UDC 678.044:678.063
IN. Yu. Dolmatov (St. Petersburg)
Polymer-diamond compositions based on detonation nanodiamonds. Message 1
The effectiveness of introducing detonation nanodiamonds into polymer films and resins based on composite plastic (glass and epoxy resin ED-20), polyamide, fluoroplastic, polyfluorinated elastomers is shown. The addition of 1 to 5 ‰ (by mass) of a diamond-containing charge to the specified polymers provides an increase in tensile strength by 1.5-3.0 times, resistance to abrasion and tearing by 2-3 times, and vulcanization speed by 30-50 ‰.
The introduction of nanodiamonds made it possible to realize in practice the hard-to-achieve effect of combining high strength indicators while maintaining elasticity at the level of unfilled elastomers.
UDC 621.002:548.571
AND. IN. Kurdyumov, V. F. Brytun, A. I. Danylenko, V. B. Zelyavsky, V. M. Volkogon (Kyiv)
The structure of polycrystals obtained by sintering nanocrystalline powders of cubic and wurtzite boron nitride
The structure and some properties of polycrystals obtained by sintering nanocrystalline powders of dense modifications of BN by shock-wave synthesis are investigated. Sintering was carried out at a static pressure of 7.7 GPa and temperatures of 1100—1800 °C. The highest values of density (3 g/cm³) and microhardness (up to 20 GPa) were obtained by polycrystals obtained by sintering a powder containing approximately equal amounts of wurtzite and sphalerite modifications. In the temperature range of 1100—1300 °С, the wurtzite phase was transformed into sphalerite phase. The average size of BNsf grains varied in this temperature range from 20 to 50 nm. The structure of sinters is characterized by the presence of intergranular (grain-boundary) interlayers with a thickness of 2-5 nm.
UDC 539.89:621.762.5:621.921.34-492.2
AND. AND. Bochecka, L. A. Romanko, V. WITH. Gavrilova, S. M. Konoval, S. N. Nazarchuk (Kyiv)
Peculiarities of sintering of diamond powders of different dispersion under high pressure conditions
The dependence of the density, porosity, and hardness of diamond polycrystals, sintered at high pressures and temperatures from diamond powders of different grain sizes, on the duration and temperature of sintering was studied. On the basis of the obtained dependences, a hypothesis was expressed about the counteraction of capillary forces to the compaction of diamond particles due to external influence. It is shown that the degassing of diamond nanopowder of static synthesis doubles the hardness of polycrystals sintered from it.
UDC 544.65:546.26-162
I. AND. Novoselova, E. N. Fedoryshena, E. IN. Panov (Kyiv)
Electrodes based on diamond and diamond-like materials for electrochemical application
Summarized results of the investigation in aqueous solutions of the electrochemical behavior of electrodes made of single crystals of dielectric and semiconducting synthetic diamonds, polycrystalline diamond films, films of amorphous and hydrogenated amorphous carbon, as well as compacts of nano- and microdispersed diamond powders are given. It is shown that the size and type of electrical conductivity of diamond materials, the quality (continuity) of the films, and their corrosion resistance play a decisive role in the use of such electrodes. The results of the work showed the perspective of using the researched materials in electrochemical processes.
UDC 621.922.079
IN. I. Kush, S. AND. Ivanov (Kyiv)
Experimental-theoretical method of determining the local density of a porous material
A method of determining the local porosity of sintered metal products is proposed, based on the measurement of their hardness and comparison of the obtained values with the data of theoretical analysis, which includes the selection of a porous material model, the identification of its material and structural parameters, and the numerical solution of a contact problem simulating Rockwell hardness measurement. The results of laboratory and numerous experiments to determine the elastic-plastic properties of solid and porous cobalt obtained by the technology of intensive electrosintering at elevated pressure are presented. Their satisfactory agreement confirms the operability of the method, including the possibility of obtaining by calculation, provided that the material and structural parameters of the model are properly specified, the hardness of the porous material. The solution of the inverse problem, consisting in estimating the porosity from the measured hardness, is the theoretical basis of the proposed method.
DK 519.711.3:621.762.5
V. A. Dutka, A. L. Maistrenko, S. A. Ivanov, V. P. Pereyaslov (Kyiv)
Modeling the diffusion process during intensive electrosintering under pressure of a powder mixture onto a metal base
A computer model of the diffusion process occurring in the contact zone of a powder composite material with a metal base during its intensive electrosintering onto a base under pressure is proposed. The model consists of two parts: a model of the temperature field in the investigated volumes of powder blanks and a model of the diffusion process in the contact zone of powder blank particles with the metal base during sintering. In the second part of the model When solving the diffusion problem, the information obtained in the first part about the change in temperature over time in the contact zone is used. The adequacy of the model is established on the basis of the agreement of the results of calculations with the data of laboratory studies of the diffusion process between a titanium powder billet and a copper plate during their sintering under pressure.
The developed model can be used to study the structural changes of powder compositions during their intensive electric baking under pressure on a metal base and to optimize the modes of the technological process of sintering products from powder compositions.
UDC 622.24.051.64
R. K. Bogdanov, A. A. Shulzhenko, A. P. Zakora, A. M. Isonkin, V. G. Gargin (Kyiv)
A new superhard material in a drilling tool
The physical and mechanical properties of a new polycrystalline diamond composite heat-resistant material and the possibility of its application in a rock-destroying tool for drilling wells in hard rocks are considered. The results of studies on establishing the influence of the size of the inserts of the new material on the performance of the drilling tool are given. The optimal size of the insert for equipping the working end of the drill bit, which provides an increase in the productivity of drilling wells in hard rocks compared to existing types of the tool, has been established.