UDC 666.233
G. P. Bogatyreva, A. L. Maistrenko, N. A. Oleynik, G. A. Bazaliy, V. L. Gvyazdovskaya (Kyiv)
Formation of dispersed systems during diamond extraction from their synthesis products
Two dispersed systems formed during diamond extraction from their synthesis products are studied. Detailed characteristics of the systems are presented: granulometric and chemical composition, distribution of the synthesis product components by the size of dispersed particles, and the degree of material disclosure. Adsorption-structural characteristics and the energy state of the surface of graphite products formed during diamond extraction are determined.
UDC 536.42
V. Z. Turkevich, V. L. Solozhenko (Kyiv)
Thermodynamic analysis of the nitrogen-hydrogen system at high pressures and temperatures
Within the framework of a model considering a mixture of real gases (N2, H2, NH3 and N2H4) as ideal, the equilibrium concentration of ammonia in the decomposition products of hydrazine at pressures up to 4 GPa and various temperatures was calculated.
UDC 548.33:539.26
V. F. Britun, A. V. Kurdyumov (Kyiv) T. Taniguchi (Tsukuba, Japan) I. A. Petrusha, V. B. Zelyavsky, A. V. Andreev (Kyiv)
Transformations of highly ordered graphite-like phases in pyrolytic boron nitride under high static compression pressures
A comparative study of the transformations of rhombohedral and hexagonal modifications of graphite-like boron nitride into dense diamond-like phases was carried out using X-ray diffractometry and texturing, as well as transmission and scanning electron microscopy. Highly textured pyrolytic BN plates served as the initial samples. Experiments at high pressures were carried out in a belt-type apparatus at a pressure of 7.7 GPa and temperatures from 200 to 2300 °C under hydro- and non-hydrostatic compression. It was shown that under the same compression conditions, phase transformations of BNp develop at a higher rate than BNg; deviation from hydrostatics leads to acceleration of transformations, which is especially significant in the case of the initial BNg. The obtained results are explained from the standpoint of the theory of martensitic transformations at high pressures. The implementation of martensitic transformations in textured pyrolytic samples with a highly ordered BNp and BNg structure ensured the production of crystal-oriented polycrystals based on cubic boron nitride with texture axes [112] and [111], respectively. UDC 666.233
N. A. Kolchemanov, A. V. Nozhkina, A. I. Laptev, D. N. Kolchemanov (Moscow)
Kinetics of Polycrystalline Diamond Formation
The kinetics of polycrystalline diamond carbonado formation was studied. It was found that the primary stage of its formation is the stage of graphite-diamond polymorphic transition. Penetration of the catalyst alloy into the reaction zone is determined by a decrease in pressure at the diamond formation boundary due to the volume effect of the graphite-diamond transformation.
UDC 621.762.5:546.261 (088.8)
G. L. Zhunkovsky, T. M. Evtushok, P. V. Mazur, V. A. Kotenko (Kyiv)
Interaction in the Ti-B4C system. Message 2. Optimization of the production process and some physical and mechanical characteristics of the composite
The results of optimization of the process of obtaining a composite material in the Ti-B4C system are presented. It is shown that the intensity of the interaction reaction can be regulated by introducing titanium diboride into the mixture. The physical and mechanical characteristics of the composite are presented depending on the content of reaction products in it.
UDC 538.95:537.226.1
I. Kh. Abdukadyrova (Tashkent)
Temperature and dose dependence of the electrical conductivity of corundum single crystals
The results of studies of the effect of ionizing radiation on various electrical properties of corundum single crystals – electrical conductivity, dielectric loss tangent, and permittivity are presented. A nonlinear change in the conductivity of the crystals with an increase in the radiation dose is established. The activation energy of conductivity is calculated. It is shown that the temperature dependence of the loss tangent becomes more complex after the action of radiation on the dielectric. Possible mechanisms of the observed dielectric effects and conductivity in corundum are discussed.
UDC 621.922.079:678
S. A. Ivanov, A. L. Vetrov, A. L. Maistrenko, V. I. Kushch (Kyiv)
Methodology and device for measuring the thermal conductivity of composite diamond-containing materials on a metal bond
A method and device for measuring the thermal conductivity of composite diamond-containing materials in the temperature range from room temperature to 200 °C are described. The temperature dependence of the thermal conductivity of the Slavutich material is given, as well as the results of measuring the thermal conductivity of other studied materials at an average measurement temperature of 55 °C. It is shown that experimental data in combination with a theoretical method for predicting the thermal conductivity of composite materials make it possible to obtain an integral assessment of the degree of perfection of the structure or “quality” of the composite.
UDC 678.029.76
V. V. Rogov, A. G. Vetrov, T. L. Krotenko (Kiev) V. N. Lebedev, V. N. Lagutin (Kharkov)
Research polishing process of polystyrene scintillators
The article presents the main requirements for polystyrene scintillators for nuclear power engineering, reports on the level of existing technologies for their processing, on the results of experimental studies and the development of a new process for polishing scintillators that meets these requirements.
UDC 621.923
V. I. Lavrinenko (Kyiv)
Roughness of the processed surface: patterns of formation and the relationship of its parameters when processing with an STM tool
The patterns of formation of surface roughness are established for various methods and techniques of processing with a tool made of superhard materials, including abrasive, blade, finishing with bonded and free abrasive. The main trends that should be followed when choosing a processing technology to achieve the required roughness parameters are shown. The presented studies can serve as a basis for obtaining fundamental dependencies linking roughness parameters and the transition to modeling the roughness of a surface processed by a tool made of superhard materials.
UDC 622.23.051.7
S. A. Golovin, V. I. Spirin, G. D. Petrushin, I. K. Arkhipov (Tula, Russia)
Damping capacity of diamond drill bit materials
Using elasticity theory methods, the elastic modulus was estimated and the damping capacity of the copper-based D30-MP composite pseudoalloy and the VK6m multicomponent powder alloy based on tungsten carbide used to manufacture the body and matrix of a diamond drill bit was determined. It was revealed that one of the main sources of energy dissipation in the VK6m alloy is the absorption of energy during the sliding of interphase boundaries in the field of acting stresses, which can be regulated by the shape and size of the relite grains. Recommendations are given for improving the damping properties of diamond crown matrices.
UDC 536.42:661.657.5
A.A. Shulzhenko, N.P. Bezhenar, S.A. Bozhko, V.L. Gvyazdovskaya, N.N.; Belyavina, V.Ya. Markiv (Kiev)
Study of cubic boron nitride powders with particle sizes in the submicro- and nanoranges
The results of the X-ray structural study of cubic boron nitride powders with particle sizes in the submicro- and nanoranges are compared with the granulometric analysis and the value of the specific surface. Submicro CBN powders with a specific surface area of over 30 m2/cm3 are characterized by high cohesive activity, which increases significantly in the nano range.