Факультет електроніки та інформаційних технологій (ЕлІТ)
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Item The cathodic electrolytic plasma hardening of the 20Cr2Ni4A chromium-nickel steel(Elsevier, 2020) Rakhadilov, B.K.; Буранич, Володимир Володимирович; Буранич, Владимир Владимирович; Buranych, Volodymyr Volodymyrovych; Satbayeva, Z.A.; Sagdoldina, Z.B.; Kozhanova, R.S.; Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr DmytrovychIn order to obtain the modified surface structure of the 20Cr2Ni4A steel plasma electrolytic hardening (PEH) method was used. The surface hardening process was conducted in the aqueous electrolyte solution of 20% sodium carbonate and 20% urea. The sample consists of a ferritic-pearlitic structure, i.e. the part retains its viscous core, and the surface layer contains carbide particles. Hardening process induces martensite transformation and creation of carbide particles in the surface layer. The presence of carbide particles in the surface layers has a positive effect on the tribo-mechanical performance. Hardened structure 600 m long was obtained with hardness increase up to 520 HV and 2.5 times higher wear resistance. Tribological test results showed the difference of the coefficient of friction as a function of surface roughness determined by plasma-electrolytic hardening process.Item Effect of the PEN/C surface layer modification on the microstructure, mechanical and tribological properties of the 30CrMnSiA mild-carbon steel(Elsevier, 2020) Zhurerova, L.G.; Rakhadilov, B.K.; Popova, N.A.; Kylyshkanov, M.K.; Буранич, Володимир Володимирович; Буранич, Владимир Владимирович; Buranych, Volodymyr Volodymyrovych; Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr DmytrovychAs a result of plasma-electrolytic nitrocarburizing 30CrMnSiA carbon steel (ferrite-perlite grade), there was a change in the elemental and phase composition, as well as the surface layer microstructure (40 ÷ 45 microns thick from the surface). A formation of Me23(CN)6 carbonitrides, FeN nitrides, Fe3C - (Fe, Cr)3C carbides and an increase in dislocation density within –phase (tempered martensite crystallites), high-temperature lamellar martensite were observed. As a result of PEN / C exposure for 7min. At 750 ◦C there is a reduction of friction coefficient and wear rate, what is connected with finely dispersed secondary phases FeN, (Fe, Cr)3C, Me23(C, N)6 formation. Thus, there is an 2,5 ÷ 3,3 times increase in hardness of 30CrMnSiA carbon steel samples.Item Multilayered vacuum-arc nanocomposite TiN/ZrN coatings before and after annealing: Structure, properties, first-principles calculations(Elsevier, 2017) Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Бондар, Олександр В`ячеславович; Бондарь, Александр Вячеславович; Bondar, Oleksandr Viacheslavovych; Постольний, Богдан Олександрович; Постольный, Богдан Александрович; Postolnyi, Bohdan Oleksandrovych; Ivashchenko, V.I.; Beresnev, V.M.; Sobol, O.; Załęski, K.; Jurga, S.; Coy, E.; Konarski, P.Nanoscale multilayered TiN/ZrN films were deposited using sequential vacuum-arc deposition of Ti and Zr targets in a nitrogen atmosphere. Studies of film's properties were carried out using various modern methods of analysis, such as XRD, STEM, HRTEM, SIMS combined with results of nanoindentation and tribological tests. To interpret the mechanical properties of the deposited multilayer films first-principles calculations of TiN(111), ZrN(111) structures and TiN(111)/ZrN(111) multilayer were carried out. To study the influence of thermal annealing, several samples were annealed in air at the temperature 700 °C. All deposited samples were highly polycrystalline with quite large 20–25 nm crystals. The crystalline planes were very ordinated and demonstrated an excellent coordinated growth. The nanohardness and elastic modulus of non-annealed coatings reached 42 GPa and 348 GPa, respectively. Annealing in air at the temperature 700 °C led to partial oxidation of the multilayered coatings, however hardness of the non-oxidized part of the coatings remained as high, as for initial coatings. All deposited coatings demonstrate good wear resistance.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 Structure and properties of arc evaporated nanoscale TiN/MoN multilayered systems(Elsevier, 2015) Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Eyidi, D.; Abadias, G.; Beresnev, V.M.; Бондар, Олександр В`ячеславович; Бондарь, Александр Вячеславович; Bondar, Oleksandr Viacheslavovych; Sobol, O.V.Using vacuum-arc evaporation method we fabricated periodic multilayered TiN/MoN structures with different bilayer periods λ ranging from 25 to 100 nm. Rutherford backscattering (RBS), X-ray diffraction (XRD), scanning electron microscopy (SEM) as well as transmission electron microscopy (TEM) and microhardness measurements were used for investigations of composition, structure and mechanical properties of the multilayered coatings. We found that molybdenum nitride and titanium nitride layers grown on steel show local partial epitaxy and columnar growth across interfaces. A molybdenum–titanium carbide interlayer was evidenced between the substrate and the multilayer. Molybdenum nitride and titanium nitride layers contain small (5–30 nm) grains and are well crystallized with (100) preferred orientation. They were identified as stoichiometric fcc TiN and cubic γ-Mo2N. Non-cubic molybdenum nitride phases were also detected. The hardness of the obtained structures achieved great values and maximal hardness was 29–31 GPa for multilayered structure with 50 nm period. Hardness of the obtained coatings is 25% higher in comparison with initial single-layer nitride coatings, wherein plasticity index (H/E) of multilayered structure is 0.075.Item Obtaining of TiN/MoN Nanocomposite Coatings and Their Research(Sumy State University, 2013) Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Бондар, Олександр В`ячеславович; Бондарь, Александр Вячеславович; Bondar, Oleksandr Viacheslavovych; Постольний, Богдан Олександрович; Постольный, Богдан Александрович; Postolnyi, Bohdan Oleksandrovych; Abadias, G.; Andreev, A.A.; Beresnev, V.M.; Chartier, P.; Sobol, O.V.; Maksakova, O.At the nanometer scale multilayer nanostructured coatings show special properties due to the depositions conditions. This paper presents results of TiN/MoN nanocomposites obtaining and their research. Multilayer coatings based on TiN/MoN were deposited using vacuum arc evaporation cathode method (CPVD). Total thickness range of obtained coatings was 2, 10, 20 and 40 nm. We used vacuum-arc device “Bulat-6” for coatings deposition. Structure and properties of multilayer coatings were analyzed using XRD (Bruker D-8 Advance) in Cu-Kα radiation, high resolution transmission electron microscopy (HRTEM system) with diffraction CFEI EO Techai F200, SEM with EDX (JEOL-7001F). Scratch tests were carried out using Rockwell-C diamond indenter (CSM Revetest Instruments) with a tip radius of 200 μm. Besides this, ball-on-plate sliding test on UMT-3MT tribometer (CETR, USA) was used for additional investigation of friction and wear. This research allowed to reveal structural and properties depending on deposition conditions of TiN/MoN multilayer coatings. The nanocomposite hardness value increases when monolayer thickness decreases. This also reduced nanograins size. Measurement of the friction coefficient demonstrates smaller values for multilayer system in comparison with TiN or MoN nanostructured coatings. Formation of a (Ti, Mo)N solid solution and nanocrystals growing were observed during annealing. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35415