Журнал нано- та електронної фізики (Journal of nano- and electronic physics)
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Item The Influence of Layers Thickness on the Structure and Properties of Bilayer Multiperiod Coatings Based on Chromium Nitride and Nitrides of Transition Metals Ti and Mo(Sumy State University, 2018) Sobol, O.V.; Meylekhov, A.A.; Mygushchenko, R.P.; Postelnyk, А.А.; Tabaza, Taha A.; Al-Qawabah, Safwan M.; Gorban, V.F.; Stolbovoy, V.A.The influence of the layers thickness of bilayer multi-period coatings of the CrNx/MoNx and CrNx/TiNx systems on their phase-structural state, substructure, stress-strain state and mechanical properties was studied using methods of precision structural analysis in combination with computer simulation of implantation processes during particle deposition. It is established that a two-phase structure of CrN and -Mo2N phases of the structural type NaCl is formed in the multi-period coatings of the CrNx/MoNx system with a nanometer thickness of the layers. Because of the small difference in periods (less than 0.5 %) for Λ < 20 nm, the layers form a coherent interlayer interface. The use of small Ub = – 20 V during deposition makes it possible to avoid significant mixing at interlayer (interphase) boundaries even at the smallest Λ = 10 nm. Nitride layers formed under conditions of vacuum arc deposition are under the action of compressive stresses. In the СrNх/TiNх system, because of the relatively large discrepancy between periods (more than 2.5 %), during the formation of the same structural components in the layers (CrN and TiN phases of the structural type NaCl), the epitaxial growth with period adjusting does not occur, even for the smallest Λ 10 nm. The action of the deformation factor at the interphase boundary allows achieving an ultrahard state (with a hardness of about 50 GPa), which causes a relatively low friction coefficient. The obtained results on the formation of phase-structural states with the nanoscale thickness of layers of multi-period nitride coatings are explained from the position of minimization of surface energy and deformation energy.Item 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, А.А.; 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.Item Structure and Physics Mechanical Properties of Multiperiod Vacuum-arc Coatings on the Basis of Two-layer System TiN[x]/ZrN[x](Sumy State University, 2017) Sobol, O.V.; Andreev, A.A.; Bochulia, T.V.; Stolbovoy, V.A; Gorban, V.F.; Yanchev, A.V.; Meylekhov, A.A.By methods of structural analysis (a precise X-ray diffraction method and raster electron microscopy) in conjunction with tests on physical and mechanical characteristics (hardness, elastic modulus, friction force and friction coefficient) comprehensive studies have been conducted. Such complex researches are the basis for optimization of properties of multiperiod systems TiNx/ZrNx by changing their structural states (structural engineering). The main parameters of changes were: number of layers (n) from 134 to 534 (at total coating thickness of about 10 microns) and magnitude of negative bias potential Ub. Formation of biphasic (TiNx and ZrNx) condition was revealed. On substructural level the most sensitive to Ub is micro-strained state. The growth of micro-strain with an increase numbers of ZrNx layers (at the greatest Ub = – 200 V) testifies about the determining contribution of irradiation of heavy Zr ions in defect formation at formation of coating. Is established that under optimal technological parameters of receiving of multiperiod TiNx/ZrNx coatings their hardness is in the range 40-50 GPa that corresponds to super hard condition. Dependence of penetration depth of indenter is revealed during testing in a pair of "diamond - multiperiod TiNx/ZrNx coating" and coefficient of friction on the ratio H/E, which characterizes the elasticity of material.Item A Computer Simulation of Radiation-Induced Structural Changes and Properties of Multiperiod ZrNx/MoNx System(Sumy State University, 2017) Sobol, O.V.; Meylekhov, A.A.; Bochulia, T.V.; Stolbovoy, V.A.; Gorban, V.F.; Postelnyk, А.А.; Shevchenko, S.M.; Yanchev, A.V.Influence of the period value Λ (at different negative potential Ub that supplied during deposition) on phase composition, structure, stress-strain state and hardness of multiperiod coatings ZrNx/MoNx is investigated by using complex methods of validation structural state at combined with microindentation. Formation in layers ZrNx and MoNx the phases with cubic lattice and preferred orientation of crystallites with axis [100] is established. Stress-strain state of compression with increasing Ub is amplified and reaches maximum value (– 6.7 GPa) at Λ = 20 nm and Ub = – 110 V. Hardness of coating increases with decreasing Λ from 300 to 20 nm. Coatings that obtained with Λ = 20 nm and Ub = – 110 V have the highest hardness 44 GPa. Relaxation of structural compressive stresses and decreasing hardness is happening at smaller Λ and larger Ub = – 110 V (as a result of radiation-stimulated forming defect and mixing). Data of computer modeling of defectiveness at atomic level at bombardment of ions that accelerated in field Ub are used to explain the results.