UDC 620.22
A. F. Lisovsky (Kyiv, Ukraine)
On the Formation of a Refractory Skeleton in Composite Materials (Review)
The article analyzes works devoted to theoretical and experimental studies of the formation of a refractory skeleton in composite materials. It is shown that the main parameters that describe the refractory skeleton are the adjacency of particles and the dihedral angle. In the theory of the formation of a refractory skeleton, certain results have been achieved on the relationship between the values of the dihedral angle, adjacency, phase content, and the conditions of the formation of the skeleton. The composition and structure of the interphase boundaries of the refractory skeleton are described and the thickness of the contact zone of the particles is substantiated. Various technologies that allow one to actively influence the formation of a refractory skeleton are considered, and ways of subsequent research in this area are proposed.
Keywords: composite materials, refractory skeleton.
UDC 666.233
V. Yu. Dolmatov (St. Petersburg, Russia)
G. S. Yuryev (Novosibirsk, Russia)
V. Myllymäki (Helsinki, Finland)
K. M. Korolev (St. Petersburg, Russia)
Why are detonation nanodiamonds small
Based on X-ray diffractometry patterns and original calculation of atomic distribution according to the proposed computer models, a conclusion was made about the existence of high-quality and low-quality detonation nanodiamonds. It was shown that high-quality detonation nanodiamonds are synthesized of small size and their structure corresponds to the structure of macrodiamond, low-quality ones consist of a core and a shell in which the atomic distribution is disturbed and differs from the atomic distribution in macrodiamond.
Keywords: detonation nanodiamonds, structure, size, X-ray diffractometry, atomic distribution.
UDC 621.921.34:621.921.34-413:621.923.4:662.23.05
A. N. Sokolov, A. A. Shulzhenko, V. G. Gargin, A. V. Kotko, V. P. Briksa, R. K. Bogdanov, A. P. Zakora, M. G. Loshak, L. I. Aleksandrova (Kyiv)
Structure and physical-mechanical properties of CVD diamond of different crystalline perfection in the hybridite material
A comparative study of the substructure of CVD diamond samples of different structural perfection in the hybridite material obtained under high pressure and temperature conditions was carried out. The thermal stability of the material and the change in hardness as a result of the formation of a polycrystalline shell of diamond composite heat-resistant material around CVD diamond under high pressure and temperature conditions were studied. Based on the obtained data on the performance of the hybridite with CVD diamond of different structural perfection in the tool, the areas of its most effective use were recommended.
Keywords: CVD diamond, substructure, high pressure and temperature, Raman scattering, hardness.
UDC 539.2.669.0176:669.018
G. S. Oleynik (Kyiv)
On the mechanism of strengthening wurtzite boron nitride under an indenter
Based on the analysis of the crystal geometry of the wurtzite lattice, the possibility of strengthening wurtzite BNв due to plastic shifts along the basal plane (0001) during normal indentation (0001) was considered. It is concluded that strengthening can be caused by the formation of basic stacking faults (as interlayers of the sphalerite phase BN) as a result of plastic shears directly in the double close-packed layers of the wurtzite lattice, as well as the appearance of stresses of dimensional mismatch of the lattice parameters of the wurtzite phase and the sphalerite phase formed from it as a result of crystal-oriented layer-by-layer transformation.
Keywords: wurtzite, layer, shears, plane, cleavage, stacking faults.
UDC 532.64:669.046
І. M. Spiridonova, O. V. Sukhova, N. V. Karpenko, A. V. Dyadkov (m. Dnipropetrovsk)
Curing of Fe–P–B alloys for the creation of wear-resistant composite materials
The structure and power of alloys of concentrated tricutaneous Fe3(P,B)–Fe5PB2–Fe2Р, Fe2B–Fe3(P,B)–Fe5PB2, Fe2B–Fe3(B,P)–Fe3(P,B) and Fe–Fe3(P,B)–Fe3P diagrams have been studied Fe–P–B. For the removal of composite materials that undergo abrasive wear at elevated temperatures, a resin alloy Fe–12.0P–1.0B is recommended. The regularities in the formation of the structure and power boundaries between Fe–12.0P–1.0B and copper-based alloys-bonds in composite materials extruded by the percolation method have been identified.
Key words: recall, structure, phase transformation, operational power, abrasion-resistant composite materials.
UDC 537.533:539.234
A. D. Pogrebnyak, Yu. A. Kravchenko (Sumy)
Modification of mechanical properties of TiN/Al2O3 and TiN/Cr/Al2O3 coatings using low-energy high-current electron beams
The results of the study of the structure, elemental and phase composition of TiN/Al2O3 and TiN/Cr/Al2O3 hybrid coatings are presented. It is shown that electron beam treatment of the surface of hybrid coatings allows increasing the microhardness of the protective layer from 8.3 to 14.4 GPa. It is established that the increase in the hardness of hybrid coatings is associated with an increase in the density of the matmaterial and the restoration of the a-phase of Al2O3 in the protective layer under the influence of thermal activation of the surface.
Keywords: plasma-detonation protective coatings, low-energy high-current electron beam, electron beam processing, surface morphology, phase composition, adhesion, micro- and nanohardness.
UDC 537.533.35
O. G. Lysenko, V. I. Grushko, V. N. Tkach, E. I. Mitskevich (Kyiv)
Assessment of the resolving power of a scanning tunneling microscope with a tip made of boron-doped diamond
Based on the analysis of the dependence of the tunneling current on the parameters of the diamond tip-sample system of the scanning tunneling microscope, the resolving power of the device was estimated when it was operating in the scanning mode. The scanning parameters and the accuracy of maintaining a constant tunneling current value by the feedback system of the device are established, at which atomic resolution is possible in the case of a single tunneling channel. An alternative (to the most well-known publications) explanation of the hexagonal structure of the pyrolytic graphite surface observed with atomic resolution is proposed. The problem of multichannel tunneling associated with the presence of several nanoprotrusions in the working area of the diamond probe, initiating tunneling and deteriorating the resolution of the scanning tunneling microscope is discussed.
Keywords: scanning tunneling microscopy, diamond tip, resolution.
UDC 621.9: 621.923
B. I. Lavrinenko (m. Kiev)
Structural changes in the surface ball of the contact surfaces of the circle with NTM and virus, which can be processed as a source of increased wear resistance (change of elemental storage)
The creation of a structure-changed surface ball of contact surfaces of a circle of supersolid materials and abraded virobu during thermal and plasma influx of shells has been observed. It has been shown that changing the elemental composition has an impact on the mechanical characteristics of the contact surfaces and, as a result, makes it possible to determine the level of their wear resistance.
Key words: elemental storage, structural changes in the surface ball, plasma infusion, contact surface, wear resistance.
UDC 679.822:544.723.237
A. V. Voloshin, E. F. Dolzhenkova, L. A. Litvinov, A. A. Petukhov, E. V. Slyunin (Kharkiv)
The effect of pH of the lubricating and cooling process medium on the productivity of mechanical processing of sapphire
The manifestation of the Rehbinder effect during abrasive processing of sapphire was studied depending on the pH of the lubricating and cooling process medium. Changing the pH from neutral to acidic led to an increase in the grinding speed of the fixed abrasive by 1.8 times. The alkaline medium also contributed to an increase in the rate of surface abrasion by the fixed abrasive. The use of an acidic solution as a lubricating and cooling process medium led to an increase in the productivity of the sapphire polishing process, while the alkaline solution led to a decrease in it.
Key words: sapphire, grinding, polishing, lubricating and cooling process environment, Rehbinder effect.