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    Effect of Yttria on the Phase Formation and Sintering of HA-Al2O3 Biocomposites
    (POLISH ACAD SCIENCES INST PHYSICS, 2017) Oksuz, K. E.; Ozer, A.
    Hydroxyapatite is very-well known as the main component of hard tissues and, as such, it has attracted much attention by researchers in the recent decades. This study was aimed to present the characterization of Y2O3 doped 50 wt.% hydroxyapatite -50 wt.% Al2O3 composite materials fabricated at relatively high temperature of 1600 degrees C. Hydroxyapatite powder was obtained from bovine bones via calcination and ball milling technique. Fine powders (<= 1 mu m) of hydroxyapatite/Al2O3 were admixed with 0.5 and 1 wt.% Y2O3 powders. Powder compacts were sintered at 1600 degrees C for 4 h in air atmosphere. The field emission scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction studies following the relative density measurements were conducted. Moreover, the microhardness was studied as the mechanical property of sintered samples. The effect of increasing Y2O3 content on surface morphology, elemental distribution and phase evaluation was investigated in hydroxyapatite/Al2O3 biocomposite materials. It was found that by increasing Y2O3 content, the relative density increased up to 98.8%, while the hardness increased to 863 HV(0.2). The main phases, which were found, are Hibonite -CaO(Al2O3)(6) and beta-tricalcium phosphate -Ca-3 (PO4)(2), according to X-ray diffraction pattern.
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    GENDER DIFFERENCES IN CLINICAL FEATURES AND BURDEN IN PATIENTS WITH FAMILIAL MEDITERRANEAN FEVER: PRELIMINARY REPORT
    (Bmj Publishing Group, 2021) Duruoz, M. T.; Ozer, A.; Gezer, H. H.; Melikoglu, M. Alkan; Hizmetli, S.; Baklacioglu, H. S.; Sahin, N.
    [Abstract Not Available]
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    High Energy Ball Milling of YAG Powders: Sintering Properties and Microstructural Evaluation
    (POLISH ACAD SCIENCES INST PHYSICS, 2017) Ozer, A.; Kilic, O. B.
    Outstanding properties of sintered ceramics due to lower sintering temperatures and smaller grain sizes are of much attention to many researchers. In this study, YAG phase was formed successfully with mechanical activation of powder mixtures by high energy ball milling of powders at different speeds. The powders were compacted and sintered at three different temperatures to evaluate the sintering density, phase formation and grain formation. It was found that increasing activation time, which agitates the powder mixing more accurately, has led to an increase in the relative density, as compared to non-activated samples, sintered at same temperatures. Up to 95% ot the theoretical density were reached, indicating the partial liquid phase formation of Y-A related phases. YAG phase formation and crystallite size were evaluated using XRD and Debye-Scherrer formula. The studies of grain size and surface morphology were conducted using SEM. Since the mechanical activation of ceramic powders occurs by fragmentation and crack propagation, by brittle fracture of powders, the main mechanism of reduction of sintering temperature can be concluded to be the decreasing grain size, as well as the increasing strain on fine powder grains.
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    MICROSTRUCTURAL AND PHASE STUDY OF Y2O3 DOPED HYDROXYAPATITE/Al2O3 BIOCOMPOSITES
    (INST MATERIALS PHYSICS, 2016) Oksuz, K. E.; Ozer, A.
    Hydroxyapatite is the mineral component of natural hard tissues and, as such, it has been studied extensively as a candidate biomaterial for its use in prosthetic applications. This study presents the fabrication and characterization of Y2O3 doped HA-Al2O3 composite materials. Hydroxyapatite ( HA) powder was obtained from bovine bones (BHA) via calcination technique. Fine powders of HA/Al2O3 were admixed with 0.5 and 1 wt % Y2O3 powders. Powder-compacts were sintered at 1550 degrees C for 4h. SEM, EDS and X-ray diffraction studies were conducted. The effect of increasing Y2O3 content on surface morphology, elemental distribution and phase evaluation was investigated in hydroxyapatite/Al2O3 biocomposite materials.
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    Phase and Morphological Evaluation of Mechanically Activated Sintered YAG Powders
    (ELSEVIER SCIENCE BV, 2015) Oksuz, K. Emre; Apaydin, F.; Bozdag, A. Enbiya; Cevik, M.; Ozer, A.; Parsa, MH; Zamani, C; Babaei, A; Sheibani, S
    High physical properties of sintered ceramics due to lower sintering temperatures and smaller grain sizes are of a great interest for researchers. In this study, YAG phase was formed successfully with mechanical activation of powder mixtures. The powders were compacted and sintered at 3 different temperatures to evaluate the sintering density, phase formation and grain morphology. It was found that increasing activation time increases the relative density according to unactivated sample sintered at same temperatures. The 80% of theoretical density was reached which indicates the partial liquid phase formation took place. Experiments for further investigations are carried on. (C) 2015 Published by Elsevier Ltd.
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    REGIONAL DIFFERENCES IN DISEASE CHARACTERISTICS OF FAMILIAL MEDITERRANEAN FEVER IN TURKEY: PRELIMINARY REPORT
    (Bmj Publishing Group, 2021) Duruoz, M. T.; Gezer, H. H.; Melikoglu, M. Alkan; Hizmetli, S.; Baklacioglu, H. S.; Sahin, N.; Ozer, A.
    [Abstract Not Available]
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    The effect of yttrium oxide in hydroxyapatite/aluminum oxide hybrid biocomposite materials: Phase, mechanical and morphological evaluationDer Einfluss von Yttriumoxid in Hydroxylapatit/Aluminiumoxid hybriden Bioverbundwerkstoffen: Gefuge, mechanische und morphologische Evaluation
    (Wiley-V C H Verlag Gmbh, 2019) Ozer, A.; Oksuz, K. E.
    This study presents the fabrication and characterization of composite materials of hydroxyapatite and aluminum oxide. Hydroxyapatite powder was obtained from bovine bones via conventional calcination routine. Although hydroxyapatite shows great biocompatibility with the human body, its applications are limited to non-load bearing areas. For this purpose, fine powders of hydroxyapatite/alumina were admixed with 1 and 5 wt.% yittria. Powder-compacts were sintered by two-step sintering route by increasing temperature to 1550 degrees C for 2 h and then sintering at 1450 degrees C for 4 h. The effect of increasing yittria content on sintering behavior and mechanical properties was investigated in biocomposite hybrid materials.