UDC 549/548.211
V. M. KvasnytsiaM. P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
vmkvas@hotmail.com
Unusual nano-microcrystals of natural diamond (pp. 3–10)
Unusual nano-microcrystals of natural diamond found in a meteorite crater in Ukraine are described, and a previously unknown mechanism of growth of diamond polyhedra – formation by globules – is reported. It was found that nano-microcrystals of diamond in a meteorite crater are very similar to globular crystals, while having octahedral faceting. The morphology and composition of diamond nano-microcrystals were studied using scanning electron microscopy and X-ray spectral microanalysis, respectively. These tiny polyhedra grew on lamellar crystals of impact apographite diamond from the Bilylivka meteorite crater on the Ukrainian Shield. Their surface morphology indicates that the nano-microdiamonds grew, most likely, during the process of precipitation from the gas phase immediately after the formation of the impact diamond – the transformation of graphite into diamond and lonsdaleite.
Keywords: natural impact apographite diamond, nano-microdiamonds, morphology, globular polyhedra, crystal growth, Bilylivka meteorite crater, Ukrainian Shield.
UDC 666.762.8: 621.762.862
E. V. Solodkyi*, Yu. I. Bogomol, M. Ya. Vterkovsky, P. I. Loboda
National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine
*evgen.solodky@gmail.com
Low-temperature synthesis of boron carbide-based ceramics (pp. 11–19)
The possibility of obtaining boron carbide-based ceramics using coarse powder (D = 25–150 μm) by infiltration with silicon melt and subsequent processing in a controlled temperature gradient field was shown for the first time. As a result, a composite ceramic B4C–SiC–Si with a hardness of 26–35 GPa and a tensile strength of 110–170 MPa was obtained. The effect of the speed of the temperature gradient on the structure, phase composition and properties of the obtained composites was studied.
Keywords: boron carbide, infiltration, hardness, temperature gradient.
UDC 661.665.2/.872.2
AND. IN. Laptev*, A. N.Myslyvchenko, A. I.Tolochyn, M. IN. Karpets, L.N.Kuzmenko, T. AND. Silinskaya
Institute of Materials Science Problems named after I. N. Frantsevich National Academy of Sciences of Ukraine, Kyiv, Ukraine
*avlaptev@ipms.kiev.ua;laptievav@gmail.com
Peculiarities of interaction and phase formation in the WC–Fe2O3–С system during heating in vacuum and argon (pp. 20–34)
Peculiarities of interactions and phase formation in the carbide-oxide mixture WC–33.5% (by mass) Fe2O3, as well as in the WC–Fe2O3–C system under vacuum and argon heating, were studied. To add free carbon to the carbide-oxide mixture, highly dispersed carbon black K354 and sucrose were used, which decomposed to high-purity carbon when heated. It was established that in the absence of free carbon in the carbide-oxide system, there is an active interaction between the carbon of the tungsten carbide and the oxygen of the iron oxide, which manifests itself in the loss of the mass of the samples. As a result, an intermetallic Fe7W6 phase is formed, a phase with a FeWO4 and W type structure. The addition of free carbon makes it possible to partially or completely preserve tungsten carbide and recover iron from the oxide. When there is a lack of free carbon, some part of the carbon of tungsten carbide begins to interact with oxygen and the complex carbide Fe3W3C is formed in the system, when there is an excess of carbon, tungsten carbide is preserved and bcc iron is formed. The process of heating in a vacuum differs from the process of heating in argon in two respects: to remove the same amount of oxygen, more carbon is consumed than during heating in argon; the temperature of the active interaction of carbon with oxygen decreases. The largest (by 300°C) temperature decrease is observed when sucrose is used as a source of free carbon.
Keywords: tungsten carbide, iron oxide, carbon black, sucrose, mass loss.
UDC 661.883.1:548.734:620.187
Liangbiao Wang1, , Dejian Zhao1, Qinglin Cheng1, Quanquan Lu1, Weiqiao Liu1, Keyan Bao2, Binglong Zhu1, Quanfa Zhou1,*
1Jiangsu Key Laboratory of Precious Metals Chemistry and Engineering, School of Chemistry and Environmental Engineering, Jiangsu University of Technology, Changzhou 213001, P.R. China
2College of Chemistry and Pharmacy Engineering, Nanyang Normal University, Nanyang, Henan 473061, P.R. China
*lbwang@jsut.edu.cn
**labzqf@jsut.edu.cn
Iodine-assisted solid-state synthesis and characterization of nanocrystalline zirconium diboride nanosheets (p. 35–40)
A solid-state route was developed to prepare zirconium diboride nanosheets with the dimension of about 500 nm and thickness of about 20 nm from zirconium dioxide, iodine and sodium borohydride at 700 °C in an autoclave reactor. The obtained ZrB2 product was investigated by X-ray diffraction, scanning electron microscope and transmission electron microscopy. The obtained product was also studied by thermogravimetric analysis. It had good thermal stability and oxidation resistance below 400 °C in air. Furthermore, the possible formation mechanism of ZrB2 was also discussed.
Keywords: solid-state route, X-ray diffraction, zirconium diboride, nanosheets, chemical synthesis.
UDC 544.137/.537:666.652
E. Kim1, *, Y. Shimotsuma1, **, M. Sakakura2, K. Miura1
1Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyoto, Japan
2Next Generation Laser Processing Technology Research Association, Kyoto, Japan
*eunhokim@func.mc.kyoto-u.ac.jp
**yshimo@func.mc.kyoto-u.ac.jp
Nano periodic structure formation in 4H–SiC crystal using femtosecond laser double-pulses (p. 41–50)
The photo-induced periodic nanostructure inside 4H–SiC has been induced by a femtosecond double pulse train.The alignment of the periodic structure is in the direction independent of crystal orientation. In particular, FE-SEM analysis revealed that the periodic structure on the fractured surface can be classified into two categories of the polarization-dependent and polarization-independent.
Keywords: 4H–SiC, periodic nano structure, femtosecond laser, double pulse, phase change, semiconductor.
UDC 539.2, 66.091.3
V. E. Panarin1, M. E. Svavilny1, *, M. A. Skoryk1, A. I. Khominych1, T. O. Prikhna2, A. P. Shapovalov2, **
1G. V. Kurdyumov Institute of Metal Physics, NAS of Ukraine, Kyiv, Ukraine
2V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
*svavil@imp.kiev.ua
**shapovalovap@gmail.com
Features of the synthesis of a CNT “forest” under the conditions of adding a controlled plasma component of the working gas (pp. 51–58)
It is shown that when synthesizing carbon nanotubes by the PECVD method on catalytic centers formed from a thin film deposited by vacuum-arc sputtering of the catalyst, the addition of a controlled plasma component of the gas to the working gas mixture leads to the formation of nanotubes of two morphological types: “forest” and multi-walled with a surface substructure. Carbon nanotubes have growth centers either on a continuous “skin” formed on the substrate surface due to the plasma component, or are located directly on the substrate surface, when sufficiently small (5–20 nm) catalytic centers of high density are formed on it. The plasma component forms a highly developed surface on multiwalled nanotubes, which is important for their application.
Keywords: carbon nanotubes, “forest” of tubes, CVD synthesis, plasma stimulation, nanoscale catalytic centers.
UDC 621.762.922.02
V. I. Lavrinenko1,, G. D. Ilnitskaya1,*, G. A. Petasyuk1, E. V. Ishchenko2, S. V. Gaidai2, O. O. Pasichny1, V. V. Skryabin1, V. V. Shatokhin1, I. N. Zaitseva1, E. F. Kuzmenko1, V. V. Timoshenko1
1Institute of Superhard Materials named after V. N. Bakul, NAS of Ukraine, Kyiv, Ukraine
2Kiev National University named after Taras Shevchenko, Kyiv Kyiv, Ukraine
*lavrinenko@ism.kiev.ua
**gil-ism@ukr.net
Research on the possibilities of improving the operational properties of AS20 diamond powders when changing their dimensional and physical-chemical characteristics (pp. 59–70)
The performance properties of AS20 diamond powders used in grinding wheels are investigated, and ways to improve them by changing their dimensional and physical-chemical characteristics are found.It was established that the selection of a narrower range of 100/90 grain sizes and obtaining a homogeneous powder with a certain grain shape factor affects the wear of the wheels, and the use of diamond grains with a larger value of the shape factor is more preferable. It is shown that when dividing diamond powders into magnetic and non-magnetic fractions, a difference in the physico-chemical state of their surface is observed, and it is better to use non-magnetic fractions to increase the wear resistance of rings on polymer bonds.
Key words: diamond synthetic grinding powders, magnetic fraction, non-magnetic fraction, narrow grain size range, powder uniformity, grinding wheels.
UDC 621.923.7-492.2:621.38
Yu. D. Filatov
Institute of Superhard Materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
filatov@ism.kiev.ua
Interaction of sludge particles with wear particles of polishing powder during polishing of optoelectronic elements (pages 71–81)
As a result of the analysis of the interaction of sludge particles and polishing powder wear, it is shown that the scattering of particles occurs at angles of 136.8°–173.2°, and the effective differential cross section of scattering is 0.4–1.8 Tb. The trajectories of particle movement are rings located in the treated surface in a zone whose thickness is approximately equal to the average radius of the polishing powder grain.
Keywords: sludge particle, polishing powder wear particle, scattering angle, scattering cross section.
UDC 546.26.057:662.237.3
IN. Yu. Dolmatov
Federal state unitary enterprise “Special design and technological bureau “Technology”, St. Petersburg, Russia
diamondcentre@mail.ru
The influence of detonation synthesis conditions on the yield of condensed carbon and detonation nanodiamond using the example of a mixed charge trethyl and hexogen (pages 82–87)
The ratio of the theoretical and practical yield of condensed carbon in the post-detonation processes of the synthesis of nanodiamonds was investigated. Their practical coincidence with optimal conduct of the synthesis process is shown. The yield of condensed carbon during industrial synthesis is 12.0% (by mass), detonation nanodiamonds ~ 8.16% (by mass), the content of DNA in AS is up to 68% (by mass).
Key words: detonation, oxygen balance, condensed carbon, detonation nanodiamond, conditions of detonation synthesis, yield of nanodiamond and condensed carbon.
UDC 539.533:661.882
WITH. N. Dub1, *, V. AND. Belous2, G. N. Tolmacheva2, O. N. Kaidash1, A. I. Lukyanov3, Yu. P. Uschapovsky 1
1Institute of superhard materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
2 National Science Center “Kharkov Physical and Technical Institute”, Kharkiv, Ukraine
3Institute of Problems of Materials Science named after I. N. Frantsevich National Academy of Sciences of Ukraine,Kyiv, Ukraine
*lz@ism.kiev.ua
Elastic-plastic transition during nanoindentation of titanium nitride (pages 88–92)
The initiation of plasticity during nanodeformation of a massive TiN sample was studied using the nanoindentation method. It is shown that with a high density of dislocations in the surface layer of the sample (mechanical polishing), the initiation of plasticity in TiN occurs smoothly at an average contact pressure equal to 18.1 GPa. Hence, in the approximation of the spherical shape of the top of the Berkovich indenter, it was obtained that the yield strength of TiN at the nanolevel is 14.5 GPa.
Keywords: titanium nitride, TiN, nanoindentation, yield strength.