UDC 548.211
V. M. Kvasnytsya1, *, I. V. Kvasnytsya2, **1M. P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation, NAS of Ukraine, Kyiv, Ukraine
2Taras Shevchenko National University of Kyiv, Research Institute “Institute of Geology”, Kyiv, Ukraine
*vmkvas@hotmail.com
**ikvasnytsya@gmail.com
Cyclic Twins of CVD Diamond Crystals (Pages 3–12)
Using the example of cyclic CVD diamond twins, their pseudopentagonal and icosahedral forms are described. It is shown that their general appearance is determined by the habit simple growth forms of individuals (octahedron, cube) in the case of cyclic twinning according to the spinel law – along the (111) plane. Varieties of cyclic twins are distinguished, topographic characteristics of the cube and octahedron faces of these complex twins are given, models of the formation of pseudopentagonal and icosahedral forms of diamond crystals are proposed.
Keywords: CVD diamond, polyhedra, cyclic twinning, pentahedrons, icosahedrons.
UDC 669.018.25
Yu. Yu. Rumyantseva1, *, V. N. Bushlya2, **, V. Z. Turkevich1, ***
1V. N. Bakulya Institute of Superhard Materials, NASU, Kyiv, Ukraine Kyiv, Ukraine
2Division of Production and Materials Engineering, Lund University, Lund, Sweden
*yrumuanceva@gmail.com
**volodymyr.bushlya@iprod.lth.se
***vturk@ism.kiev.ua
The influence of SiC and Al2O3 microfibers on the properties of reinforced composites based on cubic boron nitride (pp. 13–25)
Three types of cBN-based composite materials with the addition of TaN (without microfibers reinforced with Al2O3 microfibers and SiC microfibers) were obtained by the method of high-temperature sintering at high pressure. The density, hardness, Poisson’s ratio and crack resistance of the obtained materials were studied. Materials based on cBN reinforced with microfibers showed a higher level of mechanical properties (hardness, crack resistance) than unreinforced ones.
Key words: microfiber, reinforcement, cBN, crack resistance.
UDC 620.22-621.921.34
IN. AND. Mechnyk1, *, N. AND. Bondarenko1, V. N. Kolodnytskyi1, **, V. I. Zakiev2, I. M. Zakiev2, S. R. Ignatovych2, S. N. Dub1, N. AT. Cousin3
1Institute of superhard materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
2 National Aviation University, Kyiv, Ukraine
3Lviv branch of the Dnipropetrovsk National University of Railway Transport named after Academician V. Lazaryan, g. Lviv, Ukraine
*vlad.me4nik@ukr.net
**stmj@ism.kiev.ua
Formation of Fe-Cu-Ni-Sn-VN nanocrystalline matrix by vacuum hot pressing for composite diamond-containing material. Mechanical and tribological properties (p. 26–43)
The processes of structure formation, mechanical and tribological properties under the conditions of vacuum hot pressing of a mixture of iron, copper, nickel and tin powders with a dispersion of 5-50 microns with the addition of vanadium nitride nanopowder depending on the temperature are described. It was established that an increase in the sintering temperature from 800 to 1000 °C leads to a ferrite grain refinement to 20-400 nm, the separation of primary (d = 10-100 nm) and secondary (d £ 10 nm) VN grains, an increase in hardness from 3.75 to 5.37 GPa, and H/E parameters from 0.021 to 0.043, H3/E2 from 1.70 to 9.91 MPa, decrease in modulus of elasticity from 176 to 125 GPa, friction force from 250 to 180 mN, decrease in wear rate from 8.15×10-4 to 1.79×10-4 mm3×Н-1×m-1. The mechanism of grain grinding and improvement of physical and mechanical properties is due to a®g®a transformations occurring under the conditions of dissolution of VN in a-Fe and subsequent cooling.
Keywords: structure, temperature, composite, wear, nanohardness, modulus of elasticity, friction force.
UDC 621.891:621.793
Wen Zhao, Shouyu Zhu, Dejun Kong*
School of Mechanical Engineering, Changzhou University, Changzhou, China
*kong-dejun@163.com
Friction–wear characterization of cathodic arc ion plated CrC coating under different lubrication conditions (p. 44–54)
A CrC coating was deposited on YT14 cutting tools using a cathodic arc ion plating. The surface and cross-section morphologies, chemical elements and phases of obtained CrC coating were analyzed using a field emission scanning electron microscope, energy disperse spectrometer, and X-ray diffractometer. The tribological properties of CrC coating under the dry, water and oil lubrication conditions were investigated using a wear test, the effects of lubrication conditions on the friction coefficient and wear properties of CrC coatings were also discussed. The results show that, the average friction coefficient of CrC coating under the dry, water, and oil lubrication conditions are 0.76, 0.11, and 0.35, respectively, the wear mechanism is abrasive wear. The average residual stresses of worn tracks under the dry, water, and oil lubrication conditions are –231.1±25.0, –210.4±23.0, and –205.9±2.0 MPa, respectively, of which the stress value under the oil-lubrication condition is the smallest, showing its wear reduction property.
Keywords: cathodic arc ion plating, CrC coating; lubrication condition, friction coefficient, wear mechanism.
UDC 544.01+544.07+544.7
F. AND. Shumylov1, *, V. WITH. Levitskyi 2, 3
1Institute of synthetic rubber named after WITH. IN. Lebedeva, St. Petersburg, Russia
2Scientific and Technical Center of Thin Film Technologies, St. Petersburg, Russia
3Saint-Petersburg State Electrotechnical University “LETY”, St. Petersburg, Russia
*itachi16@mail.ru
Immobilization of single particles of detonation nanodiamonds in Langmuir-Blodgett films based on octadecylamine (pp. 55–65)
The problem of isolation of single particles of detonation nanodiamonds from an ensemble of particles is investigated. The solution to the problem is based on the use of the Langmuir-Blodgett method. Particular attention is paid to the process of formation of isolated particles of detonation nanodiamonds, the characteristics of the isolated particles are given.
Keywords: detonation nanodiamonds, Langmuir-Blodgett method, atomic force microscopy.
UDC 622.24.051:536.2
V. A. Dutka*, A. L. Maistrenko, V. G. Kulych
V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv. Ukraine
*vadutka@ukr.net
The influence of design parameters of the technological installation on the temperature drop in the workpiece during high-speed sintering under pressure (pp. 66–81)
The finite element method was used to perform computer simulation of the temperature field in the working cell of the technological installation for high-speed sintering under pressure of powder boron carbide workpieces. The dependence of the thermophysical properties of the powder workpiece on porosity and temperature was taken into account. In order to minimize the temperature difference in the powder billet, a computer study of the influence of the cell scheme on the temperature difference in the billet was performed. Based on the results of computer experiments, a working cell scheme of a high-speed pressure sintering installation and the corresponding heating modes were selected, at which the sintering temperature of the billet of 2000 ° C is reached within 80–150 s, and the temperature difference in the billet at the holding stage for 100–150 s is within 50–30 degrees. According to the results of laboratory experiments, it was established that the use of the selected cell scheme allows obtaining a practically uniform distribution of the microhardness of the sintered product material.
Keywords: computer modeling, high-speed pressure sintering, boron carbide, minimization of temperature difference, uniform distribution of microhardness.
UDC 539.31/.53:661.878
Junyu Li1†, Jianling Zhao2†, Cuiming Tang3, *, Peng Chen1, Shiquan Feng1, **
1College of Physics and Electronic Engineering, Zhengzhou University of Light Industry, Zhengzhou, China
2Division of Radiation Physics, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University, Chengdu, China
3Department of Physics and Electronic Engineering, Sichuan University of Science & Engineering, Zigong, China
*49273185@163.com
**2014079@zzuli.edu.cn
Theoretical investigation on the elastic properties, bond stiffness and hardness of WX2 (X = B and N) (p. 82–90)
In this paper, we investigate the elastic properties, bond stiffness, hardness and Debye temperatures for hexagonal P63/mmc WX2 (X = B or N).It is observed that these two compounds are stable in mechanics. Both these two have three typical bonds, W–X bonds, X–X and W–W bonds. By investigating the bond stiffness of these three types of bonds, we found that the bulk modulus of WX2 is mainly determined by W–X and W–W bonds, while the shear modulus is mainly determined by X–X bonds. In addition, using a theoretical model, we evaluate the hardness of these two compounds.Results showed that the Vickers hardness of WN2 is much lower than that of WB2. What’s more, by calculating the Debye temperatures, we found the melting point of WN2 is much lower than WB2, and the overall chemical bonds in WB2 are stronger than that of WN2.
Keywords: superhard materials, elastic properties, bond stiffness, hardness, Debye temperatures.
UDC 621.923: 621.922
IN. I. Lavrynenko1, *, V. F. Molchanov2, **, V. Yu. Malt2, L. AND. Proc3
1Institute of superhard materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
2Dnipro State Technical University, Kamenskoye, Ukraine
3Institute of Electronic Physics of the National Academy of Sciences of Ukraine, Uzhhorod, Ukraine
*lavrinenko@ism.kiev.ua
**v_molchanov@ukr.net
The influence of sludge solid particles on the roughness indicators of the treated surface during grinding and the assessment of the probability of scratches on it (pp. 91–102)
The issues of the influence of solid particles of sludge, which arise during grinding, on the formation of the roughness of the treated surface, which is reflected in the Rmax indicator, are considered. The peculiarity of the change in the ratio of roughness parameters Rmax/Ra depending on the cost of the grinding process was revealed. A theoretical assessment of the probability of scratches during grinding was carried out.
Key words: sludge particles, grinding, roughness, scratches on the surface during grinding, probability of scratches.