UDC 661.65:661.55
V. I. Kushch, S. N. Dub (Kyiv)
Assessment of elastic-plastic properties of materials based on nanoindentation data and computer modeling.
- Experimental and theoretical methodology
A methodology for assessing the elastic-plastic properties of materials is proposed, based on a comparison of nanoindentation data with the results of numerical modeling of contact interaction in the indenter-sample system. As model testing shows, it works satisfactorily for both amorphous materials and metals (annealed and strain-hardened) at the micro- and submicrolevel. Its applicability to modeling the process of nanoindentation of materials with a pronounced size effect requires additional consideration of factors that are significant for a given scale level. These include the shape and degree of blunting of the indenter, as well as the effect of the deformation gradient and grain boundaries on the mobility of dislocations and the yield strength of the material at the nanolevel determined by it.
Keywords: nanoindentation, yield strength, numerical modeling, size effect.
UDC 666.233-49.2; UDC 658.012.122:621.921
L. O. Tavares, W. S. Vianna, G. S. Bobrovnitchii, A. L. D. Skury, J. J. A. Rangel (Campos, RJ, Brazil)
Possibility of the application of the computational intelligence in the production of superhard materials. Report 2
A new system to control a 630-ton and a 2500-ton presses has been developed. By using this system it has been made possible to define new parameters related to pressure and temperature and the influence of certain factors on them. Furthermore, the new system has been shown to indicate that other parameters, such as height of the gasket formed, electrical resistance of the reaction cell, and the frequency of activation of the pump or multiplier, can serve as important indicators of the improvement of superhard material production technologies, implementing the Computational Intelligence.
Keywords: high pressure, superhard materials, synthesis, sintering, press, high-pressure apparatus, command.
UDS 621.921.34-488:621.386.82
M. Hernández-Ortiz, R. Bernal, C. Cruz-Vázquez, J. Morales, V. M. Castaño(México, United Mexican States)
High dosage thermoluminescence diamond dosimeters
Diamond thin films have been irradiated with high doses (up to 12.8 kGy) of 90Sr beta particles. The diamond thin films have been synthesized from commercial Tequila as a precursor using pulsed liquid injection by chemical vapor deposition technique reported recently. Thermoluminescence phenomena at these doses exhibit peak curve shift to higher temperatures (from 370 to 440 K) in the glow curve and the integrated thermoluminescence curve show a linear behavior. Therefore, it has been considered that diamond thin films could be used as high doses dosimeters.
Keywords: CVD diamond, thermoluminescence, dosimeters.
UDC 620.22 : 669.018.25
A. F. Lisovsky, N. A. Bondarenko (Kiev)
Thermodynamic study of doping the diamond–WC–Co composition with transition metal silicides
The interaction of CoSi2, NiSi2, CrSi2 silicides with the diamond–WC–Co composition was studied. It is shown that stable phases in this composition are CoSi, SiC, CrSi, Cr3C2, Cr7C3, WSi2. For alloying the diamond–WC–Co composition, silicides NiSi2 and CrSi2 are recommended.
Keywords: diamond, silicide phases.
UDC 519.688:536.2:669.018.25
N. V. Litoshenko (m. Kiev)
Degree of value and plasticity of medium-grained hard alloys WC–6% Co depending on the deformation characteristics of the cobalt and carbide phases
Using an additional structure algorithm, the influence of the deformation characteristics of the carbide phase and cobalt binder on the strength and plasticity of the WC–Co hard alloy was monitored.
Key words: WC–Co hard alloy, rozrokunk algorithm, phase power, structural parameters, deformation characteristics.
UDC 539.231
V. S. Antonyuk (m. Kiev)
M. O. Bondarenko, Yu. Yu. Bondarenko (metro Cherkasy)
Investigation of thin wear-resistant carbon coatings and structures formed by thermal evaporation in vacuum on poisoceramic materials
The functional features of removing thin wear-resistant coatings through the adaptation of the original mold to thermal vacuum deposition on the surfaces of ceramic materials have been studied.The influx of low-energy string electron flow on the physical and operational characteristics of the surface of poisoceramic elements that are used in the drains of aggressive media has been revealed. It has been established that modification with a low-energy electron flow (E ≤ 6 keV) on the surface of piezoelements from TsTS-19 ceramics paints the microgeometry of their surfaces, fuses the molding of carbon structures on them, so increases microhardness by 8–12%.
Key words: carbon coatings, piezoceramics, thermal evaporation in vacuum.
UDC 691.327:666.973.6
M. A. Tsysar (Kyiv)
Study of topological features of the surface of HFCVD nanocrystalline diamond film using a scanning tunneling microscope with a diamond tip
The structural features of the surface of HFCVD nanocrystalline diamond film are considered.features of nanocrystalline HFCVD diamond film and a physical and mathematical model of the atomic structure of its surface was constructed. The film was examined in air using a scanning tunneling microscope equipped with a tip made of a semiconductor single crystal of diamond doped with boron. Fractal analysis of STM images of the film surface showed the presence of diamond single crystals of various orientations with an average size of 31 nm with a fractal dimension of 2.36 and 2.73.
Keywords: nanocrystalline diamond carbon film, physical and mathematical model, scanning tunneling microscope, tip made of a semiconductor single crystal of diamond doped with boron.
UDC 621.941
L. N. Devin, N. E. Stakhniv (Kyiv)
Study of the Effect of Wear of a Cutter Made of a CBN-Based Composite on the Probability of Its Failure during Finish Turning of Hardened Steels
The effect of wear on the probability of failure of a cutter with a round cutting insert made of a cBN/Si3N4 composite during finish turning of hardened steels of different hardness was experimentally established. The maximum stresses and the probability of failure of the cutter from the front and rear surfaces were determined. Recommendations for the use of cutters equipped with a cBN/Si3N4 composite are given.
Keywords: turning of hardened steels, stresses, probability of failure of the cutter, round cutting insert, CBN-based composite.
UDC 621.762:620.22-419:669.25
A. A. Zaitsev, D. A. Sidorenko, E. A. Levashov, V. V. Kurbatkina, S. I. Rupasov, V. A. Andreev, P. V. Sevastyanov (Moscow)
Development and application of dispersion-strengthened binder based on Cu–Ni–Fe–Sn alloy for cutting tools made of superhard materials
Dispersion-strengthened binders with nanoparticles of W, WC, NbC, Al2O3, ZrO2, Si3N4, BN based on Cu–Ni–Fe–Sn alloy have been developed for diamond tools intended for cutting reinforced concrete and refractory materials. The features of cold pressing and sintering of mixtures of a binder with nanoparticles, as well as the physical, mechanical and tribological properties of compact materials were studied. The use of the developed dispersion-hardened binders allowed increasing the tool life up to 3.5 times without reducing cutting performance.
Keywords: binder, diamond tool, dispersion-hardened material, diamond cutting segment wheel, diamond annular drill, cutting, reinforced concrete, refractory material.
UDC 536.421.1:620.187:661.657.5
M. V. Nikishina (Kiev)
cBN–Cu composite: production method and physical properties
By the method of baroinfiltration of molten copper into a percolation medium based on cubic boron nitride micropowder followed by rapid quenching of the sample, a ceramic-metal composite cBN–Cu was obtained and its properties were studied.
Keywords: cubic boron nitride, copper melt, pressure, percolation.