UDC 620.22:536
A. F. Lisovsky (Kiev)
lisovsky@ism.kiev.ua
Thermodynamics of the formation of composite material structures. A review (p. 3–17)
Composite material structures at nano-, micro-, and meso-levels have been examined. The application of the Gibbs and Hill thermodynamics has allowed researchers to give the physical interpretation of the Laplace pressure for composite materials; to derive the thermodynamic functions describing the particles consolidation; to establish the new phenomenon, namely, metal melt imbibition (MMI), and to define its acting forces, to establish the criterion that allows to determine a direction of a liquid phase migration in a composite body, as well as to predict the final structure of composite materials. For the description of composite material structure, which forms under extreme conditions, it has been necessary to use nonequilibrium thermodynamics. At the extreme conditions the Prigogine concept of local equilibrium is promising.
Keywords: composite material, structure, thermodynamics.
UDC:621.921.34-492.2:536.421.5:539.89
O. I. Chernienko, O. O. Bochechka*, V. M. Tkach, N. M. Bilyavina, G. A. Petasyuk, L. O. Romanko, V. S. Gavrylova, Yu. D. Filatov (Kyiv)
*o.cherniyenko@gmail.com
**bochechka@ism.kiev.ua
Features of diamond crystallization in the Mg–Zn–B–C system (pp. 18–33)
Diamond crystallization in the Mg–Zn–B–C system under conditions of its thermodynamic stability, phase transformations that occur during the preparation of a carbon-solvent alloy and diamond crystallization, the alloy structure, and the properties of the obtained diamond crystals were studied. The processes of formation of acceptor centers and inclusions in diamond crystals caused by the introduction of boron into the growth system were described. It was established that the use of diamond powder obtained in this system for abrasive treatment of sapphire parts allows to increase the productivity and quality of treatment in comparison with the powder obtained in the Ni–Mn–C system.
Keywords: diamond crystallization, boron-doped diamond, phase transformations, strength index, thermal stability.
UDC 536.631:549.211
O. O. Vasiliev*, V. B. Muratov, L. M. Kulikov, V. V. Garbuz, T. I. Duda (Kyiv)
*o.vasiliev@kznh.kpi.ua
Features of the heat capacity of nanocrystalline diamond of detonation synthesis (pp. 34–42)
The heat capacity of nanocrystalline diamond of detonation synthesis was studied by the method of adiabatic calorimetry in the temperature range of 60–300 K. The heat capacity values of industrial samples of nanodiamond exceed the corresponding values for coarse-crystalline diamond by more than 30%. It is shown that this excess is only partially due to impurities and for impurity-free nanodiamond is more than 15%. An explanation of this feature of the heat capacity is proposed by the contribution of surface carbon atoms to the low-energy density of phonon states of diamond. Based on the experimentally obtained temperature dependences of the heat capacity, standard values of enthalpy, entropy and total Gibbs energy of industrial and impurity-free nanodiamond were calculated.
Keywords: nanocrystalline diamond, heat capacity, thermodynamic properties, enthalpy, entropy, Gibbs energy.
UDC 666.3-419:620.181.4
P. I. Loboda, T. O. Solovyova*, Yu. I. Bogomol, D. O. Remizov, O. I. White (Kyiv)
*decan@iff.kpi.ua
**tsolov@iff.kpi.ua
The influence of kinetic parameters of the crystallization process on the structure and properties of the eutectic alloy of the LaB6–TiB2 system (pp. 43–52)
The influence of the cooling rate and excess boron on the formation of the microstructure of reinforced ceramic composites LaB6–TiB2 during centrifugal spraying in an argon environment and when deposited on a copper substrate in a helium environment was studied. It was shown that increasing the cooling rate to 106 degrees/s causes a decrease in the diameter of the fibers of the composite material to 0.1–0.15 μm. Reducing the amount of boron from 2 to 1% (by mass) leads to an increase in the diameter and a decrease in the number of titanium diboride fibers by 2–3 times.
Keywords: reinforced composite materials, eutectic alloys, lanthanum hexaboride, titanium diboride, centrifugal plasma spraying, microstructure, mechanical properties.
UDC 620.22–621.921.34
M. V. Novikov, V. A. Mechnyk*, M. O. Bondarenko,
B. A. Lyashenko (Kyiv)
M. O. Kuzin (Lviv)
*vlad.me4nik@ukr.net
Composite materials of the diamond-(Co-Cu-Sn) system with improved mechanical characteristics. Message 1. Influence of hot pressing parameters on the structure and properties of the diamond-(Co-Cu-Sn) composite (pp. 53–69)
The structure and tribological properties of composite materials of the diamond-(Co–Cu–Sn) system, obtained by sintering in molds at a temperature of 800 °C for 1 h with subsequent hot pressing, were studied. It was shown that changing the hot pressing modes allows obtaining in the transition zone of the diamond–metal bond instead of structurally free graphite particles formed during graphitization of the surface of diamond grains, nanocarbide Co3C, the presence of which provides a significant increase in the wear resistance of composites.
Keywords: diamond, cobalt, copper, tin, layer, transition zone, phase, composite, decarburization, pressure, temperature, structure, wear resistance.
UDC 669.018.2
I. V. Andreyev (Kyiv)
aigor@i.ua
The influence of heat treatment of the initial tungsten-containing raw material on the structure and properties of hard alloys of the WC–Co type with a particularly fine-grained structure (pp. 70–75)
A method for obtaining tungsten hard alloys of the WC–Co type with a particularly fine-grained structure is proposed when using homogenizing annealing in the processing of the initial components, which allows obtaining a particularly dispersed tungsten-containing component. In this way, it was possible to avoid long-term grinding of the hard alloy charge and obtain alloys with high indicators of physical and mechanical properties.
Key words: hard alloy, heat treatment, cobalt tungstate, sintering.
UDC 669.294:539.216.2
AND. AND. Goncharov* (Sumy)
WITH. N. Oak (Kyiv)
AND. IN. Agulov, V. IN. Petukhov (Kramatorsk, Kharkiv)
*algon.61@mail.ru
Structure, composition, and mechanical properties of thin films of transition metal diborides (pp. 76–85)
The effect of deposition conditions on the structure, composition, and mechanical properties of thin films of transition metal diborides obtained by HF magnetron sputtering was studied. It is shown that, depending on the applied displacement potential and the temperature of the substrate, the formation of coatings of different structures takes place – from amorphous to nanocrystalline. Under optimal energy conditions – a bias potential of 50 V and a substrate temperature of ~ 500 °C – superstoichiometric thin films of transition metal diborides with a grain size of ~ 20–40 nm, a hardness of ~ 44 GPa and an abnormally high (~ 90%) elastic recovery of the imprint depth were obtained.
Keywords: thin films, nanoindentation, hardness, HfB2, TaB2.
UDC 621.922.34
M. N. Sheiko*, V. N. Skok (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 1. The size of the undercutting of the tool body for the application of diamond-galvanic coating by the electroplating method (pages 86–88)
Experimental data on the thickness of a single-layer diamond-galvanic coating using diamond powders in the grain size range from 250/200 to 800/630 are presented, which are necessary for calculating the undercutting of the body of the straightening tool for applying a diamond-galvanic coating by the electroplating method.
Key words: diamond-galvanic coating, diamond powder, straightening tool, electroplating technology.
UDC 622.24.05
M. V. Suprun, V. I. Kushch*, A. P. Zakora, R. K. Bogdanov (Kyiv)
*erchiki@ukr.net
**vkushch@bigmir.net
Evaluation of wear resistance of drill bit with reinforcing inserts hybridite (pp. 89–97)
The wear resistance of drill bit with reinforcing rock-breaking inserts was assessed, the influence of their location on the working surface of the bit was studied. An equation was obtained to determine the effective wear coefficient of the working surface of the bit depending on the method of its reinforcement with rock-breaking inserts. A mathematical model of the deformation of the drill bit profile has been developed, which can be used to optimize the design of the combined matrix, including the choice of the profile, the equipment and the use of rock-breaking inserts with different wear resistance.
Keywords: wear resistance, drill bit, hybridite, combined matrix, wear coefficient, contact pressure.
UDC 546.27:661.636:536.421.1
V. L. Solozhenko*, V. A. Mukhanov
*vladimir.solozhenko@univ-paris13.fr
On melting of boron phosphide under pressure (pp. 98–100)
Melting of cubic boron phosphide has been studied at pressures to 9 GPa using synchrotron X-ray diffraction and electrical resistivity measurements. It has been found that above 2.6 GPa boron phosphide melts congruently, and the melting curve exhibits a negative slope (–60±7 K/GPa), which is indicative of a higher density of the melt as compared to the solid phase.
Keywords: boron phosphide, melting, high pressure, high temperature.