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Ситников, Николай Николаевич

Организационные подразделения

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Институт лазерных и плазменных технологий

Стратегическая цель Института ЛаПлаз – стать ведущей научной школой и ядром развития инноваций по лазерным, плазменным, радиационным и ускорительным технологиям, с уникальными образовательными программами, востребованными на российском и мировом рынке образовательных услуг.

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Николай Николаевич

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Investigation of wear dynamics for cutting tools with multilayer composite nanostructured coatings in turning constructional steel
(2019) Vereschaka, A.; Tabakov, V.; Grigoriev, S.; Oganyan, G.; Sitnikov, N.; Ситников, Николай Николаевич
© 2018 Elsevier B.V. The paper deals with the wear dynamics shown by carbide tools with multilayer composite nanostructured coatings of various compositions. The investigation involved coatings based on nitrides of such metals as Ti, Zr, Cr, Nb, and Al with three-layer architecture, including adhesion, transition, and wear-resistant layers. The thickness of the coatings was about 4 µm. There was a series of cutting tests involving tools with the coatings under study in the turning of AISI 1045 steel at vc = 200, 250, 300, and 350 m/min. The comparative studies were conducted to investigate wear process patterns for tools with the coatings under study and for uncoated tools and tools with TiN reference coatings, depending on the cutting speed. In particular, the study considered the intensity and specific features of crater formation on the tool rake face. In particular, it was found that an increase in cutting speed led to more active movement of a crater away from the cutting edge, while at lower cutting speeds, a crater developed evenly. Diffusion and oxidation processes were registered and studied at the boundary between the coating and the material being machined. The use of the coatings under study makes it possible to significantly increase the cutting speed, while the optimal composition of the coating depends on the applied cutting speed.
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The microstructure of rapidly quenched TiNiCu ribbons crystallized by isothermal and electropulse treatments
(2020) Sitnikov, N. N.; Shelyakov, A. V.; Khabibullina, I. A.; Visotina, E. A.; Ситников, Николай Николаевич; Шеляков, Александр Васильевич
© 2020 IOP Publishing Ltd. All rights reserved.The work is devoted to the study of the effect of isothermal and electropulse heat treatments on the structure of Ti50Ni25Cu25 (at.%) alloy with the shape-memory effect. The alloy was fabricated by rapid quenching from the liquid state (melt spinning technique) at the cooling rate of the melt of about 106 K/s in the form of a layered amorphous-crystalline ribbon with a thickness of 28 μm. To obtain a completely amorphous state, the ribbon thickness was reduced to 22 μm by means of electrochemical polishing. The alloy samples were subjected to the electropulse treatment (dynamic crystallization) by passing a single electric current pulse with a duration of 10 ms through the sample. The electron microscopy and X-ray diffraction studies have shown that electropulse treatment leads to a significant change in the crystalline structure being formed, in comparison with that obtained by isothermal crystallization. It was revealed that after dynamic crystallization, the microstructure of alloys in cross-section has a non-uniform distribution of crystals (grains) over the ribbon thickness. A structure of columnar crystals is formed near the ribbon surfaces, while individual crystals or grouped large crystals are present in the ribbon bulk. In addition, the columnar structure is textured.
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Investigation of the influence of the thickness of nanolayers in wear-resistant layers of Ti-TiN-(Ti,Cr,Al)N coating on destruction in the cutting and wear of carbide cutting tools
(2020) Vereschaka, A.; Tabakov, V.; Grigoriev, S.; Milovich, F.; Sitnikov, N.; Ситников, Николай Николаевич
© 2020 Elsevier B.V.The paper presents the results of the investigation into the formation of the nanolayer structure of the Ti-TiN-(Ti,Cr,Al)N coating and its influence on the thickness of coatings, their resistance to fracture in scratch testing, and the wear resistance of coated tools in turning 1045 steel. The structure of the coatings with the nanolayer thicknesses of 302, 160, 70, 53, 38, 24, 16, and 10 nm was studied using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and high-resolution (HR) TEM. It is shown that the grain sizes in the nanolayers decrease to certain values with an increase in the thickness of the nanolayers, and then, with a further decrease in the nanolayer thickness, the grain sizes of the nanolayer grow as the interlayer interfaces cease to produce a restraining effect on the growth of the grains. The study found that the nanolayer thickness influenced the wear of carbide cutting tools and the pattern of fracture for the Ti-TiN-(Ti,Cr,Al)N coatings.
Только метаданные
Investigation of multicomponent nanolayer coatings based on nitrides of Cr, Mo, Zr, Nb, and Al
(2020) Grigoriev, S.; Vereschaka, A.; Milovich, F.; Tabakov, V.; Sitnikov, N.; Ситников, Николай Николаевич
© 2020 Elsevier B.V.This paper presents the results of the investigations of multicomponent nanolayer coatings of Cr,Mo-(Cr,Mo,Zr,Nb)N-(Cr,Mo,Zr,Nb,Al)N, Cr,Mo-(Cr,Mo)N-(Cr,Mo,Al)N, and Zr,Nb-(Zr,Nb)N-(Zr,Nb,Al)N. The data on the microstructures and nanostructures of the coatings, including the hardness, phase composition, and chemical composition by coating thickness are presented. The research considers the differences in the phase composition of the coatings and reveals the difference in the wear process on the contact pads of the carbide inserts between the studied coatings and the wear patterns on the coatings from cutting workpieces made of 1045 steel. The multicomponent Cr,Mo-(Cr,Mo)N-(Cr,Mo,Zr,Nb,Al)N coating contains two cubic phases of (Cr,Mo,Al)N and (Zr,Nb,Al)N with the space group Fm3¯m. The Cr,Mo-(Cr,Mo)N-(Cr,Mo,Zr,Nb,Al)N coating exhibited the maximum hardness among the studied coatings, and a tool with such a coating demonstrated the longest lifetime. The coating is also characterized by higher resistance to brittle fracture and cracking.
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Layered Self-Healing Composite Material with an Internal Functional Layer Based on Borosiloxane
(2020) Khabibullina, I. A.; Mashchenko, V. I.; Mostovaya, K. S.; Vysotina, E. A.; Sitnikov, N. N.; Shelyakov, A. V.; Ситников, Николай Николаевич; Шеляков, Александр Васильевич
© 2020, Pleiades Publishing, Ltd.Abstract: Borosiloxane as a functional layer in multilayer self-healing composites is studied. The provisions and principles of self-healing in artificial materials are considered. It is substantiated that rapid self-healing requires at least two factors: directional mass transfer and self-adhesion of the boundaries brought into contact. Either fluid media or viscous-flow materials may act as self-healing materials. Borosiloxane is presented as a promising material of a self-healing viscous matrix in multilayer composites or sandwich panels. The addition of various fillers, e.g., fibers, to borosiloxane leads to a decrease in fluidity; owing to the low molecular weight, high diffusion of macromolecules ensuring high self-adhesion is maintained. The addition of polyester fibers to borosiloxane makes it possible to effectively control fluidity with the high diffusion rate and consequently the coalescence rate of the material surfaces brought into contact being maintained. Experimental samples of borosiloxane are obtained from synthetic rubbers during their interaction with boronic acid in a heated reaction vessel. The addition of 6 wt % polyester fibers ~3 mm long to the synthesized borosiloxane confines its spreading, preserves its shape owing to the stiffness of the fiber framework, and at the same time retains the properties of self-adhesion while the disconnected boundaries are brought into contact. The creation of ensembles from successive borosiloxane layers with different fluidity in one multilayer material allows providing the final composite material with high self-healing characteristics after a penetration defect is made. The effect of self-healing of the developed layered composite in the case of through puncture and cut is shown.
Только метаданные
Investigation of wear mechanisms for the rake face of a cutting tool with a multilayer composite nanostructured Cr–CrN-(Ti,Cr,Al,Si)N coating in high-speed steel turning
(2019) Vereschaka, A.; Tabakov, V.; Grigoriev, S.; Milovich, F.; Sitnikov, N.; Ситников, Николай Николаевич
© 2019 Elsevier B.V.The article considers the wear pattern for the rake face of a cutting tool with the Cr–CrN-(Ti,Cr,Al,Si)N multilayer composite nanostructured coating in turning 1045 steel at vc = 300 m/min. Attention was paid to the diffusion and oxidation processes and effect of high temperature because these wear factors prevailed at high cutting speeds. Studies were conducted using a high-resolution transmission electron microscope and energy-dispersive X-ray spectroscopy. The study of the wear-crater boundary area revealed a layer with lost nanostructure (destruction layer) in the outer coating area. The thickness of the layer was 100–700 nm, depending on its location relative to the wear crater. The layer, which was formed under simultaneous exposure to high temperatures and diffusion and oxidation processes, was characterized by variable thickness and chemical composition, depending on its location relative to the wear crater. In particular, there are large volumes of oxygen in areas with freer access to air, while the oxygen content is significantly lower in the area of the bridge between the wear crater and cutting edge. The Al content increased significantly as the layer approached the cutting-edge area due to an increase in temperature and intensification of the spinodal decomposition process.
Только метаданные
Effect of temperature and oxidation in cutting zone on wear of cutting tools with multilayer composite nano-structured coatings at high speed turning
(2019) Volosova, M.; Vereschaka, A.; Okunkova, A.; Andreev, N.; Sitnikov, N.; Ситников, Николай Николаевич
© 2019, MM publishing Ltd.. All rights reserved.The article discusses the ability of multilayer composite nano-structured coatings based on the Cr-CrN-(Ti,Cr,Al,Si)N system to resist wear factors activated with increasing temperature, such as diffusion and oxidation processes, as well as spinodal decomposition of the coating material. Investigators were carried out in turning C45 steel at the following cutting conditions: f = 0.2 mm/rev, ap = 1.0 mm, vc = 300 m/min. SEM and TEM techniques were used to investigate changes in nano-structures of coatings, as well as diffusion and oxidation processes. Of particular interest was the study of a layer of nanometric thickness on the rake surface of the tool, between the adhered material being machined and the surface nanolayers of the coating. The content of oxygen, iron, and metals the coating was investigated. A lot significant difference was revealed in the content of elements in the layer investigated, depending on the location of the area studied around a crater on the rake face of the tool.
Только метаданные
Specifics in formation of nanolayer structure of coatings during their deposition using filtered cathodic vacuum arc deposition (FCVAD) technology
(2019) Vereschaka, A.; Sitnikov, N.; Oganyan, G.; Sotova, C.; Ситников, Николай Николаевич
The paper discusses the specific features of the formation of nanolayer structures of modifying coatings for metal-cutting tools using FCVAD technology. It is found that the nanolayer coating structure is affected both by the rotation speed of the turntable and by the speed of the planetary rotation of the tool set. It is found that the coating with the minimum thicknesses of nanolayers (about 4-6 nm) provides the longest tool life period. (C) 2019 Elsevier Ltd. All rights reserved.
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Influence of copper content and thermal treatment on shape memory effect in rapidly quenched TiNiCu alloys
(2021) Borodako, K. A.; Shelyakov, A. V.; Sitnikov, N. N.; Zaletova, I. A.; Sevryukov, O. N.; Бородако, Кирилл Анатольевич; Шеляков, Александр Васильевич; Ситников, Николай Николаевич; Севрюков, Олег Николаевич
© 2021 Institute of Physics Publishing. All rights reserved.Amorphous alloys of the TiNi - TiCu system with a copper content of 25 to 40 at.% were prepared by planar flow casting at a melt cooling rate of 106 K/s. Crystallization of the alloys was carried out by isothermal annealing and by action of single electric pulse with a duration of 5 ms. Shape memory behavior and structure of the alloys was investigated by means of bending tests and X-ray phase analysis. It was found that increasing the copper content to above 30 at.% considerably reduces the plasticity and shape memory effect of the alloys. However, abrupt decreasing the annealing duration significantly improves the shape memory performance due to prevention of the formation of brittle Ti-Cu phases in the alloys structure.
Только метаданные
Local atomic and crystal structure of rapidly quenched TiNiCu shape memory alloys with high copper content
(2021) Veligzhanin, A.; Sundeev, R.; Chernysheva, O.; Shelyakov, A.; Sitnikov, N.; Borodako, K.; Чернышева, Ольга Викторовна; Шеляков, Александр Васильевич; Ситников, Николай Николаевич; Бородако, Кирилл Анатольевич
© 2020 Elsevier B.V.This study aims to reveal features of the local crystal structure and environment in the quasi-binary TiNi–TiCu alloys containing 25–40 at.% Cu, by X-ray diffraction and EXAFS spectroscopy. The alloys were produced in an amorphous state by the melt-spinning technique and then crystallised by isothermal and electropulsing treatment. It was shown that Ni local structure is more disordered in comparison with Cu local environment, which is closer to the conventional crystallographic structure. An increase in the Cu content resulted in the magnification of the disordering in the nearest local environment, around both the Ni and Cu atoms, consisting of Ti atoms. No noticeable effect of the annealing rate on the local structure was found.