Статті в журналах: "Nanodispersed powder mixture"

1

Ushakov, A. V., I. V. Karpov, A. A. Lepeshev, and L. Yu Fedorov. "Copper Oxide of Plasma-Chemical Synthesis for Doping Superconducting Materials." International Journal of Nanoscience 16, no. 04 (August 2017): 1750001. http://dx.doi.org/10.1142/s0219581x17500016.

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Properties of nanodispersed powder copper oxide, synthesized during arc sputtering of copper in a gas mixture of low pressure oxygen, were studied. It was shown that the particles possess nanometer size and narrow size distribution. The issue of reduction, recrystallization and sintering of nanodispersed powder were discussed.

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2

Ivashutenko, Aleksander S., Nikita V. Martyushev, E. M. Vodopyanov, and Eugene P. Naiden. "The Analysis of Microstructure and the Properties of the Metallic-Matrix Composite on the Basis of the Copper and Aluminum Oxide." Applied Mechanics and Materials 770 (June 2015): 151–55. http://dx.doi.org/10.4028/www.scientific.net/amm.770.151.

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The article is devoted to the analysis of the possibilities to obtain gradient materials by the method of spark plasma sintering. Pure copper powders consisting of particles with the average particle size 100 microns and the nanodispersed powder of aluminum oxide were used in this study. Two powder compositions - pure copper powder and a mixture of copper powder and aluminum oxide powder were sintered:. As a result of the sintering process a sample with a double-area structure has been formed with a well-defined boundary between these areas. After sintering the copper powder porosity remained at the initial level. But having been mixed and sintered, the aluminum oxide powder particles agglomerated up to the average particle size of 80 – 100 microns.

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3

Ivashutenko, Aleksander S., Nikita V. Martyushev, E. M. Vodopyanov, and Valeriy P. Bezborodov. "The Analysis of Microstructure and the Properties of the Metallic-Matrix Composite on the Basis of the Copper and Aluminum Oxide." Applied Mechanics and Materials 770 (June 2015): 76–80. http://dx.doi.org/10.4028/www.scientific.net/amm.770.76.

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The article is devoted to the analysis of the possibilities to obtain gradient materials by the method of spark plasma sintering. Pure copper powders consisting of particles with the average particle size 100 microns and the nanodispersed powder of aluminum oxide were used in this study. Two powder compositions - pure copper powder and a mixture of copper powder and aluminum oxide powder were sintered:. As a result of the sintering process a sample with a double-area structure has been formed with a well-defined boundary between these areas. After sintering the copper powder porosity remained at the initial level. But having been mixed and sintered, the aluminum oxide powder particles agglomerated up to the average particle size of 80 – 100 microns.

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4

Ozolin, Alexander, and Evgeny Sokolov. "Effect of mechanical activation of tungsten powder on the structure and properties of the sintered Sn-Cu-Co-W material." Metal Working and Material Science 24, no. 1 (March 15, 2022): 48–60. http://dx.doi.org/10.17212/1994-6309-2022-24.1-48-60.

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Introduction. One of the methods for improving the properties of sintered materials is mechanical activation of powders. It ensures milling the powders, changing its energy state, intensifying the sintering of powder materials, and forming a fine-grained structure in it. When tungsten powders are mechanically activated in planetary centrifugal mills, nanoparticles can be formed, which have a high reactive power. The objective of the paper is to study the effect of mechanical activation of tungsten particles on the structure and properties of the sintered Sn-Cu-Co-W powder material. Research technique: Mechanical activation of W16,5 grade tungsten powder is carried out in a planetary centrifugal ball mill AGO-2U for 5…120 minutes with carrier speeds of 400…1,000 rpm. The mixture of tungsten, tin, copper, and cobalt powders are compacted by static pressing in molds and then sintered in vacuum at 820 °C. The morphology and size of powder particles, as well as the structure of the sintered samples, are studied by scanning electronic microscopy, X-ray microanalysis, and optical metallography. Porosity of the sintered samples is identified by the gravimetric method. Microhardness of the structural constituents and macrohardness of the sintered materials are measured, too. Results: in the modes under study, mechanical activation is accompanied by the formation of tungsten nanoparticles with the minimum size of 25 nm. Alongside this, the powder is exposed to cold working, which hinders further milling. Tungsten nanoparticles, characterized by high surface energy, have a significant effect on the dissolution-precipitation of cobalt during liquid-phase sintering of Sn-Cu-Co-W powder material. Addition of nanodispersed tungsten into the material slows down the growth of cobalt particles during sintering and contributes to the formation of a fine-grained structure. The sintered Sn-Cu-Co-W material, containing mechanically activated tungsten, features higher hardness of 105…107 HRB, which is explained by cold working of tungsten particles and dispersion hardening. The results can be applied for improving mechanical properties of Sn-Cu-Co-W alloys used as metallic binders in diamond abrasive tools.

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5

Dyachkova, L. N. "Features of the formation of the structure and properties of powder steels with additives that activate diffusion processes during sintering." Proceedings of the National Academy of Sciences of Belarus, Physical-Technical Series 65, no. 1 (April 6, 2020): 43–53. http://dx.doi.org/10.29235/1561-8358-2020-65-1-43-53.

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Effect of activating the sintering process of powder steel alloyed with nickel or chromium by grinding the initial powders and introducing alkali metal compounds was investigated. The kinetics of grinding the initial iron powders, Cr30, and a mixture of iron powders with 4 % nickel was studied. It is shown that, depending on the hardness of the powder, it is grinded in three or two stages. When grinding more hard powders, there is no stage of intensive deformation of particles and an increase in their size. Crystalline lattice defects resulting from grinding of powders accelerate diffusion processes. This reduces sintering temperature by 100–200 °С compared to the sintering temperature of steels from the initial powders, contributes to a homogeneous structure, reduces porosity by 4–17 %, and increase strength of powder steels by 1.5–1.6 times. The mechanism of the effect of sodium bicarbonate on the acceleration of diffusion of carbon, nickel and chromium into iron has been established. With the introduction of sodium bicarbonate under the action of water vapor, formed upon its decomposition to carbonate, thin oxide films are formed on iron particles, which are actively recovered in a protective-recovering atmosphere during sintering. This leads to formation of a metal contact between the particles, acceleration of the self-diffusion of iron atoms and the diffusion of alloying additives into iron by 5–7 times, depending on the sintering temperature and the amount of added additive. Sodium forms nanodispersed complex compounds of the ferritic type Na3Fe5O9 along the grain boundaries of the iron base, which provide grain refinement and the formation of a homogeneous structure. Changes in the structure of powder steel with the introduction of sodium bicarbonate cause an increase in its strength by 1.5–1.7 times. The results can be used to obtain structural products from alloyed powder steels.

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6

Проскуряков, В. И., та И. В. Родионов. "Формирование состава и характеристик поверхности хромоникелевой стали 12Х18Н10Т при лазерном модифицировании в слое экспериментальной легирующей обмазки". Журнал технической физики 92, № 1 (2022): 84. http://dx.doi.org/10.21883/jtf.2022.01.51856.173-21.

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The results of an experimental study of laser pulsed modification of the surface of stainless steel 12CR18NI10T in a layer of alloying compound made of graphite paste and nanodispersed titanium dioxide powder (anatase) and without coating are presented. A comparative analysis of the effect of the coating on the elemental and phase compositions, morphological characteristics and microhardness of the modified surface is carried out. It was found that as a result of the treatment, the processes of cementation and oxidation of the surface occur, which made it possible to obtain a mixture of iron carbide and high-strength oxides in the surface layer of steel. In the samples that underwent laser treatment in the coating layer, an increase in the intensity of the diffraction peaks of the graphite phase and the formation of iron oxides Fe3O4 and chromium Cr2O3 with the presence of titanium dioxide TiO2 were revealed, which created a mixed heterophase metal oxide structure with increased mechanical strength. An increase in the microhardness of the modified surface after laser pulsed scanning in the layer of the experimental alloying compound is established.

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7

Mukhin, Nikolay, Irina Sokolova, Dmitry Chigirev, Lyudmila Rudaja, Galina Lebedeva, Rene Kastro, Maxim Bol’shakov, Marc-Peter Schmidt, and Soeren Hirsch. "Composite Ferroelectric Coatings Based on a Heat-Resistant Polybenzoxazole Polymer Matrix." Coatings 10, no. 3 (March 19, 2020): 286. http://dx.doi.org/10.3390/coatings10030286.

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The polycondensation of 5,5-methylene bis(2-aminophenol) and the mixture of diamines 5,5-methylene bis(2-aminophenol) and 4,4-(hexafluoroisopropylidene)dianiline (molar ratio 0.8:0.2) with isophthaloyl dichloride was used to synthesize a new heat resistant binder of the composites for microelectronics: poly(o-hydroxyamide) (POA) and poly(amido-o-hydroxy amide) (POA-F). The thermal stability of synthesized polymer coatings, as well as based on them photosensitive compositions with a naphthoquinondiazide photosensitive component were studied in the temperature range from 100 to 500 °C. Ferroelectric composites with nanodispersed lead titanate zirconate powder filler were formed based on these polymer matrices. By manipulating the conditions of the polymer formation, we obtained matrices with different stiffnesses, which reflected on the properties of the composite. The electrophysical parameters of the synthesized polymer and ferroelectric composite coatings were measured in the frequency range from 0.1 Hz to 1.5 GHz and the temperature range from 0 to 300 °C. The frequency and temperature stability of the dielectric constant of ferroelectric composite coatings up to 10 MHz and 300 °C, respectively, are noted. The influence of the composition and structure of the polymer matrix and the grain/matrix interfaces on the thermal stability of the dielectric parameters of composite films is estimated. The shift of the phase transition region toward higher temperatures in the composite structure, as well as the sufficient rigidity of the poly(benzoxazole) matrix, provide high temperature and frequency stability of the dielectric constant of the studied composites.

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8

Dedov, N. V., A. N. Zhiganov, V. L. Sofronov, Yu N. Tumanov, and M. S. Fedorov. "Development and research of plasma chemical technology for producing mixed uranium and plutonium oxides from solutions." Physics and Chemistry of Materials Treatment 2 (2021): 34–41. http://dx.doi.org/10.30791/0015-3214-2021-2-34-41.

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This paper presents the results of work on the application of plasma-chemical technology for producing uranium and plutonium oxides and their homogeneous mixtures from nitrate solutions of a given composition for the purpose of manufacturing fuel element cores. The technology is based on the process of high-temperature decomposition of aqueous solutions of salts by spraying them into a flow of the heat-transfer gas (air) heated to 5000 – 6000 K in a plasma torch. It is a highly productive short-stage process. No reagents are required for salt precipitation; there are no filtration and high-temperature treatment precipitation operations; the resulting powders are chemically active. It was found that the transformation time of salt solution drops to oxides is 0.05 – 0.10 s for the length of 0.5 – 0.7 m. The temperature in the reactor varies in the range of 1200 – 1800 K; no sintering and fusion of particles occurs. The apparatus-technological scheme of the plant has been developed. The technological equipment is made in a nuclear-safe design and installed in the exhaust boxes. The scheme includes a high-frequency induction plasmatron (plasma torch) with coaxial gas inlet into the discharge chamber. The high-frequency induction discharge is excited by inserting a grounded ignition electrode into the plasmatron discharge chamber. The plasmatron design provides the possibility of long continuous operation at high plasma temperatures with the creation of intensive plasma-jet processes for processing radioactive solutions. The reactor provides ways to prevent product accumulation on the walls (gas curtain method, electric pulse cleaning of cylindrical surfaces, vortex tangential gas supply at the level of the outlet holes of the injectors). Equipment for the separation of nanodispersed oxide powders from high-temperature steam- and powder-gas flows (vortex precipitators, filters with a metal-woven partition) has been developed and applied. The degree of oxide recovery in vortex precipitators is 88 – 92 % per stage, in filters with a metal-cloth partition the degree of purification reaches 105 – 108. Plasma-chemical oxides are nanocrystalline and nanoscale materials represented by crystalline and amorphous structures. Mixed powders are a homogeneous mixture of oxides in the form of solid solutions. The particle size does not exceed 3 μm; the crystallite size is about 10 nm. Fuel elements were manufactured from mixed powders at FGUP “Mayak”, which passed successful tests in the “Bor-60” reactor. Seven industrial fuel elements were manufactured for the BN-600 reactor, six of which were loaded into the reactor.

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9

Yakushev, V. V., S. Yu Anan’ev, A. V. Utkin, A. N. Zhukov, and A. Yu Dolgoborodov. "Sound Velocity in Shock-Compressed Samples from a Mixture of Micro- and Nanodispersed Nickel and Aluminum Powders." Combustion, Explosion, and Shock Waves 55, no. 6 (November 2019): 732–38. http://dx.doi.org/10.1134/s0010508219060157.

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10

Lysenko, Vladimir, Vasily Gorev, Yuriy Litvinenko, and Sergey Bardakhanov. "Synthesis and Properties of Ceramics from Ferric Oxide Nanopowder." Siberian Journal of Physics 8, no. 1 (March 1, 2013): 99–103. http://dx.doi.org/10.54362/1818-7919-2013-8-1-99-103.

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Possibilities of receiving ceramics from the nanodisperse ferric oxide (II, III) powder are investigated. In a hot pressing facility (by Spark Plasma Sintering method) the ceramics with fine-grained (about 1 micron and less) structure made. Structure of the received ceramics is investigated by the method of scanning electronic microscopy. Radiographic examination of initial nanopowder and the received ceramics is also carried out. If in the phase relation the initial powder and the ceramics sintered at 800 о С are magnetite Fe3O4 (75-1610), the ceramics sintered at 900 о С – Fe3O4 (75-33), and at 1200о С the diffraction picture of a mixture of two phases – a iron protoxide FeO (46-1312) phase and a metal Fe (6-696) phase – took place. Microhardness of the ceramics was 8 GPa, ultimate compression strength – 0,8 GPa. Thereby availability of use of the SPS method is shown

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11

Ramasamy, Karthik, Weerakanya Maneerprakorn, Mohammad A. Malik, and Paul O'Brien. "Single-molecule precursor-based approaches to cobalt sulphide nanostructures." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 368, no. 1927 (September 28, 2010): 4249–60. http://dx.doi.org/10.1098/rsta.2010.0125.

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Cobalt complexes of 1,1,5,5-tetramethyl-2,4-dithiobiuret, [Co{N(SCNMe 2 ) 2 } 3 ] ( 1 ), and 1,1,5,5-tetraisopropyl-2-thiobiuret, [Co{N(SOCN i Pr 2 ) 2 } 2 ] ( 2 ), have been synthesized and characterized. Both complexes were used as single-molecule precursors for the preparation of cobalt sulphide nanoparticles by thermolysis in hexadecylamine, octadecylamine or oleylamine. The powder X-ray diffraction pattern of as-prepared nanoparticles showed the hexagonal phase of Co 1− x S from complex 1 and mixtures of cubic and hexagonal Co 4 S 3 from complex 2 . Transmission electron microscopy images of material prepared from complex 1 showed spherical and trigonally shaped particles in the size range of 10–15 nm; whereas spheres, rods, trigonal prisms and pentagonally and hexagonally faceted crystallites were observed from complex 2 . This observation is the first of the Co 4 S 3 phase in a nanodispersed form.

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12

Nguyen, Tien Hiep, Yury V. Konyukhov, and Van Minh Nguyen. "Enhancing Mechanical Properties of Various Sintered Pellets with Nano-Additives." Defect and Diffusion Forum 410 (August 17, 2021): 62–67. http://dx.doi.org/10.4028/www.scientific.net/ddf.410.62.

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The impact of Fe, Co, Ni nano-additives on the density, microhardness and bending strength was investigated for several sintered pellets. Fe, Co, Ni nanopowders (NP) were prepared in the size range 67-94 nm using chemical metallurgy techniques. These powders (0.5 wt. %) were dispersed into three sets of micron powders: Co (+0.5 wt. % Co NP); Fe (+0.5 wt. % Fe NP); Fe+0.5wt. % C (+0.5 wt. % Co and 0.5 wt. % Ni NP). Mixtures were further mixed and processed using a magnetic mill and a turbulent mixer. Sintering was carried out using spark plasma sintering (SPS) as well as pressureless sintering (PS). The densities of sintered pellets were found to increase by 2.5-3% (SPS) and 3-5% (PS) in the presence of nano-additives; corresponding increases in microhardness and bending strength were determined to be 7.9-11.1% and 17.9-38.7%, respectively. These results are discussed in terms enhanced packing due to interparticle sliding and the filling of free spaces with the nanodisperse phase.

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13

Kopylov, V. I., V. N. Pashchenko, and I. O. Svitoch. "Activation of structure formation and control of properties of chromium-nickel-plasma coatings with nanocomponents." Strengthening Technologies and Coatings, 2020, 123–29. http://dx.doi.org/10.36652/1813-1336-2020-16-3-123-129.

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The issues of plasma spraying activating and controlling the formation of coating structure with enhanced functional characteristics by imposition external magnetic field in the field of the arc discharge, as well as modifying the sprayed mixture by nanodispersed components, are considered. The possibilities of controlling the spatial distribution and energy characteristics of heterogeneous plasma stream under the influence of external magnetic field are shown. The wear resistance and physicomechanical properties of plasma coatings made from powder mixtures of macro- and microparticles in the presence of the optimal amount of nanophases in the formed coating are studied.

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14

Poluboyarov, Vladimir A., Zoya A. Korotaeva, Alexander A. Zhdanok, and Fedor K. Gorbunov. "Modification of Grey Cast Iron by Compositions Based on Nano-Disperse Powders of Tungsten and Titanium Carbides." Journal of Siberian Federal University. Engineering & Technologies, March 2019, 192–202. http://dx.doi.org/10.17516/1999-494x-0128.

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Experiments involving modification of cast iron manufactured in China which is similar to Russian grades (SCh-18 – SCh-30) using the compositions based on a mixture of tungsten and titanium carbides were carried out. Nanodispersed carbide powders were obtained by means of self-propagating high-temperature synthesis (SHS) in combination with preliminary mechanical activation (MA). The studied modifying agents were WС:TiС = 70:30 with protector metals: chromium (50/50, M1 modifying agent); chromium and copper (25/25/50, modifying agent M2) within the range of concentrations of the ceramic phase – 0.01-0.2%; the modifying agents were introduced into the casting mold and into foundry ladle. Two designs of casting molds were studied. The use of modifying agents for intra-mold modification may lead to an increase in the tensile strength up to 18.5%, relative corrosion stability in hydrochloric acid up to 58.8%. After modification in ladle, the strength of the samples increased to 25-29% only after storage for 3.5 months. The results provide evidence that the studies of grey cast iron modification by the agents containing nanodispersed ceramic phases (WС, TiС) should take into account not only the concentrations and composition of modifying agents but also various technological parameters (design, mold volume, method of introduction of the modifying agent etc.)

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15

"Sound Velocity in Shock-Compressed Samples of the Mixture of Microand Nanodispersed Nickel and Aluminum Powders." Физика горения и взрыва, no. 6 (2019). http://dx.doi.org/10.15372/fgv20190615.

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