UDC 669.018.25
A. F. Lisovsky (Kyiv)
Methods of forming mesostructures in sintered hard alloys and their properties (review)
Promising directions of forming mesostructures in sintered hard alloys are considered, an analysis of existing technologies for their production is given, physical and mechanical properties of sintered hard alloys with a mesostructure are presented, and the efficiency of using such alloys in metalworking and rock-destroying tools is shown.
UDC 666.792.34:539.89
D. A. Stratiychuk, A. A. Shulzhenko, N. N. Belyavina, V. Ya. Markiv (Kiev)
Formation of superhard ceramics based on boron carbide under high pressure
The processes of formation of superhard ceramics based on boron carbide under pressure of 5.5 GPa and temperature of 2200 K were studied. It was shown by transmission and scanning electron microscopy methods that sintering of boron carbide powders with particle sizes of 2-80 μm under high pressure initiates primary recrystallization processes in the material, resulting in refinement of its original grain structure. At high p, T-parameters, a polycrystalline material with high crack resistance was obtained.
UDC 624.921.34, 621.921.34
V. A. Mukhanov (Aleksandrov, Vladimir region, Russia)
Improving the methods of diamond extraction from various diamond-containing materials
The methods of diamond purification from graphite and methods of diamond extraction from various diamond-containing materials are described.
UDC 541.64:546.26-162
A. P. Voznyakovsky, V. Yu. Dolmatov, M. V. Veretennikova (St. Petersburg, Russia)
Nanocomposites based on polyblock polysiloxane copolymers and nanodiamonds. Features of distribution topology and properties
The effect of modifying additives of highly dispersed substances of various nature on the complex of elastic-deformation properties of polyblock polysiloxane copolymer films was studied. It has been found that the formation of a physical network of supramolecular structures as a result of self-organization processes under the influence of force fields of highly active nanosized particles allows for a preferential increase in the physical and mechanical parameters of the film in the region of small (up to 100 ‰) deformations without changing the chain microstructure. The use of compositions of H-type (with high surface activity) and L-type (with low surface activity) fillers allows for the maximum realization of the potential for interaction of force fields of units of the supramolecular structure. The latter circumstance leads to a more “effective” supramolecular organization of the polymer and provides a synergistic increase in the physical and mechanical parameters of the film when using an (L—H)-type filler. UDC 546.26-162
V. Yu. Dolmatov (St. Petersburg, Russia)
Theoretical and Applied Aspects of Modern Industrial Production of Detonation Nanodiamonds
The article describes the main theoretical aspects of the detonation decomposition of powerful mixed explosives with a negative oxygen balance with the formation of nanodiamonds (ultradispersed diamonds). The main parameters of their synthesis and the feasibility of using a molten mixture of TNT with hexogen are given. The conditions for preserving the diamond phase in the detonation products are indicated. Various options for industrial detonation synthesis of ultradispersed diamonds are designated. The most rational technology for chemical cleaning of ultradispersed diamonds with nitric acid at high temperature and pressure with the production of diamonds of the highest degree of purity is described.
UDC 666.3/7:621.931
V. B. Shipilo, A. G. Dutov, N. V. Shipilo, V. A. Komar, I. I. Azarko (Minsk)
Crystallization of diamonds at different temperatures and study of their defect structure
The degree and rate of graphite transformation into diamond in the Mn—Ni—C—nitrogen-phosphorus additive system were studied at a pressure of 5.5 GPa, a temperature of 1610—1690 K, and a synthesis time of 30, 45, and 60 s. The activation energy of the diamond formation process was determined to be 112 kJ/mol. It was shown that at the initial stage of graphite transformation into diamond, the fractional composition of diamonds changes insignificantly with a change in temperature and synthesis time, while impurity and defective compositions undergo noticeable changes. The obtained experimental data are explained in terms of the effect of carbon solution supersaturation in the metal melt on the sizes of nuclei formed during the incubation period.
UDC 621.923: 621.921.34
V. I. Lavrinenko (Kiev) L. A. Prots, A. M. Solomon, P. P. Puga (Uzhgorod)
Using X-ray diffraction methods to assess the quality of the processed surface of paratellurite single crystals
The dependences of the width of two-order reflections on the Kß-radiation of paratellurite single crystals oriented along different crystallographic planes were obtained using X-ray diffractometric scanning Θ/2Θ and rocking (fixed angle 2&Theta). For the surfaces of the TeO2 single crystal, it was shown that the rocking method is more sensitive to the general condition of the processed surface for all types of processing (splitting, cutting, grinding, polishing). At the same time there is a tendency for the width of peaks of different reflection orders to coincide, which indicates a high-quality processed surface with minimal roughness.
UDC 621.891:536.12
N. P. Starostin, A. A. Kondakov (Yakutsk, Russia)
Modeling the Thermal Regime during Diamond Processing on a Cutting Disc with a Charged Layer
The problem of determining the non-stationary temperature field in the disc-block system at medium (up to 80 m/s) sliding speeds and small overlap coefficients is considered, solved numerically by the finite difference method. The results of the analysis of the non-stationary temperature field in the cutting disc-diamond system are presented.
UDC 621.9.014
A. A. Vinogradov (Kyiv)
Calculation of chip shrinkage based on the Rz and Ry components of the chip formation force when cutting materials
The article presents the derivation of formulas for calculating the angle of the conditional shear plane when cutting materials based on the measured components of the cutting force, comparative values of these angles calculated by the formula and determined by chip shrinkage for cases of cutting OO, 20X and 40 steels under various conditions are given; a conclusion is made about the advisability of using the formula for determining the tangential stress in the conditional shear plane based on chip shrinkage. It is shown that the determined characteristics correspond to their actual values only at negligibly small values of the forces on the rear surface of the tool.
UDC 621.921.34-492.2:622.24.05
N. V. Novikov, G. P. Bogatyreva, R. K. Bogdanov, G. F. Nevstruev, A. P. Zakora, G. D. Il’nitskaya, A. M. Isonkin (Kyiv)
Homogeneous heat-resistant diamond grinding powders for impregnated drilling tools
The article considers the results of operation of drill bits of various designs and the effect of the homogeneity of diamond powders by strength on their performance. The essence of the process of effective adhesive-magnetic sorting of high-strength diamond powders by the level of defectiveness of the grain surface and by strength characteristics is presented. An increase in the operational characteristics of drill bits is shown when they are equipped with diamond grinding powders with high homogeneity in strength and thermal strength.
UDC 621.928.4:621.921.1: 621.922.34
I. V. Bondar, Yu. I. Nikitin, G. A. Petasyuk, V. G. Poltoratsky (Kyiv)
New composite material based on diamond powders
A step-by-step technological scheme and modes for manufacturing diamond granules from various grades and grain sizes of diamond powders that are not in wide demand have been developed. It has been established that during sintering of granules using the adhesive-active binder MP10, a disappearing liquid phase is present, ensuring the contraction of wettable diamond grains to the center and the formation of a strong composite granule. The results of studying the physical, mechanical and operational characteristics of powders made from the resulting composite material are presented.