Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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Now showing 1 - 4 of 4
  • Master Thesis
    Production of Composite Based Friction Materials Using Waste Gg25 Casting Material for Safety Clutches in Aviation Applications
    (01. Izmir Institute of Technology, 2024) Çelik, Ceren; Toksoy, Muhammet Fatih
    Havacılık sektöründe uçak motorları ile diğer bileşenler arasındaki gücün verimli ve güvenli bir şekilde aktarılmasını sağlayan kavrama balataları, sürdürülebilir malzemeler kullanılarak üretildiğinde hem performans hem de çevresel açıdan kritik öneme sahiptir. Bu çalışmanın amacı, uçak debriyaj sistemlerinde kullanılmak üzere GG25 atık metal lifleri içeren kompozit debriyaj balatası malzemeleri geliştirmektir. Sürdürülebilir bir üretim yaklaşımı ile geliştirilen bu balatalar hem malzeme geri dönüşümünü destekler hem de aşınma direnci gibi önemli avantajlar sunar. Bu çalışmada, ticari kompozit esaslı karama balatalarında kullanılan hammaddeler hakkında detaylı bir bakış açısı edinebilmek amacıyla mikroyapı analizleri, mineral faz analizi ve termal analiz gerçekleştirilmiştir. Havacılık uygulamalarına uygun kompozit sürtünme malzemesini oluşturan bileşenler, elde edilen karakterizasyon çalışmaları ve firma AR-GE çalışmalarından sağlanan bilgi birikimi doğrultusunda belirlenmiştir. Toz metalurjisi yöntemi ile üretim yapılan numuneler ball-on tipi aşınma test cihazı ile aşındırılmış ve sürtünme katsayısı ve aşınma direnci belirlenmiştir. Aşınan yüzeylerden alınan optik mikroskop ve SEM-EDS analiz görüntüleri değerlendirilmiştir. Değerlendirmelerin sonucunda, GG25 döküm atığı kullanılan numuneler, sürtünme katsayısı ve yoğunluğu açısından çeliğe benzer özellikler sunsa da sertlik ve aşınma direnci bakımından daha geridedir. Bu sonuçlar, pahalı çelik liflerin yerine geri dönüştürülebilir döküm atıklarının başarılı bir şekilde değerlendirilebileceğini ortaya koymaktadır. Atık durumdaki metal liflerinin, sürtünme, aşınma ve maliyet dengesini etkin bir şekilde sağlayabileceği ve standart uygulamalarda yeterli performansı karşılayabileceği öngörülmektedir.
  • Master Thesis
    Characterization and Recyclability of Pharmaceutical Blisters
    (01. Izmir Institute of Technology, 2023) Çapkın, İrem Yaren; Gökelma, Mertol; Akkurt, Sedat; Gökelma, Mertol; Akkurt, Sedat
    Packaging is one of the largest industries in the world. Pharmaceutical blister packages are the most preferred packaging type in the pharmaceutical industry. Especially after the COVID-19 pandemic, the use of pharmaceutical packaging has become widespread with the increasing demand for drugs. Pharmaceutical blister packages typically contain thin sheets of plastic and aluminium and generate substantial solid waste. Since these packages have a multi-layered and complex structure, they are difficult to recycle. Before recycling, plastic and aluminium need a separation process. Chemical separation or thermal processes can be used for separation. The aim of this study is to characterize different pharmaceutical blister types with SEM-EDS (Scanning electron microscopy- Energy dispersive X-ray spectroscopy), TGA (Thermogravimetric Analysis), DSC (Differential scanning calorimetry), ICP-MS (Inductively coupled plasma mass spectrometry), and FTIR (Fourier Transform Infrared Spectroscopy) and to review the different reagents used in the pharmaceutical blister layer separation process. In addition to thermal degradation, the parameters and results of the separation processes were evaluated using hydrochloric acid, formic acid, acetic acid, sulfuric acid, ethanol, acetone, and organic solvents. It also evaluates the recyclability of the separated layers (plastic and aluminium). Its recyclability was evaluated by melting the aluminium fraction under salt consisting of a mixture of NaCl-KCl-CaF2. The plastic fraction was obtained in solid and liquid form by thermal degradation and analysed by GC-TCD (Gas Chromatography-Thermal conductivity detector).
  • Master Thesis
    Remelting Behaviour of Pure and Az63 Magnesium Chips
    (01. Izmir Institute of Technology, 2023) Yörük, Pınar; Gökelma, Mertol; Akkurt, Sedat
    Magnesium is a widely used light metal in many areas such as the automotive, aerospace, and medical industries. Magnesium has become widely used in industrial applications despite its poor corrosion resistance and high cost. It has great machinability, weldability, and remarkable mechanical properties such as lightweight, strength, and creep resistance. Magnesium is considered by the European Union as a critical raw material. The demand for magnesium has been increasing and it is used as a substitute for other heavy materials in many applications. Thus, recycling magnesium scrap is important due to limited raw material accessibility and environmental concerns. Secondary sources of magnesium should contribute to the economy and the procedure should be as efficient as possible to prevent metal loss. Magnesium is typically remelted under a salt flux (chloride and fluoride mix) which removes the surface oxides and other contaminants from the metal or under a cover gas that covers the surface against oxidation. This research studies the effects of salt composition, different fluorides, and the compaction degree of turnings on the recovery efficiency of pure and AZ63 magnesium alloy chips that were remelted under different chemical compositions of NaF, CaF2, MgCl2, KCl, and NaCl salt fluxes. The purpose is to minimize the metal loss and increase the coalescence ability of the metal. Metal yield and coagulation efficiency were reported XRD, SEM-EDX, XRF, and TGA analysis were performed for the characterization of chips and remelted samples. The melting point and density of the salt fluxes were determined by the FactSage software.
  • Master Thesis
    Characteristic Properties and Recyclability of Aluminium Beverage Cans and Coffee Capsules
    (Izmir Institute of Technology, 2022) Önen, Rabia; Genç, Aziz; Gökelma, Mertol
    Recycling 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.