UDC 546.26:54-126
A.A. Shulzhenko, A.N. Sokolov, G.S. Oleynik, A.V. Kotko, N.N. Belyavina (Kiev)
Features of structural transformations of fullerite C60 at high pressures and temperatures
The results of experimental studies of the features of structural transformations of fullerite C60 at high pressures and temperatures are presented. It was found that when fullerite is exposed to pressure of ≈ 7.0 GPa and temperature of 2000-2200 K, graphite is formed, and in the presence of a liquid phase, diamond is formed.
Keywords: fullerite, high pressures, structural transformations, graphite, diamond.
UDC 539.89
V. V. Danilenko (Kyiv)
Assessment of the influence of particle size and degree of connectivity on the thermal stability of detonation diamonds
For detonation nanodiamonds from different manufacturers, the degree of connectivity of nanodiamond particles, which affects their quality and depends on the synthesis conditions, was estimated. Depending on the scale factor of synthesis, the degree of connectivity increases in the series: single particles – porous polycrystals – non-porous abrasive polycrystals. The kinetics of graphitization and the temperature of the onset of graphitization were calculated depending on the particle size of nanodiamonds and their connectivity.
Keywords: detonation nanodiamonds, thermal stability, oxidation, graphitization, connectivity.
UDC 544.3:621.762:669.018.25
A. F. Lisovsky (Kyiv)
Thermodynamics of Gradient Structure Formation in Nanodispersed Composite Materials
The formation of gradient structures in nanodispersed composite materials is considered from the standpoint of thermodynamics. It is shown that the formation of gradient structures is determined by the processes of consolidation of refractory particles and deconsolidation of the refractory skeleton of the composite material. Expressions describing the thermodynamics of these processes are given.
Keywords: thermodynamics, gradient structure, nanodispersed composite material, consolidation, deconsolidation, refractory particle.
UDC 621.762.5
M. O. Bondarenko, V. A. Mechnik, M. V. Suprun (m. Kiev)
Peculiarities of shrinkage and fluidity in the Sal-Fe-Cu-Ni-Sn-CrB2 system during hot-pressed samples, which are first removed by strong splicing
The infusion of chromium diboride into the vice and the house on the shrinkage of the softness and mechanical strength of composite diamond materials based on salinity powders, copper, nickel, and tin was observed. hot pre-sauce. It has been revealed that the duration of shrinkage may have a streak-like character. It has been shown that the variability of shrinkage fluidity is associated with phase and structural changes that occur in this system. The storage of output compounds i p, T-mind, for which activation of the process with instantaneous shifts in the mechanical powers of the composite is indicated.
Key words: composite, shrinkage, hot pressing, free sintering, chromium diboride, phase and structural changes, mechanical properties.
UDC 539.266;538.214
V. P. Kazimirov, A. S. Roik, A. V. Samsonnikov, V. A. Shovsky, S. Yu. Smyk, V. E. Sokolsky, V. M. Perevertaylo, O. B. Loginova (Kiev)
The nature of atomic ordering in the melt and surface properties of systems with intermetallic compounds
Using models reconstructed from experimental curves of the structure factor using the inverse Monte Carlo and Voronoi-Delaunay methods, the analysis of the local atomic structure of Ni-Al, Ni-Ge, Ni-Sn melts was performed. It has been established that the decisive influence on the formation of the short-range order structure, the nature of the interaction of atoms, and the surface properties of melts of systems with intermetallic compounds is the preservation of the intensity of the interaction of components and the type of chemical bond during melting of intermetallic phases, which determines the correlation between the structure of the liquid and solid phases. A change in the nature of the ordering of atoms in melts (increased interaction between atoms of the same type against the background of weakened interaction between atoms of different types in the series Ni–›Al–›Ni–›Ge–›Ni–›Sn) leads to a change in the thermodynamic and surface properties of the melts.
Keywords: melt structure, intermetallic compounds, ordering, clusters, surface properties.
UDC 621.762.5-022.532
E. A. Vovk, T. G. Deineka, A. G. Doroshenko, V. F. Tkachenko, A. V. Tolmachev, R. P. Yavetsky (Kharkiv) I. A. Petrusha, V. N. Tkach, V. Z. Turkevich, N. I. Danilenko (Kiev)
Production of transparent nanostructured ceramics Y3Al5O12
Nanocrystalline ceramics Y3Al5O12 with different phase composition, microstructure and optical characteristics was obtained by low-temperature consolidation of Y3Al5O12 powder in the temperature range of 250-550 °C at pressures of 6-7.7 GPa. The conditions for obtaining transparent nanostructured ceramics Y3Al5O12 with grain sizes of 20-40 nm, the transmittance of which in the visible region of the spectrum is 40-45 ‰, are determined. The transparency criteria of nanostructured ceramics are formulated, and ways to improve its optical characteristics are discussed.
Keywords: yttrium-aluminum garnet, high pressure, low-temperature consolidation, nanostructured ceramics, optical transmission.
UDC 621.923.042
M. N. Sheiko, O. O. Pasichny, V. N. Skok, P. I. Bologov (Kyiv)
Quasi-plunge dressing of abrasive wheels as an express method for testing diamond shaped rollers. Message 1. Registration of dressing forces
A method for testing complex-shaped rollers is proposed using the so-called quasi-plunge dressing scheme, which imitates true plunging and does not require expensive special equipment, but allows the use of universal equipment. The named scheme is substantiated both for the self-consistency of theoretical and experimental approaches to the study of plunging dressing, and for the efficiency of using abrasive material in model experiments.
Keywords: quasi-plunge dressing, dressing force, cutting power, mechanical and statistical description, diamond shaped roller, abrasive wheel, asynchronous motor, optical tachometer.
UDC 621.623
V. V. Rogov (Kyiv)
Physicochemistry in the processes of forming functional surfaces of electronic components and optical systems made of glass and sapphire (α-Al2O3) during tribochemical polishing
A review of information sources on the physicochemical processes of forming functional surfaces of electronic components and optical systems made of glass and sapphire (α-Al2O3) is presented. It is established that it is impossible to ensure the necessary requirements for the state of their surfaces to the level of “atomically smooth” without physicochemical interaction of the processing and processed materials at the final stage of processing – tribochemical polishing.
Keywords: physicochemical processing, tribochemical polishing, glass, sapphire.
UDC 621.762: 621.793
V. P. Konoval, O. P. Umansky, A. D. Panasyuk, I. O. Podchernyaeva, O. Yu. Koval (metro Kiev)
Formation of electric spark coatings from composite materials based on titanium-chromium carbide and diboride
Electrode composite materials of the TiCrB2-(Fe-Cr) and TiCrC-(Fe-Cr) systems are presented, their composition, structure, mechanical and tribotechnical power are investigated. The coating on 30KhGSA steel and VT3-1 titanium alloy was removed from separated materials using the electric spark method. The impact of the process of electric spark deposition of electrode materials and base on the kinetics of mass transfer was influenced. It has been shown that fragmented materials can be successfully applied by electric spark method to steel and titanium alloys.
Key words: composite material, electric spark alloying, titanium-chromium carbide, titanium-chromium diboride, coating.
UDC 666.3:539.5
M. V. Novikov, L. K. Shvedov, Yu. M. Krivoshiya, G. K. Kozina, M. O. Kuzenkova, G. S. Oliynik, T. O. Prikhna, I. P. Fesenko (m. Kiev)
Influx of deformation on structural transformations in materials of the AlN-TiN system during avantagement in diamond forges
Key words: diamond blades, wurtzite aluminum nitride, cubic aluminum nitride, titanium nitride, composite.