UDC 539.3:539.89
S. B. Polotnyak (Kyiv)
Numerical modeling of the B1–›B2 phase transformation in a KCl potassium chloride sample under deformation in a gasket of an ultra-high-pressure apparatus with diamond anvils
A numerical modeling of the phase transformation process in a polycrystalline potassium chloride KCl sample under deformation under quasi-hydrostatic conditions on anvils of an ultra-high-pressure apparatus with diamond anvils was carried out. The stages of the transformation process were investigated and its regularities were revealed. It was shown that the phase transition in the volume of a finite element leads to a significant redistribution of stress fields, plastic and volumetric deformation, as well as to a decrease in the pressure in the sample, the force applied to the anvils and, accordingly, to a decrease in the driving force of the transformation. During the transformation process, several nuclei of a new phase are formed in the sample, which is caused by plastic relaxation of stresses in the elastic-plastically deforming phase B1 KCl — the nucleation of a new nucleus becomes more favorable than the development of an old one.
Keywords: finite element method; martensitic phase transformation; potassium chloride; KCl; high-pressure apparatus with diamond anvils; transformation stages.
UDC 544.3:621.762
A. F. Lisovsky (Kiev)
Thermodynamics of Nanoparticle Consolidation in a Three-Phase System
The thermodynamic functions obtained using T. Hill’s method are presented, describing the process of consolidation of nanoparticles in a three-phase system consisting of particles of two solid phases and a mobile phase, and an expression is obtained for the shrinkage pressure arising during the consolidation of nanoparticles. Based on thermodynamic functions, a criterion is proposed that allows predicting the structure of a composite material.
Keywords: thermodynamics, nanoparticle, consolidation, three-phase systems.
UDC 62-987:666.233
A. I. Prikhna (Kiev)
Biaxial compression apparatus for diamond synthesis
A device for diamond synthesis is proposed, the pressure cavity of which is formed by four stepped radially located punches enclosed in a housing. Each of the punches is mated with the housing by two mutually perpendicular planes, one of which is parallel to the axis of the cavity, and the other is inclined to it.
Keywords: diamond, synthesis, pressure.
UDC 621.744
V. V. Ivzhenko, V. A. Popov, G. F. Sarnavskaya (Kyiv)
Study of the process of mixing thermoplastic masses based on powders of refractory compounds and paraffin
The results of the study of the process of mixing thermoplastic masses based on powders of aluminum and silicon nitrides, silicon and tungsten carbides and paraffin for injection molding of ceramic and metal-ceramic products are presented. The influence of dispersion, morphological features and specific gravity of powders on the process of mixing thermoplastic masses is established.
Keywords: powders, refractory compounds, paraffin, thermoplastic mass, binder concentration, viscosity, packing coefficient, mixing duration.
UDC 620.178.3.16:621.9.048
V. Yu. Danilchenko, O. M. Semirga (m. Kiev)
Phase warehouse of carbide electrospark coating on a carbon steel lining
The X-ray diffraction method was used to trace the high-phase deposits of the carbide coating that was formed during the electric spark machining of U8 steel and the replacement of an alloy electrode with T15K6 alloy. It has been shown that the high consistency of phase storage coatings is determined by the dissociation of WC carbide on the surface of the electrode and the synthesis of TiCN carbonitride in the interelectrode space during the flow of nitrogen from the electrode. again.
Key words: structural phase mill, X-ray diffraction, electric spark processing, carbide.
UDC 621.891:681.7:539.621
V. V. Rogov, V. N. Tkach, N. D. Rublev, A. V. Troyan, V. N. Popelnyuk (Kiev)
Study of the surface condition of sapphire parts (α-Al2O3) after their finishing
The results of experimental studies of sapphire parts after their finishing are presented using modern means of measuring the elements of the surface layer condition (roughness Rmax and the depth of the damaged layer F). The factors influencing the specified parameters during the processing and the relationship between them are established, allowing for the calculation of per-operation allowances for the processing of the part and the construction of its technology, ensuring the highest optical requirements.
Keywords: surface layer, roughness, depth of the damaged layer, precision processing, polishing, optical requirements.
UDC 621.623
Yu. D. Filatov, V. I. Sidorko, S. V. Kovalev, A. Yu. Filatov, V. P. Yashchuk, O. A. Prigodyuk (Kiev) U. Heisel, M. Storchak (Stuttgart)
Quality control of non-metallic parts surfaces during finishing diamond-abrasive processing
A technique for measuring the coefficients of reflection and scattering of laser radiation by polished surfaces of parts made of non-metallic materials is described. The relationship between the intensity of scattered light and the roughness is studied polished surface. The possibility of determining the colorimetric characteristics of non-metallic materials by the coefficients of light scattering and reflection is shown.
Keywords: quality control, roughness, reflection coefficient, light scattering spectrum.
UDC 621.77
O. A. Rosenberg, E. A. Pashchenko, A. P. Maidanyuk, O. V. Mikhailov, M. B. Shtern (Kiev) E. Olevsky (San Diego, USA)
Evolution of the distribution of density, accumulated deformation and topological features of powder cylindrical blanks under deforming drawing conditions. Message 1. Modeling and analysis of the distribution of density and accumulated deformation in powder bodies formed using various schemes of deforming drawing
The results of the study of the structure of powder bodies subjected to plastic deformation by drawing are presented. Various schemes of deforming drawing are considered, providing for direct contact of the workpiece surface with the deforming element and drawing in a closed system. A mathematical model of the process is given and calculated patterns of density distribution and accumulated deformation of powder compacts at different moments of deformation are presented. Structural manifestations of the application of both schemes of deforming drawing are compared.
Keywords: powder compact, plastic deformation, accumulated deformation, porosity.
UDC 661.657:548.73
N. P. Bezhenar, S. A. Bozhko, T. A. Garbuz, N. N. Belyavina, V. Ya. Markiv (Kiev)
Characteristics of the Crystalline Structure of Titanium Diboride Formed in Superhard Composites of the cBN—Al—TiB2 System
UDC 539.3:539.89
S. B. Polotnyak (Kyiv)
Numerical Simulation of the B1–›B2 Phase Transformation in a Sample of Potassium Chloride KCl During Deformation in a Gasket of an Ultrahigh-Pressure Apparatus with Diamond Anvils
A numerical simulation of the phase transformation process in a sample of polycrystalline potassium chloride KCl during deformation under quasi-hydrostatic conditions on anvils of an ultrahigh-pressure apparatus with diamond anvils was carried out. The stages of the transformation process are investigated and its regularities are revealed. It is shown that the phase transition in the volume of the finite element leads to a significant redistribution of stress fields, plastic and volumetric deformation, as well as to a decrease in the pressure in the sample, the force applied to the anvils and, accordingly, to a decrease in the driving force of the transformation. During the transformation, several nuclei of a new phase are formed in the sample, which is due to plastic relaxation of stresses in the elastic-plastically deforming phase B1 KCl – the nucleation of a new nucleus becomes more favorable than the development of the old one.
Keywords: finite element method; martensitic phase transformation; potassium chloride; KCl; high-pressure apparatus with diamond anvils; stages of transformation.