A method for obtaining nanopowder microgranules of the W – Ni – Fe system (composition of the VNJ-90) of a micron size range by spray drying of a suspension based on composite nanoparticles obtained by plasma chemical synthesis is considered. The parameters of operation of the Buchi Mini Spray Dryer B-290 spray drying laboratory unit with an ultrasonic nozzle have been experimentally determined, providing for the production of nanopowder microgranules of VNJ-90 with an output of the target fraction of 25 – 63 µm at the level of 65 %. The dependence of the size and morphology of the obtained granules on the choice of the dispersion medium, the concentration of the dispersed phase and the organic binder in the suspension is established. The effect of the suspension flow rate during spray drying on the yield of granules of a fraction of 25 – 63 µm was evaluated. The test of the manufactured experimental sample of nanopowder microgranules in the process of plasma spheroidization was carried out.

A method for producing tungsten powder consisting of spherical microparticles with dimensions of 20 – 50 µm is considered when processing a granular tungsten nanopowder in a flow of argon electric arc thermal plasma. Experimental studies of plasma chemical synthesis of tungsten nanopowder in a plasma reactor with a limited jet flow during the interaction of tungsten trioxide with a flow of hydrogen-containing plasma generated in an electric arc plasma torch have been carried out. The conditions of spray drying and the properties of a suspension consisting of tungsten nanoparticles have been experimentally determined, ensuring the production of mechanically strong nanopowder microgranules of rounded shape with a homogeneous internal nanostructure that does not contain cavities, with the yield of microgranules with a size of less than 60 µm at the level of 65 %. The influence of the parameters of the plasma processing of nanopowder microgranules in the thermal plasma flow on the degree of spheroidization and the microstructure of the resulting particles has been established.

Experiments were carried out on the treatment of the W – C – Co system nanopowders obtained by plasma chemical synthesis in a microwave electromagnetic field with a frequency of 2.45 and 24 GHz in different gas media. The effect of treatment time, power input and carbon content in the treated nanopowder on the yield of tungsten monocarbide WC was investigated.

The possibility to obtain composite micropowders of the W−Cu system with spherical particles having sub-microscale/nanoscale internal structure was confirmed and studied using the complex multistage approach. Composite W−Cu nanoparticles with core–shell structure (W cores and Cu shells) were produced in plasmochemical synthesis in the first stage. Further spray-drying of the aqueous suspension of the W−Cu nanopowder with sucrose enabled the formation of 25−63 μm microgranules with a yield of 50%. The last step was the treatment of the nanopowder microgranules by a thermal plasma jet, which ensured the production of dense spherical W−Cu particles. The final powder had a spheroidization degree of 90%−95%, a bulk density of up to 8.1 g/cm3 and a flowability of 12 s/50 g. The contents of impurities in the resulting spherical micropowder were 0.7 wt.% O, 0.02−0.2 wt.% C and 0.03−0.05 wt.% H.

The process of obtaining powders from the 5–50 μm fraction of a W-Ni-Fe system consisting of particles with predominantly spherical shapes was investigated. Experimental studies on the plasma–chemical synthesis of a nanopowder composed of WNiFe-90 were carried out in a plasma reactor with a confined jet flow. A mixture of tungsten trioxide, nickel oxide, and iron oxide powders interacted with a flow of hydrogen-containing plasma generated in an electric-arc plasma torch. The parameters of the spray-drying process and the composition of a suspension consisting of WNiFe-90 nanoparticles were determined, which provided mechanically strong nanopowder microgranules with a rounded shape and a homogeneous internal structure that contained no cavities. The yield of the granule fraction under 50 μm was 60%. The influence of the process parameters of the plasma treatment of the nanopowder microgranules in the thermal plasma flow on the degree of spheroidization and the microstructure of the obtained particles, seen as their bulk density and fluidity, was established. It was shown that the plasma spheroidization of the microgranules of the W-Ni-Fe system promoted the formation of a submicron internal structure in the obtained spherical particles, which were characterized by an average tungsten grain size of 0.7 μm.

The powder of 93 W – 4.9 Ni – 2.1 Fe (VNZh-93) pseudo-alloy with a spherical particle shape in the size range of 15 – 50 μm with a grain size of 0.5 – 3 μm was obtained using plasma chemical synthesis, granulation and spheroidization technologies. The possibility of using spheroidized powder VNZh-93 in additive 3D-printing is demonstrated. Studies of the physical and mechanical characteristics and microstructure of VNZh-93 test samples made using the selective laser melting technology (SLM) have been carried out. It is shown that the parameters of the SLM significantly affect the formation of the microstructure of test samples. It is possible to form a homogeneous equiaxed microstructure with an average grain size of about 1 micron using optimal SLM modes. It is shown that maximum density and Vickers hardness of VNZh-93 obtained in optimal SLM modes are 16.8 g/cm3 and 480 HV, respectively. These values are not inferior to the values for VNZh-93 samples obtained using traditional liquid-phase sintering technology. At the same time, the main problem of selective laser melting of VNZh-93 powder is the heterogeneity of the bulk samples microstructure and the formation of microcracks and micropores in their structure.

A method of obtaining highly dispersed tin (II) oxide (SnO) powder by the evaporation-condensation method was investigated when the initial material was heated by focused radiation of a subterahertz gyrotron with a frequency of 0.26 THz and a power of 1 kW. The process was carried out with a purge with nitrogen inert with respect to SnO. A powder with a SnO weight content of 92% was obtained. The specific surface was 7.20 m2/g, which corresponds to an average particle size of 130 nm. The characteristics of the obtained powder are analyzed. The applicability of the experimental setup for the production of nanopowders from compounds requiring special gas conditions during the evaporation-condensation process has been demonstrated.

The effect of processing multicomponent nanopowders of the W–C system, obtained by plasma-chemical synthesis, in microwave fields with a frequency of 2.45 and 24 GHz generated using a magnetron and gyrotron, respectively, is studied experimentally. It is established that microwave processing results in the formation of nanosized particles of tungsten carbide WC. The influence of processing time on the phase, disperse, and chemical compositions of nanopowders is investigated.

Parameters have been developed and experimental studies carried out for the synthesis of W-C-Co system nanopowders in a limited jet plasma reactor by interaction of tungsten oxide and cobalt with methane in hydrogen-nitrogen plasma flow generated in an electric arc plasma torch. Nanoscale powders with a specific surface area of about 25 m2/g, consisting mainly of tungsten-carbon phases and cobalt, have been produced.

A comparative study of the results of Spark-Plasma Sintering (SPS) of two-types of aluminum oxide nanopowders, obtained by the method of conductor explosion and plasma synthesis. When the parameters of both powders are similar (spherical form of the particles, size, phase composition) as well as SPS modes the properties of the resulting compacts are significantly different both in mechanical properties and microstructure. The reason of differences in the properties of the obtained compacts is in technological impurities in powders, obtained by different methods. Artificial addition of impurities, contained in the nanopowder, obtained by electro explosion of conductor, into the powder, made by synthesis in plasma and not containing these impurities, allowed to reveal their effect on the formation of the microstructure and properties of the sintered by SPS method sample.

A method for the preparation of a highly dispersed powder of tin monoxide (SnO) by the evaporation/condensation method under heating the initial material with focused radiation of a subterahertz gyrotron with a frequency of 0.26 THz and a power of 1 kW is investigated. The process is carried out with a purge with nitrogen that is inert with respect to SnO. A powder with a SnO content of 92 wt % is obtained. The specific surface area of the powder is 7.20 m 2 /g, which corresponds to an average particle size of 130 nm. The characteristics of the obtained powder are analyzed. The applicability of the experimental setup for the production of highly dispersed powders from compounds that require special gas conditions in the evaporation/condensation process is demonstrated.

The effect of processing multicomponent nanopowders of the W-C system obtained by plasma-chemical synthesis in a microwave electromagnetic field with a frequency of 24 GHz, generated by continuous gyrotron, has been experimentally studied. It was found that the formation of nanosized particles of tungsten carbide WC occurs during microwave treatment. The influence of the processing time, microwave power and the composition of the gas atmosphere on the phase composition of nanopowders, their morphology and specific surface area was investigated. It has been found that processing in a microwave field can reduce the time of chemical transformations, leading to the formation of tungsten monocarbide, by an order of magnitude compared to traditional heating in an electric furnace in a hydrogen environment. At the same time, the particle size is preserved in the nanometer range.

Parametric X-ray radiation associated with the diffraction of virtual photons and the diffraction of X-rays described as the diffraction of real photons are studied experimentally. The diffracted radiation was generated by a 7 MeV beam of electrons and an X-ray tube respectively. Both diffraction mechanisms occur in a tungsten powder. The processes have been compared excluding three key parameters: the attenuation in the target, the background of the diffracted signal and the spectrum of the incident radiation. Remarkable differences between the diffraction mechanisms of virtual and real photons are observed. The ratio between the PXR peak and the XRD peak decreases when the peak energy increases.

Experimental studies of aluminium boride synthesis as a result of interaction of disperse aluminum with diborane B2H6 and disperse boron in a flow of thermal plasma of different composition generated in electric arc plasma torch have been carried out. Experimental work on the synthesis of aluminium boride nanoparticles from elements (a mixture of disperse aluminum and boron) has shown the possibility of obtaining in thermal plasma arc discharge of such phases of the boride as AlB12 and AlB31. The specific surface of the powders obtained is from 3 to 27 m2/g. According to X-ray phase analysis, the powders obtained, except for aluminum boride phases, also contain boron, aluminum, aluminum nitride and boric acid phases. The greatest yield of aluminum boride phases is provided by using the nitrogen plasma with hydrogen and enthalpy 4.5 kWt∙h/m3 in the reactor with increased high-temperature zone. The use of gaseous diborane made it possible to eliminate restrictions on the evaporation of boron particles but did not provide an opportunity to obtain aluminum borides in the plasma-chemical process. It was concluded that it is necessary to perform quenching of high-temperature gas flow containing boron and aluminum vapor to form aluminum borides from the gas phase in plasma-chemical synthesis. Such an approach should ensure that the temperature is reduced to the values at which aluminum borides are stable and that the formation of aluminum boride nanoparticles will occur as a result of condensation from the gas phase under these conditions.

Spheroidization of Fe and steel powders in a plasma stream of an DC arc plasma torch is investigated. The possibility of obtaining a product with a spherical particle content of up to 100% is established. The fluidity of the best samples of obtained powder is 13–20 s with a fluidity of the feedstock of 39 s. The bulk density of the initial powder (3.05 g/cm 3 ) during the plasma treatment increases to 4.1–4.4 g/cm 3 . The nanofraction content in spheroidized powders varied from 0 to 75 wt % and it depends mainly on the enthalpy of the plasma stream, consumption of raw materials, and the organization of the flow of the plasma-forming gas in the discharge channel of the plasma torch. It is established that Fe powders spheroidized in plasma can be used in selective laser melting technology to obtain compact samples whose density reaches 7.86 g/cm 3 .

Experimental studies on the synthesis of aluminum oxynitride nanopowders in a reactor with a confined plasma jet by the interaction of disperse aluminum with ammonia and oxygen in a flow of nitrogen plasma generated in an electric arc plasma torch are performed. Preliminary calculations of the equilibrium compositions and thermodynamic characteristics of the multicomponent Al-O-N system are carried out.

The results of work on the implementation of plasma synthesis and spheroidization of powders of metals and their compounds in a thermal plasma generated in a direct current arc plasma torch are presented. The possibility of controlling the properties of the obtained powders is demonstrated.

Motivated by recent V.A. Nikitin’s reports on observation of new light charged particles with a 2-meter JINR propane bubble chamber we perform an experiment at the LPI electron synchrotron "Pakhra" with the aim to detect such particles in the Bethe–Heitler process. Theoretical limits for masses of new light charged particles of spin 0, 1/2 and 1 arising from precise data on the muon anomalous magnetic moment are recalculated and updated. A geometry of the photoproduction experiment is proposed that optimizes signal-tonoise ratio. First results of the experiment are exposed.

Spheroidization of micropowders of a heat-resistant alloy based on nickel aluminide with a particle size of 20 to 45 μm was studied. The alloy was produced by calcium hydride reduction (CHR) and elemental synthesis (SHS). The spheroidization was carried out in a flow of argon–hydrogen thermal plasma generated by a direct-current (DC) plasma torch. The degree of spheroidization of the micropowders reached 98.5%, and the flowability was 20 s/50 g.