UDC 546.26-162:537.533.7
V.D. Blank, B.A. Kulnitskiy (Troitsk, Russia) O.M. Zhigalina (Moscow)
Direct phase transformation of the intermediate carbon phase (ICP) into graphite under electron-beam irradiation
The unknown carbon phase was found and identified by TEM studies of C60 and C70 samples after thermobaric treatment and after neutron irradiation of diamond [1–3]. The direct phase transformation from this phase into graphite caused by electron-beam irradiation has been revealed by HRTEM methods in the present study. The found phase has been considered as intermediate one between graphite and diamond. This intermediate carbon phase (ICP) can be produced under direct and reversible graphite ‹–› diamond phase transitions.
UDC 621.921.34-492.2:544.22
G. V. Sakovich, V. F. Komarov, E. A. Petrov (Biysk, Russia)
Synthesis, properties, application and production of nanosized synthetic diamonds. Part 2. Application and production
The paper describes the areas of implemented and prospective practical application of nanosized particles of synthesis products and purified diamonds. Information is provided on the rational way of creating and implementing the technology for the synthesis and purification of such material.
UDC 536.42:621.762.5:661.657.5
N. P. Bezhenar, A. A. Shulzhenko, S. A. Bozhko, N. N. Belyavina, V. Ya. Markiv (Kiev)
Reorganization of the deformation substructure of polycrystals during sintering of micron and submicron CBN powders under high pressure
The evolution of the substructure of polycrystals during sintering of BNsf powders in the temperature range of 300-2700 K under a pressure of 7.7 GPa was studied using X-ray diffraction analysis. Two temperature regions of strain hardening were noted. It was shown that the relationship between the hardness of polycrystals and the dislocation density corresponds to the Taylor relation on hardening by long-range stress fields of dislocations.
UDC 548.73:661.657.5
Yu. A. Fedotova, J. Stanek, N. A. Shishonok, A. A. Leusenko, V. V. Uglov (Minsk, Belarus)
Mössbauer studies of cubic boron nitride obtained by direct phase transformation and catalytic synthesis
Samples of cubic boron nitride synthesized both by direct phase transformation and in the presence of catalysts were studied using Mössbauer spectroscopy, X-ray diffraction and X-ray energy dispersive microanalysis. It was found that in the samples obtained by direct phase transformation, 57Fe is present in the divalent state (Fe2+), and also forms local configurations corresponding to ε-Fe2N and a-(Fe—B) compounds. In the case of catalytic synthesis, the dominant state of 57Fe is the trivalent state (Fe3+). The transformation of the local environment of 57Fe in both types of samples as a result of annealing in the temperature range 400–1000 °C was studied.
UDC 535.343.546.171
I. P. Fesenko, P. S. Kisliy, M. O. Kuzenkova, G. S. Oleinik (m. Kiev)
Ceramics with AlN nanopowder
The possibility of maintaining ceramic parts of the “column” type with AlN nanopowder by hydrodynamic pressing, degassing and adhesiveness under normal pressure has been studied. It has been shown that during the sintering process of powder compacts, the average pore size increases, which is due to the polydispersity of the output syrup. The elasticity of shrinkage at temperatures of 1300–1700 °C of particles cured by the hydrodynamic method is in the same way as in the samples cured by one-weight pre-curing. Spliced without a vice at temperatures of 1800–1850 °C, spherical ceramic bodies with a diameter of 70–74 mm with a porosity of less than 5 ‰ (per volume) were extracted from powder blanks subjected to hydrodynamic pressing. and thickness close to the theoretical value of AlN thickness (3.26 g/cm3).
UDC 621.921.34-492.2
G. P. Bogatyreva, M. N. Voloshin, V. S. Shamraeva (Kyiv)
Sedimentation stability of nanodiamond suspensions in aqueous media
The sedimentation stability of nanodiamond suspensions in water, gelatin solutions, sodium pyrophosphate and sodium carboxymethylcellulose was studied. The influence of the aqueous medium characteristics and the nanodiamond surface activity on the nature of its sedimentation and the concentration of the stable suspension was established. It was shown that the use of nanodiamond with a higher surface activity contributes to an increase in the sedimentation rate of the studied suspensions and the formation of a more concentrated sediment.
UDC 669.018.25
M. G. Loshak (Kyiv)
Durability criteria for hard-alloy elements of high-pressure apparatuses for the synthesis of superhard materials
A wide range of tests of WC-Co hard alloys made it possible to evaluate each physical or mechanical characteristic when using it as a criterion for the quality, strength and durability of hard-alloy products under operating conditions. It is shown that the durability of hard-alloy products for specific conditions of cyclic loading can be predicted based on a set of characteristics obtained under static loading.
UDC 621.923
V. I. Lavrinenko, V. N. Kulakovsky (Kyiv)
Stresses arising in the grain-bond contact zone taking into account m grain inclination
With regard to diamond wheels made of superhard materials (SHM) on polymer bonds, the stresses arising in the grain-bond contact zone were calculated, and the features of their change under conditions of different grain inclinations in the working layer of the wheel were studied. Analysis of data on the influence of the grain angle in the range of values from 35 to 145° on the value of equivalent stresses and the indicators of its difference shows that the minimum values of the indicators are formed at an inclination angle of 75°. It was found that in the range of angle values from 45 to 105° (except 75°), the stress difference along the grain-bond contact line is almost the same, and the actual grain inclination with an angle of more than 120° can significantly affect their retention in the bond, since they fall into a zone unfavorable for effective work.
UDC 621.868.8
M. G. Kiselev, V. T. Minchenya, V. L. Gabets (Minsk, Belarus)
Efficiency of using ultrasonic vibrations in diamond crystal turning operations It has been established that applying ultrasonic vibrations to a diamond tool can significantly increase the intensity of stock removal from the surface of a diamond workpiece. By changing the intensity of the introduced vibrations, it is possible to control both the productivity of the turning process and the quality of the processed diamond surface within wide limits. A description of a manual ultrasonic tool for turning diamond crystals is given.
UDC 539.374
L. N. Devin, N. E. Stakhniv, V. N. Titorenko, V. N. Nechiporenko (Kiev)
Study of the effect of wear value on the performance of cutters made of CBN polycrystals
The article presents the results of a study of the process of finishing turning of hardened steel KhVG with a hardness of HRC 60-62 using cutters made of polycrystals of cubic boron nitride. The effect of tool wear on the components of the cutting force, the roughness of the machined surface, and the value of maximum stresses on the front and back faces of the cutter is established. The probability of cutter failure at different stages of wear is determined. Practical recommendations are given for choosing the optimal value of critical wear.