Факультет електроніки та інформаційних технологій (ЕлІТ)
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Item Phase transformations during the doping of zinc chloride and silver nitrate into calcium phosphates(Karagandy University of the name of academician E.A. Buketov, 2022) Sagidugumar, A.N.; Turlybekuly, A.; Dogadkin, D.; Погребняк, Олександр Дмитрович; Pohrebniak, Oleksandr Dmytrovych; Kantay, N.; Sadibekov, A.This article shows the results of a study on a biocomposite material based on calcium phosphate doped with ZnCl and AgNO3. Calcium phosphates are mainly used in dentistry and orthopedics due to their excellent bi-ocompatibility, osteoconductive properties and similarity to the inorganic components of human bone. The main objective of the study is to investigate the morphology, elemental and phase composition, and physico-chemical properties of the obtained material. The test material is obtained in the form of a suspension and subjected to ultrasonic treatment. The microstructure and phase composition of the obtained biocomposites are studied by SEM, XRD, FTIR methods. It is possible to obtain dicalcium phosphate dihydrate (DCPD) by the presented methods, and the results demonstrate a partial replacement of calcium atoms by zinc atoms. X-ray phase analysis shows that Ca(HPO4) (H2O)2 phases as well as CaZn2 (PO4)2(H2O)2 and AgCl phases were formed during the reaction. Fourier transform infrared spectroscopy revealed that the obtained samples con-tain the groups HPO42 and PO43, with the group PO42 replacing the group CO32. The biocomposite materials could be of great interest in the biomedical field, including the development of coatings that prevent or delay the development of bacterial biofilm.Item Effect of Bilayer Thickness and Bias Potential on the Structure and Properties of (TiZr/Nb)N Multilayer Coatings as a Result(MDPI, 2022) Rakhadilov, B.; Погребняк, Олександр Дмитрович; Pohrebniak, Oleksandr Dmytrovych; Sagdoldina, Z.; Buitkenov, D.; Beresnev, V.; Mukhamedova, A.This work is devoted to the study of the formation of nanostructured multilayer coatings (TiZr/Nb)N on the surface of an AISI 321 steel substrate depending on the deposition parameters of the Arc-PVD method. The results of the X-ray diffraction analysis showed the formation of solid solution (TiNb)N and ZrN in the multilayer coatings with an FCC structure, "-NbN with a hexagonal structure, as well as with a small volume fraction of the "-Ti2N and -Nb2N phase. On the basis of phase composition data, it is possible to assume that an increase in the number of bilayers leads to a decrease in the nitrogen concentration in the bilayers and, consequently, to a decrease in the volume fraction of "-NbN and -Nb2N nitrides. In all investigated systems obtained at 100 V and 200 V bias potentials, "-NbN is the main phase. The study of the element distribution over the thickness of the (TiZr/Nb)N coating confirms the results of the X-ray diffraction analysis. The use of the structure model in the form of alternating layers allows for significantly improving the adhesion characteristics of the protective coating, as well as ensuring their high hardness. Based on the experimental results, it is possible to analyze changes in the mechanical and tribological properties of multilayer coatings depending on the number of applied bilayers. The results of the study of the elastic modulus and hardness of multilayer coatings (TiZrNb)N with different numbers of bilayers showed that a large number of bilayers (small thickness of each individual layer) shows the lowest value of hardness. It is assumed that as the bilayer thickness decreases, the coating characteristics are closer to the monolayer alloy than to the multilayer structure.Item Advanced “Green” Prebiotic Composite of Bacterial Cellulose/Pullulan Based on Synthetic Biology-Powered Microbial Coculture Strategy(MDPI, 2022) Zhantlessova, S.; Savitskaya, I.; Kistaubayeva, A.; Ignatova, L.; Talipova, A.; Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Digel, I.Bacterial cellulose (BC) is a biopolymer produced by different microorganisms, but in biotechnological practice, Komagataeibacter xylinus is used. The micro- and nanofibrillar structure of BC, which forms many different-sized pores, creates prerequisites for the introduction of other polymers into it, including those synthesized by other microorganisms. The study aims to develop a cocultivation system of BC and prebiotic producers to obtain BC-based composite material with prebiotic activity. In this study, pullulan (PUL) was found to stimulate the growth of the probiotic strain Lactobacillus rhamnosus GG better than the other microbial polysaccharides gellan and xanthan. BC/PUL biocomposite with prebiotic properties was obtained by cocultivation of Komagataeibacter xylinus and Aureobasidium pullulans, BC and PUL producers respectively, on molasses medium. The inclusion of PUL in BC is proved gravimetrically by scanning electron microscopy and by Fourier transformed infrared spectroscopy. Cocultivation demonstrated a composite effect on the aggregation and binding of BC fibers, which led to a significant improvement in mechanical properties. The developed approach for “grafting” of prebiotic activity on BC allows preparation of environmentally friendly composites of better quality.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 DC and AC Tests of Moisture Electrical Pressboard Impregnated with Mineral Oil or Synthetic Ester—Determination of Water Status in Power Transformer Insulation(MDPI, 2022) Zukowski, P.; Rogalski, P.; Kołtunowicz, T.N.; Kierczynski, K.; Zenker, M.; Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Kucera, M.In this study, the conductivity and permittivity of electrical pressboard—insulating liquid—water composites were investigated, and the electrical properties of the composites and water were analysed comparatively. Mineral oil and synthetic ester were used as insulating liquids. It was found that the presence of water caused an increase in the permeability of the composite in the frequency range below 100 Hz. The value of static permittivity determined by water in the content of 5 wt. % was approximately 15. To obtain this value caused by liquid water, its volume should be approximately five (oil) and four times (ester) higher than its actual content, respectively. The determined values of the activation energy of the DC conductivity of the composites were several times higher than the values of the activation energy of the conductivity of the liquid water. The experimental values of the dielectric relaxation times were many orders of magnitude higher than the dielectric relaxation times of water. This means that the experimental results obtained for the dielectric permittivity, the activation energy of conductivity and the dielectric relaxation times for moisture electrical pressboard impregnated by mineral oil or synthetic ester exclude the possibility of the presence of liquid water in the composites. It was found that the conductivity of the composites increased exponentially with increasing water content. Such dependencies are characteristic of hopping conductivity, caused by the quantum phenomenon of electron tunnelling between nanometre-sized potential wells. As the increase in conductivity is determined by the presence of water in the composites, therefore, the nanometre potential wells were single-water molecules or nanodrops.Item Investigation of AC Electrical Properties of MXene-PCL Nanocomposites for Application in Small and Medium Power Generation(Centre of Sociological Research in co-operation with University of Szczecin (Poland); Széchenyi István University (Hungary); Mykolas Romeris University (Lithuania); Dubcek University of Trencín, Faculty of Social and Economic Relations (Slovak Republic), 2021) Kołtunowicz, T.N.; Gałaszkiewicz, P.; Kierczyński, K.; Rogalsk, P.; Okal, P.; Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Буранич, Володимир Володимирович; Буранич, Владимир Владимирович; Buranych, Volodymyr Volodymyrovych; Погорєлов, Максим Володимирович; Погорелов, Максим Владимирович; Pohorielov, Maksym Volodymyrovych; Дєдкова, Катерина Андріївна; Дедкова, Екатерина Андреевна; Diedkova, Kateryna Andriivna; Zahorodna, V.; Balitskyi, V.; Serhiienko, V.; Baginskyi, I.; Gogotsi, O.The paper examined Ti3C2Tx MXene (T—OH, Cl or F), which is prepared by etching a layered ternary carbide Ti3AlC2 (312 MAX-phase) precursor and deposited on a polycaprolactone (PCL) electrospun membrane (MXene-PCL nanocomposite). X-ray Diffraction analysis (XRD) and Scanning Electron Microscopy (SEM) indicates that the obtained material is pure Ti3C2 MXene. SEM of the PCL-MXene composite demonstrate random Ti3C2 distribution over the nanoporous membrane. Results of capacitance, inductance, and phase shift angle studies of the MXene-PCL nanocomposite are presented. It was found that the frequency dependence of the capacitance exhibited a clear sharp minima in the frequency range of 50 Hz to over 104 Hz. The frequency dependence of the inductance shows sharp maxima, the position of which exactly coincides with the position of the minima for the capacitance, which indicates the occurrence of parallel resonances. Current conduction occurs by electron tunneling between nanoparticles. In the frequency range from about 104 Hz to about 105 Hz, there is a broad minimum on the inductance relationship. The position of this minimum coincides exactly with the position of the maximum of the phase shift angle—its amplitude is close to 90°. The real value of the inductance of the nanocomposite layer was determined to be about 1 H. It was found that the average value of the distance over which the electron tunnels was determined with some approximation to be about 5.7 nm and the expected value of the relaxation time to be τM ≈ 3 × 10−5 s.Item Multilayer and high-entropy alloy-based protective coatings for solving the issue of critical raw materials in the aerospace industry(IOP Publishing, 2021) Постольний, Богдан Олександрович; Постольный, Богдан Александрович; Postolnyi, Bohdan Oleksandrovych; Буранич, Володимир Володимирович; Буранич, Владимир Владимирович; Buranych, Volodymyr Volodymyrovych; Смирнова, Катерина Василівна; Смирнова, Екатерина Васильевна; Smyrnova, Kateryna Vasylivna; Araujo, J.P.; Rebouta, L.; Погребняк, Олександр Дмитрович; Погребняк, Александр Дмитриевич; Pohrebniak, Oleksandr Dmytrovych; Рогоз, Владислав Миколайович; Рогоз, Владислав Николаевич; Rohoz, Vladyslav MykolaiovychAerospace is an actively developing industry that continuously requires the implementation of modern technologies. The rapid growth in new vehicle production demands much support. Hence, the problem of resources with complicated supply and distribution is always of current interest. These critical raw materials (CRMs) are involved in almost all areas of aerospace manufacturing and service. An efficient and profitable solution to the problem of critical materials can be found in protective coatings, especially in such advanced concepts as multilayer and high-entropy alloy (HEA)-based coatings. In this paper, we study both ways of manufacturing effective coatings. We have shown that multilayer CrN/MoN coatings with exceptional toughness and hardness could find promising applications in the aerospace industry. The developed strategy for the novel materials screening based on the prediction of their properties has been demonstrated on the example of the refractory HEA-based coatings. A brief state of the art of the EU critical raw materials and their place in the aerospace/defence industry has been given.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.