Факультет електроніки та інформаційних технологій (ЕлІТ)
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Item Mechanical and tribological characterization of nanostructured HfB2 flms deposited from compound target(Springer Nature, 2020) Буранич, Володимир Володимирович; Буранич, Владимир Владимирович; Buranych, Volodymyr Volodymyrovych; Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Budzynski, P.; Шелест, Ігор Владиславович; Шелест, Игорь Владиславович; Shelest, Ihor Vladyslavovych; Prószyński, A.; Chocyk, D.; Гончаренко, Олексій Сергійович; Гончаренко, Алексей Сергеевич; Honcharenko, Oleksii Serhiiovych; Юнда, Андрій Миколайович; Юнда, Андрей Николаевич; Yunda, Andrii MykolaiovychFabrication and development of HfB2-based nanostructured coatings was investigated. All flms were deposited on stainless-steel substrates by RF magnetron sputtering from stochiometric HfB2 target in argon atmosphere. The aim of this work is to evaluate the efects of the bias potential on the microstructure, mechanical and tribological properties. These parameters strongly depend on the experimental conditions. X-ray difraction analysis indicated the diference in microstructure: from dense hexagonal structure with (0001) preferred orientation of nanocrystallites to quasi-amorphous with blurred HfB2 phase peaks. All coatings were measured using nanoindentation (using Berkovich tip), tribology (ballon-disk) and nano-scratch (friction). Coatings with a thickness of 1–2 µm had a signifcant dependence of properties on the microstructure: hardness drastically increased from 8 to 45 GPa, H/E ratio and elastic recovery changed respectively: 0.04–0.15 and 0.26–0.72.Item Structural and mechanical characterization of (TiZrNbHfTa)N/WN multilayered nitride coatings(Elsevier, 2018) Багдасарян, Артем Анатолійович; Багдасарян, Артем Анатольевич; Bahdasarian, Artem Anatoliiovych; Pshyk, A.V.; Coy, L.E.; Kempinski, M.; Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Beresnev, V.M.; Jurga, S.The (TiZrNbHfTa)N/WN multicomponent coatings were deposited by vacuum arc evaporation under dif- ferent substrate bias (-90 and -280 V).X-ray photoelectron spectroscopy was used for analyzing of com- plex composition of investigated coatings by reflecting of atomic scale chemical interactions. The structural investigations showed the formation of a simple disordered solid solution in (TiZrNbHfTa)N layer, b-W2N phase in WN layer with fcc crystal structure and highly disordered bcc (110) and (220) -oriented high-entropy alloy phases, regardless of the applied bias potential. It was shown that with increasing of substrate bias from -90 to -280 V, there is a slight decrease of hardness from 34 to 31 GPa and increase of Young’s modulus from 325 to 337 GPa, which can be explained by annihilation of point defects and precipitation of relatively softer metallic phase.Item A new type of (TiZrNbTaHf)N/MoN nanocomposite coating: Microstructure and properties depending on energy of incident ions(Elsevier, 2018) Багдасарян, Артем Анатолійович; Багдасарян, Артем Анатольевич; Bahdasarian, Artem Anatoliiovych; Pshyk, A.V.; Coy, L.E.; Konarski, P; Misnik, M; Ivashchenko, V.I.; Kempinski, M; Mediukh, N.R.; Beresnev, V.M.; Jurga, S; Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr DmytrovychA novel (TiZrNbTaHf)N/MoN nanocomposite coatings, which consist of the nitride of the high-entropy alloy and the binary nitride, were synthesized by vacuum-arc deposition at various substrate biases. The elemental composition, chemical bonding state, phase structure, microstructure and mechanical properties of the coatings were studied by high-resolution experimental methods: SIMS, GDMS, XPS, XRD, HR-TEM and nano-indentation.It was found that the chemical state of the (TiZrNbTaHf)N/MoN coatings has a complex nature, which consist of a mixture of nitrides of constituting elements. It was also shown that the coatings are based on B1 NaCl-structured γ-Mo2N-phase with a mixture of crystallographic orientations (111), (200), (220) and (311) together with the B1NaCl-structured (TiZrNbTaHf)N solid-solution phase. First-principles calculations demonstrated that the metal sub-lattice of the (TiZrNbTaHf)N solid solution can be based on Ti1-xHfyTa1-x-y, Zr1-xHfyTa1-x-y, Zr0.25Ti0.25Ta0.5 ternary alloys, which have the lowest mixing energy. The HR-TEM results showed that the nanocomposite nitride coatings have nano-scale multilayer structure with modulation periods ranged from 20nm to 25nm. The maximum hardness of approximately 29GPa demonstrated the coating deposited at a higher energy condition (−200V) with the thinnest modulation period of bilayer of 20nm (15nm of (TiZrNbTaHf)N and 5nm of Mo2N).Item Multilayer design of CrN/MoN protective coatings for enhanced hardness and toughness(Elsevier, 2017) Постольний, Богдан Олександрович; Постольный, Богдан Александрович; Postolnyi, Bohdan Oleksandrovych; Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Бондар, Олександр В`ячеславович; Бондарь, Александр Вячеславович; Bondar, Oleksandr Viacheslavovych; Beresnev, V.M.; Abadias, G.; Rebouta, L.; Araujo, J.P.We report on CrN/MoN multilayer coatings, their structure, elemental and phase composition, residual stresses, mechanical properties and their dependence on deposition conditions. The hardness and toughness were considered as main parameters for improvement of the protective properties of coatings. Multilayers with varying bilayer periods, ranging from 40 nm to 2.2 μm, were obtained by using cathodic arc physical vapour deposition (Arc-PVD) on stainless steel substrate. The elemental analysis was performed using wavelength-dispersive X-ray spectroscopy (WDS). The surface morphology and cross-sections were analysed with scanning electron microscopy (SEM). The X-ray diffraction (XRD) measurements, including grazing incidence X-ray diffraction (GIXRD), in-plane diffraction analysis and electron backscatter diffraction (EBSD), were used for microstructure characterisation. Mechanical properties of deposited films were studied by measuring hardness (H) and Young's modulus (E) with micro-indentation, H/E and H3/E2 ratios were calculated. The dependences of internal structure and, hence, mechanical properties, on layer thickness of films have been found. Significant enhancement of hardness and toughness was observed with decreasing individual layer thickness to 20 nm: H = 38–42 GPa, H/E = 0.11.Item Nanocomposite Nb-Al-N coatings: Experimental and theoretical principles of phase transformations(Elsevier, 2017) Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Рогоз, Владислав Миколайович; Рогоз, Владислав Николаевич; Rohoz, Vladyslav Mykolaiovych; Бондар, Олександр В`ячеславович; Бондарь, Александр Вячеславович; Bondar, Oleksandr Viacheslavovych; Ivashchenko, V.I.; Shevchenko, V.; Jurga, S.; Coy, E.Phase transformations of Al doped NbN nanocomposite coatings are studied in detail focusing on their microstructural evolution and phase composition. Several techniques such as XRD, SEM, HR-TEM, Nanoindentation and molecular dynamics simulation are employed in order to understand the phase evolution of the Nb-Al-N system. The nanocomposite structures were formed in the coatings, the roughness of the coatings decreased with increasing the Al concentration due to decreasing grain size. First-principles investigation of Nb-Al-N solid solutions was carried out to interpret film properties. It was found, that for small Al fractions, the solid solutions will form in agreement with our experimental results. The spinodal decomposition of Nb-Al-N solid solutions is supposed to be responsible for the formation of the nanocomosite structure observed in the deposited Nb-Al-N films.Item Irradiation resistance, microstructure and mechanical properties of nanostructured (TiZrHfVNbTa)N coatings(Elsevier, 2016) Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Yakushchenko, I.V.; Beresnev, V.M.; Oyoshi, K.; Ivasishin, O.M.; Amekura, H.; Takeda, Y.; Opielak, M.; Kozak, C.; Бондар, Олександр В`ячеславович; Бондарь, Александр Вячеславович; Bondar, Oleksandr ViacheslavovychNitrides of high-entropy alloys (TiHfZrNbVTa)N were fabricated using cathodic-vacuum-arc-vapor deposition method. Morphology and topology of the surface of the coatings, roughness, elemental and phase composition, microstructure and mechanical properties were investigated. Dependence of deposition parameters on surface morphology and elemental composition was demonstrated. Influence of the heavy negative charged Au ions implantation on phase structure, microstructure and hardness of nitride (TiHfZrNbVTa)N coatings was investigated.Item Structural and mechanical properties of NbN and Nb-Si-N films: Experiment and molecular dynamics simulations(Elsevier, 2016) Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Бондар, Олександр В`ячеславович; Бондарь, Александр Вячеславович; Bondar, Oleksandr Viacheslavovych; Abadias, G.; Ivashchenko, V.; Sobol, O.; Jurga, S.; Coy, E.The structural and mechanical properties of NbN and Nb-Si-N films have been investigated both experimentally and theoretically, in their as-deposited and annealed states. The films were deposited using magnetron sputtering at substrate bias (UB) between 0 and 70 V. While NbN films were found to crystallize in the cubic δ-NbN structure, Nb-Si-N films with Si content of 11–13 at% consisted of a twophases nanocomposite structure where δ-NbN nanocrystals were embedded in SiNx amorphous matrix. Films deposited at UB¼0 V were highly (001)-textured. Application of substrate bias potential led to a depletion of light atoms, and caused a grain size refinement concomitantly with the increase of (111) preferred orientations in both films. The maximum hardness was 28 GPa and 32 GPa for NbN and Nb-SiN films, respectively. NbN and Nb-Si-N films deposited at UB¼ 70 V exhibited compressive stress of 3 and 4 GPa, respectively. After vacuum annealing, a decrease in the stress-free lattice parameter was observed for both films, and attributed to alteration of film composition. To obtain insights on interface properties and related mechanical and thermal stability of Nb-Si-N nanocomposite films, first principles molecular dynamics simulations of NbN/SiNx heterostructures with different structures (cubic and hexagonal) and atomic configurations were carried out. All the hexagonal heterostructures were found to be dynamically stable and weakly dependent on temperature. Calculation of the tensile strain-stress curves showed that the values of ideal tensile strength for the δ-NbN(111)- and ε-NbN(001)-based heterostructures with coherent interfaces and Si3N4–like Si2N3 interfaces were the highest with values in the range 36–65 GPa, but lower than corresponding values of bulk NbN compound. This suggests that hardness enhancement is likely due to inhibition of dislocation glide at the grain boundary rather than interfacial strengthening due to Si-N chemical bondingItem Structural and Mechanical Properties of Nanocomposite Nb-Al-N Films(Sumy State University, 2014) Ivashchenko, V.I; Skrynskyy, P.L.; Kozak, A.O; Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Timofeyeva, I.I.; Dub, S.N.Nb-Al-N films were deposited by magnetron sputtering of the Nb and Al targets in the Ar-N2 atmosphere on silicon wafers at various currents supplied to the magnetron device with the Al target (IAl=100, 150, 200, 300 mA). The films were studied with XRD, FTIR spectroscopy, as well by nanoindentation and Knoop indentation tests. The films were found to have the nanocomposite nc-B1-NbNx/a-AlN structure and exhibit the nanohardness and Knoop hardness in the ranges of 29-33.5 GPa and 46-48 GPa, respectively. The hardness and elastic modulus has an extreme dependence on IAl.