UDC 539.533:549.51/.53
WITH. N. Dub1, *, R. P. Yavetskyi2, V. AND. Belous3, E. F. Dolzhenkova2, G. N. Tolmacheva3, O.Ts.Sydletskyi4
1Institute of superhard materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
2Institute of Single Crystals of the National Academy of Sciences of Ukraine, Kharkiv, Ukraine
3National Scientific Center “Kharkiv Physical and Technical Institute” of the National Academy of Sciences of Ukraine, Kharkiv, Ukraine
4Institute of scintillation materials of the National Academy of Sciences of Ukraine
*lz@ism.kiev.ua, sergey-dub@bigmir.net
Genesis of plastic flow during nanodeformation of Y3Al5O12 aluminum yttrium garnet (pages 3–11)
The generation of plastic flow during nanodeformation of alumino-yttrium garnet (AIG) with a low (single crystal (111) AIG after annealing at a temperature of 1300 °C) and a high (polycrystalline AIG with a grain size of ~20 μm after mechanical polishing) dislocation density was investigated using the nanoindentation method in the mode of continuous control of contact stiffness. For the sample with a high density of dislocations, a smooth elastoplastic transition in the nanocontact was observed as a result of the movement and propagation of dislocations already existing in the sample. A sharp elastoplastic transition (pop-in) was observed for the (111) AIH single crystal after annealing at a temperature of 1300°C, caused by the homogeneous nucleation of dislocations in the contact region.
Key words: nanoindentation, aluminum yttrium garnet, plastic flow initiation, theoretical shear strength.
UDC 544.146.5:621.921.34
IN. I. Zabuga1, G. G. Tsapyuk1, *, T. AT. Kurylyak2, O. AT. Bochechka2, **1National University named after Taras Shevchenko, m.Kyiv, Ukraine
2Institute of superhard materials named after IN. M. Bakulya National Academy of Sciences of Ukraine, m.Kyiv, Ukraine
*tsapyuk@ukr.net
**bochechka@ism.kiev.ua
Oxidation kinetics of diamond nanopowder modified with tungsten by chemical adsorption from solution (pp. 12–18)
The oxidation kinetics of statically synthesized diamond nanopowder ASM5 0.1/0 in the presence of tungsten in amounts of 1 and 5% (by weight) introduced into the sample by wetting it with an aqueous solution of (NH4)2WO4 was studied. It was found that during chemical modification of diamond nanopowder with tungsten by adsorption from solution, the inhibitory effect of tungsten on the diamond oxidation process is manifested. This is consistent with the proposed kinetic scheme of the reaction, which includes the stage of interaction of diamond with gaseous tungsten oxide.
Key words: oxidation kinetics, diamond, tungsten oxide, nanopowder.
UDC 666.762.856
IN. F. Horban1, *, A. AND. Andreev2, L. R. Shaginyan1, S. AND. Firstov1, M. IN. Karpets1, N. I. Danylenko1
1Institute of Materials Science Problems of the National Academy of Sciences of Ukraine named after I. N. Frantsevicha, g. Kyiv, Ukraine
2 National Scientific Center “Kharkov Physical and Technical Institute” National Academy of Sciences of Ukraine, Kharkiv, Ukraine
*gvf@ipms.kiev.ua
High-entropy coatings – structure and properties (pp. 19–36)
Metal and nitride coatings from high-entropy alloys (VES) with different phase compositions obtained by various sputtering methods are investigated. It is shown that high-entropy coatings are characterized by the presence of a nanostructural state, which, along with the cluster structure, provides metallic coatings with a hardness of ~10–19 GPa; for nitride coatings, hardness values equal to 50–60 GPa and reduced modulus of elasticity are more than 300 MPa.The ratio of lattice parameters, determined experimentally, to the lattice parameter of the refractory metal itself in VES reflects the level of the modulus of elasticity in relation to the theoretically possible both in cast VES and metal coatings based on them.
Key words: high-entropy alloys, coatings, phase composition, lattice parameter, hardness, reduced modulus of elasticity.
UDC 669.295.539.121.537.534
IN. M. Beresnev1, O. IN. Sobol2, A. AND. Andreev3, V. F. Horban 4, S. AND. Klymenko5, *, S. IN. Lytovchenko1, D. IN. Kovteba3, A. AND. Meilekhov2, A. AND. Postelnyk2, U. WITH. Nemchenko1, V. Yu. Novikov6, B. AND. Ointment 1
1 Kharkiv National University named after IN. N. Karazyna, Kharkiv, Ukraine
2 National Technical University “Kharkiv Polytechnic Institute”, Kharkiv, Ukraine
3National Scientific Center “Kharkiv Physical and Technical Institute” NAS of Ukraine, Kharkiv, Ukraine
4Institute of Problems of Materials Science named after I. N. Frantsevich National Academy of Sciences of Ukraine,Kyiv, Ukraine
5Institute of superhard materials named after IN. N. Bakulya National Academy of Sciences of Ukraine, Kyiv, Ukraine
6 Belgorod National State Research University, Belgorod, Russia
*atmu@meta.ua
Formation of the supersolid state of the vacuum-arc high-entropy TiZrHfNbTaYN coating (pp. 37–46)
Complex studies of the formation of the superhard state in the vacuum-arc high-entropy TiZrHfNbTaYN coating were carried out. The regularities of the implementation of the composition-structure-physical-mechanical properties triad are established depending on the applied displacement potential Ub. It is shown that an increase in Ub when applying a coating leads to a decrease in the relative content of light (Ti) and an increase in heavy (Ta, Hf) metal components, which is determined by radiation-stimulated processes essami in the near-surface region during deposition. The formation of a single-phase state (on the basis of the fcc metal lattice) in the Ub range from –50 to –250 V was established, and the predominant orientation of the crystallites with the [111] axis, perpendicular to the growth plane, was revealed.An increase in the degree of texture perfection along the [111] axis with an increase in Ub is accompanied by an increase in the hardness of the coating, which allows reaching a superhard (H = 40.2 GPa) state at Ub = –250 V.
Key words: high-entropy coating, displacement potential, composition, structure, properties, texture, superhard state.
UDC 536.722:621.762
Delong Xie*, Leyin Xiao, Feng Lin, Xiaoyi Pan, Yu Su, Xiaohu Fang, Haiqing Qin, Chao Chen
Guangxi Key Laboratory of Superhard Materials, Chinese National Engineering Research Center for Special Mineral Materials, China Nonferrous Metal Geology and Mining Co, Ltd, Guilin, China
*xiedelonghn@foxmail.com
Thermal analysis of FeCoCu pre-alloyed powders used for diamond tools (p. 47–56)
By simulating the pressureless sintering process, the thermal effects of FeCoCu pre-alloyed powders have been investigated. According to the notions of the Kissinger method, the activation energies in the expansion-shrinkage conversion stage are analyzed. Results show that with Fe content increasing, the specimens’ specific heat capacity values present the increasing trend. The 25%Fe–15%Co–60%Cu specimens have negative enthalpy value at 10 and 20°C/min heating rate but positive values at 30°С/min. For the specimens with lower Cu content, the enthalpies are always positive. It is established that both the specific heat capacity and enthalpy are larger when at higher heating rates. The activation energy of the 65%Fe–15%Co–20%Cu specimens is 10 times higher than that of the 25%Fe–15%Co–60%Cu specimens and the 45%Fe–15%Co–40%Cu specimens.
Keywords: pre-alloyed powder, specific heat capacity, enthalpy, activation energy.
UDC 669.27:620.191
Ding Chen1, *, Liang Yao1, Zhenhua Chen1, 2, Huiping Wang2, 3, Wen Peng2, 3
1College of Materials Science and Engineering, Hunan University, Changsha, China
2State Key Laboratory of Cemented Carbide, Zhuzhou, China
3ZhuZhou Cemented Carbide Group Co., LTD, Zhuzhou, China
*chending@hnu.edu.cn
Investigation on the static fatigue mechanism and effect of specimen thickness on the static fatigue lifetime in WC–Co cemented carbides (p. 57–67)
The static fatigue mechanism and effect of specimen thickness on static fatigue lifetime for four WC–Co cemented carbides were studied with different binder contents and carbide grain sizes. Static fatigue tests under three-point bend loading were conducted on different sized specimens. The fracture surfaces of rupture specimens were examined by scanning electron microscopy to investigate the static fatigue micromechanisms. Experimental results show that microcracks nucleate from defects or inhomogeneities and the connection of microcracks produces a main crack. The main crack propagates rapidly, resulting in the fracture of specimens. The extension of static fatigue lifetime with the increase of specimen thickness is due to the decrease of plastic zone size near the crack tip and relevant energy change during the crack growth. The effect of specimen thickness on static fatigue lifetime is much greater for cemented carbides with larger WC grain size or higher cobalt content, which is attributed to operative toughening mechanisms.
Keywords: cemented carbides; static fatigue; size effect; microstructure.
UDC 669.018.25
I. V. Andreev*, I. O. Hnatenko, S. O. Lysovenko, V. G. Gargin
Institute of Superhard Materials named after V. N. Bakulya, National Academy of Sciences of Ukraine, Kyiv, Ukraine
*aigor@i.ua
The influence of high pressure and temperature on the structure and properties of the hard alloy WC–6Co (pp. 68–73)
The results of studies of barothermal treatment of the hard alloy WC–6Co at high (7 GPa) pressure are presented. It is shown that such treatment of the hard alloy leads to a deterioration of the main physical and mechanical characteristics, in particular the strength during contact and the coercive force, which is due to an increase in the number of defects in the structure of the carbide phase of the hard alloy.
Keywords: hard alloy, sintering, high pressure, physical and mechanical properties.
UDC 621.941
L. N. Devyn*, N. E. Stakhnyv, Yu. A. Melnychuk
Institute of Superhard Materials named after V. N. Bakulya, NAS of Ukraine, Kyiv, Ukraine
*ldevin@ism.kiev.ua
The influence of the roughness of cutting inserts made of a diamond–tungsten carbide composite on the cutting force and quality of processing when turning aluminum and brass alloys (pp. 74–81)
The influence of the roughness of the front surface of cutting plates made of diamond–tungsten carbide nanocomposite on cutting forces, vibrations, and surface quality during finishing of aluminum and brass alloys was investigated. The optimal cutting modes for obtaining surfaces with minimal roughness and waviness are substantiated.
Key words: nanocomposite, diamond, tungsten carbide, cutting forces, vibrations, roughness, waviness.
UDC 621.9 23: 621.891
V. I. Lavrinenko1, , V. Yu. Solod2, *
V. M. Bakul Institute of Superhard Materials, NAS of Ukraine, Kyiv, Ukraine
Dnipro State Technical University, Ministry of Education and Science of Ukraine, Kamianske, Ukraine
*lavrinenko@ism.kiev.ua
**v_solod@ukr.net
The process of abrasive treatment as a frictional interaction of dissimilar materials (pp. 82–882)
The share of friction energy in the abrasive process for various processed tool materials was evaluated and ways of reducing friction during grinding with wheels made of superhard materials were proposed, primarily reducing friction on the surface of the bond of wheels with NTM.
Keywords: abrasive treatment, frictional interaction, wheels made of superhard materials, wheel bond.
UDC 666.233
IN. Yu. Dolmatov
FSUE SKTB “Technology”, St. Petersburg, Russia
diamondcentre@mail.ru
The content of impurity elements in the diamond charge and detonation nanodiamonds after nitric acid cleaning (pp. 89–102)
The influence of the composition of the shell of the explosive charge and its modification with various compounds on the yield of DNA, AS, the content of impurities and their elemental composition was investigated. With the appropriate selection of compounds, it is possible to increase the yield of AS up to 18.6% (by mass), and DNA – up to 7.6% (by mass); reduce the amount of impurities in AS to 0.23% (by mass), and in DNA – to 0.3% (by mass). The phosphorus content in AS was brought up to 0.665% (by mass), and in DNA – up to 0.244% (by mass); the boron content was increased to 0.96% (by mass) in AS, and to 0.472% (by mass) in DNA.
Key words: detonation synthesis, detonation nanodiamonds, DNA, diamond charge, AS, non-combustible impurities, charge armor (shell), doping of nanodiamonds, elemental composition of impurities.