UDC 666.3-135:536.24
V. N. Kolodnitsky (Kyiv)
Evaluation of Thermal Stability of Ceramic Materials under Intensive Thermal Loading (Review)
The article provides information on the selection of the shape of ceramic samples and methods for testing them for thermal stability. The criteria for thermal stability are presented, as well as a mathematical model for assessing the thermal stability of ceramic materials, taking into account the complex stress state of the sample under thermal shock conditions depending on its geometry, which in turn depend on the temperature of the thermophysical and elastic properties of the material, and the intensity of heat exchange. The thermal stress state and fracture statistics of silicon carbide samples are analyzed.
UDC 666.792.34:539.89
A. A. Shulzhenko, D. A. Stratiychuk, M. G. Loshak, L. I. Alexandrova, G. S. Oleynik, N. I. Zaika (Kyiv)
Composite superhard materials containing boron carbide
The possibility of obtaining composite superhard materials containing boron carbide, which have increased thermal stability, as well as high elastic characteristics, hardness and crack resistance, is shown. Sufficiently high crack resistance of the composite is provided by a structure with increased strength of interphase boundaries, formed under conditions of high p, T-parameters.
UDC 536.42:661.657.5
M. P. Bezhenar, S. A. Bozhko, N. M. Bilyavina, P. A. Nagorny, S. M. Konoval (m. Kiev)
Phase storage of composites removed by reaction adhesions in the cubic boron nitride-diamond-aluminum system at a high pressure
Using the method of X-ray diffraction analysis, the phase composition of composites that were sintered under high pressure (4.2 GPa, 1750 K) of cBN and Al powders with houses into a diamond charge was determined. It has been shown that as a result of reaction interaction during sintering of the charge components in the warehouse of composites in the order of cBN and diamond, there can be nitride, diboride, carboboride and carbide aluminum, as well as solid boron and/or carbon based on crystalline combs Al, AlN, cBN. The possibility of dispersing the composite when washed instead of diamond below the percolation threshold is shown. In addition to diamond, the abrasive resistance of composites is increased by the Al3BC phase, distributed at the interphase boundaries.
UDC 666.233
V. V. Lysakovsky, S. A. Ivakhnenko, A. N. Katrusha (Kiev)
The effect of titanium alloying of the Fe-Co-C solvent on the nitrogen content in diamond single crystals grown at high pressures and temperatures
Experimental studies were conducted on growing diamond single crystals in carbon alloys-solvents based on Fe-Co with a change in the titanium content in them from 1 to 2 ‰ (by weight), average growth rates and morphological features of the grown crystals were determined, their defect-impurity composition and characteristics of macroinclusions were studied. It has been established that an increase in the titanium content from 1 to 2 ‰ (by weight) in the Fe–Co–C solvent leads to a change in the type of diamond single crystal from Ib to IIa. The use of a solvent with a titanium content of 1.5 ‰ (by weight) allows the growth of mixed type Ib+IIb diamond single crystals.
UDC 539.266
S. O. Lisovenko (m. Kiev)
Using a quasi-force algorithm to investigate the structure of melts
A new method has been developed for modeling the structure of solids, including melts, which are under a high pressure. The application of this method for studying diamond growth centers is demonstrated using the Ni—C system (92 ‰ (at.) Ni, 8 ‰ (at.) C). A number of its advantages over the Reverse Monte Carlo algorithm are shown.
UDC 621.923
A. Yu. Filatov, V. I. Sidorko, Yu. D. Filatov (Kiev)
Features of the formation of macro- and microrelief of flat surfaces of parts made of non-metallic materials during diamond grinding
Based on the physical-statistical model of the formation of sludge particles of the workpiece during grinding and the analysis of their interaction in the contact zone, the regularities of the formation of macro- and microrelief of the flat surface of the workpiece and the working layer of the tool are described.
UDC 621.922.34
M. N. Sheiko (Kyiv)
Abrasive wear of individual grains in diamond rollers and stones during dressing of abrasive wheels and its relationship with diamond wear in the tool as a whole
The abrasive wear of individual grains of a diamond dressing tool during dressing of abrasive wheels is investigated. An analytical assessment of the wear intensity is given taking into account the mechanical-statistical and temperature characteristics of the grains under roller and stone dressing conditions, as well as taking into account temperature changes in the hardness of diamonds. A relationship is established between the wear of individual grains and the wear of the diamond layer of the dressing tool as a whole.
UDC 621.921.34-492.2:539.215
G. A. Petasyuk, G. P. Bogatyreva (Kyiv)
Extrapolation-analytical method for determining the external specific surface of superhard material powders
A new method for determining the external specific surface of superhard material powders is presented. The method is based on the methodology of 3D modeling using the mathematical apparatus of affine space mapping. The initial data are the grain height, area, perimeter, maximum and minimum diameters of its projection. The results of testing the extrapolation-analytical method for determining the external specific surface area on standard DSTU 3292-95 ground and micro powders of synthetic diamond are presented. Recommendations for the practical application of the developed method are given.
UDC 661.665.7
T. M. Duda, V. M. Tkach, A. M. Kutsay, A. G. Dovgan, S. V. Tkach (Kiev)
Phase composition and surface properties of cubic boron nitride micropowders
The phase composition of cubic boron nitride powders of KM grades with grain sizes of 0.5/0, 1/0, 2/1, 3/1 and 3/2 was studied using X-ray diffraction analysis and IR spectroscopy. The presence of hexagonal modification of boron nitride along with sphalerite (from 0.8 to 6.0 ‰ (by weight)) is shown. The kinetics of capillary absorption during the interaction of the surface of KM grade powders with various systems is studied and the effect of the introduction of surfactants and metallization on the flow rate constant of working media is determined. The dynamics of powder activation by palladium is studied and optimal conditions for the restoration and growth of active centers on their surface are determined.
UDC 539.374
L. N. Devin, N. E. Stakhniv, A. G. Sulima (Kyiv)
The effect of wear on the stress state of a diamond-hard alloy plate
The nature of the change in the magnitude of maximum stresses on the front and rear surfaces of the cutter, as well as the probability of tool failure with increasing wear, are established. The maximum tool life is calculated based on the wear intensity diagram. The results of a study of the influence of a ni-resist cast iron insert on the wear resistance of a diamond-hard alloy plate are presented.