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Item Microstructure, Mechanical and Tribological Properties of Advanced Layered WN/MeN (Me = Zr, Cr, Mo, Nb) Nanocomposite Coatings(MDPI, 2022) Смирнова, Катерина Василівна; Смирнова, Екатерина Васильевна; Smyrnova, Kateryna Vasylivna; Sahul, M.; Harsani, M.; Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Ivashchenko, V.; Beresnev, V.; Stolbovoy, V.; Caplovic, L.; Caplovicova, M.; Vanco, L.; Kusy, M.; Kassymbaev, A.; Satrapinskyy, L.; Flock, D.Due to the increased demands for drilling and cutting tools working at extreme machining conditions, protective coatings are extensively utilized to prolong the tool life and eliminate the need for lubricants. The present work reports on the effect of a second MeN (Me = Zr, Cr, Mo, Nb) layer in WN-based nanocomposite multilayers on microstructure, phase composition, and mechanical and tribological properties. The WN/MoN multilayers have not been studied yet, and cathodic-arc physical vapor deposition (CA-PVD) has been used to fabricate studied coating systems for the first time. Moreover, first-principles calculations were performed to gain more insight into the properties of deposited multilayers. Two types of coating microstructure with different kinds of lattices were observed: (i) face-centered cubic (fcc) on fcc-W2N (WN/CrN and WN/ZrN) and (ii) a combination of hexagonal and fcc on fcc-W2N (WN/MoN and WN/NbN). Among the four studied systems, the WN/NbN had superior properties: the lowest specific wear rate (1.7 × 10−6 mm3/Nm) and high hardness (36 GPa) and plasticity index H/E (0.93). Low surface roughness, high elastic strain to failure, Nb2O5 and WO3 tribofilms forming during sliding, ductile behavior of NbN, and nanocomposite structure contributed to high tribological performance. The results indicated the suitability of WN/NbN as a protective coating operating in challenging conditions.Item Electric-Spark Alloying of Metal Surfaces with Graphite(G. V. Kurdyumov Institute for Metal Physics of the N.A.S. of Ukraine, 2022) Tarelnyk, V. B.; Гапонова, Оксана Петрівна; Гапонова, Оксана Петровна; Haponova, Oksana Petrivna; Konoplianchenko, Ye.V.The article reviews and analyses the current scientific research in the field of surface treatment of metal surfaces with concentrated energy fluxes (CEF) — the electric-spark (in the literature, known also as electrospark) alloying (ESA), which makes it possible to obtain surface structures with unique physical, mechanical and tribological properties at the nanoscale. The ESA method with a graphite electrode (electrospark carburizing — EC) is based on the process of diffusion (saturation of the surface layer of a part with carbon), and it is not accompanied by an increase in the size of the part. In this article, the influence of the EC parameters on the quality of the carburized layer is investigated. The microstructural analysis shows that the three characteristic zones could be distinguished in the structure: the carburized (‘white’) layer, the finely dispersed transition zone with fine grain, and the base metal zone. The analysis of the results of the durometric studies of the coatings is carried out. To achieve the required parameters of dimensional accuracy and roughness of the working surface of the part after the EC process, it is necessary to use the method of non-abrasive ultrasonic finishing (NAUF). In addition, because of applying the NAUF method, the surface roughness is decreased, the tensile stresses are changed to the compressive ones, and the fatigue strength is increased too. In addition, to reduce the roughness of the treated surface, it is proposed to apply the EC technology in stages, reducing the energy of the spark discharge at each subsequent stage. In order to increase the quality of the carburized layer obtained by the EC process, it is proposed to use a graphite powder, which is applied to the treated surface before alloying. The comparative analysis shows that, after the traditional EC process at Wp = 4.6 J, the surface roughness of steel 20 is Ra = 8.3–9.0 μm, and after the proposed technology, Ra = 3.2–4.8 μm. In this case, the continuity of the alloyed layer increases up to 100%; there increases the depth of the diffusion zone of carbon up to 80 μm as well as the microhardness of the ‘white’ layer and its thickness, which increase up to 9932 MPa and up to 230 μm, respectively. The local micro-x-ray spectral analysis of the obtained coatings shows that, at the EC process carried out in a traditional way, the applying Wp = 0.9, 2.6, 4.6 J provides the formation of the surface layers with high-carbon content depths of 70, 100, 120 μm, respectively, and with the use of a graphite powder, they are of 80, 120, 170 μm. While deepening, the amount of carbon is decreasing from 0.72–0.86% to the carbon content in the base metal — 0.17–0.24%. In the near-surface layer formed with the use of the new technology, the pores are filled with free graphite, which could be used as a solid lubricant to improve the operating characteristics of the friction-pairs parts processed thereby.Item Microstructure and tribological properties of nitride coatings based on Zr, Ti, Cr, Nb, and Si elements(Beggel House, 2017) Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Багдасарян, Артем Анатолійович; Багдасарян, Артем Анатольевич; Bahdasarian, Artem Anatoliiovych; Beresnev, V.M.; Kupchishin, A.I.; Plotnikov, S.V.; Кравченко, Ярослав Олегович; Кравченко, Ярослав Олегович; Kravchenko, Yaroslav OlehovychThe structure and tribological properties of the nitride coatings (Zr–Ti–Nb)N, (Zr–Ti–Cr–Nb)N, and (Zr–Ti-Cr–Nb–Si)N, f abricated by vacuum arc deposition have been investigated. Their ele- mental composition and crystal structure are characterized by EDS and SEM analyses, XPS, and X-ray diffraction. The multicomponent (Zr–Ti–Cr–Nb–Si)N and (Zr–Ti–Nb)N coatings are f ound to be a simple f ace-centered cubic (f cc) solid solution. For the coatings without Si, the struc- ture is mainly composed of the TiN f cc phase and Cr2N trigonal modification. The (Zr–Ti–Nb)N and (Zr–Ti–Cr–Nb)N coatings provided the best adhesive strength in different conditions. The (Zr–Ti–Cr–Nb–Si)N coatings exhibited the worst adhesive strength, which may be attributed to the relative low hardness.Item Effect of Alloying Oxides Y2O3 and ZrO2 on the Microstructure of Austenitic Steel 18Cr10NiTi(Sumy State University, 2015) Voyevodin, V.N.; Velikodniy, A.N.; Tikhonovskiy, M.A.; Kalchenko, A.S.; Starostenko, S.V.; Danilenko, N.I.Nanomaterials are materials of new generation with unique characteristics which are not characteristic for other materials. Nanofilms, nanoprocessors, nanorobots – the more well known technologies, but demands of modern industry, electronic industry, power industry dictate the development of nanomaterials in higher scales. The use of nanomaterials is very promising direction in nuclear power. Conditions of operation of structural materials in nuclear reactors, namely, high temperature (higher 300°C for thermal reactors and higher 600°C for fast reactors) which together with high density of neutrons (~1021-1022 neutrons/cm-2) cause the degradation of initial physical-chemical characteristics and the significant dimension changes. These factors influence considerably on safe and long-term operation period of reactor.Item Cold-spray technique as efficient alternative process for consolidation of powdered Al-Fe-Cr alloys reinforced by nanoquasicrystalline particles(Sumy State University, 2011) Byakova, A.V.; Yurkova, A.I.; Cherednichenko, V.V.; Sirko, A.I.A brief outline of the processing parameters involved in the search for technique offering efficient consolidation of high-temperature strength Al-based powdered alloys reinforced by metastable nanoquasicrystalline particles is presented. Feedstock powder of Al94Fe3Cr3 alloy was employed in experiments. Superior advantages of the coldspraying as alternative solid-state process for consolidation and structural performance of quasicrystalline alloys by plastic deformation is discussed in comparison with that resulted from currently employed hot extrusion put into practice at the 623 K. As opposed to extrusion assisted by unidirectional deformation, adiabatic shear instability is primary responsible for creating the mostly effective intimate metallic bonding between the adjacent Al-powder particles under cold spraying when the temperature was even well below melting point, i.e. 473 K. The main benefit of cold-spraying is that the composite quasicrystalline structure in the interior of heavily deformed particles was believed to be actually the same as that of feedstock powder while warm extrusion results in the decrease by 23% fraction volume of metastable quasicrystalline particles, shifting their decomposition to the lower temperatures. Advantage of cold-sprayed Al94Fe3Cr3 alloy concerns excellent balance between high ductility (plasticity characteristic H 0.9) and high strength that superior roughly about 35% to that of as-extruded composite. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20578