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Документ The Influence of Layer Thickness and Deposition Conditions on Structural State of NbN/Cu Multilayer Coatings(Sumy State University, 2019) Sobol, O. V.; Andreev, A. A.; Meylekhov, A. A.; Postelnyk, A. A.; Stolbovoy, V. A.; Ryshchenko, I. M.; Sagaidashnikov, Yu. Ye.; Kraievska, Zh. V.The influence of the main physical and technological factors of structural engineering (layer thickness, nitrogen atmosphere pressure and bias potential) on the structural-phase state of the NbN/Cu coatings was studied. It was established that with an increase in the thickness of niobium nitride layers from 8 to 40 nm (in the NbN/Cu multilayer composition), the phase composition changes from the metastable NbN (cubic crystal lattice, NaCl structural type) to the equilibrium ε-NbN phase with a hexagonal crystal lattice. At low pressure PN = 7·10 – 4 Torr in thin layers (about 8 nm thick), regardless of the Ub, the NbN phase is formed. The reason for the stabilization of this phase can be the uniformity of the metallic fcc crystal lattice of the δ-NbN phase with the Cu crystal lattice. As the pressure increases from РN = 7·10 – 4 Torr to 3·10 – 3 Torr, a more equilibrium ε-NbN phase with a hexagonal crystal lattice is formed. An increase in the bias potential during deposition from – 50 V to – 200 V mainly affects the change in the preferred orientation of crystallite growth. In thin layers of the NbN phase (about 8 nm), a crystallite texture with the [100] axis is formed. In layers with a thickness of 40-120 nm, crystallites of the NbN phase are predominantly formed with a hexagonal (004) plane parallel to the growth plane. At the greatest layer thickness (more than 250 nm), the NbN phase crystallites are predominantly formed with a (110) hexagonal lattice plane parallel to the growth plane. The results obtained show great potential for structural engineering in niobium nitride when it is used as a constituent layer of the NbN/Cu multilayer periodic system.Документ Mixing on the Boundaries of Layers of Multilayer Nanoperiod Coatings of the TiNх/ZrNх System: Simulation and Experiment(Sumy State University, 2017) Sobol, O. V.; Meylekhov, A. A.; Mygushchenko, R. P.; Postelnyk, A. A.; Sagaidashnikov, Yu. Ye.; Stolbovoy, V. A.Using the complex of methods for attestation of the structural state in combination with computer simulation and measurement of mechanical properties (hardness), the influence of the period Λ on the mixing process on the interlayer boundaries of multilayer coatings TiNх/ZrNх is studied. The formation of two phases (TiN and ZrN) with one type of crystal lattice (structural type NaCl) is identified in the layers of multiperiodic compositions TiNx/ZrNx with a period of Λ = 20 ... 300 nm. At Λ = 10 nm, the formation of a solid solution (Zr, Ti)N, as well as a small volume of the TiN phase is revealed on XRD spectras. The presence of TiN component is due to the larger initial value of the layer based on titanium nitride. To explain the results obtained, the results of computer simulation of damage at the atomic level during bombardment by ions accelerated in the Ub field are used. The critical thickness of mixing (about 7 nm) in the TiNx/ZrNx system is determined upon condition that Ub = – 110 V. It is established that a decrease in the period from 300 to 20 nm leads to increase in hardness. The highest hardness of 44.8 GPa corresponds to the superhard state. It is established that the critical thickness of radiation-stimulated defect formation has a significant effect on the stress-strain state and hardness of coatings with a small Λ ≈ 10 nm. In this case, relaxation of the stress-strain compression state occurs and the hardness decreases. However, the formation of a solid solution, while retaining part of the unreacted layer of titanium nitride at Λ = 10 nm, makes it possible to obtain an ultrahigh (44.8 GPa) hardness of the coating.Документ Structural Engineering and Mechanical Properties of (Ti-V-Zr-Nb-Hf-Ta)N Coatings Obtained at Different Pressures(Сумський державний університет, 2019) Sobol, O. V.; Andreev, A. A.; Postelnyk, H. O.; Meylekhov, A. A.; Sagaidashnikov, Yu. Ye.; Stolbovoy, V. A.; Yevtushenko, N. S.; Syrenko, T. O.; Kraievska, Zh. V.; Zvyagolskiy, A. V.Effect of pressure of the reaction gas on the texture, structural stress state and mechanical properties (hardness and resistance to abrasive wear) in vacuum-arc coatings based on Ti-V-Zr-Nb-Hf-Ta nitrides of high entropy alloys were investigated in this work. At a bias potential of – 200V, an increase in nitrogen pressure during deposition from 2.5·10⁻⁴ to 4.5·10⁻³ Torr leads to an increase in the content of nitrogen atoms in the coating, and the formation of a bittexture state [111] + [311] is established. The formation of a biaxial texture occurs due to the presence in alloys of atoms with very different masses (Ti, V and Hf, Ta). The use of a multi-element composition in a single-phase state with a simple cubic lattice allows to achieve high values of microstrain (up to 1.4 %) with a low deposition pressure. It is determined that the increase of nitrogen pressure during deposition leads to an increase in macrostresses. The highest hardness of 53 GPa is achieved in coatings obtained at a pressure of 2·10⁻³ Torr. It has been established that coatings with high resistance to abrasive wear are found to be: crystallite grain size 12-25 nm, absent of texture (or a low level of texture perfection), and also rather high microstrain in crystallites.Документ Structural engineering of NbN/Cu multilayer coatings by changing the thickness of the layers and the magnitude of the bias potential during deposition(2019) Sobol, O. V.; Andreev, A. A.; Stolbovoy, V. A.; Kolesnikov, D. A.; Kovaleva, M. G.; Meylekhov, A. A.; Postelnyk, H. O.; Dolomanov, А. V.; Sagaidashnikov, Yu. Ye.; Kraievska, Zh. V.To determine the patterns of structural engineering of vacuum-arc coatings based on niobium nitride in the NbN/Cu multilayer composition, the effect of layer thickness and bias potential on the structural-phase state and physico-mechanical characteristics of vacuum-arc coatings was studied. It was found that the metastable δ-NbN phase (cubic crystal lattice, structural type NaCl) is formed in thin layers (about 8 nm thick) regardless of Ub. With a greater thickness of the layers of niobium nitride (in the multilayer NbN/Cu composition), the phase composition changes from metastable δ-NbN to the equilibrium ε-NbN phase with a hexagonal crystal lattice. An increase in the bias potential during deposition from -50 to -200 V mainly affects the change in the preferential orientation of crys-tallite growth. The highest hardness (28.2 GРa) and adhesive resistance is achieved in coatings obtained at Ub = -200 V with the smallest layer thickness. The highest hardness corresponds to the structurally deformed state in which the crystallite texture is formed with the [100] axis perpendicular to the growth surface, as well as a large microstrain (1.5%) in crystallites.