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Öğe Spark plasma sintering of B4C-TiB2 composite: effect of combustion synthesized nanoparticle on sinterability and mechanical properties(2025) Çoban, Ozan; Buğdaycı, Mehmet; Özer, Salih Çağrı; Başlayıcı, Serkan; Turan, Servet; Açma, Mahmut ErcanThis study investigated the effects of fine particles with high surface area synthesized by Self-propagating High-Temperature Synthesis (SHS) on the SPS process and the properties of the resulting products. Correlations were established between particle size, SHS product addition, sinterability, and mechanical properties. The products were characterized by measuring shrinkage percentages, relative density, microhardness, elastic modulus, and fracture toughness, which were further correlated with SEM–EDS results. The results revealed that SHS nanoparticles significantly increased fracture toughness, especially with additions above 60%, by reducing average particle size, increasing powder porosity, and adding composite powder. The product exhibited high relative density (99.03%), elastic modulus (464 GPa), and fracture toughness (4.65 MPa.m1/2) when SPS was used on B4C-TiB2 powders containing 80% SHS product at a low temperature of 1550 °C. By adding 80% SHS product, hardness increased by 62% (19.5 GPa) and fracture toughness by 24%, even at low sintering temperatures, thus reducing energy consumption.Öğe The efficiency assessment of Ni(40)Ti(50)Cu(x)Fe(10-x) shape memory alloy produced by combustion synthesis through thermal analysis(2024) Keskin, Berk; Derin, BoraIn this investigation, Ni(40)Ti(50)Cu(x)Fe(10−x) (x = 2.5, 5, 7.5) alloys were synthesized through the self-propagating high-temperature synthesis (SHS) process, employing preheating temperatures of 240 and 450 °C. To optimize thermal analysis, samples were drawn from the middle and upper sections of specimens exhibiting superior propagation results at a preheating temperature of 450 °C. Omitting additional heat treatment ensured a precise result interpretation. While the Ti50Ni40Fe2.5Cu7.5 sample displayed minimal variations in martensite and austenite transformation temperatures, others exhibited diverse transformation profiles. Apart from the B19' martensitic phase, distinct B19 martensitic phases were identified in Ti50Ni40Fe5Cu5 and Ti50Ni40Fe2.5Cu7.5 alloys, each showcasing unique transformation temperatures and full-width at half-maximum (FWHM) values. The inquiry unveiled that an increased Fe content prompted the segregation of Fex(Ni)Ti-based intermetallic phases from Cu-based phases, with this effect intensifying in alloys featuring higher Fe atomic ratios. This influence significantly impacted transformation temperature outcomes, overshadowing the inherent impact of the synthesis method.Öğe Exploring photocatalytic tetracycline removal performance under simulated sunlight irradiation: Milling time effect on metallic reduction of MnO/ZrO2 mixed oxide(2024) Kanmaz, Nergiz; Buğdaycı, Mehmet; Demircivi, PelinIn the present research, it is reported that ball milling technique can be applied to enhance the photocatalytic properties of MnO and ZrO2 metal oxide powders (MZOx) furthermore the fabricated photocatalyst can be used for the degradation of tetracycline (TTC). XRD analyses revealed that increasing the milling time resulted in the formation of a pure metallic Mn crystal phase, which boosted the antibiotic degradation rate. It was confirmed by SEM technique that the morphological structures of the particles were generally small and uniform. The band gap energy was calculated as 3.70 eV for the hybrid metal oxide. Additionally, the adsorptive and photoluminescence features were illuminated via DRS and PL analyses. The effect of milling time had a major impact on the photodegradation rate of TTC, and the 8 h milling sample (MZOx-8h) exhibited the highest catalytic degradation activity (79.4 %). Low photocatalytic activity was obtained at acidic pHs and increased at alkaline pHs. The presence of H2O2 sharply decreased photocatalytic process time (60 min) and 94.3 % of the TTC was degraded at 7.5 mM H2O2. The photocatalytic degradation process proceeded through superoxide radicals and was supported by holes. The stability of MZOx-8h almost remained constant (70.02 %) even after seven cycles. It was determined that the presence of oxalic acid positively affected the progress of TTC degradation reactions. Further, practical application areas were investigated and MZOx-8h doped on support materials was found to be suitable for such applications in proportion to the doping ratio. Finally, it was demonstrated that MZOx-8h exhibited remarkable performance in photocatalytic reactions of different types of organic pollutants. The synergistic nature of MnO and ZrO2 with the contribution of ball milling time effect resulted in high photocatalytic activity.Öğe The effect of tempering time and cooling environment on the corrosion behavior of AA5083-H111 alloy(2024) Karagöz, İdris; Buğdaycı, Mehmet; Öncel, LeventThe tempering process can increase the mechanical properties of the material, such as hardness and impact strength, as well as enhance the corrosion resistance. Therefore, the selection of appropriate tempering time and cooling environment is crucial. This study aims to investigate changes in properties such as hardness, tensile strength, corrosion resistance, and microstructure of AA5083-H111 alloy after a brief tempering process (30 minutes, 45 minutes and 60 minutes) at 320 °C, followed by cooling in air and water environments. The study found that tempering time and cooling environment significantly affect the mechanical properties and corrosion rate. The results show that samples labeled as S30 and S60 have the highest hardness and impact strength, but the best corrosion resistance is achieved in the S60 sample. This study demonstrates that even after a limited-term tempering process, the mechanical properties and corrosion resistance of AA5083-H111 alloy can be improved. This information is crucial data for use in the production and application of alloys. The findings of this study could have important implications for the production and application of AA5083-H111 alloy in industries such as aerospace, automotive, and marine engineering.Öğe A comparative study about production of vanadium carbide via self propagating high temperature synthesis and reduction(2024) Buğdaycı, Mehmet; Öncel, Levent; Alkan, Murat; Turan, Ahmet; Çınarlı, 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°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 Synthesis of CuBDC metal-organic framework supported zinc oxide via ball-milling technique for enhanced adsorption of Orange-II(Elsevier B. V., 2024) Yardımcı, Batuhan; Kanmaz, Nergiz; Buğdaycı, Mehmet; Demirçivi, PelinFor the first time, copper-based metal-organic framework (CuBDC) supported ZnO composite was successfully prepared by the ball-milling method for effective adsorption of anionic azo orange-II (OII) dye. After comparing the OII adsorption performances of ZnO and composites, with two different CuBDC support ratios, focused on the investigation of 1:1 CuBDC@ZnO. The crystal structures, physicochemical properties, and surface morphologies of the adsorbents were characterized by XRD, FTIR, SEM-EDX, and BET analyses. The adsorption process fitted the Langmuir isotherm model (R2=0.98) and the monolayer adsorption capacity of 1:1 CuBDC@ZnO composite was found to be 132.12 mg g?1. The adsorption process was well described by the pseudo-second-order model, which indicates the adsorption process of 1:1 CuBDC@ZnO composite on OII is chemisorption. Moreover, 1:1 CuBDC@ZnO composite can be an alternative as an effective and innovative adsorbent for the removal of toxic OII dye contaminant.Öğe Thermodynamic analysis of production parameters and microstructural evolution in shape memory Ni(50-x)Ti(50)Fe(x) (x = 5, 10) alloy synthesized by combustion synthesis(Springer Science and Business Media Deutschland GmbH, 2024) Keskin, Berk; Derin, BoraThis study represents an initial effort to produce NiTiFe shape memory alloys via the self-propagating high-temperature synthesis (SHS) process. The synthesis successfully yielded Ni45Ti50Fe5 and Ni40Ti50Fe10 alloys from elemental Ni, Ti, and Fe powders at three distinct preheating temperatures (240, 330, 420 °C). To support empirical findings, thermodynamic analysis using Factsage Thermodynamic Software was employed to correlate reaction propagation behavior with chemical composition. The calculation showed that the addition of 5 at.% Fe to the B2 phase did not hinder reaction self-propagation. This conclusion was supported with the ?Hf/Cp ratio and transient liquid ratio, computed using the sub-lattice model, which closely resembled that of NiTi. Whereas 10 at.% Fe that synthesized at preheating temperature of 240 °C exhibits struggle, thus an increase in triggering time causes an effect on crystallite size and a decrease in porosity. Empirical results confirmed these findings, albeit influenced by ignition times. An increase in the liquid ratio due to the adiabatic temperature rise can also result in a reduction of NiTi content when the Fe ratio is increased, consequently diminishing the driving force for the reaction. In the sample containing – 5% Fe, the main phase is B2, and the R martensitic phase is also present. Ms is determined to be – 38.7 °C. SEM analyses revealed the presence of Ti2Ni and Ti2Ni3 phases in the upper and lower regions, while the distribution in the middle section is more homogeneous. No martensitic transformation was observed in 10% Fe. Additionally, nanocrystalline regions were detected within the samples by transmission electron microscopy, contributing to a nuanced understanding of their structural properties. Graphic abstract: (Figure presented.).Öğe Vacuum carbothermal synthesis of TiB2(Pleiades Publishing, 2023) Buğdaycı, Mehmet; Güleç, ŞeymaAbstract: In this study, the formation conditions of TiB2, whose main production method is carbothermal reduction, at lower temperatures with additional processes (vacuum, mechanical activation and functional addition effect) were investigated. In this study, firstly the 100% stoichiometric mixture was reduced at 1200°C under vacuum for varying experimental durations. Afterwards, the effect of mechanical activation amount on TiB2 formation was determined by keeping the 4-h reduction time, which was determined as optimum in the first set of experiments. At the last stage of the experiments, the addition of 2.5 and 5% NaCl effect on the mixtures in the first set of experiments was determined. The samples obtained after the experiment were characterized by XRD and SEM techniques, and it was observed that the undesired phases were completely removed as a result of the reduction performed after 16 h of ball mile operation, and this experiment was determined as the optimum experimental condition.Öğe Promoting photo-fenton catalytic performance of novel NiZrO3-type perovskite: Optimization with response surface methodology(Elsevier B.V., 2024) Kanmaz, Nergiz; Buğdaycı, MehmetPerovskite type NiZrO3 photocatalysts were synthesized by ball-mill technique and used for tetracycline (TC) degradation. NiZrO3 milled for 6 h (NiZrO3-6h) had significant-99 % photo-Fenton catalytic activity on TC removal It was determined that the characteristic peaks of NiZrO3 with XRD, spherical shaped structures with SEM, no organic peaks in the structure with FTIR, band gap of 4.40 eV with DRS and stable colloids with zeta potential. Response surface methodology (RSM) including Box-Behnken design (BBD) was applied to examine H2O2, Fe2+ and initial TC concentration effects on degradation and it was observed that H2O2 concentration had the highest effect on TC degradation. The photocatalytic efficacy of NiZrO3 could still eliminate 78 % of initial antibiotic molecules after eight-cycle. The application potential for Photo-Fenton assisted NiZrO3-6h was also observed in the degradation of other organic pollutants such as drugs (salicylic acid, ciprofloxacin, ampicillin) and dye (methylene blue, rhodamine-b, orange-II, malachite green, crystal violet). It suggests that the mechanochemically synthesized NiZrO3-6h perovskite could be suitable for its effective use in the photo-Fenton catalytic system.Öğe Combustion synthesis of B4C-TiB2 nanocomposite powder: Effect of Mg particle size on SHS and optimization of acid leaching process(Pleiades Publishing Inc., 2023) Çoban, Ozan; Buğdaycı, Mehmet; Başlayıcı, Serkan; Açma, Mahmut ErcanIn this study, composite nanoparticles of B4C-TiB2 were produced by combustion synthesis. Production was carried out by self-propagating high-temperature synthesis (SHS) method in atmospheric conditions by using oxide raw materials (B2O3, TiO2), carbon black and magnesium as a reducing agent. The effect of Mg particle size on SHS efficiency was investigated. Single-stage and 2-stage leaching processes were carried out to remove undesired phases in the SHS product. In the 1st HCl acid leaching process, the leaching temperature and leaching duration were optimized. As a result of the 2nd leaching process with the addition of carbonic acid and H2O2, commercial quality nanoparticle synthesis was performed. Results revealed that the increase in Mg particle size decreased the SHS efficiency, however very fine particle sized Mg usage decreased the SHS efficiency due to the evaporation and scatter of Mg. The optimum Mg particle size was determined as 75-150 mu m. Since it has a significant effect on the removal of Mg-borate phases, 90 degrees C was determined as the optimum leaching temperature. The optimum leaching duration was determined to be 60 min. As a result of optimized leaching processes, 99.11% purity B4C-TiB2 nanoparticle with 193.5 nm particle size and 30.65 m(2)/g surface area was synthesized.Öğe Investigation on structural and adsorptive features of BaO modified zeolite powders prepared by ball milling technique: Removal of tetracycline and various organic contaminants(Elsevier B.V., 2023) Kanmaz, Nergiz; Buğdaycı, Mehmet; Demirçivi, PelinIn the current study, the removal of tetracycline (TC) antibiotic via BaO-doped zeolite (80BaO@zeolite), which synthesized by ball-mill technique, from water by adsorption process was studied. The structure and properties of 80BaO@zeolite was determined by XRD, FTIR, SEM and BET/N2. TC adsorption capacity of 71.4 mg g?1 was obtained for 80BaO@zeolite. The Langmuir isotherm model was found to be compatible for 80BaO@zeolite. The kinetic results indicate that the adsorption rate is compatible with the pseudo second order model and the time for the adsorption to reach equilibrium was achieved as 360 min. Maximum TC removal was obtained at pH:10, in the presence of NaCl and CaCl2 salts, and compared to in tap water drinking water and distilled water. The sorption process has shown thermodynamically exothermic and spontaneous nature. The desorption of TC molecules attached to the 80BaO@zeolite surface was investigated using different eluents. The 88% TC removal and 94% TC recovery rates achieved in the first cycle with the 1 M NaOH eluent decreased to 72% and 70%, respectively, in the fourth cycle. High adsorption capacities of 161.3 mg g?1, 59.3 mg g?1 and 85.5 mg g?1were obtained in the removal of malachite green, murexide and basic violet-16, respectively.Öğe Solvent-free mechanochemical synthesis of TiO2-ethyl cellulose biocomposite for adsorption of tetracycline and organic dyes(Elsevier B.V., 2023) Kanmaz, Nergiz; Buğdaycı, Mehmet; Demirçivi, PelinIn the study, polymeric-metal oxide hybrid composite was synthesized by mechanochemical method in ball-mill by adding different amounts of TiO2 to ethyl cellulose (EC) and its potential in tetracycline (TC) removal from aqueous solutions was investigated. In order to investigate the adsorption capacity, isotherm, kinetic and thermodynamic parameters of the adsorption process, the amount of adsorbent, contact time, solution pH, temperature effect, inert electrolyte effect and different water environment effects were experimentally carried out in batch adsorption experiments. The adsorption capacity of all sorbents was conformed according to the Freundlich isotherm model and the maximum capacity is found for 80%TiO2@EC with 23.26 mg g?1. The system reached equilibrium with 89% TC removal in 480 min and complied with the pseudo second order kinetic model. In the pH effect experiments, maximum TC removal found in pH:6. Thermodynamic parameters indicate that TC adsorption on 80%TiO2@EC is endothermic and spontaneous. Different water medium and inert electrolyte effect were found compatible with each other. Also, a decrease was observed in the specific TC removal in the presence of any ions in the system. The removal of methylene blue (MB) and malachite green (MG) azo dyes as another organic environmental pollutant was also studied and their adsorption capacities were found as 105.7 mg g?1 and 109.9 mg g?1, respectively. XRD, FTIR and SEM analyzes were performed to explain the interaction mechanism between sorbent samples and TC.Öğe Synthesis and microstructure investigation of Ni40Ti50Cu10 intermetallic shape memory alloys by self-propagating combustion method(Springer India, 2022) Keskin, Berk; Bassani, Paola; Bakan, Feray; Sezen, Meltem; Derin, BoraThis study concerns the substitution of copper for nickel in the Ni-Ti system in order to obtain a molar ratio of Ni40Ti50Cu10. Effects of preheating temperature were studied to understand the morphology, phase transformation, and microstructure of the samples by using self-propagating high-temperature synthesis. Therefore, three distinct preheating temperatures (230 degrees C, 320 degrees C, and 410 degrees C) were used for the study. The thermochemical calculations performed with FactS age presented similar results with the experimental data in terms of solid-liquid ratios and adiabatic temperature during the reactions. An increase in the preheating temperature very slightly changed the transformation temperature, but it was shown to be insignificant. B2 crystal structure was found as the main phase besides a small amount of martensite, Ti2Ni(Cu), and Ni(Cu)(2)Ti-Ni(Cu)(3)Ti by various characterization methods. The monoclinic twinned martensitic (B19') structure was encountered in transmission electron microscopy analyses.Öğe Corrosion behavior of hydroxyapatite coated AZ31 and AZ91 Mg alloys by electrostatic spray coating(Walter de Gruyter GmbH, 2022) Başlayıcı, Serkan; Buğdaycı, Mehmet; Benzeşik, Kağan; Yücel, Onuralp; Açma, Mahmut ErcanMagnesium and its alloys are excellent implant material candidates with their biodegradable structure and mechanical properties close to human bone. In order to provide the desired strength in implant applications, the corrosion resistance of the materials is expected to be high. In this study, to improve the corrosion resistance of AZ31 and AZ91 magnesium alloys, an electrostatic hydroxyapatite coating process was applied, and optimum conditions were determined. The samples were structurally characterized by scanning electron microscopy/energy dispersive X-ray spectroscopy and stereo microscopy methods, and their corrosion behavior was determined by the weight loss method. As a result of the coating, the corrosion resistance of the samples increased up to 250 %.Öğe Synthesis of Eu doped SrAl2O4 composite: Adsorption characteristics on tetracycline and ciprofloxacin antibiotics(Taylor and Francis Inc, 2021) Turan, Büşra; Buğdaycı, Mehmet; Benzeşik, Kağan; Demirçivi, PelinIn the present study, evaluation and characterization of Eu-Strontium aluminate(SrAl2O4) composites was studied. A new technic, volume combustion synthesis, was applied to synthesis of Eu-SrAl2O4 composites. Tetracycline (TC) and ciprofloxacin (CIP) were used to investigate the adsorption capacities of the composites. Experimental results showed that monolayer adsorption occurred for both of TC and CIP with adsorption capacities 26.24 mg g(-1) and 7.10 mg g(-1), respectively. Pseudo-second order kinetic model well described the TC and CIP adsorption with k(2) values 7(*)10(-4) and 4(*)10(-5) g mg(-1) min(-1), respectively. The highest adsorption were found at pH 7 (98%) for TC and at pH 10 (80%) for CIP. Eu-SrAl2O4 composite is a good candidate for the removal of various type of antibiotics from wastewater.Öğe Corrosion behaviour of hydroxyapatite coatings on AZ31 and AZ91 magnesium alloys by plasma spray(Hanyang University, 2021) Başlayıcı, Serkan; Buğdaycı, Mehmet; Açma, Mahmut ErcanIn the scope of this study, AZ31 and AZ91 magnesium alloys are to be coated with hydroxyapatite by plasma spray to be used as biodegradable implant material and their in-vitro corrosion behaviors are to be examined. There are a number of researches on the production of biodegradable cortical screws and plates used in orthopedic surgery in last decade. The advantage of biodegradable implants is that they do not need to be surgically removed. Moreover, the elastic modulus and the mechanical properties of magnesium are relatively close to those of the human bone, and this prevents the phenomenon of the human bone named “stress shielding. During this study, the hydroxyapatite coating processes, characterizations and corrosion behaviors of AZ31 and AZ91 will be examined. The aim of this work is to determine the optimal coating conditions for magnesium alloys for biodegradable implants. As a result of the plasma spray coating, the corrosion rate has decreased from about 1.2 mm/year to 0.4 mm/year.Öğe Hydrometallurgical nickel and cobalt productıon from lateritic ores: Optimization and comparison of atmospheric pressure leaching and pug-roast-leaching processes(SciCell s.r.o., 2021) Çoban, Ozan; Başlayıcı, Serkan; Buğdaycı, Mehmet; Açma, Mahmut ErcanCorresponding to the technological developments, production and consumption of nickel have increased greatly over time due to its unique mechanical and chemical properties. Therefore, the production of nickel will always keep its importance. The availability of laterite ores, which are oxide type ores, is 86% of the nickel reserves on the Earth, and the processes used in the production of nickel from sulphide type ores have negative environmental effects. Therefore, recovery of nickel from lateritic ores has become increasingly important in recent years. In this study, the aim was to determine the optimum parameters of nickel and cobalt production from limonite type lateritic nickel ores, which were taken from Manisa Caldag region of Turkey, using atmospheric pressure sulfuric acid leaching and pug-roast-leach process. When the results obtained in these processes were compared, it was found that the Ni leaching efficiency is nearly 8% higher and iron leaching efficiency (contamination) is nearly 4% lower in the pug-roastleach process. Furthermore, the pug-roast-leach process was completed in 33% lower time compared to the atmospheric pressure sulfuric acid leaching process.Öğe Effects of reductant type on the combustion synthesis of NiB(Elsevier, 2021) Odabaş, Ömür Can; Buğdaycı, Mehmet; Kan, Selçuk; Turan, Ahmet; Yücel, OnuralpNi-B intermetallic alloys are important filler materials which are used in brazing applications. Carbothermic and aluminothermic synthesis routes are main methods to produce NiB. Carbothermic synthesis is carried out in electric arc furnaces and consumes high amount of energy whereas aluminothermic synthesis mainly uses its own reaction energy. Thus, via aluminothermic synthesis, the consumption of energy drops. Aluminothermic synthesis is a sub-group of combustion synthesis methods and, its name is based on the Al which is used as reductant in reactions. In the present study, aluminothermic synthesis conditions of NiB (mainly containing 15% B by wt.) were investigated for increasing B2O3 stoichiometry in reactants. Moreover, some experiments were conducted to understand the magnesiothermic synthesis conditions, as an alternative reductant. Results were compared to each other and to thermochemical simulations which were carried out by using HSC Chemistry 6.12 and FactSage 7.1 softwares. Chemical analysis, SEM-EDS and XRD were the main techniques to characterize raw materials and the products. Increasing B2O3 stoichiometry and the use of the Mg as reductant positively affected the chemical content of obtained NiB phases although metal recovery yields were lower for magnesiothermic experiments than that of aluminothermic experiments. For instance, in the magnesiothermic experiment carried out with 100% B2O3 stoichiometry, the obtained metallic fraction consisted of 84.2% Ni, 15.1% B and 0.1% Mg.
