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    Al2O3 Recovery From Waste Tetra Pak Packages
    (Erciyes Üniversitesi, 2023) Bugdayci, Mehmet; Turan, Ahmet; Öncel, Levent; Bayiroglu, Fatih
    In this study, it was aimed to obtain Al2O3 from waste Tetra Pak packages by using the hydrometallurgical method. Tetra Pak recycling has become an increasingly researched topic around the world. Cellulose, polyethylene and aluminum, which form the structure of Tetra Pak packages, are raw materials that can be reused after recycling. Cellulose was separated from Tetra Pak's structure by hydropulping process and polyethylene was separated from Tetra Pak's structure by leaching with HCl, and optimum parameters of these processes were investigated in experimental studies. Aluminum in the structure was dissolved in acid solution with 100% efficiency in the experiments carried out with 0.1750 M and 0.1312 M acid concentration. Aluminum, which was dissolved in acid solution, was obtained as the AlCl3 phase and precipitated as Al(OH)3 with the addition of 100% stoichiometric NaOH, and the precipitates were calcined at 950 °C for 1 hour to obtain the Al2O3 structure. The materials used in the experimental studies and the products obtained as a result of these experiments were analyzed by Atomic Absorption Spectrometry (AAS), Fourier Transform Infrared (FTIR) Spectroscopy, Scanning Electron Microscopy (SEM) / Energy-Dispersive X-ray Spectroscopy (EDS), and optical microscopy techniques.
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    Öğe
    Alüminotermik Yöntem Yoluyla Tufalden Ferromolibden Üretimi
    (Sinop Üniversitesi, 2020) Öncel, Levent
    Bu çalismada, bir demir bazli alasim olan ferromolibdenin (FeMo) üretimi metalotermik reaksiyon ile gerçeklestirilmistir. Bu metodun seçilme nedenleri maliyetinin düsük olmasi, prosesin kisa süre içinde tamamlanmasi ve enerji ihtiyacinin çok düsük olmasidir. Deneysel çalismalar öncesinde FactSage ve HSC yazilimlari kullanilarak termokimyasal simülasyonlar gerçeklestirilmistir. Deneylerde baslangiç malzemesi olarak bir atik malzeme olan ve kütlece %70 demir içeren hadde tufali kullanilmistir. MoO3 molibden kaynagi olarak, alüminyum ise indirgeyici olarak kullanilmistir. Deneyler sonucunda üretilmis olan numuneler Atomik Absorbsiyon Spektrometresi (AAS), X-Isini Floresans Spektrometresi (XRF) ve sertlik testleri (micro-Vickers) ile karakterize edilmistir. Deneysel çalismalarda öncelikle indirgeyici olarak kullanilan alüminyumun stokiyometrisinin FeMo verimi üzerindeki etkisi arastirilmistir. XRF sonuçlarina göre, %105 alüminyum stokiyometrisine sahip olan numune hedef alasima en yakin sonucu vermistir. Bu numunede elde edilen Fe verimi %95,16, Mo verimi ise %97,21 olmustur. Agirlik degisiminin Fe ve Mo verimleri üzerindeki etkisi %105 alüminyum stokiyometrisine sahip olan numuneler kullanilarak arastirilmistir. Hedef alasima en yakin sonucun 75 gram agirligindaki sarj ile elde edildigi görülmüstür. Bu numunedeki Fe verimi %99,10, Mo verimi ise 97,98 olmustur. Bu numunede elde edilen Fe ve Mo verimleri bütün deneylerde elde edilen en yüksek verim degerleridir. Numunelere yapilan sertlik testlerinde 678 HV10 ve 767 HV10 arasinda degerler elde edilmistir. En yüksek sertlik degeri %100 stokiyometrik alüminyum içeren numune ile elde edilmistir. Numunelerin kimyasal yapilarinin birbirine yakin olmasi sebebiyle birbirine yakin sertlik degerlerinin elde edildigi sonucuna varilmistir.
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    Öğe
    Effect of heat treatment conditions on the phase transformation characteristics of nitinol
    (2024) Öncel, Levent; Acma, Mahmut Ercan
    Nitinol is the most widely used shape memory alloy in medical applications. In this study, the effect of different heat treatment conditions on the phase transformation characteristics of medical-grade nitinol was investigated. Nickel-rich nitinol wires containing 50.6% nickel with a diameter of 120 μm were used in the experimental studies. The nitinol wires were heat treated for 10 minutes at heat treatment temperatures between 540 and 570 °C. Then, nitinol wires were heat treated at a heat treatment temperature of 550 °C between 8 and 14 minutes. The austenitic and martensitic transition temperatures of these samples were measured using differential scanning calorimetry (DSC). In the experiments with 10 minutes of heat treatment time, transition temperatures decreased, and hysteresis increased with the increase in heat treatment temperature. This is related to the amount of precipitates in the structure. In the experiments carried out at 550 °C, transition temperatures decreased, and hysteresis increased with increasing heat treatment time. Experimental studies showed that the austenite finish (Af) temperature of all nitinol wire samples was below 37 °C, and they will exhibit superelasticity in the human body.
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    Öğe
    Production of ferronickel from mill-scale via metallothermic process
    (TUBITAK, 2020) Öncel, Levent
    In this study, the production of ferronickel (Fe-Ni), which is an iron-based alloy, was carried out by aluminothermic methods. Mill scale obtained from continuous casting process was used as starting material. Mill scale is oxidized layers of steel alloys containing iron oxide with +2 and +3 values, it is formed on the surface of slabs and billets during annealing process at integrated iron and steel plants. In the metallothermic experiments, effect of aluminium (Al) powder addition to various ratios of starting oxide powders [mill scale (Fe, Fe2O3, FeO, Fe3O4), NiO] on metal recovery and alloy compositions were investigated. Before the experiments, reduction conditions were simulated via FactSage 6.4 database and convenient stoichiometric ratios were determined. Samples were characterized by chemical analysis (AAS), XRD, XRF and optical microscopy techniques. Highest metal recovery was obtained as 81.24% by using 110% stoichiometric Al containing mixture. © 2020, TUBITAK. All rights reserved.