Master Degree / Yüksek Lisans Tezleri
Permanent URI for this collectionhttps://hdl.handle.net/11147/3008
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Master Thesis Effect of Arc Deposition and High Power Impulse Magnetron Sputter Coatings on the Performance of Tools for Machining Various Ferrous Materials and Ti6al4v Alloys(Izmir Institute of Technology, 2023) Nohuz, Mine; Davut, Kemal; Davut, Kemal; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this thesis, the performance of different coating techniques in machining various steels and Ti6Al4V is investigated. Currently, most of the carbide tools with the coating because of the tool life. In order to increase the productivity of the manufacturing processes and to use new materials, the research on the coating of cutting tools has been increased. Recently, the interest in physical vapor deposition has increased because the tool life is increased for many difficult-to-machine materials and difficult machining conditions. Two types of PVD coating were used in this work. The surfaces of the coated tools were examined under scanning electron microscope. The effects of cathodic arc deposition and high pulse magnetron sputtering on tool performance were investigated on various workpieces such as 4140 and CK45 steels, D2 tool steel (60HRC), GG25 cast iron and also on Ti6Al4V alloy. In the performance tests, the cutting forces were measured over a period of time and the wear patterns were recorded. The results indicate that HIPIMS coated tools perform better in operations where normal load is low and torsion forces are high. Those tools also work better in materials harder than 250 BHN. The better performance of HIPIMS coated tools were attributed to their less smooth and droplet free surfaces.Master Thesis Sintering and Densification Behavior of Nanoparticle-Infiltrated Alumina Scaffolds(Izmir Institute of Technology, 2023) Özbekler, Meti̇n; Akkurt, Sedat; Akkurt, Sedat; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyThis study explores high-purity Alumina's sintering and densification behavior, specifically the CT3000 SG variation, which traditionally requires high temperatures for full densification. The goal is to lower processing costs by achieving densification at lower temperatures through nanoparticle infiltration. The process involves a two-step heat treatment and infiltration technique. Alumina scaffolds are initially bisque-fired at 1100 °C and then infiltrated with a polymer precursor solution containing Al+3 ions, followed by decomposition at 400 °C to precipitate alumina nanoparticles in the scaffold pores. Multiple infiltration cycles are performed to enhance density. The relative density of furnace-sintered pellets increases with decreasing heating rate and increasing sintering temperature in reference samples. Infiltrated samples and "P" pellets (formed by washing CT3000 SG Alumina loose powder with the polymer precursor solution) follow a similar trend, with higher infiltration numbers leading to increased relative density. However, "P" samples have lower relative densities than reference samples. In-depth analysis using a horizontal dilatometer reveals that the 15 times infiltrated scaffolds exhibit better densification due to early activation of nanoparticles, leading to neck formation, reduced porosity, and altered particle shape. On the other hand, "P" pellets fail to achieve sufficient densification compared to reference samples. In summary, this study investigates lowering the sintering temperature of Alumina by nanoparticle infiltration. It involves bisque firing, multiple infiltration cycles, and a polymer precursor solution. Results indicate that 15 times infiltrated scaffolds achieve better densification, while "P" pellets fall short of achieving adequate densification compared to reference samples.Master Thesis Lithium Extraction From Geothermal Brine by Adsorption Method With Electrolytic Y-Mno2 Sorbent(Izmir Institute of Technology, 2022) Baba, Alper; Demir, Mustafa Muammer; Demir, Mustafa Muammer; Baba, Alper; 03.03. Department of Civil Engineering; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn recent years, studies on the recovery of lithium metal have attracted great attention due to its wide application areas, especially in lithium-ion batteries. Recovery of lithium from brines is preferred considering the environmental impacts in mining. The application of manganese oxide sorbents to recover lithium from geothermal brines has been extensively studied as it is a potential source of lithium. In this thesis, adsorption was performed in Tuzla Geothermal Power Plant (TGPP) at 87 °C and 2 bar using a mini-pilot system in the reactor near the reinjection well of the plant to investigate the adsorption performance in field conditions. As a new approach, electrolytic manganese dioxide (γ-MnO2), which is widely used as cathode material in batteries, was used as the sorbent material for lithium and its adsorption/desorption performance was investigated. Batch adsorption experiments were performed in synthetic lithium solution and the optimum working conditions were determined as pH 12, adsorbent concentration of 3 g/L, and initial lithium-ion concentration of 200 mg/L. The highest adsorption capacity of the sorbent in the Langmuir model was found as 9.74 mg/g. The maximum adsorption performance was obtained at 1h adsorption in Tuzla GPP. In the continuation of the study, desorption was carried out in acidic medium with the brine-treated sorbent. Lithium concentration was enriched to around 250 ppm with repetitive desorption studies. Reusability of the sorbent was investigated and the reused sorbent showed almost 40% performance compared to virgin powder. γ-MnO2 was found as a promising sorbent for the separation of lithium from geothermal brines.Master Thesis Characteristic Properties and Recyclability of Aluminium Beverage Cans and Coffee Capsules(Izmir Institute of Technology, 2022) Gökelma, Mertol; Genç, Aziz; Genç, Aziz; Gökelma, Mertol; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyRecycling is an effective way to reduce environmental pollution. Recycled aluminium uses 95% less energy than primary production. Therefore, there is a high demand for more efficient recovery technologies. Aluminium is used in transportation, consumer products, and electronics. Short life cycles, thin walls, and surface coatings make aluminium recycling difficult. This study focuses on UBCs and coffee capsules' properties and recyclability (CCs). A lab-scale electrical resistance heating chamber furnace was used for the de-coating and remelting experiments. The coatings were characterized using Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS). As a result of the study, it was found that thermal pre-treatment temperature is more critical for alloys that have high Mg content due to their oxidation tendency. Suitable thermal pre-treatment temperature was observed between 520 to 550 °C for the samples. On the other hand, when the volatile organic content of the scraps was analyzed, it was observed that clean UBCs and CCs contain 2.2% and 9% volatile organic content, respectively, but it can be increased with increasing drink rest inside of it. A result of these experiments shows that the metal yield can differ up to 3.5% due to the drink residues (sugar). Also, it was observed that high-density pressing of the samples prior to the de-coating process increases the amount of the entrapped carbonaceous materials and decreases the de-coating efficiency. Finally, it was observed that samples with low wall thicknesses should be remelted under a salt flux to prevent oxidation and allow coalescence.Master Thesis Synthesis of Titanium-Based Powders From Machining Waste by Using the Hydrogenation-Dehydrogenation Method(Izmir Institute of Technology, 2022) Genç, Aziz; Gökelma, Mertol; Gökelma, Mertol; Genç, Aziz; Gökelma, Mertol; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologySustainability and recycling activities have gained importance in almost every field all over the world. Many studies are conducted to recycle titanium and titanium alloys owing to their outstanding properties like low density, biocompatibility, corrosion resistance, and high strength-to-weight ratio. Although they offer superior properties, their usage is limited due to their high production cost and potential to generate waste, and therefore, recycling activities in this area should be expanded using an appropriate method. Cold hearth melting, vacuum arc re-melting, and hydrogenation and dehydrogenation process are widely used for recycling titanium scraps in industry. Among them, the hydrogenation and dehydrogenation (HDH) process has a significant environmental and economic impact. In this thesis, titanium powders were synthesized from additive manufacturing turnings. Ti-6Al-2Sn-4Zr-6Mo turnings were used as starting materials on which HDH characteristics were not investigated in the literature. Both hydrogenation and dehydrogenation parameters were studied to reach optimum conditions. Our results revealed that hydrogenation was accomplished at 500 °C for 120 minutes with 5 °C/minute heating rate. The optimum dehydrogenation condition was found at 600 °C for 90 minutes. Ti-6Al-2Sn-4Zr-6Mo powder with average 56 μm particle size was synthesized; however, hydrogen and oxygen concentrations in the powder were not at the desired level and non-spherical shaped powders were produced end of the process.Master Thesis Preparation of Drug Loaded Albumin Nanoparticles in Water / Ionic Liquids Microemulsion Systems(Izmir Institute of Technology, 2021) Akdoğan, Yaşar; Yıldırım, Barış; Akdoğan, Yaşar; 03.09. Department of Materials Science and Engineering; 01. Izmir Institute of Technology; 03. Faculty of EngineeringNanoparticles (NPs) have been used in various applications such as biotechnology, nanomedicine, and drug delivery systems. Many nanoparticle drug delivery systems have been promoted for cancer treatment, and numerous materials have been investigated to use as drug delivery agents to enhance the therapeutic efficiency and safety of anticancer drugs. Albumin is a natural biopolymer and the most abundant protein in blood plasma. Due to its versatile binding capacity of widespread therapeutical drugs, albumin becomes an ideal material to obtain nanoparticles. In this study, the ionic liquid (IL) based emulsification methods were investigated. Instead of classical toxic and volatile solvents, using ILs in microemulsions, environment-friendly media were received to synthesize bovine serum albumin (BSA) NPs. In order to obtain BSA NPs, high-speed homogenizer processing was applied by following crosslinker addition. The IL microemulsions are a thermodynamically stable colloidal dispersion containing spherical droplets (W/IL or IL/W) in submicron sizes that act as nanoreactors for NP formation. Chlorambucil (CHL) was used as a model drug to investigate drug loading and releasing kinetics of BSA NPs as a drug delivery candidate. Results showed that chlorambucil loading capacities and release kinetics depended on the synthesized medium such as anion-type of ILs and surfactants. CHL loaded to the BSA NPs synthesized in hydrophilic IL BmimBF4 in relatively higher amounts and released in the same trend. In addition, the cell viability effect of CHL-loaded BSA NPs synthesized in different types of ILs were investigated. The CHL-loaded BSA NPs synthesized in BmimOTf and BmimPF6 reduced the cancer cell viability more than the used same dose of free CHL.Master Thesis Comparison of Powder Synthesis Methods for the Production of Potassium Sodium Niobate (knn)(Izmir Institute of Technology, 2021) Pişkin, Cerem; Ahmetoğlu, Çekdar Vakıf; Adem, Umut; Ahmetoğlu, Çekdar Vakıf; Adem, Umut; 03.09. Department of Materials Science and Engineering; 01. Izmir Institute of Technology; 03. Faculty of EngineeringAlkali niobate-based, i.e., potassium sodium niobate, KxNax-1NbO3 at x=0.5 (the composition at the morphotropic phase boundary (MPB)), based materials have been reported as promising lead-free piezoelectrics to be substituted with the most extensive lead-based, i.e., lead zirconate titanate (PZT) ones. In this thesis, KNN particles were obtained using three discrete powder synthesis routes: conventional solid-state reaction, hydrothermal synthesis, and sol-gel processing. The as-synthesized powders were characterized via several techniques to provide a comparative study and underline the difficulties upon KNN synthesis. In the conventional method, the phase pure K0.5Na0.5NbO3 powders were obtained at 850°C with 382 ∓ 68 nm particle size. Unfortunately, the process cannot be considered sustainable due to the high risk of non-perovskite impurity phase formations. Also, the results demonstrated that single phase KNN powder having the MPB composition could not be accomplished via a one-step hydrothermal reaction process because of the inevitable formation of the second NaNbO3 phase. Instead, post-heat treatment of biphasic (K-rich (x>0.5) KNN and NaNbO3) samples lead to induction of sodium incorporation into the crystal lattice, and eventually, phase-pure KNN particles with high proximity (x=0.58) to MPB were achieved. The KNN powder with the smallest particle size (145 nm) was obtained using the sol-gel method at 500°C. However, the samples showed carbonate impurities resulting from the reaction of unreacted alkali cations (K+ and/or Na+) with the ambient CO2. Hence, the KNN samples needed to be stored under inert atmosphere to ensure purity.Master Thesis Studying Dopa Adhesion on Polystyrene Under Water(Izmir Institute of Technology, 2021) Yıldız, Remziye; Yıldız, Remziye; Akdoğan, Yaşar; Emrullahoğlu, Mustafa; Akdoğan, Yaşar; Emrullahoğlu, Mustafa; 03.09. Department of Materials Science and Engineering; 01. Izmir Institute of Technology; 04.04. Department of Photonics; 03. Faculty of Engineering; 04. Faculty of ScienceMussels wet adhesive performance has been arousing curiosity for a long time. It is found that 3,4-dihydroxyphenylalanine (DOPA) is responsible for adhesive properties of mussels. Despite a large body of research characterizing the interactions DOPA with hydrophilic surfaces, relatively few works have addressed the mechanism of interactions with hydrophobic surfaces. The benzene ring of DOPA is the main attributor to the adhesion on hydrophobic polystyrene (PS) surface. However, here we showed that two hydroxyl groups of catechol have also effects on wet adhesion. We studied wet adhesive properties of DOPA, tyrosine and phenylalanine functionalized PEG polymers, PEG-(N-Boc-L-DOPA)4, PEG-(N-Boc-L-Tyrosine)4, PEG-(N-Boc-L-Phenylalanine)4, on spin labeled PS nanobeads (SL-PS) by electron paramagnetic resonance (EPR) spectroscopy. Surface coverage ratio of SL-PS upon additions of PEG-(N-Boc-L-DOPA)4, PEG-(N-Boc-L-Tyrosine)4 and PEG-(N-Boc-L-Phenylalanine)4 showed that SL-PS was covered with 70%, 50% and 0%, respectively. This showed that spontaneous wet adhesion on PS increases with the number of amino acids hydroxyl groups. This is also supported with the density functional theory (DFT) energy calculations and ab-initio molecular dynamics (AIMD) simulations. In water, interactions between water molecules and hydroxyl groups on the catechol induce catechol adhesion via π-π stacking between the catechol and double styrene rings which were already tilted out with water.Master Thesis Experimental Analysis of Inkjet Printed Multi Metal Oxide Photoelectrodes for Water Splitting Applications(Izmir Institute of Technology, 2020) Karabudak, Engin; Adem, Umut; Karabudak, Engin; Adem, Umut; 04.01. Department of Chemistry; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 04. Faculty of Science; 01. Izmir Institute of TechnologyRecently, scientific research studies focus on renewable energy solutions as well as energy efficiency in managing the upcoming climate crisis which manifests itself in the form of global warming. However, the chaotic nature of renewable energy sources caused energy storage technologies to gain importance. In addition to battery technologies consisting of lithium and post-lithium ion, zinc-air, nickel-zinc and lead-acid; artificial photosynthesis products such as hydrogen and methanol also show superiority in transportation. Especially hydrogen fuel is in the leading position with gravimetric energy density of approximately 140 MJ/kg. In this study, the experimental procedure is conducted and analyzed to produce cost-effective multi-metal oxide catalysts at high speed and efficiency with a combinatorial approach using inkjet printing technology to obtain hydrogen by splitting water. Considering the abundancies in nature, especially nickel, cobalt, iron, manganese, copper and chromium salts were preferred to obtain oxide derivatives. Inkjet printing experiments were conducted with the printer provided by Sağlık İzleme Sistemleri A.Ş.. The precision of the printed layers was examined and compared with the literature values. In cases involving differences from the literature value, possible causes are emphasized and solutions are suggested. Problems in transition from single metal oxide printed layers to more complicated multi-metal oxide prints have been examined and solutions have been proposed. As a result, this experimental study is aimed to provide foresight for large-scale (photo)electrocatalyst production with the utilization of inkjet printing.Master Thesis Ferroelectric Ceramic Polymer Nanocomposites for Electrocaloric Cooling Applications(Izmir Institute of Technology, 2020) Tokkan, Melike; Adem, Umut; Adem, Umut; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study, nanocomposites consisting of the polymer matrix and nanometer sized ceramic supporting phase were produced for electrocaloric cooling applications, which show potential as alternative refrigerant system. The aim of this study was to be able to estimate adiabatic temperature change (?T) of the composites by measuring saturated hysteresis loops for the composite materials that allow accurate calculation of the ?T using the indirect method based on Maxwell's relations. Ba0.94Ca0.06Ti0.925Sn0.075O3(BCST) composition ceramic was used as the supporting phase of the composite and P(VDF-TrFE)(55-45) co-polymer was chosen as the matrix. The ceramics were synthesized, as pellets by conventional solid-state method. Ferroelectric nanocomposites were manufactured by solution casting method by adding 5, 7.5, 10 volume percent of the ceramic powder, which was obtained by grinding the pellets by using ball milling. Phase analysis of all materials done using X-ray Diffraction method. Fourier Transform Infrared Spectroscopy was used to clearly understand the phase structure of polymer. Scanning electron microscopy was used for understand the distribution of ceramic particles in polymer matrix. Dielectric constant-dielectric loss and ferroelectric hysteresis loops were measured as a function of temperature for the electrical characterization of the materials. Adiabatic temperature change under electric field (?T) of the materials were calculated based on Maxwell's equations indirectly using the temperature dependent electrical polarization data. The dielectric constant and electrical polarization of the polymer matrix have increased with the addition of ceramic particles. The hysteresis loops of thebn pure polymer and composites were saturated, therefore the temperature change can be calculated accurately with the indirect method. Maximum ?T was calculated on the composite having 10vol% ceramic particles. (6.964K at 900 kV/cm).