UDC 549.2:539.1
S. N. Dub (Kiev) A. A. Goncharov (Kramatorsk) V. V. Petukhov (Donetsk)
The effect of nitrogen on the mechanical properties of thin films of the Ta—B—N system
Amorphous-crystalline thin films of the Ta—B—N system on a steel substrate were obtained by RF magnetron reactive sputtering of a TaB2 target in a gas mixture of nitrogen and argon. The effect of nitrogen content in the mixture on the mechanical properties of the films was studied. It was found that the formation of an amorphous-crystalline structure leads to a decrease in nanohardness, elastic modulus and an increase in the plasticity of Ta—B—N films compared to nanocrystalline TaB2 films. The formation of amorphous boron nitride also causes viscoelastic mechanical behavior of thin films of the Ta—B—N system.
Keywords: thin films, Ta—B—N system, nanohardness, viscoelasticity.
UDC 541.1:546.273.171
V. Z. Turkevich, A. V. Kozyrev (Kiev)
Thermodynamic calculation of the melting diagram of the Mg—MgO—B system at a pressure of 2 GPa
Within the framework of model concepts of phenomenological thermodynamics, the calculation of phase equilibria with the participation of the liquid phase in the ternary Mg—MgO—B system at a pressure of 2 GPa was performed. The melting diagram of the system is characterized by the presence of five invariant four-phase equilibria, three of which are peritectic and two are eutectic. The primary crystallization region of magnesium diboride MgB2 is located near the binary system Mg—B and wedges out as the oxygen concentration increases, giving way at the peritectic equilibrium point L + MgB2 = MgO + MgB4 (1345 K, 68%(at.)B, 10 ‰(at.)O) to the crystallization regions of MgO and MgB4.
Keywords: high pressures, phase diagram, magnesium borides and oxide.
UDC 621.762
S. V. Chornobuk, A. Yu. Popov, V. A. Makara (Kiev)
Structure and mechanical properties of reaction-sintered ceramic composite materials based on titanium and hafnium diborides
The structure and mechanical characteristics of ceramic composite materials based on titanium and hafnium diborides obtained by reaction hot pressing are presented. It is shown that the ultra-dispersed structure provides high mechanical characteristics of the synthesized composites.
Keywords: structure, mechanical properties, reaction-sintered ceramic composite materials, titanium and hafnium diborides.
UDC 621.762.669.018.95
S. Yu. Marinenko, L. G. Bodrova, G. M. Kramar, V. V. Lazaryuk (m. Ternopil)
Peculiarities of structure in hard alloys on a polycarbide base
The structure formation of alloys based on TiC—(VC, NbC, WC) with a nickel-chromium binder, extracted using traditional technology and technology that includes an additional operation for the advanced synthesis of carbides, has been studied. The alloy was studied using metallographic, X-ray phase and micro-X-ray spectral analysis methods. The process of molding the microstructure of alloys in storage using production technology and chemical storage has been developed.
Key words: hard alloys, polycarbide base, microstructure, ring structure, phase structure.
UDC 621.744:666.798.2
A. A. Leshchuk, T. A. Tsysar, V. V. Ivzhenko (Kiev)
Computer Simulation of Heat Transfer Processes in Injection Molding of Complex-Shaped Products
The results of computer simulation of heat transfer process in injection molding are presented. The temperature distribution in the working path of the installation and molds for casting ceramic products in the form of nozzles, solid balls, balls with a hole and rings is obtained. The initial technological dependences of the cooling time of thermoplastic mass based on AlN, SiC and WC to a temperature of 40 °C for products of various shapes and sizes are calculated.
Keywords: computer simulation, heat transfer processes, injection molding, ceramic products.
UDC 539.266
O. S. Roik, S. O. Lisovenko, V. M. Perevertailo, V. P. Kazimirov, O. B. Loginova (m. Kiev)
Modeling and analysis of the structure of binary melts of the Ni–Mn system
Structural models of Ni–Mn binary melts were derived using the Rolled Monte Carlo method and experimental structure factor curves. The analysis of the local atomic structure was carried out using the statistical-geometric Voronoi-Delaunay method. It has been established that, after excluding the mathematical modification and dispersion of the subsection of the sphericity coefficient of Voronoi polyhedrons, the concentration distribution of the structural parameters of Ni–Mn melts may be of an additive nature. Analysis of the metric characteristics of polyhedrons indicates the implementation of strong non-crystalline packing of atoms in subsequent melts, part of which grows instead of manganese, reaching a maximum value in the vicinity of the melt Ni66.7Mn33.3. However, for the melt, which is indicated by the azeotropic point on the Ni–Mn diagram, it is characterized by increased interaction between the Ni–Mn and Mn–Mn atoms. This interferes with the creation of non-crystalline crevice packing and enhances the diversity in the local sharpening of atoms for melting at this point.
Key words: RMC method, space cut, Voronoi-Delaunay method, surface tension, interatomic interaction, structures factor
UDC 544.31:621.762
A. F. Lisovsky (Kyiv)
On the stability of liquid layers in nanodispersed composite materials
A thermodynamic study of the process of liquid leaving a flat capillary located in a nanodispersed composite body into its volume was carried out. An expression was obtained for the change in the Gibbs free energy of a nanodispersed system during this process. The conditions under which liquid layers are stable in the volume of the composite body or unstable were determined. The classes of composite materials in which liquid layers are stable regardless of the size of refractory particles, as well as composite materials in which liquid layers are unstable were determined.
Keywords: thermodynamics, liquid layers, nanodispersed body.
UDC 621.941
A. S. Manokhin, N. E. Stakhniv, S. A. Klimenko (Kyiv)
Surface irregularities processed by a vertex-less oblique tool equipped with a CBN-based PSM
The article presents the results of a study of the regularity of changes in the surface irregularities parameters processed by a vertex-less oblique tool equipped with a CBN-based PSM, depending on the cutting modes and geometric parameters of the tool.
Keywords: vertex-less oblique tool equipped with a PSM, “shaving” turning, waviness, surface roughness, shape deviation.
UDC 621.921.34-492.2:539.215
G. P. Bogatyreva, G. A. Petasyuk, G. A. Bazaliy, V. S. Shamraeva (Kyiv)
On the issue of homogeneity of diamond micropowders by morphometric characteristics
The article presents the results of the study of the characteristics of the initial powders and the products of their separation by the flotation method, the analysis of the adequacy of the average values of the morphometric characteristics and the assessment of the homogeneity of the powders by the system-criteria method. It is shown that as a result of sorting, the homogeneity of the powders by dimensional characteristics and shape index increases significantly. It is established that the flotation products have the greatest homogeneity, which explains their higher abrasive capacity. The expediency of using the flotation separation method as a tool for increasing the homogeneity of diamond micropowders by morphometric characteristics and the effectiveness of the developed package of computer-analytical methods for the quantitative analysis of these characteristics are proven.
Key words: diamond micropowders, morphometric characteristics, uniformity of powders, flotation products.
UDC 621.923
V. I. Lavrinenko (m. Kiev)
Grinding wheels made of superhard materials in the bench system: cutting according to the hardness criterion
The results of the study on the necessary values of the hardness indicator of grinding wheels made of hard materials as one of the warehouse bench systems during the processing process. It is shown that standard grinding wheels have a sufficient reserve of hardness and ensure critical values.
Key words: grinding wheel, wheel body, wheel hardness, superhard material, wheel wear resistance, roughness.
Review of the monograph “Formation of the structure of composite materials during processing with metal melts” by A. F. Lisovsky.