UDC 620.178.015
B. AND. Galanov1, Yu. IN. Milman1, S. AND. Ivakhnenko2, E. M. Suprun2, *, S. I. Chugunova1, A.AND. Golubenko1, V. N. Tkach2, P. M. Lytvyn3, I. IN. Voskoboynyk1
1Institute of Problems of Materials Science named after I. N. Frantsevich National Academy of Sciences of Ukraine, Kyiv, Ukraine
2Institute of superhard materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
3 Institute of Semiconductor Physics named after IN. THERE ARE. Lashkareva National Academy of Sciences of Ukraine, Kyiv, Ukraine
*alona_suprun@mail.ru
An improved nuclear model of indentation and its application for measuring diamond hardness (pp. 3–24)
A model of indentation with conical and pyramidal indenters is proposed, in which not only the sample but also the indenter are deformed elastically-plastically, and their materials satisfy the Mises flow condition. Such conditions are typical for measuring the hardness of a diamond with a diamond indenter. The proposed model generalizes and refines the known simplified Johnson model with an elastically deformable indenter. The model makes it possible to approximately determine the dimensions of the elastic-plastic zones in the indenter and the sample, the effective angle at the top of the indenter under load, as well as the effective angles of the indenter and the impression after unloading. On the basis of this model, a technique for determining the yield strength of the sample YS and the indenter Yi was developed, in which the theoretical relations of the indentation model are supplemented with relations using experimental values of the effective angle of the impression in the sample and measured values of Meyer hardness HM (average contact pressure). The developed computational technique was used in experiments on indentation of synthetic diamond at a temperature of 900 °C (at which the diamond has noticeable plastic properties) using pyramidal indentors made of natural diamond with different angles at the top. According to the proposed model, the stress-strain states of samples and indentors were investigated, and their yield points and plasticity characteristics were determined. The diamond deformation curve is plotted in the stress–total deformation coordinates. The deformation hardening of diamond was also studied.
Key words: diamond, mechanical properties, hardness, yield strength, strain hardening, atomic force microscopy.
UDC 621.762.4
IN.IN.Ivzhenko*, O.N.Kaidash, G.F.Sarnavskaya, S.N.Dub, V.N.Weaver
Institute of Superhard Materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
*ivv@ism.kiev.ua
Preparation and properties of hot-pressed materials based on silicon carbide with additions of boron and titanium carbides (pp. 25–34)
Peculiarities of sintering under pressure of materials based on silicon carbide with additions of boron and titanium carbides are investigated. The kinetic parameters of the compaction process were established. The peculiarities of the structure and the level of physical and mechanical properties of hot-pressed materials of the SiC–(8–20)% (by mass) system (В4С–TiС) were studied. Dense materials based on silicon carbide with increased (3.8 MPa·m1/2) crack resistance and low (0.07 Ω·m) electrical resistance were obtained.
Key words: silicon carbide, boron carbide, titanium carbide, pressure sintering, bending strength, crack resistance, electrical resistance.
UDC 53.096:669.784
P. Bhardwaj*, S. Singh
High Pressure Research Lab., Department of Physics, Barkatullah University, Bhopal, India
*purveebhardwaj@gmail.com
Temperature and pressure investigation of HfxTa1–xC and ZrxNb1–xC carbide alloys (p. 35–49)
Structural mechanical and thermal properties of refractory carbides have been investigated using the Realistic Interaction Potential Approach (RIPA) model. The study has been extended to mixed crystals of HfxTa1–xC (0 ≤ x ≤ 1) and ZrxNb1–xC (0 ≤ x ≤ 1) alloys and the effect of composition on structural and elastic properties are investigated. Phase transition pressure and associated volume collapses (ΔV(Pt)/V(0)) calculated from this approach are in good agreement with available literature for the parent compounds (x = 0 and x = 1). The results for the mixed crystal counter parts are also in fair agreement with experimental data generated from the application of Vegard’s law to data for the parent compounds.
Keywords: alloy, crystal structure, phase transitions, high pressure, elastic properties.
UDC 621.762
I. AND. Podchernyaeva*, O. N. Grigoriev, A. D. Panasiuk, D. IN. Yurechko
Institute of Materials Science Problems named after I. N.Frantsevich National Academy of Sciences of Ukraine, Kyiv, Ukraine
*panavic@ipms.kiev.ua
High-temperature laser coatings of the ZrB2–MoSi2 system on graphite (pages 50–62)
Coatings of the ZrB2–MoSi2 system with a thickness of 50 μm and a hardness of 14–15 GPa were obtained on graphite by pulsed laser melting in air of a two-layer powder coating with sublayers based on ZrB2 with ZrSi2 and SiC additives. Depending on the composition of the sublayer, which controls the thermal conductivity of the coating, and, accordingly, the rate of crystallization of the melt bath, different coating structures are formed: eutectics of the zirconium-based ZrSiO4–SiO2 system or a structure made of micron-thick fibers of the Zr(Mo)B2 composition. The perspective of this on the board of research is the improvement of the laser technology of applying high-temperature coatings using continuous lasers.
Key words: laser coating, graphite, zirconium diboride, molybdenum disilicide, structure, composition.
UDC 661.888.1:621.793
J.C. Caicedo1, *, R. Gonzalez1, H.H. Caicedo2, 3,
M. Gholipourmalekabadi4, C. Amaya5
1Tribology, Powder Metallurgy and Processing of Solid Recycling Research Group, Universidad del Valle, Cali, Colombia
2Janssen BioTherapeutics, Janssen Research & Development, LLC, Pharmaceutical Companies of Johnson & Johnson, Spring House, PA, USA
3National Biotechnology and Pharmaceutical Association, Chicago, USA
4Biotechnology Department, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran
5Grupo de Investigación en Materiales ASTIN SENA, Cali, Colombia
*jcaicedoangulo1@gmail.com
Mechanical and tribological properties of V–C–N coatings as a function of applied bias voltage (p. 63–79)
The aim of this work is to determine the mechanical and tribological behavior of V–C–N coatings deposited on industrial steel substrates (AISI 8620) by using carbon–nitride coatings as a protective material. The coatings were deposited on silicon (100) and steel substrates via magnetron sputtering and by varying the applied bias voltage. The V–C–N coatings were characterized by X-ray diffraction (XRD), exhibiting the crystallography orientations (111) FCC for V–C–N conjugated by VC (111) and VN (111) phases and (200) FCC for V–C–N conjugated by VC (200) and VN (200) phases. X-ray photoelectron spectroscopy (XPS) was used to determine the chemical composition of metallic carbon–nitride materials. Atomic force microscopy (AFM) was used for determination of the change in grain size and roughness with deposition parameters. By using nanoindentation, pin-on-disk, and scratch test curves, it was possible to estimate the hardness, friction and critical load of V–C–N surface material. Scanning electron microscopy (SEM) was performed to analyze morphological surface changes. Mechanical and tribological behavior in VCN/steel[8620] system, as a function of a bias voltage deposition, showed an increase of 58% in the hardness, and reduction of 39% in the friction coefficient, indicating thus that the
V–C–N coatings may be a promising material for industrial applications.
Keywords: surfaces, crystal growth, physical vapor deposition, mechanical testing, tribology and wear.
UDC 621.924.93
AND. F. Salenko1, V. T. Shchetinin1, G. IN. Gabuzyan1, V. AND. Nikitin1, N. V. Novikov2, S. AND. Klymenko2, *
1Kremenchug National University named after Mikhail Ostrogradskyi, Kremenchug, Ukraine
2Institute of superhard materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
*atmu@meta.ua
Cutting blanks from polycrystalline superhard materials by jet methods (p. 80–94)
The intensity of cutting workpieces made of hard alloy, polycrystalline superhard material based on cubic boron nitride, as well as diamond-hard alloy plate using hydrojet, laser, laser with liquid cooling and laser-jet technologies was studied. The features of the cutting of two-layer compositions, including a layer of polycrystalline diamond on the basis of hard alloy, are analyzed. The effectiveness of the hybrid processing process, combining laser-jet and hydrojet technology, is shown, which allows productive cutting of workpieces of the required profile.
Key words: jet processing, hybrid cutting, hard alloy, PSTM, diamond-hard alloy plate.
UDC 621.922
T. P. G. Nguyen
Hanoi University of Science and Technology, Hanoi, Vietnam
ntpgiang@gmail.com
The quality of the machined surface of parts during rough machining of materials of different hardness with the help of segmented grinding wheels produced in Vietnam (pp. 95–101)
Segmented grinding wheels designed to improve the grinding ability of the abrasive during intermittent machining have been developed.An assessment of the cutting ability of segmented grinding wheels has been made.The segmentation coefficient h of the working surface of the segmented grinding wheel is defined as the ratio of the total length of the intervals between the segments to the length of the entire circumference of the wheel.For grinding unhardened and hardened steels, as well as aluminum alloys, five variants of developed segmented grinding wheels with h = 10.91, 16.37, 18.19, 20.01, 21.83% and one traditional wheel (h = 0%) were used.The results of the research showed that a smooth surface of the workpiece was obtained when using segmented grinding wheels with h = 18.19% when processing unhardened steels and with h = 20.01% when processing aluminum alloy.
Key words: grinding, intermittent machining, segmented grinding wheel, roughness.
UDC 621.922.34
M. N. Sheiko
Institute of Superhard Materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
max-kiev@i.ua
To the question of the theoretical justification of the choice of the effective shape of the grain profile when modeling the diamond layer of the straightening tool. Message 1. Galvanostegia (pp. 102–108)
The theoretical justification of the phenomenon of the round shape of the cross-section of the scratch, averaged over a set of slices, produced by the by no means round tops of the diamond grains of the straightening tool, made by the galvanostegia method and working on the abrasive material of the grinding wheels, is given. The shape of the specified section is defined as the effective shape of the scratch-producing grain. Information about the scratch parameters and their relationship with the grain size of the diamond powder in the tool is necessary for the calculation of unit and total cross-sections, straightening forces and surface roughness of products polished with abrasive wheels with a diamond roller straightening.
Keywords: diamond powder, straightening tool, electroplating technology, diamond grain, scratch cross-section.
UDC 666.233
IN. Yu. Dolmatov
FSUE “Special Design and Technology Bureau “Technology”, St. Petersburg, Russia
diamondcentre@mail.ru
Assessment of the applicability of explosive charges for the synthesis of detonation nanodiamonds (pp. 109–113)
A new method for assessing the applicability of explosive charges for the synthesis of nanodiamonds based on oxygen balance and charge density is presented. The recommended value for oxygen balance is –35–(–60), for charge density – 1.6–1.7 g/cm3.
Key words: explosive substances, detonation nanodiamonds, charges of explosives, oxygen balance, charge density of explosives.