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The article contains the main ideas expressed by Russian and foreign participants in the international scientific discussion on the topic «Communication regimes in Central Asian countries». The discussion was held by National Research Institute for Communications Development. Studies of communication regimes conducted on the basis of the author’s methodology revealed: (1) asymmetry of actor models of communication regimes in Central Asian countries (Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, Uzbekistan); (2) pronounced etatism and policy of state regulation and control of processes and structures of public communication; (3) specifics of social engineering of communication regimes based on securitization of issues of ethnic cultural and national identity; (4) attempts to update communication regimes that have not yet attained serious success. In the course of discussions, scientists from Central Asian countries offered their research materials and keynoted: the role of cultural and religious factors in the formation of communication regimes; the influence of the financial basis of mass media on their structure and media discourse; frequent borrowings of the content from foreign information channels. Russian experts noted: artificially accentuated problems of «historical trauma» in the information space in the Central Asian countries; changes in communication formats within the context of COVID-19; the importance of studying communication regimes in the context of ensuring collective information security, the need to develop common terms and concepts for Russia and Central Asian countries in the drawing up the legislation on communication and information.

A review of articles on the influence of the composition and structure of the binding phase on the properties of hard alloys is given. The role of the binding phase influencing the properties of hard alloys on the basis of data of domestic and foreign researchers is emphasized. The existing and new data on testing of the elements of periodic system as a binding phase which impacts the microstructure and properties of a hard alloy are presented. The existing and new proposals on replacing of the main element (cobalt) with iron, nickel, rhenium, molybdenum, chromium, etc., are considered in order to obtain higher properties and lower the price of the alloy. It is shown that obtaining the best operational properties in each particular case of application of the alloy requires an optimal combination of grain size and cobalt content. Various hard-alloy products are indicated for different areas of application. Techniques of reinforcement of the binding of hard alloys by means of introduction of various types of reinforcers are considered. Their influence on average grain size and properties of hard alloy is shown by examples of various grain growth inhibitors. The ways of further development of submicron, ultrathin, and nanophase alloys with a nanostructured binder reinforced with nanoparticles are presented. The way of further development of hard alloys is shown by example of alloy WC–50% Со with additions. The properties of replacing the cobalt binder with nickel alloyed with small additives are indicated: Мо, W, TiC, HfC, VC, NbC, TaC, Cr3C2.

The results of analysis of domestic and foreign hard alloys showed the possibility of their improvement as a cutting tool. Their development and improvement are tightly connected with solution of problems of robust definition of rational areas of application. The main directions of the proposed improvements in the hard alloy industry are listed.

Analysis of domestic and foreign tungsten-free hard alloys demonstrated the possibility of their application not only in cutting tools but also in the manufacture of nozzles, dies, and bushings operating in compressed and abrasive media, as well as in measuring tools and drawing dies for the fabrication of products from molybdenum, nickel, and Kovar. Higher quality of products increases the prime yield and economic efficiency. Major directions of the proposed improvements in the hard-alloy industry are specified.

—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.

—The optimum modes of spark plasma sintering (SPS)—temperature, time, and pressure amplification—were determined; the structure and properties of blanks of boron carbide sintered by the above method from the powders obtained by the mechanochemical synthesis from carbon char and amorphous boron, by self-propagating high-temperature synthesis (SHS), and by the carbon reduction technique were studied. The optimum modes of the spark plasma sintering of the powder mix of carbon char and amorphous boron were determined.

This article provides an overview of the stages of occurrence and development of the manufacturing of domestic hard alloys. It describes the contribution of domestic scientists to the development of various brands of hard alloys and establishment of their production. It shows the outstanding role of G.A. Meerson in the development of the hard-metal industry.

Fossil remains of brown bear from Kaninskaya cave in the northern Ural are described. They were accumulated during the Late Bronze Age, Early Iron Age, and Late Iron Age as a result of human activity. We analyze the composition of skeletal elements and the nature of their fragmentation. Sex and age of individuals whose bones were apparently used in rituals are assessed, and the seasonality of these ceremonies is evaluated. The main object of ceremonial actions during all chronological periods was the head. Crania and mandibles were cracked into several parts according to one and the same fashion. Other skeletal parts were used much less often. Most postcranial bones were likewise broken into several pieces. Such practices differ from modern Ob Ugrian bear rituals. In the Bronze Age, heads of adult male and female bears were used, and the ceremonies were performed mainly in winter, less often in summer and autumn, and very rarely in spring. In the Iron Age, too, heads of adult animals, mostly males, were used, and ceremonies were held throughout the year but more often in summer and in winter. Seasonal bear rites were not practiced. Certain elements of rites, differing from those of modern Ob Ugrians, are reconstructed. Modern Ob Ugrian bear rituals were formed in the Late Iron Age.

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.

Results of complex paleontological and geochemical analysis are reported for a new locality of the Upper Oligocene–Lower Miocene Kosh-Agach carbonaceous formation in the Dzhazator River valley. This find specifies the scales of lacustrine–marsh sedimentation at the end of the Paleogene and beginning of the Neogene, as well as the character and amplitude of post-Neogene neotectonic movements in the southeastern highest mountain part of Russian Altai. Systematic rejuvenation of the radiocarbon age of the sequences studied, which has been established for the first time in Altai, is related to influx of young carbon during the subsequent complex geological history. This fact is of great importance for deciphering the chronology of Pleistocene glacial–dammed lakes in the intermontane basins of Altai and Tuva, the erosion zone of which spanned exhumed Tertiary deposits.

The environmental changes in the southern part of the Chukchi Sea over the last 2300 years (two warmings during the ~262 BC–630 AD and ~630–1300 periods AD and 1 cooling ~1300–1840 AD) were inferred from changes in the content of diatoms in sediments (per gram), the ratio of dominant species, and the ecological structure of diatom assemblages. The sediment age was determined based on the recent 210Pb sedimentation rates at the sampling point (0.43 mm/yr) and radiocarbon dating of mollusk shells. The environmental changes in the southern Chukchi Sea that were inferred from the diatom analysis correlate with global climate changes, viz., the warming events of the early (Roman) and the middle (Medieval) Subatlantic and the cooling of the late (Little Ice Age) Subatlantic.

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.

Detailed study of a peat plateau near the southern boundary of the East European permafrost zone has been performed. The botanical and palynological compositions of the peat to the depth of 10 m, its radiocarbon dates (the AMS method), and its physical and chemical characteristics have been determined. The accumulation of peat in this area began about 8300 years ago at the end of the Boreal period. In the middle of the Atlantic period, the rate of peat accumulation reached 1.44 mm/yr. During the warming phase in the Middle Subboreal period, the peat plateau was subjected to active thermal erosion; part of the peat was eroded. The processes of thermal erosion are also active at present and destroy the edges of peat mounds. At the same time, the gradual accumulation of peat on the plateau continues. An increase in the degree of peat mineralization is expected upon the establishment of aerobic conditions against the background degradation of the permafrost. Peat plateaus and large peat mounds have been the sinks of atmospheric carbon for a larger part of their history. In this context, we do not expect their significant negative influence on the climate in the future.

Today there are numerous research works meant to improve nuclear fuel element performance in order to ensure reliable operation under increased burn-up conditions. In this context the pellet microstructure seems to be a very important parameter. An increase in the grain size diminishes the branching of boundaries and reduces the migration speed of gas-filled pores to the grain boundaries which are the routes of accelerated diffusion. The problem can be solved by introducing nano additives to uranium dioxide considering the influence of small addition agents upon the grain growth activation and microstructure evolution. The addition of nano particles of different powders should stimulate agglomeration process. This is one of modern tendencies in the development of new material technologies for fast reactors. In the research process the mechanical activation with simultaneous size reduction of gadolinium oxide and aluminum and gadolinium hydroxide powders (Gd2O3 №1, Gd2O3 №2, Al(OH)3 and Gd(OH)3) was done in planetary centrifugal mill "Pulverisette 5" made by Fritsch GmbH company (Germany). The technology of UO2 nuclear fuel manufacture has been developed in several variants including the agglomeration with pre-pressing or extruding, isostatic and hot pressing, rotary swaging, vibratory compacting, slip casting, etc. Today the main UO2 fuel element manufacturing technologies are cold pressing and agglomeration considering their simplicity and affordability. The conducted research permitted to ascertain some specific features of initial TiO2, Al(OH)3, Gd2O3, and Gd(OH)3 additives and determine their basic properties. The authors determined the most optimal modes of fine-grained additives production and proposed and optimal method of their introduction into UO2 mixtures. The paper also considers possible mechanisms of fine-grained additives influence on the fuel pellet production.

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 influence of the mixing method and nature of the administered nanoparticles on the mechanical properties of powder steels is considered. The dependences of hardness and tensile strength under three-point bending on the concentration of nanosized additives and conditions of mixing and sintering were determined. The obtained experimental dependence showed that the maximum values of hardness and strength are achieved at a silicon nitride concentration of 0.1 wt % and under a two-stage mixing technology: mixing in an ultrasonic bath and subsequent mixing in a Turbula mixer for 30 min. It is shown also that, after mixing according to a two-stage scheme and mixing in a planetary centrifugal mill, the mechanical properties almost reached their maximum values already during sintering at the temperature of 1273 K for 120 min, and a further increase in time and temperature of exposure does not have a significant effect on their value.

The main production methods of WC powders, notably, rapid carbothermic reduction (RCR), “calcination–reduction–carburization” (CRC), reduction of tungsten oxide with carbon in rotating furnaces, spray conversion process (SCP), high-energy milling, etc., are considered. The influence of growth inhibitors of the carbide grain on the structure of hard alloys is analyzed. According to the data of some authors, the optimal inhibitor content is 0.5–1.5 wt %, and the alloy embrittles at its higher content due to the formation of complex carbide phases. It is shown that nanosized hard alloys (d WC < 100 nm) cannot be prepared by the traditional liquid-phase sintering the mixtures, and the application of alternative solid-phase consolidation methods is necessary. The structure, properties, and application regions of submicron and nanosized hard alloys fabricated by hot pressing, high-frequency induction pressing, electric discharge sintering under the plasma pressure consolidation (PPC), spark plasma sintering (SPS), etc., are considered.

Production processes for fine powders of tungsten, tungsten carbide, and WC–Co and sintering methods for nanosized WC–Co hard metals are reviewed. The properties, structure, and applications of nanosized WC–Co hard metals described in the literature are analyzed. It is established that, regardless of the process, the mandatory requirements for the production of fine hard metals are: (i) purity of starting materials, (ii) precise compliance with the process procedure, and (iii) careful control at all production stages, which exclude unwanted phases and defects in the structure.

It is revealed that the Altyn-Emel mud volcanic field (43°52′56″ N, 79°06′31″ E) in the Yli depression (Dzharkent trough) is structurally linked to the northeastern end of the Chilik-Kemin deep fault. The mud volcano is related to hydrocarbon-rich gases (including methane) and pressure artesian mineralized thermal waters, which uplifted to the surface along the fault zone. It is suggested that the earthquakes with M≤ 5 related both to the Chilik-Kemin fault and other seismic generating structures intensified the mud volcanic activity. In some cases, the eruptions were accompanied by the short-lived ignition of hydrocarbon gases and formation of the Na-rich paralavas. The mud volcanism of the Altyn-Emel field has been manifested during the last 15–20 k.a., and, consequently, the northeastern part of the Chilik-Kemin fault is an active structure.

The features of sintering of the WC-Co hard alloy of the VK5 brand using the feedstock of tungsten carbide powder fabricated by self-propagating high-temperature synthesis (SHS) are investigated. It is established that the physicochemical processes occurring when sintering hard alloys are similar to sintering processes of standard alloys made of traditional tungsten carbide powders. The hard alloy produced in this study possesses high hardness, strength, and crack resistance, which are characteristic of quasi-nanocrystalline materials.

The influence of alloying additives Al(OH)3 and TiO2 on the structure and properties of uranium dioxide fuel pellets is investigated. It is established that their introduction improves the characteristics of the macrostructure and microstructure of fuel pellets and positively affects their properties. For example, the grain size in the fuel pellet increases to 39 mm (instead of 10–15 mm in the case of usual technology), the number of large (>10 mm) pores decreases, and the strength and thermal conductivity increase slightly.

A short review of works by A.V. Elyutin et al. in the field of rare metals is presented. Technologies of the recovery of zirconium, hafnium, tungsten, tantalum, and niobium from various types of secondary raw materials, notably, scrap metal, scrap of refractory materials, wastes and scrap of hard alloys, and obsolete scrap of capacitors, are considered. Possibilities of increasing the purity of these metals by electrolytic refining and electron-beam melting are shown.

The influence of the process temperature, the SiCl4/NH3 gas-phase ratio, and the gas-phase pressure on the equilibrium degree of transformation is investigated. A mathematical model of the dependence under study is selected to describe the experimental results and coefficients of equations are calculated.

In the article the study of the effect of temperature electropulse sintering of powder on the properties of steel. The optimal conditions for obtaining medium-carbon steels, cold brittleness threshold is defined, which allows to judge about the possibility of powder steel for use with impact loads at low temperatures.

An M1 tooth of Asian black bear (Ursus (Euarctos) thibetanus G. Cuvier, 1823) was found in deposits of the Tetyukhinskaya cave (Middle Sikhote-Alin, 44°35'N, 135°36'E). This finding is the first reliable evidence of Asian black bear's presence in Pleistocene of Primorye. Its morphological and morphometric descriptions are given. The period of inhabitation of U. (E.) thibetanus determined based on the radiocarbon date obtained during the study of the tooth, is 39 874 ± 133 BP (NSK-850, UGAMS-21786), which corresponds to the middle of Marine Isotope Stage 3 (MIS 3) of Late Pleistocene. The composition of ancient theriofauna indicates the existence of wide variety of landscapes in Primorye in the middle of Late Pleistocene. A refugium of forest fauna, in which species of taiga, nemoral, and Central Asian mountain-forest theriocomplexes were present, was located in southern Primorye in Late Pleistocene.

Finely dispersed powders of gadolinium hydroxide are obtained by chemical deposition (dispersing). The influence of various factors on the powder characteristics such as dispersity, morphology, and chemical composition is investigated. The dependence that the mentioned characteristics have on the character of the anion of the gadolinium salt, the concentration and acidity of its solution, and the concentration of the precipitant and pH of precipitation, is established. The optimal results are observed with the use of diluted chloride solutions of gadolinium and a 5–10 wt % precipitant in the form of the NH3 solution.

The parameters of tests and the main results of investigations into the behavior of VVER- and RBMK-type domestic fuel pellets under the effect of thermal shocks are investigated. Fine-grain pellets with a high level of closed porosity are shown to be more resistant to failure, which can appear in the pellets during startup and while maneuvering over the reactor power, as well as if there is cladding failure of the fuel cell. The pellet strength decreases as the grain size increases to ≥25 μm. The residual failure resistance of pellets simultaneously decreases, which leads to a loss in their integrity.

The trends in the improvement of the economic characteristics of nuclear power plants, one of which is the prolongation of the reactor campaign, i.e., the period in which the fuel is situated in the active zone under the due increase in its burnup level, are considered. Such an increase can be achieved, specifically, via using fuel with burnable absorbers, as well as by improving the quality of fuel pellets obtained by powder metallurgy. It is necessary to toughen the technical requirements for fuel pellets and improve the technology of their production and the equipment used in their fabrication. It is noted that the works for improving the operational factors of fuel pellets (particularly, lowering their gas release and decreasing the interaction of the fuel with the cladding) are currently mainly oriented to producing pellets with burning absorbers; obtaining the optimal microstructure (porosity and grain size) of the pellets; improving their shape; excluding dust on their surface after smoothing; and stabilizing their properties in regards to geometric sizes, density, and aftersintering.

Questions of interrelation of reactor compaction of fuel under irradiation and its behavior during the repeated thermal treatment (resintering) are considered. It is shown that testing the fuel via its resintering allow one to monitor its quality, to evaluate the stability of the production process of its obtaining, and to forecast its in-pile behavior via determining the amount of unstable small pores in it. The main statements for selection of parameters of the repeated thermal treatment of the fuel are presented. Formulas for calculation of capacity of the fuel to resinter are presented.

The paper examines the effect of the wetting time on the contact angle θ of WC and Ti wetting by Ni 3 A melt. It is shown that the equilibrium θ value varies between 38 and 0°. It is established that the miscibility of WC in Ni 3 Al intermetallic compound is 3 to 4% at T = 1500°C. A differential thermal analysis has revealed that the liquid phase in the WC–Ni 3 Al system shows up 20 to 25°C lower than the melting point of pure Ni 3 Al. A microstructural analysis has shown that WC–Ni 3 Al alloys contain two phases: WC-based phase and solid solution of WC in Ni 3 Al. The work of adhesion is calculated; it shows that chemical interaction prevails. The microstructure of the contact area is analyzed.

The effect of the holing time on the wetting angle (θ) of tungsten and titanium carbides by the melt of the Ni3Al intermetallic compound is investigated. It is shown that the equilibrium value of θ varies from 38 to 0 deg. It is established that the solubility of WC in the Ni3Al intermetallic compound equals 3–4% at t = 1500°C. The temperature of the appearance of the liquid phase in the WC-Ni3Al system is determined by differential thermal analysis. This temperature turned out to be 20–25°C lower than for pure Ni3Al. It is revealed that the WC-Ni3Al alloys consist of two phases. The first phase is based on WC, and the second phase is based on the solid solution of tungsten carbide in Ni3Al. The values of the adhesion work, which indicate that the chemical interaction is prevalent in this system, are calculated. The microstructure of the contact region is evaluated.

Features of the macrostructure and microstructure of uranium dioxide powders are considered. Assumptions are made on the mechanisms of the behavior of powders of various natures during pelletizing. Experimental data that reflect the effect of these powders on the quality of fuel pellets, which is evaluated by modern procedures, are presented. To investigate the structure of the powders, modern methods of electron microscopy, helium pycnometry, etc., are used. The presented results indicate the disadvantages of wet methods for obtaining the starting UO2 powders by the ammonium diuranate (ADU) flow sheet because strong agglomerates and conglomerates, which complicate the process of pelletizing, are formed. The main directions of investigation that can lead to understanding the regularities of formation of the structure of starting UO2 powders, which will allow one to control the process of their fabrication and stabilize the properties of powders and pellets, are emphasized.

A mathematical model allowing one to analyze consolidation and compaction processes of uranium dioxide powders of ceramic grade and mixtures based on it is suggested and confirmed experimentally. The model makes it possible to predict the final parameters of powder products that are simple in form starting from the results obtained during testing of the powders on the basis of the deformation function of a powdered body at two pressing pressures without subsequent sintering. This decreases the time and expense compared to the technological testing used in industry.

We have studied the effect of barothermal processing (BTP) on the properties of samples prepared by sintering mixtures of tungsten carbide and aluminum nickelide powders (92 vol % WC + 8 vol % Ni3Al) in vacuum and hydrogen. X-ray diffraction data indicate that BTP influences the unit-cell parameters of the WC and improves the mechanical properties of the alloy. In particular, it increases its fracture toughness, bending strength, compressive strength, and fracture work. BTP at 1450°C and 150 MPa produces the most significant changes in the properties of the alloy.

Publications on ultradispersed and nanodimensional powders of tungsten and its carbide and the technologies of their obtainment and production based on their WC-Co solid alloys are reviewed. The main areas of application of solid alloys with nanodimensional structural elements are noted.

1. A study was made of the comminution to powder, in a rotary ball mill, of R18 high-speed steel swarf containing niobium carbide additions and of the subsequent processing of the resultant composite powders to dense blanks. 2. Niobium carbide was found to intensify the swarf comminution process: In powder milled for 48 h, the presence of 5 vol.% NbC increased the yield of the −0.25-mm fraction from 46 to 81% and that of the finest (−0.04-mm) fraction from 35 to 45.5%. At the same time, the mean particle size decreased from 0.31 to 0.18 mm. 3. A study was made of the pressing and sintering of the high-speed steel powder with niobium carbide additions. Strong compacts with a relative density of 70–73% were produced by pressing the powder, with a rubber addition, under a pressure of 8–10 tons/cm2. 4. Sintering, in the absence of a liquid phase, for 60 min at 1250°C in very dry hydrogen was found to yield blanks with a relative density of more than 95%. The blanks were characterized by a fine-grained structure and a mean carbide grain size of 1.5–2μ. 5. The addition of niobium carbide affected the size of the austenitic grain, reducing it from 18μ at 1 vol.% NbC to 7μ at 5 vol.% NbC. 6. The introduction of niobium carbide raised the hardness of the sintered steel, from 59 HRC (without NbC) to 65 HRC at a NbC content of 5 vol.%.

1. A study was made of the milling of high-speed steel swarf with a titanium carbide addition and of the production of dense blanks from the resultant composite powders. 2. It is shown that titanium carbide additions intensify the comminution of high-speed steel swarf and result in the formation of structures with evenly distributed fine (2.0–2.5 μ) carbide grains. 3. The addition of titanium carbide raises the hardness of high-speed steel from 62 to 68 HRC.

An investigation was carried out into the effect of particle size of powders produced by comminution of R6M5 high-speed steel waste (swarf) on their compressibility and sinterability. It is shown that with decreasing mean particle size the compressibility of such powders deteriorates, but their sinterability improves. The finer the steel powder, the lower is the sintering temperature necessary for the attainment of a given density. Varying the powder particles size brings about marked changes in the microstructure of the steel in the sintered condition. The liquid phase (ledeburitic eutectic) appearing during the sintering of steel powders of different particle sizes varies in form and distribution. With coarse powders (dm=100 μm) the eutectic is similar to that in cast steel, but with powders of small particle size (dm=22 μm) it is finer and evenly distributed throughout the structure in the form of thin lamellae.

1. Data have been obtained on the effect of cobalt content and heat treatment conditions on the electrical resistivity of TiC-WC-Co alloys. 2. X-ray diffraction investigations have shown that the carbide phase in WC-Co alloys is subjected to compressive stresses, while the titanium phase in TiC-WC-Co alloys in the presence of structurally-free tungsten carbide is subjected to tensile stresses. 3. Curves of bending strength and Vickers hardness vs cobalt content have been plotted for WC-Co and TiC-WC-Co alloys.

1. A study was made of the single-stage reduction of WO3 to W in an industrial GSPI muffle furnace with a direct-flow feed of hydrogen into the furnace muffle. 2. It is shown that, with hydrogen supplied by the direct-flow technique, it is possible to produce in a single stage, at unchanged furnace output, a homogeneous, fine-grained tungsten powder with an adsorption of more than 0.2 mg/g and a mean particle size of < 1μ. 3. An investigation was carried out of the effect of sintering temperature on the properties of T15K6 alloy produced from tungsten powder prepared by the direct hydrogen flow technique. 4. It is shown that, compared with a standard T15K6 alloy, an alloy of the same composition produced from tungsten powder prepared in a muffle furnace with a direct-flow hydrogen supply possesses a finer-grained WC phase structure and superior physicomechanical and cutting properties.

1. A study was made of the atmospheric oxidation of WC-NbC-Co alloys with varying niobium carbide contents at a constant cobalt content (25 vol.%) over the temperature range 500–800°C. 2. It was demonstrated that the oxidation of WC-NbC-Co alloys obeys an approximately linear law, which is due to the high ratio of the volumes of the resulting oxides to the volume of the basis metal. 3. It was established that an addition of niobium carbide to WC-Co alloys does not increase their oxidation resistance in air at 500–800°C. 4. The phase composition of the oxide films forming on WC-NbC-Co alloys was determined and shown to remain practically unchanged when exposure time is increased and oxidation temperature is raised from 500–800°C.