Non-covalent modifications of SWCNT were examined using functionable TT derivatives without any b... more Non-covalent modifications of SWCNT were examined using functionable TT derivatives without any binding agents. Three novel hybrids based on TTs and SWCNT were investigated by surface and computational studies.
Türkiye’nin ilk magnezyum alaşımı levhası, ikiz merdaneli sürekli döküm... more Türkiye’nin ilk magnezyum alaşımı levhası, ikiz merdaneli sürekli döküm tekniği ile üretilmiştir. Magnezyum AZ31, AZ61, AZ91, AM50 ve AM60 alaşımı levhalar 4-8 mm kalınlığında, 1500 mm eninde başarılı bir şekilde elde edilmiştir. Levhalar daha sonra homojenleştirme ısıl işlemlerine maruz bırakılmıştır. Levhaların mikroyapıları yüzey, en ve boy yönlerinde optik mikroskop ve Taramalı Elektron Mikroskobu (SEM) ile incelenmiştir. Daha detaylı mikroyapı incelemeleri Geçirimli Elektron Mikroskobu (TEM) ile yapılmıştır. Yarı nicel ve nicel elementel analizler SEM-EDS (Enerji Dağılım Spektrometresi), TEM-EDS ve EPMA (Elektron Prob Mikro Analiz Cihazı)-WDS (Dalgaboyu Dağılım Spektrometresi) sistemleri ile yapılmıştır. X-ışınları difraksiyonu (XRD) teknikleri karakterizasyon ve yönlenme incelemeleri amaçlı olarak kullanılmıştır. Malzemelerin mekanik özellikleri çekme deneyi ve sertlik deneyleri ile ölçülm...
In this study, we report a new design paradigm for an electrode preparation method that drastical... more In this study, we report a new design paradigm for an electrode preparation method that drastically improves the fast-charging capabilities of a graphite (Gt) anode by controlling the crystallographic orientation. The crystallographic orientation of the Gt electrode is achieved under a dynamic magnetic field using commercially available neodymium magnets. When the slurry of the Gt electrode is tape casted using the conventional method with no magnetic field, the crystallographic orientation is dominated with (002) planes along with other random planes. However, once the slurry of the Gt electrode is casted and dried under a magnetic field, the Gt particles tend to orient themselves along the (100), (101), and (110) planes which are all aligned vertically to the current collector. This striking difference allows the oriented Gt electrode to reach 80% state of the charge in only 50 min at 1C charge rate, whereas the randomly distributed Gt electrode reaches 80% state of the charge in 138 min at 1C charge rate using a constant current-constant voltage charging protocol. The outstanding electrochemical performance of the oriented Gt electrodes was characterized by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, electrochemical cycling, and electrochemical impedance spectroscopy techniques.
International Journal of NanoScience and Nanotechnology, 2019
Here, we report that the reduced graphene oxide nanosheets were successfully synthesized using th... more Here, we report that the reduced graphene oxide nanosheets were successfully synthesized using the Lactobacillus plantarum biomass in a simple, environmentally friendly and scalable manner. We produced graphene oxide by oxidization and exfoliation of graphite flakes with modified Hummer's method and then reduced to reduced graphene oxide by using Lactobacillus plantarum biomass as a reducing agent. Samples were characterized using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, microconfocal raman spectroscopy and thermogravimetric analysis. After the reduction, we observed that a considerable decrease in the oxygen containing functional groups of graphene oxide and an increase in C/O ratio from 1.7 to 3.3 in which confirms sp2 graphitic carbons increase. Mainly, we observed a significant decrease in epoxy and alkoxy functionalities. Furthermore, we determined an exfoliation of g...
Titanium and titanium alloys have been mostly used as biomaterials especially for dental implants... more Titanium and titanium alloys have been mostly used as biomaterials especially for dental implants due to their great combination of high mechanical strength and high corrosion rate. However, one of the most important drawback of them is the insufficient osseointegration. Therefore, the main purpose of this study is to improve the surface properties of Ti6Al4V by anodic oxidation and gold decoration. Initially, the surface of the alloy was anodized to thicken TiO2 layer. Subsequently, gold nanoparticles were produced using Turkevich method. Gold decoration on the oxidized surface were achieved by immersion of the alloy in gold solution after the oxidized alloy surfaces were activated by APTES solution. As a result of surface treatment highly rough surface containing thick oxide layer composed of 20 nm gold nanoparticles in addition to silane groups. Invitro tests displayed no apatite formation in 20 days. Therefore, further tuning is needed on the surface in terms of oxide layer and ...
Turkiye’nin ilk magnezyum alasimi levhasi, ikiz merdaneli surekli dokum teknigi ile uretilmistir.... more Turkiye’nin ilk magnezyum alasimi levhasi, ikiz merdaneli surekli dokum teknigi ile uretilmistir. Magnezyum AZ31, AZ61, AZ91, AM50 ve AM60 alasimi levhalar 4-8 mm kalinliginda, 1500 mm eninde basarili bir sekilde elde edilmistir. Levhalar daha sonra homojenlestirme isil islemlerine maruz birakilmistir. Levhalarin mikroyapilari yuzey, en ve boy yonlerinde optik mikroskop ve Taramali Elektron Mikroskobu (SEM) ile incelenmistir. Daha detayli mikroyapi incelemeleri Gecirimli Elektron Mikroskobu (TEM) ile yapilmistir. Yari nicel ve nicel elementel analizler SEM-EDS (Enerji Dagilim Spektrometresi), TEM-EDS ve EPMA (Elektron Prob Mikro Analiz Cihazi)-WDS (Dalgaboyu Dagilim Spektrometresi) sistemleri ile yapilmistir. X-isinlari difraksiyonu (XRD) teknikleri karakterizasyon ve yonlenme incelemeleri amacli olarak kullanilmistir. Malzemelerin mekanik ozellikleri cekme deneyi ve sertlik deneyleri ile olculmustur. Cekme deneyleri hadde yonu, hadde yonune 45 derece aci ve 90 derece aci olmak uzer...
Ti-6Al-4V is one of the most promising alloys for electron beam melting (EBM) of structural parts... more Ti-6Al-4V is one of the most promising alloys for electron beam melting (EBM) of structural parts due to its outstanding properties and its extensive use in the aerospace, automotive, and energy industries. In this study, we report a detailed and systematic micromechanical characterization of additively manufactured Ti-6Al-4V parts produced via EBM. The specimens were characterized by microhardness, nanoindentation, micropillar compression, and microscratch measurements. The results show that the Ti-6Al-4V exhibits a strong indentation size effect and higher strain rate sensitivity compared to those obtained from macroscale measurements. The high scratch resistance and the high hardness of the alloy at small indentation depths suggest that the EBM-produced Ti-6Al-4V parts can provide good performance in service under sliding wear conditions.
In this study, AZ31 in form of sheet, plate and extruded rod and AZ61 wire with different initial... more In this study, AZ31 in form of sheet, plate and extruded rod and AZ61 wire with different initial grain sizes were used to investigate the effect of initial grain size on recrystallization behavior and the formation of fine recrystallized grain (the so-called necklace) structure. Nucleation and growth of recrystallized grains along grain boundaries has been examined. In order to observe the effect of initial grain size and deformation on static recrsytallization and necklace formation, the specimens were annealed at 100-250°C for 10min--2hr. Specimens are also stretched to a total strain of 10, 20 and 40% at 300°C at an initial cross head speed of 1x10-3 s-1 for dynamic recrystallization studies. The results suggest that there exists a grain size limit, below which a necklace structure is not observed.
Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2009Thesis (PhD) -- İstan... more Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2009Thesis (PhD) -- İstanbul Technical University, Institute of Science and Technology, 2009Türkiye’nin ilk magnezyum alaşımı levhası ikiz merdaneli sürekli döküm tekniği ile üretilmiştir. Magnezyum AZ31, AZ61, AZ91, AM50 ve AM60 alaşımı levhalar 4-8 mm kalınlığında, 1500 mm eninde başarılı şekilde elde edilmiştir. Levhalar daha sonra homojenleştirme ısıl işlemlerine maruz bırakılmıştır. Levhaların mikroyapıları yüzey, en ve boy yönlerinde optik mikroskop ve Taramalı Elektron Mikroskobu (SEM) ile incelenmiştir. Daha detaylı mikroyapı incelemeleri Geçirimli Elektron Mikroskobu (TEM) ile yapılmıştır. Elementel analizler SEM-EDS (Enerji Dağılım Spektormetresi), TEM-EDS ve EPMA (Elektron Prob Mikro Analiz Cihazı)-WDS (Dalgaboyu Dağılım Spektormetresi) sistemleri ile yapılmıştır. X-ışınları difraksiyonu (XRD) teknikleri karakterizasyon ve tekstür incelemeleri amaçlı kullanılmıştır. Malzemelerin mekanik özellikleri çe...
Non-covalent modifications of SWCNT were examined using functionable TT derivatives without any b... more Non-covalent modifications of SWCNT were examined using functionable TT derivatives without any binding agents. Three novel hybrids based on TTs and SWCNT were investigated by surface and computational studies.
Türkiye’nin ilk magnezyum alaşımı levhası, ikiz merdaneli sürekli döküm... more Türkiye’nin ilk magnezyum alaşımı levhası, ikiz merdaneli sürekli döküm tekniği ile üretilmiştir. Magnezyum AZ31, AZ61, AZ91, AM50 ve AM60 alaşımı levhalar 4-8 mm kalınlığında, 1500 mm eninde başarılı bir şekilde elde edilmiştir. Levhalar daha sonra homojenleştirme ısıl işlemlerine maruz bırakılmıştır. Levhaların mikroyapıları yüzey, en ve boy yönlerinde optik mikroskop ve Taramalı Elektron Mikroskobu (SEM) ile incelenmiştir. Daha detaylı mikroyapı incelemeleri Geçirimli Elektron Mikroskobu (TEM) ile yapılmıştır. Yarı nicel ve nicel elementel analizler SEM-EDS (Enerji Dağılım Spektrometresi), TEM-EDS ve EPMA (Elektron Prob Mikro Analiz Cihazı)-WDS (Dalgaboyu Dağılım Spektrometresi) sistemleri ile yapılmıştır. X-ışınları difraksiyonu (XRD) teknikleri karakterizasyon ve yönlenme incelemeleri amaçlı olarak kullanılmıştır. Malzemelerin mekanik özellikleri çekme deneyi ve sertlik deneyleri ile ölçülm...
In this study, we report a new design paradigm for an electrode preparation method that drastical... more In this study, we report a new design paradigm for an electrode preparation method that drastically improves the fast-charging capabilities of a graphite (Gt) anode by controlling the crystallographic orientation. The crystallographic orientation of the Gt electrode is achieved under a dynamic magnetic field using commercially available neodymium magnets. When the slurry of the Gt electrode is tape casted using the conventional method with no magnetic field, the crystallographic orientation is dominated with (002) planes along with other random planes. However, once the slurry of the Gt electrode is casted and dried under a magnetic field, the Gt particles tend to orient themselves along the (100), (101), and (110) planes which are all aligned vertically to the current collector. This striking difference allows the oriented Gt electrode to reach 80% state of the charge in only 50 min at 1C charge rate, whereas the randomly distributed Gt electrode reaches 80% state of the charge in 138 min at 1C charge rate using a constant current-constant voltage charging protocol. The outstanding electrochemical performance of the oriented Gt electrodes was characterized by X-ray diffraction, scanning electron microscopy, Raman spectroscopy, electrochemical cycling, and electrochemical impedance spectroscopy techniques.
International Journal of NanoScience and Nanotechnology, 2019
Here, we report that the reduced graphene oxide nanosheets were successfully synthesized using th... more Here, we report that the reduced graphene oxide nanosheets were successfully synthesized using the Lactobacillus plantarum biomass in a simple, environmentally friendly and scalable manner. We produced graphene oxide by oxidization and exfoliation of graphite flakes with modified Hummer's method and then reduced to reduced graphene oxide by using Lactobacillus plantarum biomass as a reducing agent. Samples were characterized using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy, scanning electron microscopy, microconfocal raman spectroscopy and thermogravimetric analysis. After the reduction, we observed that a considerable decrease in the oxygen containing functional groups of graphene oxide and an increase in C/O ratio from 1.7 to 3.3 in which confirms sp2 graphitic carbons increase. Mainly, we observed a significant decrease in epoxy and alkoxy functionalities. Furthermore, we determined an exfoliation of g...
Titanium and titanium alloys have been mostly used as biomaterials especially for dental implants... more Titanium and titanium alloys have been mostly used as biomaterials especially for dental implants due to their great combination of high mechanical strength and high corrosion rate. However, one of the most important drawback of them is the insufficient osseointegration. Therefore, the main purpose of this study is to improve the surface properties of Ti6Al4V by anodic oxidation and gold decoration. Initially, the surface of the alloy was anodized to thicken TiO2 layer. Subsequently, gold nanoparticles were produced using Turkevich method. Gold decoration on the oxidized surface were achieved by immersion of the alloy in gold solution after the oxidized alloy surfaces were activated by APTES solution. As a result of surface treatment highly rough surface containing thick oxide layer composed of 20 nm gold nanoparticles in addition to silane groups. Invitro tests displayed no apatite formation in 20 days. Therefore, further tuning is needed on the surface in terms of oxide layer and ...
Turkiye’nin ilk magnezyum alasimi levhasi, ikiz merdaneli surekli dokum teknigi ile uretilmistir.... more Turkiye’nin ilk magnezyum alasimi levhasi, ikiz merdaneli surekli dokum teknigi ile uretilmistir. Magnezyum AZ31, AZ61, AZ91, AM50 ve AM60 alasimi levhalar 4-8 mm kalinliginda, 1500 mm eninde basarili bir sekilde elde edilmistir. Levhalar daha sonra homojenlestirme isil islemlerine maruz birakilmistir. Levhalarin mikroyapilari yuzey, en ve boy yonlerinde optik mikroskop ve Taramali Elektron Mikroskobu (SEM) ile incelenmistir. Daha detayli mikroyapi incelemeleri Gecirimli Elektron Mikroskobu (TEM) ile yapilmistir. Yari nicel ve nicel elementel analizler SEM-EDS (Enerji Dagilim Spektrometresi), TEM-EDS ve EPMA (Elektron Prob Mikro Analiz Cihazi)-WDS (Dalgaboyu Dagilim Spektrometresi) sistemleri ile yapilmistir. X-isinlari difraksiyonu (XRD) teknikleri karakterizasyon ve yonlenme incelemeleri amacli olarak kullanilmistir. Malzemelerin mekanik ozellikleri cekme deneyi ve sertlik deneyleri ile olculmustur. Cekme deneyleri hadde yonu, hadde yonune 45 derece aci ve 90 derece aci olmak uzer...
Ti-6Al-4V is one of the most promising alloys for electron beam melting (EBM) of structural parts... more Ti-6Al-4V is one of the most promising alloys for electron beam melting (EBM) of structural parts due to its outstanding properties and its extensive use in the aerospace, automotive, and energy industries. In this study, we report a detailed and systematic micromechanical characterization of additively manufactured Ti-6Al-4V parts produced via EBM. The specimens were characterized by microhardness, nanoindentation, micropillar compression, and microscratch measurements. The results show that the Ti-6Al-4V exhibits a strong indentation size effect and higher strain rate sensitivity compared to those obtained from macroscale measurements. The high scratch resistance and the high hardness of the alloy at small indentation depths suggest that the EBM-produced Ti-6Al-4V parts can provide good performance in service under sliding wear conditions.
In this study, AZ31 in form of sheet, plate and extruded rod and AZ61 wire with different initial... more In this study, AZ31 in form of sheet, plate and extruded rod and AZ61 wire with different initial grain sizes were used to investigate the effect of initial grain size on recrystallization behavior and the formation of fine recrystallized grain (the so-called necklace) structure. Nucleation and growth of recrystallized grains along grain boundaries has been examined. In order to observe the effect of initial grain size and deformation on static recrsytallization and necklace formation, the specimens were annealed at 100-250°C for 10min--2hr. Specimens are also stretched to a total strain of 10, 20 and 40% at 300°C at an initial cross head speed of 1x10-3 s-1 for dynamic recrystallization studies. The results suggest that there exists a grain size limit, below which a necklace structure is not observed.
Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2009Thesis (PhD) -- İstan... more Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2009Thesis (PhD) -- İstanbul Technical University, Institute of Science and Technology, 2009Türkiye’nin ilk magnezyum alaşımı levhası ikiz merdaneli sürekli döküm tekniği ile üretilmiştir. Magnezyum AZ31, AZ61, AZ91, AM50 ve AM60 alaşımı levhalar 4-8 mm kalınlığında, 1500 mm eninde başarılı şekilde elde edilmiştir. Levhalar daha sonra homojenleştirme ısıl işlemlerine maruz bırakılmıştır. Levhaların mikroyapıları yüzey, en ve boy yönlerinde optik mikroskop ve Taramalı Elektron Mikroskobu (SEM) ile incelenmiştir. Daha detaylı mikroyapı incelemeleri Geçirimli Elektron Mikroskobu (TEM) ile yapılmıştır. Elementel analizler SEM-EDS (Enerji Dağılım Spektormetresi), TEM-EDS ve EPMA (Elektron Prob Mikro Analiz Cihazı)-WDS (Dalgaboyu Dağılım Spektormetresi) sistemleri ile yapılmıştır. X-ışınları difraksiyonu (XRD) teknikleri karakterizasyon ve tekstür incelemeleri amaçlı kullanılmıştır. Malzemelerin mekanik özellikleri çe...
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