UDC 666.11.01 : 621.921—419
S.A. Kukharenko, A.E. Shilo, E.K. Bondarev, E.A. Pashchenko, V.N. Tkach, A.G. Gontar (Kyiv)
Study of Diffusion Processes in a Mixture of Glasses of the Na2O—B2O3—TiO2—SiO2 and PbO—ZnO—B2O3—SiO2 Systems
The main results of the study of diffusion processes at the interphase boundary formed by melts of oxide glasses of the Na2O—B2O3—TiO2—SiO2 and PbO—ZnO—B2O3—SiO2 systems are presented and summarized. The analysis of the features of ion migration and microvoids in the structure of softened glass is carried out and a qualitative model of migration processes based on the mechanism of bond translation is proposed. The adequacy of this model for lead-zinc-borosilicate glasses with a PbO content of ≈ 75 ‰ (by weight) used in this study is shown.
UDC 546.26:621.793:669.715
P. Niedzielski, W. Kaczorowski (Lodz, Poland) P. Couvrat (Lyon, France)
Hard carbon coatings for cutting aluminum alloys
The characteristics of carbon layers such as the high hardness, thermal conductivity, low coefficient of friction, high wear resistance and chemical inertness make diamond like carbon, and nanocrystalline diamond coatings an attractive film material for cutting tools. In the present work, the behavior of hard carbon coating in cutting aluminum alloy has been investigated.
UDC 539.37:539.5
S. B. Polotnyak, N. V. Novikov, L. K. Shvedov, Yu. N. Krivosheya (Kyiv)
Shear resistance of materials at ultra-high pressures
A calculation and experimental method for determining the plastic properties of materials deformed in high-pressure apparatuses with diamond anvils has been developed. An original device based on a three-channel capacitive sensor equipped with a computer information processing system has been manufactured to measure the thickness of a sample during compression. A finite element study of the effect of deformation of the apparatus elements on the accuracy of measuring the thickness of samples has been conducted. Nonlinear dependencies of shear resistance on pressure of materials used in high-pressure apparatuses have been determined.
UDC 539.266; 538.214
A. S. Roik, V. P. Kazimirov, V. M. Perevertaylo, O. B. Loginova (Kyiv)
Structure and Surface Properties of Sn—Ge Melts
The results of X-ray diffraction studies of liquid Sn—Ge melts are presented and the relationship between the ordering of atoms in the melt and its surface properties is discussed.
The analysis of the local structure of atoms is carried out using models reconstructed from experimental curves of the structure factor using the inverse Monte Carlo and Voronoi-Delaunay methods. It is shown that the structure of melts in the concentration range of 0—52% (at.) Ge is formed on the basis of the structure of liquid tin, in the range of 52—100 ‰ (at.) Ge — liquid germanium, which indicates a tendency to microstratification in melts. It has also been established that against the background of the presence of stable microgroups formed on the basis of the structure of liquid tin, the process of formation of diatomic chains of germanium atoms, which are an element of its structure in the liquid state, is underway. The growth in the number of germanium atoms participating in the formation of the said structural elements noticeably outpaces the growth of its content in the melts. Microgroups with a structure close to the structure of liquid germanium actually appear in melts at ≈ 20 ‰ (at.) Ge and their final formation is completed at a germanium content of ≈ 30 ‰ (at.), which most likely explains the appearance of a minimum in the isotherm of the surface tension of the melts in this concentration range. UDC 546.26-162:541.183
A. V. Romanyuk (Vyshgorod) N. V. Novikov, G. P. Bogatyreva (Kyiv) Yu. I. Gorlov (Vyshgorod) A. N. Kuzmich (Kiev)
Structure of the functional and adsorption coating of finely dispersed synthetic diamonds
The functional coating of the surface of micropowders of synthetic diamonds from various manufacturers was studied using the temperature-programmed desorption method. It was shown that this coating is determined not only by the technology of manufacturing micropowders, but also by the quality of the original diamond raw material.
UDC 549.2: 539.1
O. V. Sobol (Kharkiv) O. N. Grigoriev, S. N. Dub (Kyiv) A. N. Stetsenko, A. A. Podtelezhnikov (Kharkiv)
Features of the phase composition, structure, stress state and mechanical characteristics of condensates of the boride system W—Ti—B obtained by triode sputtering
Comparative studies of the structure and mechanical characteristics of ion-plasma nanocrystalline condensates of the Ti—W—B system were carried out. In the study of the phase composition and structure of coatings obtained by triode sputtering of a target with the composition of 80 ‰ (by volume) W2B5 — 20 ‰ (by volume) TiB2, a critical range (0.11—0.25 nm/s) of condensation rates was revealed, below which a phase with a cubic lattice of the type (W, Ti)B0.7…1.2(O, N, C)0.3…0.2 is formed, and above which a solid solution (W, Ti)B2 with a hexagonal lattice and an elemental composition close to the sputtered target is formed. A change in the structural state of the material from cluster-crystalline at low (U = 0.6—1.0 kV) values of the sputtering nstress and to textured crystalline at U > 2.2 kV. The growth of structural perfection with increasing stress leads to an increase in the hardness and elastic modulus of the condensates, the maximum values of which were achieved at U = 3.2 kV: hardness – 19.9 and 37.9 GPa, elastic modulus – 205 and 389 GPa for phases with a cubic and hexagonal lattice, respectively. The conditions for the formation of the cluster component in condensates and its effect on the hardness and elastic modulus of materials are discussed.
UDC 62.987
A. I. Prikhna (Kyiv)
Installation for the synthesis of superhard materials
A high-pressure apparatus for uniaxial compression with an extruded seal and two versions of horizontal press installations for driving it are described. In one of the versions, the high-pressure apparatus is built into the plunger of the press.
UDC 541.138.2
V. A. Shvets, V. N. Talash, V. A. Lavrenko, O. A. Frenkel (Kyiv)
Features of corrosion-electrochemical behavior of titanium nitride with different nitrogen compositions in 3 ‰ NaCl solution
Corrosion behavior of titanium nitride with different nitrogen content (in the homogeneity region) was studied for TiN1.00, TiN0.97 and TiN0.70 compositions in 3 ‰ sodium chloride solution using the potentiodynamic method of polarization curves and X-ray phase analysis. The obtained polarization curves indicate an increase in the anodic oxidation activity in the Ti–>TiN1.00–>ТiN0.97–>TiN0.70 series, with the TiN0.70 sample, unlike the others, having a significant active dissolution region. It is shown that TiNx corrosion is controlled by the formation of passivation layers, which are titanium oxynitrides with different oxygen contents, and a very thin layer of rutile TiO2 is also formed on the TiN1.00 surface. The studied samples are characterized by a complex nature of the cathodic polarization curves with a pronounced transition region controlled by oxygen diffusion and its electrochemical desorption associated with the presence of surface passivation films, as well as Tafel regions of hydrogen evolution. UDC 621.014
A. A. Vinogradov (Kyiv)
On the shear stress in the conditional shear plane during micro-speed cutting of metals
The article presents the results of calculating the shear stress in the conditional shear plane during micro-speed (v = 0.0088-0.76 m/min) free orthogonal cutting of steel 40 (HB = 1700 MPa) with a cut thickness of a = 0.014-0.25 mm and a width of b = 3.0-3.08 mm without lubrication and with lubrication with a 1% soap solution. It is concluded that the shear stress during micro-speed cutting has the same values as during conventional cutting of steel of the same grade, does not depend on the method of cooling the cutting zone, and should be calculated from the measured components of the cutting force and chip shrinkage taking into account the forces on the rear surface of the tool.
UDC 621.922.079.678
O. A. Rosenberg, S. V. Sokhan, A. L. Puzyrev (Kyiv)
The influence of lapping material on the productivity of diamond finishing of ceramic materials for medical purposes
The article presents the methodology and results of studying the productivity and relative durability of lapping pads made of gray cast iron in comparison with the same indicators of lapping pads made of other materials during diamond finishing of ceramic materials for medical purposes. It is shown that the best indicators of finishing productivity of both aluminum oxide and zirconium ceramics are shown by lapping pads made of gray cast iron, and with the improvement of the physical and mechanical properties and the increase in the hardness of such lapping pads, the finishing productivity increases. At the same time, the roughness of the treated surface decreases with a decrease in the hardness of the lapping pads.
UDC 621.91
M. L. Kheifets (Novopolotsk, Belarus) A. A. Minevich (Hannover, Germany) S. V. Sychev (Novopolotsk, Belarus)
Wear and Failure of High-Speed Steel Tools with TiN Coatings
The article considers wear and failure of high-speed steel tools with TiN coatings. It is shown that reducing friction and creating a thermal barrier for a coated tool leads to a redistribution of contact loads on the front and back surfaces of the cutting wedge. It is noted that the permissible wear for a coated tool decreases, but at the same time, the wear intensity drops sharply.