http://hdl.handle.net/20.500.12416/18 Malzeme Bilimi ve Mühendisliği yayınlarını içerir. Wed, 28 Oct 2026 17:21:27 GMT 2026-10-28T17:21:27Z http://hdl.handle.net/20.500.12416/8432 Coating of Si3N4 with HAp via atomic layer deposition Kuşhan Akın, Şeniz Reyhan Silicon nitride (Si3N4) is an attractive implant material, particularly in orthopedic surgery. Although it has only been on the market for spinal fusion surgery requirements so far, it is also a promising candidate for other implant applications where load-bearing is crucial. In this study, we aimed to examine the potential of making the material surface more advantageous for various implant applications by coating it with a very thin hydroxyapatite (HAp) layer using the atomic layer deposition (ALD) method. This was done to improve the material's bioactivity without sacrificing its mechanical properties. Characterization results showed that using a 3:1 CaO:PO4 ALD cycle ratio resulted in the formation of very fine crystalline HAp after heat treatment at 500 °C. The bioactivity assessment made by immersing the coated film in SBF revealed HAp formation on the surface, and it was observed that the bioactivity of this surface improved compared to the uncoated one. Tue, 01 Aug 2023 00:00:00 GMT http://hdl.handle.net/20.500.12416/8432 2023-08-01T00:00:00Z http://hdl.handle.net/20.500.12416/8228 Reaksiyon Bağlı Silisyum Nitrür Seramiklerinde Sinterleme İlavesinin Mikroyapı ve Antibakteriyel Davranışa Etkisinin İncelenmesi Kuşhan Akın, Şeniz Reyhan Silisyum 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. Fri, 01 Jan 2021 00:00:00 GMT http://hdl.handle.net/20.500.12416/8228 2021-01-01T00:00:00Z http://hdl.handle.net/20.500.12416/7697 Microstructural Refinement of Ti-6Al-4V Alloy Fabricated by Additive Manufacturing Using Thermochemical Processes Bilgin, Güney Mert; Esen, Ziya; Kuşhan Akın, Şeniz Reyhan; Dericioğlu, Arcan Fehmi Fri, 01 Jan 2016 00:00:00 GMT http://hdl.handle.net/20.500.12416/7697 2016-01-01T00:00:00Z http://hdl.handle.net/20.500.12416/7574 Effect of post fabrication aging treatment on the microstructure, crystallographic texture and elevated temperature mechanical properties of IN718 alloy fabricated by selective laser melting Ozer, Seren; Bilgin, Güney Mert; Davut, Kemal; Esen, Ziya; Dericioglu, Arcan F. The effect of building direction and post fabrication aging treatment on the microstructure, crystallographic texture and high temperature mechanical properties of Inconel 718 (IN718) alloy fabricated by selective laser melting (SLM) method was investigated. After aging, arc-shaped structures seen in as-fabricated samples disappeared and converted into a mixture of columnar and equiaxed grains. Nano-sized γ″ and/or γ′ precipitates were formed upon aging; however, MC type carbides and Laves phase encountered in as-fabricated samples were not dissolved completely after aging. Moreover, aging did not alter the texture ((001)//building direction (BD)) of as-fabricated samples. Mechanical properties of the alloys under tension were influenced by the build direction, aging time and test temperature. As-fabricated samples produced in vertical direction exhibited higher room temperature strengths with lower ductility due to orientation of overlapped prior melt pools. Room temperature tensile test results revealed that peak aging caused a significant improvement in ultimate tensile strength (UTS), from 1066.5 MPa and 998.4 MPa to 1408.5 MPa and 1330.4 MPa whereas elongation values decreased from 27.5% and 32.2% to 19.6% and 23.7% in vertically and horizontally built samples, respectively. Peak-aged samples (aged at 700 °C for 8 h) tested at 600 °C displayed serrated regions in their stress-strain curves due to dynamic strain aging (DSA). Although strength values of the samples displayed an expected decrease by temperature, ductility of the samples reduced to minimum at temperatures around 700–800 °C, which was attributed to intermediate temperature embrittlement. Mon, 01 Aug 2022 00:00:00 GMT http://hdl.handle.net/20.500.12416/7574 2022-08-01T00:00:00Z