UDC 661.657.5:621.9.025.1
A. S. Osipov1, 2, *, P. Klimczyk1, S. Cygan1, Iu. A. Melniichuk2, I.A. Petrusha2, L. Jaworska1
1Institute of Advanced Manufacturing Technology, Krakow, Poland
2V. Bakul Institute for Superhard Materials, National Academy of Sciences of Ukraine, Kiev, Ukraine
*dialab@ism.kiev.ua
Composites of the cBN–Si3N4 system reinforced by SiCw for turning tools (p. 3-11)
The cBN–Si3N4–SiCw composites with different SiCw contents up to 20 vol % have been produced at high pressure of 8.0 GPa and high temperature of 2500 K. It has been defined that the Young modulus of the composites were within 740–846 GPa, the Vickers hardness and fracture toughness values were 37.5–42.0 GPa and 11.4–12.9 MPa×m1/2, respectively. An important feature of the composite microstructure is the breaking of SiCw as a result of HPHT action. It has been shown that at the addition of 10 vol % SiCw to the structure of a cBN–Si3N4 composite the interrupted turning of hardened steel results in the flank wear reduction up to 20%.
Keywords: cBN, SiC whiskers, composite, HPHT-sintering, interrupted turning.
UDC 544.146.5:621.921.34
V. Ya. Zabuga1, O. O. Bochechka2, *, G. G. Tsapyuk1, 2, T. O. Kurylyak2, **, O. S. Fedorchuk1 (Kyiv)
1 Taras Shevchenko National University of Kyiv
2 V. M. Institute of Superhard Materials Bakulya NAS of Ukraine
*bochechka@ism.kiev.ua
**tetiana.sh@ukr.net
The influence of tungsten on the kinetics of oxidation of diamond nanopowder (pp. 12-23)
The kinetics of oxidation of diamond nanopowder of static synthesis ASM5 0.1/0 without additives and with the addition of 1, 3, 5 % (by weight) of tungsten nanopowder were studied. It was shown that tungsten is an inhibitor of the reaction of diamond with oxygen. The kinetic scheme of the reaction was substantiated, which explains the mechanism of the inhibitory effect of tungsten.
Keywords: oxidation kinetics, diamond, tungsten, nanopowder.
UDC 669.27’2578:548.5
N. V. Lytoshenko (Kyiv)
Institute of Superhard Materials named after V. M. Bakulya NAS of Ukraine
tverdosplav@ism.kiev.ua
Mathematical modeling of diffusion processes of ring structure formation during sintering of TiC–Ni alloys with the addition of alloying carbide (pp. 24-32)
The kinetics of the formation of a ring structure of TiC grains during isothermal liquid-phase sintering of a TiC–Ni hard alloy doped with transition metal carbide was studied using mathematical modeling. The corresponding algorithm for studying the nature of the concentration distribution of the diffusant in the TiC grain takes into account the structural characteristics of the alloy, the diffusion coefficients of the alloying additive in the metal melt and grain, the limiting solubility of the diffusant in the bundle and its concentration in the alloy, the temperature and time of sintering.
Keywords: TiC–Ni hard alloy, WC alloying carbide, mathematical modeling, diffusion, ring structure, concentration distribution.
UDC 620.178.1:539.533
L. R. Shaginyan, V. F. Horban, N. AND. hives, WITH. AND. Firstov, I. F. Kopylov
Institute of Problems of Materials Science named after I.N.Frantsevich National Academy of Sciences of Ukraine, Kyiv
*lrshag@yandex.ru
**gvf@ipms.kiev.ua
***fsa@ipms.kiev.ua
Properties of coated from high-entropy alloy Al–Cr–Fe–Co–Ni–Cu–V obtained by magnetron sputtering (p. 33-44)
It was established that the coatings of the high-entropy equiatomic alloy Al–Fe–Co–Ni–Cu–Cr–V, obtained by magnetron sputtering, have a nanocrystalline microstructure, are textured, and represent a solid two-phase solution that crystallizes in bcc (a = 2.91 Å) and fcc (a = 3.65 Å) phases. Ion bombardment of the growing coating, created by the bias voltage (0–(–200) V) applied to the substrate, reduces the growth rate of the condensate and affects its composition and structure. It is shown that the composition of the coatings deposited without ion bombardment coincides with the composition of the target, and increasing the intensity of ion bombardment leads to its depletion in Al, Cu, and Ni and increases the microhardness of the coated. The anisotropy of the obtained coatings is revealed.
Key words: alloys, coatings, sputtering, electron diffraction, scanning electron microscopy, mechanical properties.
UDC 621.9.01
K. Sobiyi*, I. Sigalas
School of Chemical and Metallurgical Engineering University of the Witwatersrand
*kk_sob@yahoo.com
High-speed machining of martensitic stainless steel using PcBN (p. 45-51)
The performance of PcBN cutting tool during its application in the mass production of components made from AISI 440B stainless steel has been considered. The experimental tests have been performed at cutting speed ranging between 350–500 m/min at dry cutting conditions. The machining operations that have been explored include facing, turning, grooving and boring and the 3D topography of the machined surface is presented. The results show that good surface finish similar to grinding and dimensional accuracy can be achieved with PcBN tools.
Keywords: stainless steel, PcBN, surface finish, machining.
UDC 621.923: 621.922
IN. I. Lavrynenko
Institute of Superhard Materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv
lavrinenko@ism.kiev.ua
The coefficient of abrasive cutting as a characteristic chart reflecting the performance indicators of the grinding process with wheels made of ultra-hard materials (p. 52-60)
The physical meaning and trends of the change in the abrasive cutting coefficient fa = Pz/Py are considered, applicable to the processes of grinding wheels made of superhard materials. It is shown in what cases it is necessary to strive to increase ego value. This classification of processed materials according to this coefficient.
Keywords: coefficient of abrasive cutting, components of cutting forces, thermal processes, grinding, wheels made of superhard materials.
UDC 621.922.34
M. N. Sheiko*, V. N. Skok, O. AT. Pasichny
Institute of Superhard Materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv
*max-kiev@i.ua
The shape of the grains as a factor determining the parameters of the diamond-galvanic coating of the straightening tool. Message 2. The actual area of contact between the grains and the graphite mold and related characteristics as the starting point for calculating the modes of application of the diamond-galvanic coating by the electroplating method (p. 61-66)
The experimentally determined data of the actual contact area of the grains with the graphite mold, used in the technology of applying the diamond-galvanic coating of the straightening tool by the electroplating method, are given. The results of determining the maximum cross-section of diamond grains of powders of various grain sizes, the specific number of grains on the surface, their orientation, which are necessary for calculating the area of the free surface of deposited nickel, and consequently the rate and time of deposition, as well as the final thickness of the diamond-galvanic coating, are also given.
Keywords: diamond-galvanic coating, diamond powder, straightening tool, electroplating technology.
UDC 621.941: 534.647
L. N. Devin, S. IN. Rychev*
Institute of Superhard Materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv
*ldevin@ism.kiev.ua
**therion66694@mail.ru
Experimental study of the influence of the tool material and fine turning modes on the level of acoustic emission signals (p. 67-74)
The effect of cutting modes on acoustic emission signals during fine turning of aluminum alloys is investigated. Each acoustic emission signal was divided into two sections, the first of which is mainly associated with the formation of chips, the second – with the friction of the tool on the workpiece. Single crystals of natural and synthetic diamond, as well as hard alloy VK6, were used in the study. Experimental data indicate that during diamond turning, the main signal of acoustic emission is emitted during the formation of chips, and when turning with a hard alloy, the proportion of the emitted signal from friction on the back surface is often higher, and it depends on the processing modes.
Keywords: acoustic emission, friction process during machining, chip formation.
UDC 666.233
IN. Yu. Dolmatov1, *, I. I. Kulakova2, V. Myllymäki3, A. Vehanen3, A. AND. Bochechka4, **, A. N. Panova4, B. T. T. Nguyen5
1 FSUE “Special Design and Technology Bureau “Technology”, St. Petersburg, Russia
2Moscow State University named after M. IN. Lomonosova,Moscow, Russia
3Carbodeon Ltd. Oy, Vantaa, Finland
4Institute of superhard materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
5Belarusian State University, Minsk, Belarus
*DiamondCentre@mail.ru
**bochechka@ism.kiev.ua
Infrared spectra of diamonds of different genesis and cleaning methods (p. 75-84)
IR spectra of diamonds of different genesis, both natural and artificial – detonation, dynamic and static synthesis, subjected to cleaning in various conditions. It is shown that in the IR range there are absorption bands at 421, 945, 1022, 2854, 2920, and 3368 cm–1, characteristic of the majority of the studied samples. It was established that, regardless of the genesis of diamonds, when they are purified using sulfuric acid, the absorption bands of S–S and C–S bonds are present in the IR spectra, and after purification in nitric acid – C–N bonds. The presence of functional groups C–H and –ОН was confirmed.
Key words: detonation nanodiamonds, polycrystalline diamonds, diamond of static synthesis, natural diamond, infrared spectroscopy, chemical cleaning, functional surface groups.
UDC 544.344.015.4:546.28:543.89
Z. Jouini1, 2, O. O. Kurakevych1, *, H. Moutaabbid1, Y. Le Godec1, M. Mezouar3, N. Guignot4
1IMPMC, UPMC Sorbonne Universités, CNRS, MNHN, IRD, Paris, France
2LACReSNE, Faculté des Sciences de Bizerte, Zarzouna, Tunisia
3European Synchrotron Radiation Facility, Grenoble, France
4Synchrotron SOLEIL, Gif-sur-Yvette, France
*oleksandr.kurakevych@impmc.jussieu.fr
Phase boundary between Na–Si clathrates of structures I and II at high pressures and high temperatures (p. 85-91)
Understanding of the covalent clathrate formation is a crucial point for the design of new superhard materials with intrinsic coupling of superhardness and metallic conductivity. It has been found that silicon clathrates have the archetype structures, which can serve an existence nt model compounds for superhard clathrate frameworks Si–B, Si–C, B–C and C with intercalated atoms (e.g., alkali metals or even halogens) that can ensure the metallic properties. Here we report our in situ and ex situ studies of high-pressure formation and stability of clathrates Na8Si46 (structure I) and Na24+xSi136 (structure II). Experiments have been performed using standard Paris–Edinburgh cells (opposite anvils) up to 6 GPa and 1500 K. We have established that chemical interactions in the Na–Si system and transition between two structures of clathrates occur at temperatures below silicon melting. The strong sensitivity of crystallization products to the sodium concentration has been observed. A tentative diagram of clathrate transformations has been proposed. At least up to ~ 6 GPa, Na24+xSi136 (structure II) is stable at lower temperatures as compared to Na8Si46 (structure I).
Keywords: silicon clathrates, superhard clathrates, phase diagram, high-pressure synthesis.