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We consider actual problems of production, transportation, and storage of hydrogen and demonstrate the urgency and prospects of subsequent investigations and introduction of hydrogen-based technologies in powder metallurgy. We present predictions of an international organization according to which commercial mass production of hydrogen is expected in the nearest future. This will make hydrogen less costly and more available for the extensive applications in various branches of science and industry. It is indicated that hydrogen is not only a promising alternative energy carrier but also an efficient reducer for numerous metals and alloys and an element applied in various technologies of powder metallurgy aimed at getting broad ranges of high-quality products. It is assumed that hydrogen can find extensive applications in industry in the future.

Dysprosium hafnate Dy2HfO5 powders are prepared through mechanochemical synthesis from hafnium and dysprosium oxides. The structure and main physicochemical characteristics are studied using XRD, scanning electron spectroscopy, Raman spectroscopy (CS spectra), TEM, and chemical analysis. XRD and analysis of CS spectra shows that full transformation of initial oxides into single-phase nanodispersed dysprosium hafnate (Dy2HfO5) occurs during mechanical treatment of the mixture for 40 min. Raman spectrometry of the dysprosium hafnate powder prepared through mechanosynthesis shows the absence of unreacted hafnium and dysprosium oxides and the formation of single-phase dysprosium hafnate.

This work describes the influence of VK carbonyl iron powder on the properties of 60Kh2N steel powder. It has been demonstrated that addition of the VK powder to sprayed powder of grade PZhRV 2.200.26 in an amount up to 15% makes it possible to increase the tensile strength from 417 to 482 MPa because carbonyl iron in combination with carbonyl nickel powder in coarse pores between the particles of sprayed iron forms a sintered frame, which positively influences the strength of the obtained material. The mechanical properties of this steel have been improved by hot rolling with subsequent annealing in a protective environment. As a consequence of this additional treatment, the ultimate tensile strength reached 595 MPa.

This article describes manufacturing of powdered high speed steel by hydrogen coreduction of oxide mixture and oxalate of alloying elements on iron powder. The degree of reduction of the final powder and the morphology of obtained particles have been analyzed, a distribution map of elements has been composed, and the degree of compaction of the reduced powder as a function of compacting pressure has been studied.

New data were obtained on the effect of small additions of magnesium oxide nanoparticles on the mechanical properties of aluminum. For the preparation of samples of composites, cold pressing and sintering of powdered aluminum, including those with copper, were used in the forvacuum. As a result, a significant increase in the strength properties of materials modified with magnesium oxide nanoparticles was found: tensile strength, compression, bending strength, and yield strength.

New data were obtained on the effect of small additions of zirconium oxide nanoparticles on the strength properties of powder matrices based on pure aluminum, including those with the addition of 1.5% copper cold pressed and sintered in forevacuum. It is shown that even with an insignificant concentration of nano-additives, there is a noticeable increase in the mechanical properties of materials: tensile strength, bending, compression, and yield strength.

—The structure and the physicochemical properties of boron carbide powders obtained by the mechanochemical synthesis of the carbon char and amorphous boron mix by applying the methods of the X-ray phase analysis (XPA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and chemical analysis were investigated. On the basis of the X-ray phase analysis, it was found that full transformation of the original materials (carbon char and amorphous boron (B4C) takes place during the mechanical treatment of the mix for 30–60 min. Judging by the micro-electron diffraction pattern of the B4C obtained by the mechanical synthesis, the product of synthesis was amorphized and it contained some inclusions of the crystal phase.

Electrospark treatment of OT4-1 titanium alloy was performed sequentially with a hard-alloy electrode STIM-20H (TiC—20% Ni) and carbon-containing material (graphites and carbon-based composite materials). Phase composition and relief of the coatings formed were analyzed. It was established that with regard to the applied carbon-containing material, the electrospark treatment can decrease the friction coefficient of the coatings and increase wear- and heat resistance of the titanium alloy.

Electrospark treatment of OT4-1 titanium alloy was performed sequentially with a STIM-20N hard-alloy electrode (TiC–20% Ni) and carbon-containing material (graphite and carbon-based composite materials). Kinetics of the mass transfer of the hard-alloy electrode was studied. The cathode mass loss during the first minute of the treatment was established. The kinetics results were processed using the methods of mathematical statistics. The erosion resistance of the applied carbon-containing materials was determined. Phase composition and relief of the coatings formed were analyzed. It was found that the application of the carbon-containing material increases the content of refractory phases in the coatings. Increase in the time of the treatment using the carbon-containing materials decreases the roughness of the coatings.

New data were obtained on the effect of small additions of nanoparticles on the mechanical properties of a metal matrix produced by cold pressing of powders with subsequent sintering in a forevacuum. The matrix was a sintered aluminum powder or aluminum–1.5 vol % copper powder mixture. The strengthener was alumina nanoparticles at concentrations of 0.01–0.15 vol %. It was shown that the strength characteristics of these materials as determined by tensile, compressive, and flexural testing and by the offset yield strength method are significantly higher.

Crystalline nanopowders of dysprosium titanate were prepared by the mechanochemical synthesis method using anatase and dysprosium oxide as the initial reagents. The duration of the mechanochemical treatment was 180 min. The crystal structure of mechanochemically synthesized Dy2TiO5 corresponds to a high-temperature cubic modification. The particle sizes of mechanochemically synthesized dysprosium titanate were 20–30 nm. The properties of the obtained nanopowders and bulk samples consolidated from them were studied. Commercial Dy2TiO5 powders prepared by melting the oxides were used for comparison. It was found that the Dy2TiO5 phase decomposes and the metastable DyTiO3 phase is formed during the sintering of mechanochemically synthesized nanopowders, which contradicts the classical Dy2O3–TiO2 phase diagram. No phase decomposition was observed in the case of sintering of commercial Dy2TiO5 powders.

New data were obtained on the effect of small additions of magnesia nanoparticles on the mechanical properties of aluminum. Composite specimens were produced by cold pressing of aluminum powders with or without copper added with subsequent sintering in a forevacuum. As a result, a significant increase was detected in the strength properties of materials modified by magnesia nanoparticles, namely, in tensile, compressive, flexural, and offset yield strengths.

New data were obtained concerning the effect of small additions of zirconia nanoparticles on the strength properties of powder matrices produced by cold pressing of powders with subsequent sintering in a forevacuum. The matrices were either a pure aluminum powder or an aluminum–1.5 vol % copper powder mixture. It was shown that the introduction of nanoadditives to even an insignificant concentration causes a tangible increase in the mechanical properties of the materials, such as tensile, flexural, compressive, and offset yield strengths.

We obtained the amorphous dysprosium titanate nanopowders by the means of mechanochemical synthesis using a low-temperature modification of titania and dysprosium oxide as raw materials. TEM, SAED, XRD and Raman spectroscopy data show that complete transformation of initial oxides into X-ray amorphous dysprosium titanate (Dy 2 TiO 5 ) occurs after the mechanochemical treatment of a mixture of oxides during 30 min. Differential Scanning Calorimetry data suggests the possibility of formation of metastable phases (not indicated in the Dy 2 O 3 -TiO 2 phase diagram) during the annealing of amorphous dysprosium titanate. The specimen produced by nanopowder sintering had a honeycomb structure with ordered porosity, whereas the specimen produced by commercial powder sintering had a homogeneous structure. Dysprosium depletion was observed for sintered specimens, produced both from commercial and mechanochemically synthesized dysprosium titanate powders; for commercial powder, depletion was 10 times higher than for the mechanochemically synthesized one.

Mechanochemical and SHS methods are up-and-coming ways to produce finely dispersed boron carbide nano powder. With optimal process conditions the synthesized phases have ultra dispersed state with well-developed surfaces of the boundaries of grains and subgrains that have either a nano or microcrystalline structure, and that ensures its higher density after vibrocompaction treatment, which in its turn can result in a reduced burn-out rate and a slow-down absorption activity under the influence of neutron irradiation. The products of mechanochemical synthesis and SHS have specified composition and specific structural state and are related with fast solid-phase reactions. The presented research dealt with boron carbide powders that had been produced by mechanochemical or SHS methods, as well as by carbon char or amorphous boron reduction, or the reduction of boron carbide that had been produced by SPS sintering. The purpose of the research was to determine the most optimal SPS sintering modes and to investigate the structure and properties of the sintered boron carbide workpieces made from the powders produced by the above mentioned methods. Source materials for boron carbide synthesis by mechanochemical method or carbon reduction with subsequent crushing and grinding, as well as for SHS treatment were carbon char of PM-15 grade and amorphous boron of A grade taken in stoichiometric composition. SPS sintering of boron carbon powders produced as above mentioned took place at Spark Plasma Sintering (SPS) - Labox 650 plant in graphite dies of 15 mm in diameter in vacuum under 25… 50 MPa pressure. The study of В4С powder workpieces that had been produced by mechanical synthesis, SHS or carbon reduction or SPS sintering of carbon char and amorphous boron mixture, yielded the most efficient modes of SPS sintering for each powder under research. The highest relative density was observed with SPS sintering of В4С powders produced by mechanosynthesis or SHS.

The production method of efficient composite uranium–gadolinium fuel, the application of which will make it possible to improve the technical and economic performance of nuclear power plants, is developed in a laboratory. Based on the analysis of results, the substantiation of implementing the proposed method in industrial conditions is performed. Methods for the preparation and production of the initial materials to prepare gadolinium oxide are described. Necessary characteristics of the pellets of the promising composite uranium–gadolinium fuel are established in the course of experiments, and final requirements for these pellets are formulated allowing for them.

The structure and main physicochemical properties of dysprosium titanate powders prepared by mechanochemical synthesis from the low-temperature modification of titanium oxide and modification of dysprosium oxide are investigated applying X-ray phase analysis (XPA), scanning electron microscopy, Raman spectroscopy (Raman spectra), transmission electron microscopy, and chemical analysis. It is established based on XPA that the initial oxides completely transform into X-ray amorphous dysprosium titanate (Dy2TiO5) during the mechanochemical treatment of a mixture for 30–60 min. A microelectron diffraction pattern of Dy2TiO5 powders prepared by mechanosynthesis has a ring structure characteristic of the X-ray amorphous phase with a certain amount of inclusions of a crystalline phase. The dysprosium titanate powder fabricated by induction melting possesses the regular cubic crystalline lattice with a parameter of 3.4 A.

The article is devoted to studying the effect of introduced strengthening nanosize particles on composite material (CM) structure. The nature of strengthening particle distribution, the distance between dispersed particles, and the size of a critical nucleus are determined. It is shown that use of centrifugal forces in a crystallizing field provides uniform particle distribution within a matrix with predominant arrangement of particles within grains. The critical nucleus radius determined during crystallization in a centrifuge of CM based on aluminum shows that the critical nucleus radius is close to that of strengthening nanoparticles. A version is proposed for production parameters making it possible to obtain a critical nucleus with a size markedly greater than that of added particles.

In this work, the production of cermets in the system of nickel-aluminum alloy – aluminum oxide by the method of mechanical activation and spark plasma sintering was carried out. The analysis of the features of the microstructure of composites, phase analysis at room and elevated temperatures, as well as the dependence of the flexural strength on the temperature and composition of cermets are presented.

Sintered aluminum materials with small additions (0.01-0.15 vol.%) of aluminum, zirconium and magnesium oxide nanoparticles were obtained by powder metallurgy. The microstructure of the samples and the effect of the nature and concentration of nanoparticles on the matrix grain size, density, microhardness, and corrosion resistance in 10% solutions of nitric and sulfuric acids were studied. The addition of nanoparticles led to matrix grains decrease, an increase in the density, microhardness, and corrosion resistance of sintered aluminum samples. The lowest value of grain size was shown by the sample with 0.1% vol. magnesium oxide. Sintered aluminum material with 0.05% vol. zirconium oxide nanoparticles had the highest density∼ 2.67 g/cm3. The highest Vickers microhardness at the level of 0.474 GPa was obtained for material with the addition of 0.1 vol.% Al2O3 nanoparticles. All samples showed significantly greater corrosion resistance in comparison with pure sintered aluminum. The samples with nanoparticles withstood 30 hours of testing, and pure aluminum dissolved in nitric acid in 15 hours, and in sulfuric acid in 10.

Some results of the development of a composite material based on sintered aluminum powder containing small additives of Al2O3 nanoparticles produced by the plasma-chemical method are described. The reasons for using small nanoparticle concentrations from the point of view of the role of interphase layer, Orowan hardening mechanism, etc., are given. Some properties and microstructure of produced alumocomposites with various contents of nanoparticles are demonstrated. According to the known laws, the Orowan stress is calculated for investigated composites as one of the possible contributions to an increase in material strength.

Many proteins require a non-covalently bound ligand to be functional. How ligand binding affects protein conformation is often unknown. Here we address thermal unfolding of the free and ligand-bound forms of photoprotein obelin. Fluorescence and far-UV circular dichroism (CD) data show that the various ligand-dependent conformational states of obelin differ significantly in stability against thermal unfolding. Binding of coelenterazine and calcium considerably stabilizes obelin. In solution, all obelin structures are similar, except for apo-obelin without calcium. This latter protein is an ensemble of conformational states, the populations of which alter upon increasing temperature.

The Scientific Training Center for Self-Sustaining High-Temperature Synthesis at the Moscow Institute of Steel and Alloys has conducted a study of the structure and properties of two-layer electrospark coatings on titanium alloy OT4-1. The coatings were applied by the successive use of STS electrode material STIM-2 (TiC - 20% Ni) (primary treatment) and several different carbon-bearing materials (secondary treatment). It was established that treatment of the surface with carbon-bearing materials decreases the friction coefficient and increases the resistance of specimens of the titanium alloy to heat and wear.

It is established that hot-deformed powder carbon steels with carbon-containing additions form as a result of the complex effect of various factors associated with the composition of the charge, parameters of its preparation, and conditions of the formation and sintering of the billets, as well as the characteristics of the iron powder on the structure, mechanical, and tribological properties of these steels.

In order to improve the properties of powdered carbon steels and grain refinement, thermal-cycle treatment was performed with the use of both induction and furnace heating. This resulted in an extra-fine-grain structure and it increased the values of strength, plasticity, and impact strength. The optimum number of cycles is 3–10.

On the basis of the analysis of the many-year data on the vertical distributions of particulate organic carbon and nitrogen, we compute their annual average amounts for three typical layers of water in the deep part of the Black Sea: for a layer located above the oxycline and characterized by the formation of new portions of particulate organic matter in the course of photosynthesis, inside the oxycline, where the major part of oxygen is consumed and the major part of the flux of particulate organic matter is oxidized, and for the upper part of the anoxic zone characterized by the most active microbiological processes of oxidation of the organic substances and production of sulfides. The available literature data on sedimentation traps are used to study the downward annual average fluxes of particulate organic matter from the euphotic zone into the oxycline and into the anaerobic zone. The seasonal variability of the amounts and fluxes of particulate carbon and nitrogen is revealed.

We analyse the distribution of the dissolved forms of cadmium, lead, cobalt, copper, and manganese in the near-Danube part of the Black Sea and in a section made at 45° 10′N in the autumn of 1997. It is shown that the discharge of rivers results in the appearance of significant amounts of cadmium, lead, cobalt, copper, and manganese in the near-Danube region. Copper is the most labile element in this collection of metals. Its behaviour is correlated with the vital activity of diatomic algae. The distribution of dissolved manganese in the near-bottom region is correlated with the distribution of O2. Indeed, the elevated concentrations of manganese are observed in the regions with low concentrations of oxygen.

Multicomponent diffusional saturation with manganese’ chromium’ and silicon has been found to increase the wear resistance and longevity of locking sleeves. Comparative bench tests indicated that treated sleeves had fewer nicks’ and that the surface roughness was lower than that of batch-produced sleeves. The process that was developed enables substantial increases in the service life of machinery and equipment used in agriculture’ the timber industry’ and railroad equipment.

The paper discusses the data on distribution and composition of suspended matter in Guinea’s coastal zone (Tonkima and Tabunsu river estuaries) during November–December 1990. Tidal events, bottom topography and coast-line configuration are shown to influence sediments’ biochemical composition and distribution. The content of the organic carbon, nitrogen, total phosphate and chlorophyll in the particulate organic matter has been determined.

Ca(2+) -regulated photoproteins use a noncovalently bound 2-hydroperoxycoelenterazine ligand to emit light in response to Ca(2+) binding. To better understand the mechanism of formation of active photoprotein from apoprotein, coelenterazine and molecular oxygen, we investigated the spectral properties of the anaerobic apo-obelin-coelenterazine complex and the kinetics of its conversion into active photoprotein after exposure to air. Our studies suggest that coelenterazine bound within the anaerobic complex might be a mixture of N7-protonated and C2(-) anionic forms, and that oxygen shifts the equilibrium in favor of the C2(-) anion as a result of peroxy anion formation. Proton removal from N7 and further protonation of peroxy anion and the resulting formation of 2-hydroperoxycoelenterazine in obelin might occur with the assistance of His175. It is proposed that this conserved His residue might play a key role both in formation of active photoprotein and in Ca(2+) -triggering of the bioluminescence reaction.

Relationships between the surface concentrations of phytoplankton pigments (Cph), total suspended matter (Csm), particulate organic carbon (Cpoc), and total suspended phosphorus (Csp), on the one hand, and the relative water transparency determined through the Secchi disc depth (zd), on the other, are analysed using the data compiled in the Guinean coastal waters (Tabunsu and Tonkima river estuaries) during November–December 1990. The functions ofCph,Csm=f(zd) are matched up with the experimentally derived data, as well as with the model bio-optical state of seawater. The general regression equation has been calculated using the data characteristic of various types of water.