Malzeme Bilimi ve Mühendisliği Bölümü
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Article Citation Count: Karataş, Mustafa Serdar...et al. "A Comparison of Radiation Shielding of Stainless Steel With Different Magnetic Properties", Nuclear Technology and Radiation Protection, Vol. 29, No. 3, pp. 186-189, (2014).A Comparison of Radiation Shielding of Stainless Steel With Different Magnetic Properties(Vinca Inst Nuclear Sci, 2014) Çalık, Adnan; Akbunar, Şahin; Uçar, Nazim; Yılmaz, Nihat; Karakaş, Mustafa Serdar; Akkurt, İskender; 48915The radiation shielding properties of three different stainless steels have been investigated. For this purpose, linear attenuation coefficients at photon energy levels of 662 keV and 1250 keV have been mea sured. The obtained results showed that ferritic stainless steel was more capable in stopping the high energy photons than its non-magnetic counterpart. © 2014 Vinca Inst Nuclear Sci. All rights reserved.Article Citation Count: Kuşhan Akın, Şeniz R.; Dölekçekiç, Emrah; Webster, Thomas J. (2021). "Antibacterial behavior of oxynitride glasses as a glassy grain boundary phase for silicon nitride-based ceramics", Internatİonal Journal of Applied Glass Science, Vol. 12, No. 3, pp. 328-336.Antibacterial behavior of oxynitride glasses as a glassy grain boundary phase for silicon nitride-based ceramics(2021) Kuşhan Akın, Şeniz R.; Dölekçekiç, Emrah; Webster, Thomas J.; 224219Silicon nitride-based ceramics have provided significant advantages due to their high chemical resistance, high elastic modulus, and combination of hardness and fracture toughness (depending on self-reinforcement). Over the past two decades, a significant amount of interest has been generated for the bio-applications of these materials. However, the effect of the grain boundary phase on such applications is still not very well understood. In this study, the effect of different cations on biological (such as antibacterial and cytocompatibilty) and material properties (like wetting angles and isoelectric points [IEP]) of oxynitride glasses, mimicking the grain boundary phase in Si3N4 and SiAlON ceramics, were investigated. Results revealed that the antibacterial behavior and mammalian cell viability were inversely correlated in glasses with rare-earth cation additions. Ca was the best cation when the two properties (bacterial response and cell proliferation) were considered together, and, thus should be further studied for a wide range of applications.Article Citation Count: Bütev Öcal, Ezgi...et al."Comparison of the Short and Long-Term Degradation Behaviors of As-Cast Pure Mg, Az91 and We43 Alloys",Materials Chemistry and Physics, Vol. 241, (2020).Comparison of the Short and Long-Term Degradation Behaviors of As-Cast Pure Mg, Az91 and We43 Alloys(Elsevier LTD., 2020) Bütev Öcal, Ezgi; Esen, Ziya; Aydınol, Kadri; Dericioğlu, Arcan F.; 52373The corrosion behaviors of pure magnesium, AZ91, and WE43 alloys have been evaluated by weight loss, hydrogen evolution rate, pH change measurements and potentiodynamic polarization as well as electrochemical impedance spectroscopy (EIS) methods. Main corrosion product formed on the surface of Mg/Mg-alloys after immersion of 24 h was Mg(OH)2 on the other hand, at the end of the 20 days additional CaCO3 which was found to display a critical role in degradation characteristics of the samples, was found. Examination in the cross section of the polished surfaces revealed that protective layers became thicker and corrosion rate of the samples decreased possibly due to increased protective abilities of the surfaces. Intermetallics in AZ91 and WE43 alloys acted as cathodic centers and induced micro galvanic corrosion. Undermining of intermetallics in WE43 alloy intensified the corrosion rate. AZ91 alloy exhibited the lowest corrosion rate among the samples when tested in simulated body fluid (SBF).Article Citation Count: Esen, Z...et al. "Corrosion Behaviours of Ti6Al4V-Mg/Mg-Alloy Composites", Corrosion Science, Vol. 166, (2020).Corrosion Behaviours of Ti6Al4V-Mg/Mg-Alloy Composites(Elsevier LTD., 2020) Esen, Ziya; Öcal, Ezgi Bütev; Akkaya, Aslı; Gürçay, Bensu; Özcan, Ceren; Özgümüş, Burcu Aslı; Duygulu, Özgür; Dericioğlu, Arcan F.; 52373The effect of coupling of unalloyed Mg and Mg-alloys (AZ91 and WE43) with Ti6Al4V alloy on corrosion and degradation behaviours of produced composites has been investigated in simulated body fluid (SBF) by hydrogen evolution, and surface and electrochemical characterization techniques. Combining of unalloyed Mg with Ti6Al4V intensified galvanic corrosion and catastrophic failure occurred by initiation of microcracks formed by sudden hydrogen gas evolution. In contrast to other composites, Ti6Al4V-AZ91 composites, containing new TiAl3 interface layer formed during composite production, preserved their mechanical integrities due to lowest corrosion and degradation rate of AZ91 alloy.Article Citation Count: Ucar, N...et al. (20169. Diffusion Kinetics of Binary Ti-Ni Shape Memory Alloys. (2017)Conference: 3rd International Conference on Computational and Experimental Science and Engineering (ICCESEN) Location: Antalya, TURKEY Date: OCT 19-24. Acta Physica Polonica A, 132(3), 524-526.Diffusion Kinetics of Binary Ti-Ni Shape Memory Alloys(Polish Acad Sciences Inst Physics, 2017) Uçar, Nazım; Doğan, Şule; Özdemir, Ahmet Faruk; Karakaş, Mustafa Serdar; Çalık, A.; 48915In this work, the boriding of binary Ti-Ni shape memory alloys was carried out in a solid medium at 1173 and 1273 K for 2, 4, and 8 h using the powder pack method with Ekabor-Ni powders. The boride layer was characterized by optical microscopy and scanning electron microscopy. The obtained results show that boride layer thickness increases with the increasing boriding temperature and time. Depending on temperature and boride layer thickness, the diffusion process is thermally activated, with the mean value of the activation energy being close to 67 kJ/mol.Article Citation Count: Cetinel, Oktay; Esen, Ziya; Yildirim, Bora, "Fabrication, Morphology Analysis, and Mechanical Properties of Ti Foams Manufactured Using the Space Holder Method for Bone Substitute Materials", Metals, Vol. 9, No. 3, (March 2019)Fabrication, Morphology Analysis, and Mechanical Properties of Ti Foams Manufactured Using the Space Holder Method for Bone Substitute Materials(MDPI, 2019) Çetinel, Oktay; Esen, Ziya; Yıldırım, Bora; 52373Porous titanium (Ti) offers several key attributes as a biomedical material. Among the known characteristics of Ti relevant to biomedical applications, the mechanical performance and effects of a pore structure on the deformation characteristics under compressive loading were examined. The space holder method was employed to generate Ti foams with target porosities of 60%, 70%, and 80%. A micro-computed to mography analysis and light and scanning electron microscopy were performed to examine the pore morphology and microstructure. The mechanical properties along with the elastic modulus and compressive strength were evaluated via uniaxial compression testing. Ti foam samples with three porosity levels displayed average elastic moduli and compressive strengths comparable with those of human cancellous and cortical bone. All the Ti foam samples had elastic moduli similar to those of cancellous bone with their open porous structures. Although the foam samples with similar to 60% porosity had compressive strength comparable to that of cortical bone, the samples with similar to 80% porosity displayed compressive strength similar to that of cancellous bone. The results indicate that Ti foam scaffolds produced using the space holder method have great potential for applications in hard tissue engineering, as their mechanical properties and pore structures are similar to those of bone.Article Citation Count: Calik, A.; Ozbakir, O.; Karakas, S.; Ucar, N. (2017). Investigation of the Erosive Wear Resistance of Boronized Ash-Blowing Nozzles, Acta Physica Polonica A, 131(2), 252-254Investigation of the Erosive Wear Resistance of Boronized Ash-Blowing Nozzles(Polish Acad Sciences Inst Physics, 2017) Çalık, A.; Özbakır, O.; Karakaş, S.; Uçar, N.; 48915In this study, pack boronizing was applied to ash-blowing nozzles manufactured from AISI 1040 steels using Ekabor II powders as the boronizing source at a temperature of 1273 K for a duration of 8 h. Erosive wear tests of boride ash-blowing nozzles were carried out in ash delivery line of thermal reactor under actual working conditions. It was observed that erosive wear resistance of borided ash-blowing nozzles were increased 3 times as a result of the boronizing process. The improved wear resistance of the borided samples can be explained by increased surface hardness and higher work hardening.Article Citation Count: Kalay, İlkay (2020). "Microstructure and Mechanical Properties of CoCrFeNi(TiAl) High Entropy Alloys", Hittite Journal of Science and Engineering, Vol. 7, No. 2, pp. 157-162.Microstructure and Mechanical Properties of CoCrFeNi(TiAl) High Entropy Alloys(2020) Kalay, İlkay; 101579The structure and mechanical properties of CoCrFeNi and CoCrFeNiTi0.5Al0.5 (in molar ratio) high entropy alloys were investigated using X-ray diffraction (XRD), optical microscope (OM), scanning electron microscope (SEM), hardness and compression tests. With the addition of Ti and Al, the crystal structure of CoCrFeNi changed from FCC to a mixture of FCC and double BCC structures. The lattice parameter of FCC increases upon addition of Al and Ti. The microstructure analysis shows the morphological transition of dendrites from non-equiaxed to equiaxed during the suction casting of CoCrFeNiTi 0.5Al 0.5 alloy. The Vickers microhardness testing of CoCr-FeNi alloy reveals significant increase in hardness with the addition of Al and Ti. The hardness values are improved in as-suction cast CoCrFeNi and CoCrFeNiTi0.5Al 0.5 alloys compared to their ascast alloys due to strengthening. The CoCrFeNiTi0.5Al 0.5 alloy yields at 1997 MPa and fails at 2344 MPa. The fracture mechanism of CoCrFeNiTi 0.5Al 0.5 alloy reveals a cleavage mode.Article Citation Count: Kuşhan Akın, Şeniz Reyhan. (2021). "Reaksiyon Bağlı Silisyum Nitrür Seramiklerinde Sinterleme İlavesinin Mikroyapı ve Antibakteriyel Davranışa Etkisinin İncelenmesi", Uluslararası Mühendislik Araştırma ve Geliştirme Dergisi, Vol.13, No.2, pp.375-381.Reaksiyon Bağlı Silisyum Nitrür Seramiklerinde Sinterleme İlavesinin Mikroyapı ve Antibakteriyel Davranışa Etkisinin İncelenmesi(2021) Kuşhan Akın, Şeniz Reyhan; 224219Silisyum Nitrür (Si3N4) genellikle yüksek sıcaklık ve yapısal uygulamalarda tercih edilen, üstün özellikli bir oksit dışı seramiktir. Çok sert bir malzeme olmasının yanı sıra, çubuksu beta () tanelerin gelişimi ile seramik malzemeler içinde yüksek kabul edilebilecek tokluk değerleri elde etmek mümkün olabilmektedir. Bu özelliklerine ilave olarak biyo uyumluluğunun da anlaşılması ile birlikte özellikle, bu malzemenin biyoseramik olarak kullanım potansiyelini arttırmak amacıyla son on yılda yapılan çalışmaların sayısı da artmıştır. Bu çalışmada da reaksiyon bağlama tekniği ile, çevre biyolojik dokularla entegrasyon açısından avantajlı olan gözenekli Si3N4 seramiklerinin üretilmesi amaçlanmıştır. Sinterleme ilavesi olarak sisteme yapılan CaO, Y2O3 ve CeO2 katkılarının, elde edilen Si3N4 seramiklerin fiziksel ve mikroyapısal özelliklerine ve bunların sonucu olarak antibakteriyel davranışlarına etkileri incelenmiştir. Elde edilen sonuçlar CeO2’in hem E. coli hem de S. aureus açısından dezavantajlı bir sinterleme ilavesi olduğunu, Y2O3’in ise en avantajlı ilave olduğunu görülmüştür. CaO ilavesi yapılan sistem ise E. coli için düşük, S. aureus için yüksek oranda bakteri üremesi ile sonuçlanmıştır.