UDC 666.792.34:539.89
D. A. Stratiychuk, M. A. Tonkoshkura, N. N. Belyavina, V. Z. Turkevich (Kyiv)
Phase formation in the ternary Al–B–C system under high pressures and temperatures
The results of studying the formation of composites in the Al–B–C system under high p, T-parameters are presented, using aluminum borides, diamond, boron carbide and aluminum as initial components. Using transmission and scanning electron microscopy for the Salm–AlB2 and Salm–AlB12 systems, it was shown that starting from 1500 °C, chemical interaction of diamond with aluminum borides occurs, which becomes more pronounced at T ³ 1700 °C. The composite obtained at 1900–2100 °C is characterized by only intragranular diamond fracture, which indicates high strength of the interphase boundaries. The Al–B4C system is characterized by the formation of high-strength composites consisting of substitution solid solutions based on the boron carbide lattice.
Keywords: high pressure, interphase boundary, boron carbide, aluminum boride, sintering of diamond micropowders, ternary Al–B–C system.
UDC 620.18:539.22
V. F. Britun, A. V. Kurdyumov, A. V. Bochko, A. I. Danilenko (Kyiv)
N. N. Kuzin (Troitsk, Moscow Region, Russia)
Structure formation of superhard carbon ceramics during sintering of amorphous carbon powders mixed with nanocrystalline diamond
at high static pressures
The article presents the results of a study of the structure and hardness of polycrystals obtained from nanodispersed powders – mixtures of amorphous carbon phase and nanocrystalline diamond. The initial powders were synthesized by high-temperature shock compression. The powders were sintered at a pressure of 13 GPa and temperatures from 1100 to 2000 °C. The sintering process was accompanied by the transformation of amorphous carbon into diamond. With an increase in the proportion of diamond in the sample from 10 to 100%, the hardness increased from 45 to 80 GPa.
Keywords: diamond, amorphous carbon, sintering, nanocrystalline structure, high pressures, hardness.
UDC 541.183:621.921.43-488
V. M. Perevertaylo, O. G. Gontar, S. P. Starik, O. B. Loginova, O. M. Kutsay (m. Kiev)
Study of the kinetics of water spreading through solid phases of carbon alotropic materials
First, the kinetics of water dispersion on the surface of solid phases of various types of carbon materials was studied using high-speed video recording (up to 1200 frames/s).It has been established that the hourly parameters of the fluidity of the rosette and the wetting of the solid phase with low-temperature liquids and metal melts (process hour 10–2–10–3 s) are close to the values. In both cases, the expansion operates in an inertial mode. For low-temperature liquids at the terminal stages of growth there is a place characteristic of the manifestation of a viscous regime (10–30 minutes), the formation of the presence of an adsorbed ball (“coat”) on the surface of the solid phase in the surface of the natural medium.
Key words: growth kinetics, soaking, carbon materials, water, plasma-chemical treatment.
UDC 666.295:620.17
A. V. Starostina, T. A. Prikhna, M. V. Karpets, S. N. Dub (Kiev)
P. Chartier, T. Kabiech (Poitiers, France)
V. B. Sverdun, V. E. Moshchil, A. V. Kozyrev (Kiev)
Synthesis of ternary compounds of the Ti–Al–C system under high pressures and temperatures
Ternary carbides were synthesized from a mixture of Ti, Al, and C powders taken in a stoichiometric ratio of 3/1.2/2 under high quasi-hydrostatic pressures and temperatures. Two-stage synthesis using high pressures (1–2 GPa) and temperatures and subsequent homogenizing annealing allows increasing the amount of the MAX phase in the samples and the density of the material. The material obtained under a pressure of 2 GPa (1200 °C) and annealed in an argon atmosphere contained, % (by weight), 94.3 Ti3AlC2, 4.3 TiC, 1.4 Al2O3. Its density was 4.27 g/cm3, and the Vickers microhardness was 3.3 GPa (at a load of 4.9 N).
Keywords: MAX phase, Ti–Al–C system, two-stage synthesis, high quasi-hydrostatic pressure, sintering at atmospheric pressure, microhardness.
UDC 544.47:665.777.2
V. Ya. Zabuga, G. G. Tsapyuk, O. V. Ishchenko, T. V. Kartashova, T. O. Shpadkivska, L. V. Lutsenko, O. V. Mischanchuk (m. Kiev)
The level of catalytic activity of copper and cobalt oxides in the reaction of soot oxidation depending on the method of their introduction into the medium
The kinetics of soot oxidation by acidic air in the presence of copper and cobalt oxides introduced into the form of acetates was studied. or metal nitrates.The activity of the oxides is assessed by the fluidity constants of the catalytic reaction isolated from the overall process. Oxides contained from nitrates are more active, compatible with the activity of oxides of copper and cobalt, which are the precursor from which they are contained.
Key words: transition metal oxides, catalytic oxidation of soot.
UDC 536.421.5
N. M. Prokopiv, O. V. Kharchenko, S. V. Tkach, L. E. Vasilenko, N. N. Prokopiv (Kiev)
Yu. D. Serdyuk, O. A. Semizhon (Mariupol)
The effect of thermocompression treatment under argon pressure of 3.0 MPa on the microstructure of standard hard alloy (Ti, W)C–WC–10Co
The results of the comparison are presented detailed studies of the microstructural and Fourier analysis of the structure of the alloy (Ti, W)C–WC–10Co before and after thermocompression treatment under argon pressure of 3.0 MPa at a temperature of 1480 °C and isothermal holding for 20 min.
Keywords: hard alloy, cutting inserts, thermocompression treatment, pressure, argon, structure, porosity, carbides, cobalt, Fourier analysis.
UDC 621.762:921.34
V. M. Volkogon, G. S. Oleynik, S. K. Avramchuk, A. V. Stepanenko, A. V. Kotko, N. A. Efimov (Kiev)
Structural transformations in the wurtzite boron nitride–titanium nitride composition at high pressure and temperature
The article presents the results of electron microscopic and X-ray studies of structural transformations in the powder composition of wurtzite boron nitride–titanium nitride of plasma-chemical synthesis at p = 8 GPa in the range of T = 1100–1700 °C. It is concluded that the interaction in this system occurs with the formation of solid solutions of the composition Ti–B–N. Already at T = 1300 °C, continuous BN–TiN conjugation boundaries are formed in the composition, and at T ≥ 1500 °C, a monolithic interlayer is formed between the boron nitride grains, which is a nanodispersed composite of the composition TiN–TiB2.
Keywords: wurtzite boron nitride, titanium nitride, pressure, temperature, structure, solid solution.
UDC 621.91
A. S. Manokhin, S. A. Klimenko, Yu. A. Melniychuk (Kyiv)
Stress-strain state in the chip formation zone during finish turning of hardened steel parts
The finite element method was used to simulate the stress-strain state in the chip formation zone during cutting of hardened steels with tools equipped with cutting inserts made of polycrystalline superhard material based on cubic boron nitride. The features of the stress-strain state in the chip formation zone during machining with tools with flat and cylindrical front surfaces are considered.
Keywords: cutting tools, PSTM, CBN, modeling, finite element method, machining, hardened steel.
UDC 621.623
A. Yu. Filatov, V. I. Sidorko (Kyiv)
Localization of plaque fragments on the workpiece surface during polishing of non-metallic materials
The paper describes the interaction of wear particles in the contact zone of the tool and the workpiece during polishing of flat surfaces of non-metallic parts using tools with bonded polishing powders. The values of the differential and total cross-sections of scattering of tool wear particles on sludge particles and on wear particles during forward and backward scattering are determined. The coordinate dependencies of the total cross-section of scattering of tool wear particles are calculated. The regularities of the discrete arrangement of plaque fragments on the workpiece surface are described. Fragments of plaque on parts made of fused basalt, glass, quartz and natural stone are experimentally studied.
Keywords: polishing, sludge particle, wear particle, scattering cross-section, plaque fragment.
UDC 621.923:666.3:621.922
M. M. Yakhutlov, B. S. Karamurzov, U. D. Batyrov, Z. Zh. Berov, M. R. Kardanova (Nalchik, Russia)
Thermal regime and stress-strain state of the grain-matrix system of a diamond tool
Numerical modeling of stationary and non-stationary temperature, strain and stress fields in the diamond-matrix system was carried out. It was shown that the stress-strain state of the system is largely determined by thermal effects, and the highest stress intensity in the system occurs in the transition layer between the grain and the matrix. An analysis was made of the influence of the physical properties of the matrix and the transition layer, the depth of grain embedment in the matrix, and the heat transfer coefficient to the environment on the temperature field and stress state of the system.
Key words: diamond, matrix, mathematical model, temperature field, stress-strain state.