UDC 620.178.1
B. AND. Galanov1, *, S. N. Oak2
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
*gbaprofil@gmail.com
Critical comments on the Oliver-Farr method for measuring hardness and elastic modulus by means of instrumental indentation and refinement of its basic relations (pp. 3–24)
A critical analysis of the Oliver and Farr method for determining the hardness and modulus of elasticity of materials using instrumental indentation devices with continuous recording of P–h diagrams (P – force acting on the indenter, h – convergence of the indenter and the sample) was performed. In the basic theoretical relations of this method, errors and their insufficient justification are revealed. In particular, this refers to the incorrect definition of the “elastic contact depth hc”, which is the basis of these relations. New refined basic relations and formulas for determining hardness and modulus of elasticity are proposed, in which the specified shortcomings are eliminated and which are based only on the assumption of elastic unloading of the indenter in accordance with classical theories of elastic contact. According to the data of the P–h diagram measured in an arbitrary laboratory coordinate system, a refined method of stable determination of the contact stiffness S = dP/dh at the beginning of unloading and the determination of the position of the P–h diagram in the generally accepted theoretical coordinate system, in which its main classical model relations are recorded, are additionally proposed. These clarifications are made without additional assumptions and experimental measurements to the hypotheses of Oliver and Far’s method.
Key words: indentation, hardness, modulus of elasticity, contact stiffness, elastoplastic deformations.
UDC 548.736
T. S. Panasyuk*, O. O. Leshchuk, V. V. Lysakovsky, V. A. Kalenchuk, O. O. Zanevsky
V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
*scripse@ukr.net
Modeling of temperature fields in the growth volume of a high-pressure cell of a six-punch AVT during the growth of diamond crystals by the T-gradient method (pp. 25–32)
Based on the finite element method, a computer model was developed to determine the thermal state of a six-punch high-pressure apparatus with a high-pressure cell for the growth of structurally perfect diamond single crystals. Calculations of temperature fields in a high-pressure cell during the growth of diamond single crystals have been carried out depending on the values of the outer and inner diameters of the graphite current lead, which allows changing the temperature at characteristic points of the high-pressure cell by 20–110 °C, horizontal and vertical temperature drops in the growth volume by 3–18 °C, and temperature gradients in it by 0.17–2.0 deg/mm. Based on the calculations of temperature fields, experiments were conducted and diamond single crystals up to 5 mm in size were obtained. The quality of the crystals depends on the location in the growth volume and corresponds to the calculated data.
Keywords: diamond, temperature gradient method, temperature field, computer modeling.
UDC 537.874.7:620.22-419
V. I. Chasnyk1, V. G. Poltoratskyi2, *, O.IN.Leshchenko2, **
1State-owned enterprise “Orion” Research Institute,Kyiv, Ukraine
2Institute of superhard materials named afterIN.M.Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
*vg.poltoratsky@gmail.com
**olesh@ism.kiev.ua
Attenuation of microwave radiation at frequencies of 34.09–34.19 GHz in a composite material based on diamond micropowder structured by a nanocarbon bond deposited from the gas phase at subatmospheric pressure (pages 33–43)
Attenuation of microwave radiation in samples of a composite material based on ASM 5/3 diamond micropowder structured with a nanocarbon bond at subatmospheric pressure was measured at frequencies of 34.09–34.19 GHz in a cylindrical resonator of the H111 mode. Based on the measurement results, reverse losses are calculated. The specific volumetric electrical resistance of the samples was measured. The possibility of using composite diamond-containing structured materials as absorbers of microwave radiation is shown.
Key words: attenuation of microwave radiation, return loss, microwave absorber, composite, diamond micropowders, carbon nanotubes, nanocarbon.
UDC 621.921:547.639
IN. WITH. Gavrilova1, *, E. AND. Pashchenko1, S. IN. Zhiltsova2, V. M. Mikhalchuk2, E.P.Mamunya3, S. N. Dub1, V. N. Weaver1
1Institute of superhard materials named after IN. N. Bakulya National Academy of Sciences of Ukraine,Kyiv, Ukraine
2Donetsk National University named after Vasyl Stus,Vinnytsia, Ukraine
3Institute of Chemistry of High Molecular Weight Compounds of the National Academy of Sciences of Ukraine,Kyiv, Ukraine
*vsgavrilova@gmail.com
Thermophysical and physical-mechanical properties of antifriction solid lubricant for cold plastic deformation of titanium alloys (pp. 44–58)
The results of studies of thermophysical characteristics, thermomechanical and mechanical properties of epoxy-polysiloxane nanocomposite with different content of modifying additives in the presence of highly dispersed antifriction fillers.It is shown that the joint influence of the modifier (polysiloxane particles) and the filler (graphite) on the formation of the composite structure during the curing process leads to a significant improvement in its physical and mechanical properties.The optimal composition of the composite was determined for use as an antifriction solid lubricant for cold plastic deformation of titanium alloys.
Keywords: epoxy-polysiloxane nanocomposite, differential scanning calorimetry, thermomechanical analysis, nanoindentation, hardness, creep, dissipation of elastic energy, solid lubricant for cold plastic deformation.
UDC 544.723
L. M.Melnyk1, N. AND.Tkachuk1, O. IN.Turchun1, V. THERE ARE.Diyuk2, O. IN.Ishchenko2, O. AND. Bieda2, L. D.Kisterska3, O. B. Loginova3, *, S. O. Lysovenko3, O. G. Gontar3, V. V. Garashchenko3
1National University of Food Technologies, Kyiv, Ukraine
2Taras Shevchenko National University of Kyiv, Kyiv, Ukraine
3V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
*pol@ism.kiev.ua
Adsorption properties of shungite in the process of purification of aqueous-alcoholic solutions (pp. 59–66)
Adsorption properties of shungite in the removal of higher alcohols and other impurities from aqueous-alcoholic solutions were investigated by nitrogen adsorption, thermogravimetry, wetting, thermoprogrammed desorption with mass spectrometric registration of products, and IR spectroscopy. It has been shown that shungite is able to effectively sorb impurities from aqueous-alcoholic solutions with the formation of fairly strong adsorption complexes. As a result of heat treatment at 180 °C in vacuum, the adsorption complexes are almost completely decomposed, which leads to regeneration and a slight increase in the specific surface area and sorption volume of shungite. The obtained data indicate the principle possibility of restoring adsorption centers on the surface of shungite, which will extend the term of its use as a sorbent.
Keywords: natural sorbents, shungite, wetting, adsorption complexes, thermally programmed desorption, functional surface groups.
UDC 661.657.5
V. L. Solozhenko1, *, V. Bushlya2
1LSPM–CNRS, Université Paris Nord, Villetaneuse, France
2Division of Production and Materials Engineering, Lund University, Lund, Sweden
*vladimir.solozhenko@univ-paris13.fr
Mechanical properties of superhard boron subnitride B13N2 (p. 67–72)
Microstructure and mechanical properties of bulk polycrystalline rhombohedral boron subnitride B13N2 synthesized by crystallization from the B–BN melt at 7 GPa have been systematically studied by micro- and nanoindentation, atomic force microscopy and scanning electron microscopy. The obtained data on hardness, elastic properties and fracture toughness clearly indicate that B13N2 belongs to a family of superhard phases and can be considered as a promising superabrasive or binder for cubic boron nitride.
Keywords: boron subnitride, hardness, elastic moduli, fracture toughness.
UDC 621.623
Yu. D. Filatov
Institute of Superhard Materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
filatov@ism.kiev.ua
Diamond polishing of crystalline materials for optoelectronics (p. 73–82)
As a result of studies of the regularities of mechanical polishing of optoelectronic parts made of crystalline materials, it was established that the polishing productivity decreases with an increase in their binding energy and transfer energy, and increases with an increase in the coefficient of thermal conductivity of the processed material, the friction path of the element of the processed surface on the lapping surface, and the Lifshitz force. It is shown that the ratio of the coefficient of volumetric wear to the coefficient of thermal conductivity of the processed material depends on the specific heat capacity and the transfer energy.
Key words: polishing, productivity, transfer energy, thermal conductivity coefficient, specific heat capacity, volumetric wear coefficient.