UDC 004.94:666.233:62-987
N. V. Novikov, A. A. Leshchuk, A. I. Borimsky (Kiev)
Computer modeling of crystallization zones of diamonds of different habits in high-pressure apparatuses of cylindrical type
The analysis of the efficiency of high-pressure apparatuses (HPA) of cylindrical type is carried out based on the results of computer modeling of crystallization zones of diamonds of different habits depending on the method of placement of reaction components, design features of the reaction cell and the power of the heating current.
UDC 666.792.6.621.921.34.025
I. A. Petrusha, A. A. Shulzhenko, S. A. Klimenko, N. P. Bezhenar, A. S. Osipov, S. A. Bozhko, S. N. Oak (Kyiv)
Deformation-hardened cBN-based composite for blade processing of nickel alloys
A new cBN composite with a deformation-hardened fine-grained structure has been obtained. In its main component (particles of high-strength reinforcing filler made of polycrystalline cBN), during sintering under high pressures and temperatures, as a result of deformation processes, a structure with ultrafine grains ranging in size from tens to hundreds of nanometers is formed. The second component, which acts as a cementing particle of the matrix filler, is a ceramic material also based on cBN, the structure of which is formed during conventional activated sintering. Its Knoop hardness is 36-39 GPa. The material works effectively under high cutting temperatures of nickel alloys.
UDC 548.736.15
V. Yu. Kulikovsky, A. V. Kurdyumov (Kyiv)
Superhard carbon films with a graphite-like structure
The effect of ion bombardment (IB) of the growing surface of carbon films obtained by magnetron sputtering of a graphite target on their hardness and structure was studied. Using the example of films obtained under IB conditions, the fundamental possibility of realizing ultra-high hardness of carbon films (HV up to 50 GPa) was shown due to the formation of a specific graphite-like nanostructure, and not due to the formation of diamond sp3 bonds.
UDC 680.181
V. F. Britun (Kyiv)
Structural Features of Martensitic Transformations of Graphite into Lonsdaleite and Diamond
A generalized structural model of diffusionless transformations of hexagonal and rhombohedral graphite into lonsdaleite and diamond is proposed. The structural rearrangements are considered as a set of similar processes of deformation of the lattice of the initial structure. Within the framework of the model, variants of orientation relationships between phases are discussed, as well as the reasons for the high disorder of lonsdaleite. An analysis of the reason for the simultaneous formation of diamond and lonsdaleite in the crystal is carried out.
UDC 62-987:666.233
A. I. Prikhna (Kyiv)
A cylinder-piston type apparatus for diamond synthesis
A high-pressure apparatus (apparatus) of the cylinder-piston type, made of steel, capable of developing pressure up to 6 GPa is proposed. Unlike traditional apparatuses of this type, there are gaps between the cylinder sections and the cylinder and piston, and a sleeve made of plastic material is installed on the part of the piston protruding from the cylinder. The advantages of the apparatus in the reliability of pressure creation and the possibility of independent regulation of pressure and temperature are shown.
UDC 535.343.546.171
I. P. Fesenko (Kyiv)
Functional and Structural Materials Based on AlN
The regularities of obtaining ceramic materials based on AlN by hot pressing and free sintering methods are studied using electron microscopy, X-ray diffraction analysis, and measurements of mechanical, thermal and electrophysical properties. The characteristics of the developed materials are presented: structural with a hardness of HV = 16.8 GPa, crack resistance K1c = 4.7-4.9 MPa m1/2, bending strength (20 °C) s = 400-470 MPa; functional for absorbing microwaves with a permittivity of e = 23 at a frequency of 3 GHz and a dielectric loss tangent tg; d = 0.066 at a frequency of 3 GHz; heat-resistant and wear-resistant AlN-TiN composite, maintaining a high level of mechanical properties up to 1200 °C.
UDC 666.3/7:621.931
V. B. Shipilo, A. G. Dutov, N. V. Shipilo, V. A. Komar, I. I. Azarko, M. S. Tseluevsky (Minsk)
Kinetic Features of Diamond Crystallization from the Melt of the Mn-Ni-C System
The effect of synthesis time on the degree and rate of graphite transformation into diamond in the Mn-Ni-C-nitrogen-phosphorus additive system at p = 5.5 GPa and T = 1620 K, on the size and impurity composition of diamonds and their strength was studied. It was shown that the kinetics of diamond crystallization in the system under consideration is characterized mainly by local changes in the supersaturation of the carbon solution in the metal melt, causing a change in the crystallization parameters and properties of diamonds.
UDC 669.785.532:018.29.71
O. V. Pshenichnaya (Kyiv)
Production of nanocrystalline composite powders by nitriding titanium and zirconium aluminides
For the first time, a non-traditional method for producing high-purity and homogeneous AlN—TiN and AlN—ZrN composite powders using titanium and zirconium aluminides as precursor phases, in which Similar metals are mixed at the atomic level; their nitriding at 600-1400 °C in nitrogen and ammonia was studied. It was shown that the process should be carried out at the lowest possible temperature (1250 °C), which allows maintaining the distribution of elements in the resulting powders close to that in the precursor phase, as well as preventing the growth and aggregation of phase components. Nanodispersed AlN-TiN composite powder with high purity and homogeneity allows obtaining high-density (> 93 ‰) and durable material not only by hot pressing, but also by sintering in nitrogen without applying pressure.
UDC 621.923
A. I. Grabchenko, V. A. Fedorovich (Kharkiv)
The influence of anisotropy of crystallite properties on the process of mutual destruction of elements of the STPM-grain system during grinding
It is shown that the quality of the processed surface of superhard materials largely depends on the anisotropy of the physical and mechanical properties of their constituent crystallites and diamond grains, which determines the intensity and nature of mutual microdestruction of elements of the STPM-grain-bond system. It must be taken into account when assigning diamond grinding modes and wheel characteristics in productive and precision processing.
UDC 621.923
V. I. Lavrinenko (Kyiv)
The angle of the direction of action of tangential stresses is the key to the tool made of STM
A new view is presented on the concepts of the working layer of a tool made of superhard materials (SHM) as a composite, in which the direction of action of tangential stresses during its formation is decisive. The angle of the direction of action of such stresses (p/4 or 3p/4) is the key to understanding the structure and nature of tendencies to increase the wear resistance of grinding wheels made of STM.
UDC 548.33
V. L. Solozhenko, O. S. Kondratenko, V. G. Litovchenko, N. L. Dmitruk (Kyiv)
On the issue of the refractive index of cubic boron carbonitride
UDC 666.764 A. S. Smolyar, Yu. I. Sozin, V. A. Barkholenko, S. N. Maloshtan, V. A. Kuts, V. G. Gurin, A. P. Arkhipov, A. Yu. Gerasimov, N. A. Razvadovsky, A. N. Titenko (Kiev) On the question of the existence of cubic graphite.