THE MOST SIGNIFICANT SCIENTIFIC RESULTS OF THE INSTITUTE IN 2021.

  1. It was experimentally and by thermodynamic calculations established that when adding SiC and Si3N4 fibers (5–15 vol %) to a mixture of cBN with TaN (35–45 vol %) and Al (5 vol %) during sintering at a pressure of 7 GPa in the temperature range of 1900–2000 ° C, the interaction of boron nitride with the binder is activated, causing the formation of tantalum boride (TaB). At the same time, no noticeable destruction of the fibers is observed, which leads to an improvement in the mechanical characteristics of the composites compared to the properties of the composite without the addition of fibers.

Academician of the National Academy of Sciences of Ukraine V.Z. Turkevich, Yu.Yu. Rumyantseva, I.A. Petrusha.

  1. The regularities of solid-phase transformations of highly crystalline powders of graphite-like boron nitride (hBN) in direct conversion sintering (DCS) processes under conditions of high pressures (up to 10.5 GPa) and temperatures (up to 2500 °C) were studied, which culminated in the formation of a highly hard (up to 80 GPa according to Vickers, F=20 N) heat-resistant and highly thermally conductive (up to 200 W/(m×K)) polycrystalline cubic BN material. In a series of 10 initial hBN powders, optimal varieties were identified according to morphological indicators, which are compacted to a density of 93% of the theoretical value, even during “cold” pressing in molds. At the same time, a powerful texture appears in the compacted material. The crystal-oriented nature of the subsequent solid-phase transformation of hBN®cBN allows to ensure the parallelism of the basic planes-polymorphs, which causes the emergence of the corresponding texture in the submicrocrystalline structure of dense cBN.

Acad. NAS of Ukraine V.Z. Turkevich, I. A. Petrusha, O. S. Osipov, Corresponding Member NAS of Ukraine S.A. Klymenko, Yu.O. Melniychuk, Acad. NAS of Ukraine T. O. Prikhna, V.E. Moshchil; N.M. Bilyavina (Taras Shevchenko National University of Kyiv), Corresponding Member NAS of Ukraine O.M. Grigoriev (IM Frantsevich Institute of Metal Physics NAS of Ukraine), O. I. Zaporozhets, V.A. Mykhailovsky, M.O. Dordienko (G.V. Kurdyumov Institute of Metal Physics NAS of Ukraine) Dr. Antionette Can (ElementSix (UK) Limited (E6) LTD, United Kingdom.

  1. The regularities of the formation of the two-phase structure of superhard PCBN composites of the cBN-Al system were established. By controlling the thermodynamics and kinetics of the chemical interaction of cBN with Al through the grain size of the starting powders, pressure and sintering temperature. The optimal conditions for obtaining a two-phase composite (cBN, AlN) were determined, which, in comparison with the three-phase (cBN, AlN, AlB2), has higher hardness (30 vs. 27 GPa), thermal stability (1400 vs. 1250 K), Young’s modulus (680 vs. 660), impact strength (550 vs. 400 MPa) and a 35% higher decrement of oscillations. During the finish turning of hardened HVG steel (hardness HRC 58-60) with cutters made of a two-phase composite, the average temperature in the zone cutting is greater; and the componentsPx,Py,Pz and the resultant R of the cutting force, the roughness parameters Ra and waviness Raw are smaller than with cutters made of a three-phase composite.

M.P. Bezhenar, L.M. Devin, M.E. Stahniv, Ya.M. Romanenko.

  1. Thermodynamic calculations were performed to clarify the state diagram of the Fe–Ga–N system. It was established that up to a pressure of 6 GPa in the Ga–N system, the gasoperitectic reaction of gallium nitride decomposition persists: 2GaN → 2GaL + N2↑. Congruent melting of GaN is not observed. The absence of delamination in the liquid phase is confirmed in the Fe–N system. Nitrogen solutions in fcc iron, γ’ and ε-phases retain stability up to 6 GPa. In the ternary system Fe– Ga–N, the metastability of the compounds GaFe19N5, GaFeN2, GaFe2N3, Ga2FeN3, GaFe7N2, GaFe3N, which are not displayed on the equilibrium phase diagram, has been proven. The presence of the liquidus surface of gallium nitride on the phase diagram of the ternary system Fe–Ga–N has been confirmed, which makes its crystallization from the liquid phase at 6 GPa possible.

Acad. NAS of Ukraine V.Z. Turkevich, I.A. Petrusha, D.A. Stratiychuk, Y.Yu. Rumyantseva.

  1. Directed stimulation of nucleation using Fe-Co-Mg-C and Fe-Co-Mg-B-C solvent alloys has been carried out by varying the pressure and temperature during the crystallization of diamond grinding powders. The use of such systems for growth cells of six-punch presses allowed to grow diamonds up to 3 mm in size of type IIa and IIb with record mass growth rates of up to 15 mg/h while maintaining the structural perfection of such crystals

V.V. Lysakovsky, A.V. Burchenya, O.O. Zanevskyi, Corresponding Member of the National Academy of Sciences of Ukraine S.O. Ivakhnenko, A.P. Zakora.

  1. The conditions for the formation of mixed types of diamond single crystals when doping Fe-Co-based solvent alloys with titanium and magnesium were established. The limiting values ​​of their concentrations were determined, which are 2.5 ÷ 3.5 at. % for Ti (type Ib+IIb) and 2.2 ÷ 3.5 at. % for Mg (type Ib+IIa). At the same time, boron acceptors, which are mostly concentrated in the octahedron growth sectors in the presence of a small amount of paramagnetic nitrogen, are redistributed on the crystallization front of the cube faces and cause the formation of the indicated mixed types of diamond in the corresponding growth sectors.

V.V. Lysakovsky, A.V. Burchenya, O.O. Zanevsky, Corresponding Member of the NAS of Ukraine S.O. Ivakhnenko, A.P. Zakora.

  1. The wear resistance of polycrystals obtained by sintering was studied pits under high pressure of diamond powders synthesized in the MgZn-C system, by turning them into a cylindrical core of granite of the Korostyshivskoye deposit of the X drillability category. It is shown that samples sintered at a pressure of 8 GPa and a temperature of 1780 oC from an unclassified synthesis product have a wear resistance 30 times higher than the wear resistance of polycrystals sintered from finely dispersed powder with a particle size of less than 40 μm. The introduction of 40% of diamond particles larger than 80 μm into the fine powder in the initial mixture for sintering polycrystals at the same density and similar hardness values ​​of the obtained samples increases their wear resistance by 5.8 times.

O.O. Bochechka, O.M. Isonkin, O.I. Cherniyenko, O.V. Kushch, V.S. Gavrilova.

  1. Highly productive and cheap methods of obtaining nano- and micropowders of metals (Fe, Al, Sn, Ti), their oxides and carbides by the method of electroerosion dispersion in plasma in liquids (water, kerosene, alcohol), which are characterized by high reactivity, have been developed, on the basis of which new highly effective composite materials have been created: superconducting, electrically conductive with high corrosion resistance at high temperatures, high degree of absorption of electromagnetic radiation in a wide frequency range and for medical purposes, sorbents-coagulants for wastewater treatment from ions of heavy metals, alkali and alkaline earth metals. The developed dietary and feed additives based on polyvalent nanopowders of iron oxides have been tested for toxicological and environmental safety and have received permission for sale.

Acad. of the National Academy of Sciences of Ukraine T.O. Prikhna, M.K. Monastyryov, V.E. Moshchil.

  1. A technology for precision machining of ceramic balls for hybrid bearings has been developed. The conditions and diamond machining modes have been experimentally determined, which allow the production of ceramic balls from B4C, the dimensions of which correspond to the accuracy class G16 with a deviation from the spherical shape of 0.2-0.3 microns. It has been shown that the wear resistance of ceramic balls during dry rolling friction for 120 minutes exceeds the wear resistance of steel ShKh-15 by 1.49-2.44 times, and in the environment of kerosene TS-1, on the contrary, it is inferior to steel by 1.75 times. This phenomenon is explained by the Rebinder effect of wedging surface microcracks in ceramic balls and their chipping. The determined effect gives reason not to recommend kerosene TS-1 as a lubricating medium in hybrid bearings.

Corresponding Member NAS of Ukraine A.L. Maistrenko, S.V. Sokhan, O.I. Borymsky, V.G. Kulych.

  1. Based on the experimental data obtained and the literature analysis conducted, it was established that the temperature of barothermal (NRNT) treatment of hard alloys under high pressure conditions (8 GPa) in the cell of a high-pressure apparatus of the “Toroid” type should be within or below the temperature of formation of the liquid phase of the WC-Co system. I.V. Andreyev, I.O. Gnatenko. The optimal modes of NRNT of sintered hard alloys were experimentally determined, under which the hardness of the materials increases from 0.5 HRA units (for WC-6Co) to 2 HRA units (for WC-15Co) and the value of the stress intensity factor increases from 10.6 MPa•m1/2 to 11.8 MPa•m1/2 (for the WC6Co alloy), which may be due to a slight decrease in the parameter “c” of the crystal lattice of WC carbide.

I.V. Andreev, I.O. Gnatenko, T.O. Kosenchuk, O.S. Osipov.

  1. The optimal concentration of chromium diboride (4%) in diamond-containing composites based on the WC‒Co matrix, sintered by the method of electric plasma-spark sintering in a two-stage mode with temperatures T1 = 1300 °C and T2 = 1400 °C, at which the highest indicators of the physicomechanical properties of the composites are achieved (КIc = 15.4 MPa ∙ m1/2, H = 14.3 MPa, Rbm = 2950 MPa and Rcm = 5780 MPa). This occurs due to the dispersion mechanism of strengthening and modification of the structure (reduction of the average grain size of the carbide phase from 5.6 to 3.4 μm, disappearance of pores at the site of the binding Co phase, formation of clusters of the inhibitor phase at the interphase boundaries) and the phase composition of the composites.

M.O. Bondarenko, V.A. Mechnyk, V.M. Kolodnitsky.

  1. It was found that adding the required amount of vanadium nitride (VN) nanopowder to the composition of diamond-containing composites based on the Fe‒Cu‒Ni‒Sn matrix, formed by the method of electric plasma-spark sintering at a temperature of 1000 °C and a pressure of 30 MPa for 3 min, leads to a significant increase in mechanical parameters: ultimate strength during bending (from 790 to 1110 MPa) and ultimate strength during compression (from 816 to 1410 MPa). This is explained by the formation of a finer-grained homogeneous structure, which consists of a solid solution of vanadium in α-iron and a mixture of Fe, Cu, Ni, Sn phases, primary and secondary dispersed phases of vanadium nitride. In addition, obtaining composites of the specified system with high performance characteristics provides significant economic benefits not only due to reduced energy consumption in the sintering process, but also due to a sharp decrease in the cost of composites.

V.A. Mechnyk, M.O. Bondarenko, V.M. Kolodnitsky.

  1. Nanostructured a multilayer coating of the TiN/CrC system on the surfaces of tools with PCNB with a layer alternation period of 40 nm, which has a microhardness of 41–50 GPa depending on the pressure of the working gases, which is achieved due to the presence of a nanostructured carbide phase, optimal conditions for coating application were established and their tribological studies were conducted, which showed that in order to increase the adhesion strength, physical-mechanical and operational properties of the coating, it is advisable to use preliminary nitriding in a gas discharge and apply a 1 nm thick chromium sublayer on the surface of PCNB plates, the nitrogen pressure when applying TiN/CrC type coatings is p = 3·10-3 Torr, and the shear potential on the substrate Uz = (–150)–(–200) V.

Corresponding Member of the NAS of Ukraine S.A. Klymenko, A.S. Manokhin, S.An. Klymenko; V.O. Stolbovoy (KhFTI NAS of Ukraine)).

  1. It was found that increasing the cutting speed to 150 m/min when using a tool made of polycrystalline cubic boron nitride (PCBN) of the BH group causes an increase in the wear intensity – from 5 to 11.6 μm/min., while for a tool with a heat-resistant coating with a mixture of chromium and aluminum nitrides, this characteristic changes from 4 to 6 μm/min. The effectiveness of the coating depends on its chemical composition – for example, in films containing Mo2N, oxidation begins already at temperatures of 350–400 °C and for such coatings the recommended range of cutting speeds is 90–120 m/min, while the wear intensity is 30% lower compared to a standard tool.

Yu.A. Melniychuk, S.An. Klymenko.

  1. It has been established that drilling carbon and fiberglass with drills equipped with ATP allows achieving 8 times higher tool stability compared to carbide drills, and the wear of diamond drills occurs evenly on the rear and front surfaces, while that of carbide drills is much more intense on the rear surface, which leads to an increase in the contact area of ​​the rear and machined surfaces, and as a result to an increase in the defect rate of holes.

A.I. Grechuk (Lund University, Sweden), L.M. Devin.

16.  As a result of studying the stress-strain state of the tool blade, it was established that under conditions when the slice thickness reaches a maximum value of 0.15 mm, which corresponds to a feed rate of 1.9 mm/rev, the equivalent stresses according to Pisarenko-Lebedev in the dangerous zones located on the side of the front surface of the tool are 725 MPa and less than the failure criterion – the tensile strength Rm = 800 MPa. This indicates the possibility of processing hardened steels with a tool equipped with a polycrystalline superhard material based on cubic boron nitride – borsinite.

A.S. Manokhin, Yu.A. Melniychuk, S.An. Klymenko.

  1. Scientific foundations and scientifically substantiated practical recommendations have been created to solve the current scientific and technical problem of designing technological operations of deformation broaching (DB) for forming a complex-profile surface of a hole in parts made of 38Kh3MFA steel and ensuring the specified survivability of the finished product. Technological modes of the DB operation when forming grooves on the inner surface of tubular products should be assigned taking into account the factors that affect obtaining a groove according to the requirements. It has been experimentally proven that the effectiveness of DB technology is determined by the absence of setting of the processed material with the broaching tool, avoiding microcracks in the areas of the formed groove and ensuring the accuracy of the hole. The cause of setting and the formation of microcracks is large plastic deformations in the corners of the groove and the resulting depletion of the plasticity resource of the processed metal due to the loss of continuity of the technological lubricant separating the contacting surfaces.

S.E. Sheikin, S.F. Studenets.

  1. The current scientific and technical problem of increasing the efficiency of diamond processing of large-diameter ceramic balls has been solved. The main regularities of diamond-abrasive processing of ceramic balls have been established. For the process of diamond centerless grinding of ceramic balls with a wheel end, the ratio of the time-averaged feed rate of the wheel for cutting to the speed of rotation of the table with balls has been experimentally determined, which are different for three ranges of changing the deviation from the spherical shape of the balls, namely: above 300 μm, between 300 and 150 μm and below 150 μm. From the condition of correcting the deviation from the spherical shape of the ball surface in the last two ranges, the ratio should be within 0.1…0.3 μm/rev provided that the table with balls rotates at a speed of 20…35 rpm, in the first, where priority should be given to the productivity of the process – 2-2.5 times higher.

S.V. Sokhan, V.G. Sorochenko, V.V. Vozny.

  1. It was experimentally established that the limiting parameter for achieving the accuracy of gear tooth machining is the dimensional wear of the KNB cup wheel, which is proportional to the number of machined teeth without dressing and determines the accuracy of gear tooth machining. After accelerated wear of the wheel during the first