthesized SrFe1 − xMxO3 − z (M = Mo, W; 0 < x ≤ 0.5) solid solutions. Our results indicate that the introduction of stable MO6 octahedra narrows the range of oxygen stoichiometries of the material and suppresses the perovskite-brownmillerite structural phase transition at low temperatures and oxygen partial pressures. We have studied the thermal stability of the synthesized materials in a reducing atmosphere and the effect of oxygen stoichiometry on their electronic and oxygen-ionic conductivity and phase transformations.

Partial isomorphous substitutions on the strontium and cobalt sites in the SrCo0.8Fe0.2O3 − z perovskite have been shown to have a significant effect on its properties. Aluminum substitution for cobalt suppresses the brownmillerite-perovskite structural phase transition, stabilizes the cubic perovskite structure in a wide range of oxygen stoichiometries, and markedly enhances the thermal stability of the material in reducing atmospheres, without reducing the oxygen mobility. Partial lanthanum and calcium substitutions for strontium lead to the formation of Sr1 − x M x Co0.5Al0.3Fe0.2O3 − z (M = La, Ca) perovskite-like oxides, which have cubic and orthorhombic structures, respectively. The Sr1 − x La x Co0.5Al0.3Fe0.2O3 − z perovskites possess high chemical stability in reducing atmospheres and are potentially attractive as materials for oxygen-permeable membranes of catalytic methane-to-syngas conversion reactors.

Reasons for a phase transition in zirconia subjected to intensive mechanical treatment in planetary mill have been considered. If steel balls and vials are used for milling the comminution is accompanied by oxidation of wear metal particles and successive mechanochemical reaction with ZrO2. Aluminum has been shown to behave similarly and, being deliberately added to zirconia powder, to form solid solutions. Foreign metal cations introduced into the lattice stabilize a modification with higher crystal symmetry thus increasing the threshold size above which the monoclinic modification is stable. An increase of surface energy contribution to the Gibbs’ energy of zirconia plays an important role in phase transformation at the initial stages of mechanical treatment, while henceforth thermodynamic stability is more and more determined by the stabilizing effect of the impurity cations. Under the conditions that rule out contamination of ZrO2 with wear material or other metal additives, dynamic equilibrium sets in between the direct transition to the tetragonal phase and the reverse transition to the monoclinic form.