UDC 539.381, 538.911, 538.97, 548.74
I. M. Fodchuk1, S. AND. Ivakhnenko2, V. N. Tkach2, *, S. IN. Balovsiak1, M.D.Borcha1, N. WITH. Sweet1, I. I. Hutsulyak1, A. R. Kuzmin1, O.V. Sumaryuk1
1 Chernivtsi National University named after Yury Fedkovicha, Chernivtsi, Ukraine
2Institute of superhard materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
*tkach@ism.kiev.ua
Distribution of local deformations in synthetic diamond crystals from the analysis of parameters of the energy spectrum of Kikuchi paintings (pp. 3–12)
The average deformation in local areas of synthetic diamond was determined using the energy Fourier spectrum when analyzing digital pictures of Kikuchi. The degree of blurring of diffraction bands and their intersections in images caused by deformations is quantitatively described through the average spatial period and the area of the radial distribution of the energy spectrum. The planar distribution of local deformations made it possible to determine their anisotropy in the crystal in terms of magnitude and direction.
Keywords: synthetic diamonds, Kikuchi lines, diffraction of reflected electrons, Fourier transform, energy Fourier spectrum.
UDC 548.517:621.921.34:539.89
T. V. Kovalenko*, S. O. Ivakhnenko, V. V. Lysakovskyi
V. Bakul Institute for Superhard Materials, National Academy of Sciences of Ukraine, Kyiv, Ukraine
*tetiana.v.kovalenko@gmail.com
Effect of temperature and alloy-solvent content on diamond crystallization in Mg-based systems for HPHT method (pp. 13–19)
Defect-impurity composition of diamond single crystals grown in Mg–C and Fe–Mg–C systems depending on growth temperature and magnesium content at pressure 7.7 GPa and temperature 1700–2000°C was studied. It was established that in the Mg–C system an increase in the growth temperature leads to an increase in the amount of uncompensated boron in crystals in ~ 3 times.In Fe–Mg–C system with an increase of the magnesium content in the growth medium up to 70 at% the concentration of boron in the grown crystals increases 1.5–2.6 times.All these features can be explained by the change in the thermodynamic activity of the main impurities in the diamond crystal lattice on the crystallization front depending on the composition of the growth system and the growing temperature.
Keywords: high pressure, high temperature, diamond, single crystal growth, Mg-based systems, boron.
UDC 544.3:621.762
AND. F. Lysovsky
Institute of Superhard Materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
lisovsky@ism.kiev.ua
On the thermodynamics of nanoparticle formation (pp. 20–30)
The results of thermodynamic studies of the genesis and conditions of stable existence of nanoparticles are presented. An expression for the change in the Gibbs free energy during the generation of nanoparticles has been obtained. It is proved that the ensemble of nanoparticles is an unstable system, the conditions under which a nanoparticle is stable are substantiated. Methods of formation of nanostructured materials from stable nanoparticles are proposed.
Keywords: nanoparticle, thermodynamics, structure, composite materials.
UDC UDC 661.883.2/888.1:621.793.7
J. C. Caicedo1, *, W. F. Piedrahita1, W. Aperador2
1Tribology Powder Metallurgy and Processing of Recycled Solids Research Group, Universidad del Valle
2Department of Engineering, Universidad Militar Nueva Granada, Bogotá, Colombia
*julio.cesar.caicedo@correounivalle.edu.co
Physical properties comparison between hafnium and vanadium carbonitride coatings (pages 31–46)
Hf–C–N and V–C–N coatings were deposited onto silicon (100) and AISI 8620 steel substrates by reactive r.f. magnetron co-sputtering from hafnium, vanadium and carbon targets in a reactive nitrogen atmosphere, with a negative bias voltage of –50 V. The effect of the Hf and V elements on the crystalline structure, chemical composition, and mechanical properties was observed via X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, computational simulation, atomic force microscopy, scanning electron microscopy, nanoindentation, pin on disk and scratch test techniques. The results show that the samples present a constant stoichiometric ratio, exhibiting structural characteristics very similar to simulated structures. The changes in the mechanical properties by substituting the element Hf by V could increase the hardness from 22 to 24 GPa and the elastic modulus from 235 to 246 GPa. For tribological properties, changes from 0.49 to 0.42 for the friction coefficient and from 21 to 25 N for the critical load were found.So the influence of deposition conditions on the structure and properties of coatings was associated to differences in the content of hafnium and vanadium in ternary coatings. Therefore, the Hf–C–N and V–C–N coatings can be used as future hard coating materials.
Keywords: Magnetron sputtering, metal carbon-nitrides, HfCN, VCN, mechanical properties.
UDC 621.762.53
M. I. Upatov1, *, E. R. Abdullayeva1, V. V. Bolbut2, Yu. I. Bogomol1
1National Technical University of Ukraine “Kyiv PolytechnicIgor Sikorsky Technical Institute, Kyiv, Ukraine
2Otto von Guericke University, Magdeburg, Germany
*nikitaupatov@gmail.com
Structure and properties of a directionally crystallized alloy of the B4C–NbB2–SiC system (pp. 47–55)
A 32B4C–30NbB2–38SiC composite (% (mol.)) was obtained by the crucible-free zone melting method. The structure of the obtained composite consists of a coarse-grained two-phase eutectic (NbB2–SiC), a fine-grained three-phase eutectic (B4C–NbB2–SiC) and large SiC dendrites. The effect of the crystallization rate on the structure and properties of the obtained composite was studied. Vickers hardness, crack resistance and flexural strength for the 32B4C–30NbB2–38SiC composite (% (mol.)) are 31–36 GPa, 4–5.1 MPa∙m1/2 and 203–252 MPa, respectively.
Keywords: three-phase eutectic, hardness, boron carbide, silicon carbide, niobium diboride.
UCD 661.685:621.762.5
Junxi Zhang*, Baiming Chen, Wu Yue, Hui Chen
School of Materials Engineering, Lanzhou Institute of Technology, Lanzhou Gansu 730050, China
*57764866@qq.com
Microstructure and wear properties of Ni–Ni3Si composites prepared by mechanical alloying and hot pressing sintering (pp. 56–66)
Ni3Si and Ni–Ni3Si composites were prepared by mechanical alloying and hot pressing sintering method with Ni and Si powders as raw materials. The phase composition, microstructure, mechanical properties and friction and wear properties of the Ni3Si and Ni–Ni3Si composites were investigated. The results showed that the Ni (Si) solid solution, Ni74Si26 and Ni31Si12 intermediate phases were formed during the ball milling process and then Ni3Si nanocrystalline powder was produced after 30 h of milling. Based on Miedema’s semi-empirical theory, the formation free energies of different phases formed during mechanical alloying of 3Ni–Si mixed powders were calculated. The results showed that the ordered phase of Ni3Si is stable under equilibrium conditions and has the lowest formation enthalpy during ball milling. Compared with the monolithic Ni3Si, the Ni–Ni3Si composite has an excellent friction and wear resistance and comprehensive strength and toughness. With the increase of load, the friction coefficient of the composite decreases, the wear rate of the composite increases first and then decreases. When the load is 10 N, the friction coefficient and wear rate of the composite are 0.246 and 5.23×10–4 mm3/(N×m), respectively. The main wear mechanism of the material experiences a transition from adhesive wear to abrasive wear with the increase of load, and exhibits a significant tribo-oxidation wear under all loads.
Keywords: metal silicides, hot pressing, microstructure, friction and wear behavior.
UDC 621.887
IN. F. Horban*, A. AT. Andreev, V. AND. Stolbovoy, A. M. Myslyvchenko, A.D.Kostenko
Institute of Problems of Materials Science named after I. N. Frantsevich National Academy of Sciences of Ukraine,Kyiv, Ukraine
*gorban1944@ukr.net
Properties of vacuum-arc multilayer coated metal–metal nitride (pp. 67–72)
Physico-mechanical and tribotechnical characteristics of composite multilayer coated metal–metal nitride in air during friction in steam with 65G steel, diamond indenter and abrasive tape are determined. Friction was carried out in the range of speeds from 16 mm/s to 12 m/s with a load of up to 100 N. The lowest wear was recorded for the Mo/MoN composite coating, which is characterized by hardness values of ~25 GPa and a friction coefficient of 0.065. It is shown that the composite multilayer coated metal–metal nitride is characterized by small values of abrasive belt wear.
Keywords: sliding speed, pressure, wear, hardness, Young’s modulus, coatings.
UDC 621.623
Yu. D. Filatov
V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
filatov@ism.kiev.ua
Polishing of precision surfaces of optoelectronic elements made of glass, sitals, and optical and semiconductor crystals. Review (pp. 73–98)
The work on the creation of modern methods for polishing precision surfaces of electronic elements and optical systems made of glass, optical and semiconductor crystals is considered. The mechanism of material removal from the treated surface during polishing with a tool with a bonded polishing powder, during mechanical polishing with suspensions of polishing powders, and during chemical-mechanical polishing is described. The results of the study of the mechanism of formation of the nanoprofile of optical surfaces during polishing are presented and the relevance of studying the regularities of formation of supersmooth surfaces during chemical-mechanical polishing is noted.
Keywords: polishing, material removal rate, surface roughness.
UDC 666.3:539.5
I. P. Fesenko1, *, L. V. Viduta2, D. V. Chasnyk3, I. A. Petrusha1, Yu. Yu. Rumyantseva1, V. M. Tkach1, V. I. Chasnyk4, V. Z. Turkevich1, V. B. Nechytaylo2, O. M. Kaidash1, V. V. Garashchenko1
1V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv. Ukraine
2Institute of Physics, NAS of Ukraine, Kyiv. Ukraine
3Ukrainian Research Institute of Special Technologyof Forensic Examinations of the Security Service of Ukraine, Kyiv, Ukraine
4State Enterprise Scientific Research Institute “Orion”, Kyiv, Ukraine
*igorfesenko@ukr.net
Structure of Gold Island Films on Thermobarically Sintered Cubic Boron Nitride (pp. 99–101)
The structure of gold island films on the surface of cubic boron nitride is reported. The average size of the islands, the nature of their distribution on the surface, and the average number per unit surface are given.
Keywords: thermobaric sintering, cubic boron nitride, gold, island film.
UDC 661.657.5:620.186
V. L. Solozhenko1, *, F. Lenrick2, V. Bushlya2
1LSPM–CNRS, Université Paris Nord, 93430 Villetaneuse, France
2Division of Production and Materials Engineering, Lund University, Lund, Sweden
*vladimir.solozhenko@univ-paris13.fr
On twinning in ultrahard nanocrystalline cubic boron nitride (pages 102–104)
Microstructure of bulk nanocrystalline cubic boron nitride synthesized at 20 GPa and 1770 K has been studied by scanning and high-resolution transmission electron microscopy. The material is characterized by a high density of twins with an average size of 5.5 nm, and multiple stacking faults within the twin domains that result in exceptional material hardness.
Keywords: cubic boron nitride, transmission electron microscopy, nanotwinning.