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Öğe A COMPARATIVE STUDY ABOUT PRODUCTION OF VANADIUM CARBIDE VIA SELF PROPAGATING HIGH TEMPERATURE SYNTHESIS AND REDUCTION(Polska Akad Nauk, Polish Acad Sciences, Inst Metall & Mater Sci Pas, 2024) Bugdayci, Mehmet; Oncel, Levent; Alkan, Murat; Turan, Ahmet; Cinarli, UmayVanadium carbide is important for industrial applications because of its high hardness, high temperature resistance, high chemical, and thermal stability. It is generally obtained from the reaction between V and C powders at a high temperature ranging from 1100 to 1500 degrees C. Investigations on these high strength, high abrasion resistant, hard materials have been intensified in recent years and consequently, significant improvements have been achieved. In this study, VC alloys are produced with low cost processes, by reducing the oxides of their components by SHS methods and ball mill-assisted carbothermal reduction. In the experimental stage, V2O5 was used as oxidized Vanadium source, Cblack as carbon source, magnesium and Cblack as reductant. In the study, VC powders were synthesized by two different methods and optimum production conditions were determined. Furthermore, the effect of different stoichiometric charge components and the effect of experiment durations were realized by X-ray diffraction, HSC Chemistry, and SEM analyses for different reductants.Öğe Advances in Combustion Synthesis and Technology(Bentham Science Publishers, 2022) Bugdayci, Mehmet; Oncel, LeventThis reference is an accessible update on combustion synthesis and the chemical technology for synthesizing composite materials. Nine chapters offer an overview of the subject with recent references, giving the reader an informed perspective. The book starts with an introduction to thermodynamic models used in combustion synthesis. Subsequent chapters explain the application of combustion synthesis to manufacture different materials such as nanostructured non-ferrous alloys, ceramic powders, functionally graded materials, boron carbide-based superhard materials, shape memory alloys, biomaterials, high-entropy alloys and rare earth phosphates. The range of topics makes this book a useful guide for students, scientists and industrial professionals in the field of chemical engineering, metallurgy and materials science. © 2022, Bentham Books imprint.Öğe Biodegradable Implant Materials(wiley, 2022) Oncel, Levent; Bugdayci, MehmetImplants are medical devices that have critical importance for human health. The functions expected from implant materials have increased with the advancement of medicine and engineering. Implants are used for different purposes in different areas of the body. While some implants must be permanent in the body to fulfill their duties, some implants must be removed from the implanted area after a certain period. If an implant is to be removed from the relevant area after a certain period, an operation is required for this and then, there will be a healing process. The use of biodegradable implant materials eliminates the need for this additional operation. Biodegradable materials leave their place to the tissue gradually in a certain period. Biodegradable implant materials are one of the popular research areas today and many studies are carried out in this field every year. In this chapter, information about implants, biomaterials, biodegradability concept, biodegradable metals, and biodegradable polymers is shared. Also, examples of the use of biodegradable materials in biomedical applications are included. © 2022 Scrivener Publishing LLC.Öğe Carbon Materials for Nanogenerators(CRC Press, 2022) Bugdayci, Mehmet; Oncel, Levent[No abstract available]Öğe Construction of a novel NiO-bentonite composite for enhanced tetracycline degradation under visible light irradiation(Springer, 2026) Oncel, LeventIn this study, a novel ceramic composite based on NiO and bentonite (NiO/BEN) was successfully synthesized via the hydrothermal method for the effective photocatalytic degradation of tetracycline (TC) in aqueous solutions. The synthesized composites were characterized using XRD, SEM/EDS, UV-Vis DRS, PL, XPS, BET, and FTIR techniques. The analyses revealed that NiO and bentonite formed a well-integrated heterostructure, and NiO/BEN had absorption in both the UV and visible light regions, with stronger absorption in the UV region. BET analysis confirmed a mesoporous structure with a specific surface area of 9.66 m(2)/g, considerably higher than those typically reported for pristine NiO, indicating improved accessibility of active sites. FTIR spectra exhibited characteristic peaks at 1042.8, 1012.9, 790.05, and 466.33 cm(-)(1), confirming the coexistence of NiO and bentonite phases with preserved structural integrity. The composite had a band gap of 4.05 eV, which effectively promoted electron-hole pair generation, while the shallow and deep defects in the structure facilitated efficient charge separation. In photocatalytic degradation experiments, NiO-bentonite composite showed much better performance compared to pristine NiO (19.51%), while increasing the NiO: bentonite ratio from 1:0.2 (52.41%) to 1:0.5 (85.58%) significantly enhanced the tetracycline removal efficiency after 120 min of visible-light irradiation at neutral pH. The composite also exhibited strong photocatalytic activity across different water matrices, achieving 85.58% removal in distilled water and maintaining appreciable efficiencies of 69.52% in tap water and 70.67% in drinking water, where competing ions and dissolved organics are present. Reusability tests showed a gradual decline in efficiency from 85.58% in the first cycle to 69.09%, 50.65%, 39.34%, and 24.34% over five consecutive cycles, likely due to the accumulation of non-degradable by-products on active sites. The degradation reaction was found to be driven primarily by photogenerated holes, with superoxide radicals also playing an important role. Under sole visible-light irradiation and without added oxidants, the NiO-bentonite composite removed 85.58% of tetracycline at neutral pH, 93.61% at pH 3, and 78.47% at pH 10-each value representing a more than fourfold improvement over pristine NiO (19.51%) and surpassing all NiO/clay systems reported to date-thereby offering an energy-efficient, environmentally friendly, and readily scalable photocatalyst for next-generation water-treatment technologies targeting antibiotic contamination.Öğe Production of Fe-B compounds via the self-propagating high-temperature synthesis technique(Redakcia Kovove Materialy, 2025) Bugdayci, Mehmet; Oncel, Levent; Benzesik, KaganThis study investigated the conditions for self-propagating high-temperature synthesis (SHS) of FeB. Hematite (Fe2O3) and magnetite (Fe3O4) powders were used as iron sources, and phases generated under varied aluminum stoichiometries were identified. The SHS reactions produced loose powder products. Significant levels of impurities were detected in both experimental sets along with the FeB compounds. XRD analysis of the SHS products revealed the presence of only Fe2B and MgO phases. Removal of Mg-based impurities was carried out through HCl leaching at different concentrations. The targeted FeB structure was obtained as intended in the experiments. Optimal conditions were identified as a reduction of the hematite-boron oxide mixture with 110 % stoichiometric Mg and subsequent leaching in 8 M HCl.Öğe Production of Shape Memory Alloys with Combustion Synthesis(Bentham Science Publishers, 2022) Oncel, LeventShape memory alloys(SMAs) have become an important class of materials following the discovery of the shape memory effect(SME) in nitinol in 1963. The important properties of these alloys have paved the way for their use in various applications. Combustion synthesis has become an important production method because of its advantages. The production of SMAs by combustion synthesis is a subject that has been studied in recent years. The use of porous nitinol produced by this method in artificial bone implants has become a particularly remarkable issue in this area. In this section, information about SMAs and combustion synthesis will be shared, and then information about the studies conducted on the production of SMAs by combustion synthesis will be shared. © 2022, Bentham Science Publishers.Öğe Thermodynamic modeling and production of FeCo alloy from mill scale through metallothermic reduction(Elsevier - Division Reed Elsevier India Pvt Ltd, 2020) Bugdayci, Mehmet; Deniz, Gul; Ziyreker, Ceren; Turan, Ahmet; Oncel, LeventMill scale is a waste material arises during the continuous casting of steel. It contains approximately 70% iron by mass. Mill scale is used as an iron source in many applications to reduce costs. In this study, it was aimed to produce FeCo alloy through the metallothermic reduction of mill scale and Co3O4. The metallothermic reduction was chosen because of its advantages such as minimum energy need, short process time and no need for high-tech equipment. The system was thermochemically simulated with FactSage and HSC software. In the experimental studies, the effects of the use of aluminium, as a reductant, in different stoichiometries on total metal recovery yield were investigated. The effects of aluminium stoichiometry on hardness and microstructure were also investigated. As a result of the experimental studies, it was seen that highest metal recovery yields were obtained as 81.25% for iron and 93.78% for cobalt with the mixture including 105% stoichiometric aluminium. (c) 2020 Karabuk University. Publishing services by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Öğe Thermodynamic modeling, metallothermic synthesis, and characterization of ferrotitanium(Walter De Gruyter Gmbh, 2025) Oncel, LeventFerrotitanium is widely used in alloying stainless steels to enhance their strength, corrosion resistance, and high-temperature resistance. Ferrotitanium's advantages over pure titanium - such as better solubility in the liquid steel bath and lower cost - have made it the preferred choice in stainless steel alloying. In this study, it was aimed to produce ferrotitanium alloy through the metallothermic reduction of Fe2O3 and TiO2. The system's thermodynamic modeling was performed using HSC Chemistry 6.12 and FactSage 7.1. The experimental studies investigated the effect of using aluminum as a reductant with varying stoichiometries on the total metal recovery yield, hardness, and microstructure. Atomic absorption spectrometry (AAS), optical microscopy, scanning electron microscopy (SEM), X-ray fluorescence spectrometry (XRF), and hardness measurement techniques were employed in characterization studies. The results of the experimental studies showed that the highest metal recovery yields were obtained with 105 % stoichiometric aluminum as 97.9 % for Fe and 100 % for Ti.Öğe Thermodynamic modelling and production of manganese boride compounds via self-propagating high temperature synthesis(Taylor & Francis Ltd, 2025) Oncel, Levent; Bugdayci, MehmetTransition metal borides are advanced materials with superior mechanical and thermal properties. Manganese borides combine high hardness with thermal stability and wear resistance, making them suitable for energy-storage parts, magnetic devices, and high-temperature service. In this study, Mn-B compounds were synthesised via self-propagating high-temperature synthesis (SHS) for the first time. The MnO-B2O3-Mg system was thermodynamically modelled in FactSage 7.1 to define the reaction conditions. Experiments were conducted using magnesium as the reductant at stoichiometries ranging from 100% to 115%. XRD showed MgO as the dominant phase at all levels; MgB2 appeared at 100% Mg, and MnB with Mn3B2O6 was present in every composition. Mg-based by-products appeared in all stoichiometries and were removed by acid leaching with 6 M HCl. After leaching, the primary phases were Mn2B, MnB, and MnB2, while boron-related peaks appeared only at 100% stoichiometry. Accordingly, the formation of manganese - boron compounds requires at least 105% Mg stoichiometry. SEM/EDS analysis of the leached sample confirmed the removal of Mg- and O-containing impurities. Since 110-115% offered no advantage but raised magnesium use, 105% was identified as the optimum stoichiometry. These findings confirm SHS as a viable route for producing manganese boride ceramics for advanced applications. Les borures de m & eacute;taux de transition sont des mat & eacute;riaux avanc & eacute;s aux propri & eacute;t & eacute;s m & eacute;caniques et thermiques sup & eacute;rieures. Les borures de mangan & egrave;se combinent une duret & eacute; & eacute;lev & eacute;e & agrave; une stabilit & eacute; thermique et une r & eacute;sistance & agrave; l'usure, ce qui les rend adapt & eacute;s aux pi & egrave;ces de stockage d'& eacute;nergie, aux dispositifs magn & eacute;tiques et aux applications & agrave; haute temp & eacute;rature. Dans cette & eacute;tude, on a synth & eacute;tis & eacute; des compos & eacute;s Mn-B par synth & egrave;se autopropag & eacute;e & agrave; haute temp & eacute;rature (SHS) pour la premi & egrave;re fois. On a mod & eacute;lis & eacute; thermodynamiquement le syst & egrave;me MnO-B2O3-Mg dans FactSage 7.1 afin de d & eacute;finir les conditions de r & eacute;action. On a effectu & eacute; des exp & eacute;riences en utilisant le magn & eacute;sium comme agent r & eacute;ducteur & agrave; des st oe chiom & eacute;tries allant de 100% & agrave; 115%. La DRX a montr & eacute; le MgO comme phase dominante & agrave; tous les niveaux; MgB2 apparaissait & agrave; 100% de Mg, et MnB avec Mn3B2O6 & eacute;tait pr & eacute;sent dans toutes les compositions. Des sous-produits & agrave; base de Mg apparaissaient dans toutes les st oe chiom & eacute;tries et & eacute;taient & eacute;limin & eacute;s par lixiviation acide avec du HCl 6 M. Apr & egrave;s lixiviation, les phases principales comprenaient Mn2B, MnB et MnB2, tandis que les pics associ & eacute;s au bore n'apparaissaient qu'& agrave; 100% de st oe chiom & eacute;trie. Par cons & eacute;quent, la formation de compos & eacute;s de mangan & egrave;se-bore n & eacute;cessite une st oe chiom & eacute;trie en Mg d'au moins 105%. L'analyse MEB/EDS de l'& eacute;chantillon lixivi & eacute; a confirm & eacute; l'& eacute;limination des impuret & eacute;s contenant Mg et O. Puisque 110 & agrave; 115% n'offraient aucun avantage mais & eacute;levaient la consommation de magn & eacute;sium, on a identifi & eacute; la st oe chiom & eacute;trie optimale & agrave; 105%. Ces r & eacute;sultats confirment la SHS comme une voie viable pour la production de c & eacute;ramiques de borure de mangan & egrave;se pour des applications avanc & eacute;es.
