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 Modification of Gold Surface by Layer-By Reactive Coating of Polyester-Polyethyleneimine Based Gel(Izmir Institute of Technology, 2020) Yıldız, Ümit Hakan; Yıldız, Ümit Hakan; 04.01. Department of Chemistry; 04. Faculty of Science; 01. Izmir Institute of TechnologyPolymeric gels defined as soft and solid-like systems that enable to retain a large volume of solvent and their high molecular weight provides long-term stability without crystallization. Therefore, the use of polymeric gels in the fields of energy and sensor technologies has become advantageous. In this thesis, the polymeric gel is successfully synthesized on the gold surface by Aza-Michael addition reaction of the polyester scaffold with a triple covalent bond and branched polyethyleneimine which is a secondary amine source. The polyester-polyethyleneimine based gel was generated on the isocyanate functionalized gold surface by using the grafting-to methodology. The morphology of the surface and thickness of the coating can be adjusted by layer-by-layer reactive coating on the gold surface of polymer structures. Electroactive properties are acquired for different application areas of the synthesized gels. To provide modular electron transfer, polyethyleneimine was modified with ferrocene carboxaldehyde prior to obtaining gel on the surface. The gel interface on the gold surface will increase the surface area and activity due to its three-dimensional structure and adjustable morphology. The number of the immobilized structures, the electroactive species in a unit area and electron transfer increases. The modified electrode surfaces coating yields and electroactivity examined with electrochemical methods, Cyclic Voltammetry and Electrochemical Impedance Spectroscopy. The morphological properties investigated by Atomic Force Microscopy. Additionally, polyester-based gels lithium-ion conductivity was investigated. Dissociation of lithium perchlorate in the gel and enhancing the conductivity was investigated. Indium tin oxide coated glasses were used as an electrode to characterize lithium ion conductivity.Master Thesis Anti-Reflective and Optical Transparent Coatings for Thin Film Solar Cells and Glasses(Izmir Institute of Technology, 2020) Özyüzer, Lütfi; Özyüzer, Lütfi; Özyüzer, Lütfi; 04.05. Department of Pyhsics; 04. Faculty of Science; 01. Izmir Institute of TechnologyAntireflective coatings in some implementation necessary for the decreasing surface reflection, but in some applications also for increasing transmittance. Incident radiation on the surface of the optical material is divided into transmitted, reflected, scattered, and absorbed proportions, and the proportion of current energy that deployed among them is defined by RI (refraction indices). Solar panels made from crystalline or polycrystalline silicon, but another type of solar panel is a thin-film solar panel. Thin-film technology has several advantages, such as low material consumption, which leads to cost savings to production, the ability to absorb diffused solar radiation, a relatively high efficiency (up to 20%), long service life (efficiency decreases by 10-15% of the initial efficiency). For all types of photovoltaic devices, energy loss is an important issue. Single-layer and two-layer antireflection coatings with a low refractive index, coated and uncoated (SiO2) thin-film with the sol-gel method were prepared and compared in terms of performance and continuity. The photocatalytic performance of (SiO2) thin films in 1, 2, 3, 4, 5 and 24 hours was defined with methylene blue dye solution (20 mL) under UV source and was illuminated by it. The I-V characteristics curve of solar cells for small and large area was learned and increasing efficiency was observed. Adhesion tests in this study was applied by tape tests on substrates of glass. As a result, the field tests of small and large area glasses coated solar panels were realized, the low reflectance and high efficiency were obtained.Master Thesis Coating of La1-Xsrxco1 Films on Zirconia and Cgo (cerium Gadolinium Oxide) by Electrostatic Spray Deposition (esd)(Izmir Institute of Technology, 2010) Büyükkebabçı, Hande; Akkurt, Sedat; Akkurt, Sedat; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyIn this study preparation and characterization of coating of La0.6Sr0.4Co0.8Fe0.2O3-δ and La0.6Sr0.4Co0.2Fe0.8O3-δ materials on TZ-3Y (3 mol % doped yttria) and CGO (Ce0.9Gd0.1Oxide) ceramic electrolytes was studied. Electrostatic spray deposition (ESD) was used for depositing the coatings on ceramic electrolytes to develop a well bonded electrolyte-cathode material for potential IT-SOFCs (intermediate temperature solid oxide fuel cells) applications. Precursor solutions having La0.6Sr0.4Co0.8Fe0.2O3-δ or La0.6Sr0.4Co0.2Fe0.8O3-δ stoichiometry were prepared from various salts before being sprayed on a heated ceramic substrate which rapidly evaporated the solvent in the salts and the droplets struck and covered its surface. A high voltage was maintained to accelerate the droplets to high speeds. A coating with a minimal 1 µm of thickness was successfully produced. Effects of experimental parameters like the flow rate of the solution (0.3-1.5 ml/h), distance between the nozzle and substrate (15-45 mm), temperature of the substrate (250-375 °C), post heat treatment temperature (900-1300 °C) of the coated substrate and applied voltage on the quality of the coating were studied. Analytical tools like DTA/TGA, Scanning Electron Microscopy (SEM) and Xray Diffraction (XRD) were used to investigate the samples to check for the quality of the coating. Coating microstructures ranged from dense to porous depending on the deposition parameters. Sample with 30 mm distance and 0.7 ml/h of flow rate produced the best reticulated structure of the coating. No preferential landing effect was observed on any of the samples studied. Zirconia was not an effective substrate for formation of La0.6Sr0.4Co0.8Fe0.2O3-δ or La0.6Sr0.4Co0.2Fe0.8O3-δ. Cerium gadolinium oxide, however, was effective for La0.6Sr0.4Co0.8Fe0.2O3-δ but not for La0.6Sr0.4Co0.2Fe0.8O3-δ.