Sürdürülebilir Kalkınma Amaçları
Yazarlar
- Dogan, Akar(5)
- Kismet, Yilmaz(5)
- Cemalgil, Selim(4)
- Etli, Serkan(4)
- Wagner, Manfred H.(4)
- Guler, Omer(3)
- Yön, Merve Şahin(3)
- ALMisned, Ghada(2)
- Akgül, Melek(2)
- Akkurt, Nevzat(2)
- Aslan, Naim(2)
- Bahceci, Ersin(2)
- Chen, Xingli(2)
- Gul, Ali Oktay(2)
- Gönen, Tahir(2)
- Kısmet, Y.(2)
- Kısmet, Yılmaz(2)
- Onat, Onur(2)
- Qiang, Yujie(2)
- Taşgın, Yahya(2)
- Tekin, H.O.(2)
- Xiong, Yaxuan(2)
- Xu, Qian(2)
- Yang, Gang(2)
- Yilmaz, Mehmet(2)
- Zheng, Qiang(2)
- Zhong, Liqiong(2)
- Zou, Zhenwei(2)
- Acikgoz, Abuzer(1)
- Agar, Salih(1)
- Akpolat, Mustafa(1)
- Aksakal, B.(1)
- Aksakal, Bunyamin(1)
- Aktas, Bulent(1)
- Albayrak, M. Gokhan(1)
- Arman, Yusuf(1)
- Arslan, Furkan(1)
- Arıkan, Volkan(1)
- Askin, Ali(1)
- Aydoğmuş, Ercan(1)
Yayınlar
- Kitap BölümüAçık Erişim2023Production technique–structure relationship in bioceramic-coated scaffold applications
Aslan, Naim; Topuz, Mehmet; Aksakal, Bunyamin; Dikici, Burak
It is well known that the surface of metal-based implants is very resistive in aggressive body environments due to the noble oxide layer naturally formed on their surfaces. However, their osseointegration properties are very low. By the way, specific cells attached are desired on the implant surface when the surface of an implant connects with tissue in many circumstances. Thus in parallel with technological developments, biomedical engineering focuses on the growth of new tissue on the implant surface or in the porosities of the implant. The bulk properties of metallic scaffolds, especially Young’s modulus, can be controlled by the porosity ratio of the scaffold but cannot form a bond between the implant and tissue interfaces. Thus the coating of scaffold walls with a bioactive material is required. In this chapter, bioceramic coating techniques of scaffolds, mechanical and corrosion behavior, biocompatibility, and interactions of surface/tissue interface, especially considering the last published reports, were reviewed, in detail.
AtıfScopus4OpenAlex4
İncele - MakaleAçık Erişim2023Scopus SJRQ3Effect of glass sand used as aggregate on micro-concrete properties; [Učinak recikliranog stakla kao agregata na svojstva mikrobetona]
Etli, Serkan
Micro-concrete (MC) can be defined as a high-performance cement-based material produced using microaggregates and cement in the required proportions. Owing to its high performance, it has the potential to be used in the structural repairs of existing building elements. Within the scope of this study, an evaluation was conducted by creating a usage scenario under which glass, which is a waste product, can be reduced and applied in a way that provides a sufficient MC performance. There are four different binder contents in the mixtures within the scope of the present study, i.e., 570, 580, 599, and 658 kg/m3. From these mixtures, together with the control mixture, 12 %, 27 %, and 50 % microaggregates were replaced with glass sand and 16 different mixtures with a total of 4 different aggregate contents were produced. For the mechanical, physical, and durability tests, 40 × 40 × 160 mm sized prisms and 50 × 50 × 50 mm sized cubes were produced. For the purposes of this research, mechanical tests were carried out on 144 7-, 28- and 56-day old prismatic specimens. In addition, the effects of a freeze-thaw and temperature on the mechanical properties were investigated on 192 prismatic samples. In determination of the durability, physical properties such as the porosity, sorptivity, and specific gravity were tested and determined using cubic samples. The test results show that the replacement of MA with GS has positive effects on all mechanical behaviours of MC.
AtıfScopus7OpenAlex12İncele - MakaleYalnız künye2023Scopus SJRQ1Analysis of the mechanical behavior and prediction of the plastic zone of a large-diameter buried gas pipeline under ground overload
Xu, Qian; Zhong, Liqiong; Shu, Mengjie; Zou, Zhenwei; Yang, Gang; Zheng, Qiang; Chen, Xingli; Akkurt, Nevzat; Zhang, Hui; Qiang, Yujie
Plastic failure of pipelines caused by ground overload is increasing. The one-dimensional model based on mechanical nodal parameters cannot predict the plastic failure characteristics of the three-dimensional structure of the pipeline. In order to predict the evolution of the plastic failure of the pipeline with the yield strength as the evaluation criterion, a multidimensional model is needed to consider the changes in the external loads and the changes in the mechanical properties of the pipeline along the circumferential and axial directions. In this study, a finite element calculation model for a large-diameter gas pipeline underground overload was established to investigate the law of stress change in the plastic zone. The nonlinear surface fitting method was used to establish the angle fitting model of the plastic zone and the depth fitting model of the plastic zone. The variation of the area of the plastic zone was described, and the reliability of the results was verified. In addition, the accuracy of the fitting model and the cost of the finite element calculation were evaluated. The results showed that the pipeline entered plasticity at a ground load of P = 25 MPa, and the plastic zone developed continuously in the axial and circumferential directions as the ground load increased. The angle and depth increased to 36° and 1.8 m, respectively, at P = 50 MPa. The average absolute errors for the plastic zone depth fitting model and the plastic zone angle fitting model were 6.42% and 6.64%, respectively, both of which can provide an accurate description of the plastic zone. The calculation results of the plastic zone angle fitting model could meet requirements of data processing and analysis. The plastic zone depth fitting model could be used to obtain solutions with higher accuracy, but it increases the cost of finite element simulation.
AtıfScopus6OpenAlex6
İncele - MakaleAçık Erişim2023Scopus SJRQ3Morpho-structural and compressive mechanical properties of graphene oxide reinforced hydroxyapatite scaffolds for bone tissue applications
Fidan, Ferzan; Aslan, Naim; Koç, Mümin Mehmet
Hydroxyapatite (HA) is a unique material that has the potential to be used to replace bones and teeth in the field of orthopedics and dentistry since HA exhibits quite similar biological and chemical characteristics to human bone. Hydroxyapatite ceramics are bioactive materials used to repair damaged human tissue. The pores in the porous hydroxyapatite ceramics provide a mechanical interlock, enabling a solid bond and fixation between the implant and bone. In this study, 0.5wt%, 1wt%, and 1.5wt% graphene oxide (GO) reinforced porous HA structures were obtained using the space-holder method to increase the strength of hydroxyapatite with low mechanical strength. NaCl was used as a spacer, and PEG 400 as a binder. Scaffold structures with 40% porosity rates were sintered at 1000 °C under vacuum. Finally, a compression test was applied to the samples which were previously analyzed by SEM, EDS and XRD. The compressive strengths of 0.5%, 1%, and 1.5% graphene oxide reinforced porous HA samples were determined between 8.04 and 31.14 MPa. The highest compressive strength was recorded as 31.14 MPa in the 1% GO added sample, and the lowest compressive strength was recorded as 8.04 MPa in the 1.5% GO added sample. In addition, it was understood that the mechanical properties did not increase regularly with the increase of graphene oxide reinforcing.
AtıfScopus4OpenAlex3
İncele - Yüksek Lisans TeziAçık Erişim2022Nadir toprak elementleriyle katkılandırılmış borat camların fiziksel ve radyasyon zırhlama özelliklerinin incelenmesi
İlyas İzgüden
Bu çalışmada Ülkemizde yer alan zengin bor madeni rezervinin daha verimli kullanılması amacıyla ana maddesi bor oksit olan ve içerisine yine ülkemizde ham madde olarak bulunan ve yeni keşifler ve incelemelere konu nadir toprak elementleri katkılanarak hazırlanan ve kurşun katkılı camlara alternatif olabilecek ve yüksek teknoloji ürünlerinde (Akıllı cihaz ekranları, uzay ve sağlık teknolojileri gibi) kullanılabilecek yeni nesil radyasyon kalkanlayıcı camlar üretmektir. Üretimi yapılan ürünlerin öncelikle XRD yöntemi ile faz tanımlaması yapılmış ve numunelerin amorf yapısına sahip cam olduğu belirlenmiştir. Üretilen numunelerin FTIR yöntemi ile kimyasal bağları ve moleküler yapıları araştırılarak düzgün bağlar oluşturan camlar olduğu belirlenmiştir. Elde edilen numunelerin UV-Vis Spektroskopisi yöntemi ile ışık geçirgenliği ve soğurma spektrumları belirlenerek normal cam karakteri gösterdiği belirlenmiştir. Camların camsı özelliklerinin iyi sonuçlar verdiği tespit edilmiş ve mekanik özelliklerden yoğunluk, sertlik, kırılma toklukları ve gevreklikleri incelenmiş ve sonuçları değerlendirilmiştir. Cam örneklerinin radyasyon zırhlama ölçümleri Atatürk Üniversitesi Fen Fakültesi Fizik Bölümü Prof. Dr. Wolf Weyrich Yüksek Enerji Spektroskopisi Laboratuvarı'nda bulunan deney düzeneği kullanılarak yapılmış ve cam örneklerinin kurşun katkılı camlara alternatif olabilecek seviyede radyasyon kalkanlama yaptığı belirlenmiştir. Bu çalışmanın amacı yapılan nadir toprak elementleri katkılı borat camlarda radyasyon zırhlamanın yanı sıra mekanik ve fiziksel özelliklerinin iyileştirilmesinde yardımcı olacak bir yayın (Tez) oluşturarak bilimsel çözümler sunmaktır.
- Yüksek Lisans TeziAçık Erişim2022Dolgu takviyeli plastiklerde üretim parametrelerinin optimizasyonu için hibrit bir model önerisi
Rifat Kerim Özbek
Polimerleri üretip, şekillendirmeye başladığımız andan itibaren birçok sektörde endüstrinin ve ekonominin gelişmesine katkı sunan önemli bir büyüme yaşanmıştır. Bu sebeple polimer bilimi üzerindeki araştırma ve geliştirme faaliyetleri hızla artmış ve günümüzde malzeme biliminin gelişmesi ile polimerik malzemeye dayalı kompozit üretimi yaygınlaşmıştır. Düşük ağırlığı, yüksek mukavemeti, şekillendirme kolaylıkları ve düşük maliyeti nedeniyle plastikler diğer hammaddelere göre tercih edilir. Plastikler yaygın olarak kullanılmasının yanı sıra malzeme bilimindeki gelişmeler ile birçok ihtiyaca cevap verebilmektir. Plastik sektörün ihtiyaçlarını karşılamak için üretim ve kalite parametrelerinin bir modelle çözümlenip, planlanabilir bir yapı içinde sunulması işletmeler için oldukça önemlidir. Bu çalışmada termoplastiklerin yaygın olarak kullanılan poliolefinler grubuna ait alçak ve yüksek yoğunluklu polietilen matris malzeme olarak kullanılmış ve midye tozu ile güçlendirilerek veri setinin karakteristiğini etkin bir biçimde yansıtacak deney numuneleri üretilmiştir. Üretim parametrelerini modelleyebilmek için regresyon modelleri oluşturulmuştur. Regresyon modelinde kuvvet bağımlı değişken ve birincil basınç, ikincil basınç, kullanılan deniz kabuğu ile plastik malzemenin kalıpta soğuma süresi ve plastiğin cinsini gösteren bir kukla değişken kullanılmıştır. Üretim parametrelere uygun numuneler ve bu parametrelerin maksimum kuvvet ve maksimum gerilmeye hangi oranda etki ettiği matematiksel olarak belirlenmiştir. Gerilme ile kuvvet tahmininde bölge basınçları, dolgu malzemesi oranı ve soğuma süresinin malzemenin mekanik davranışı üzerinde etkisi incelenmiştir.
- MakaleYalnız künye2022Scopus SJRQ1Dynamic response model and equivalent solution method of large-diameter buried energy transportation pipeline under moving load
Xu, Qian; Yang, Gang; Li, Zhuorui; Zou, Zhenwei; Zheng, Qiang; Zhong, Liqiong; Chen, Xingli; Akkurt, Nevzat; Du, Yanping; Xiong, Yaxuan
Long-distance energy pipeline pass under roads, subjecting them to repeated stress and posing pipeline safety problems. To simulate the effects of vehicles driving over energy transmission pipeline, this paper examines large-caliber buried pipelines in the suburbs. In this study, a mechanical action model of vehicle-soil-pipeline (VSP) interactions to transform the process of a vehicle driving into the dynamic process of a load changing with time in the specified area was created. The VSP model was used to analyze the influence of moving load and position on the structural characteristics of the pipeline section. An equivalent solution method with high precision and high calculation efficiency was proposed. The results showed that as the loading position approaches the pipeline or the load increases, the stress value at the top of the pipeline gradually exceeded the stress value at the bottom of the pipeline and became the area with the maximum stress value. The minimum stress location also changed from the lower half near the pipeline bottom (Point D-135°) to the upper half near the pipeline top (Point B-45°or Point H-315°). Using the polynomial fitting method, the stress values of the maximum points were equivalently converted. Under the premise of considering pipeline safety, the most suitable functional relationship for the moving load equivalent model was obtained.
AtıfScopus16OpenAlex13İncele - MakaleAçık Erişim2022Scopus SJRQ1Evaluation of the mechanical properties and durability of self-compacting alkali-activated mortar made from boron waste and granulated blast furnace slag
Yön, Merve Şahin; Karataş, Mehmet
The production of high-strength alkali-activated mortar and concrete by using waste materials instead of cement in order to reduce the amount of carbon dioxide released to nature in cement production is an important study that attracts the attention of researchers. In this study, self-compacting alkali-activated mortar samples were produced using boron waste (BW) and granulated blast furnace slag (GBFS). Prismatic samples of 40 × 40 × 160 mm and cubes of 50 × 50 × 50 mm were produced, in which 0%, 5%, 10%, 15%, 20%, 25% of BW were used. To achieve self-compacting alkali-activated mortar (SCAAM) slump-flow test method was conducted by per The European Federation of Specialist Construction Chemicals and Concrete Systems (EFNARC) guidelines. The samples prepared using Na2SiO3 (NS)/NaOH (NH) = 3.0 were exposed to oven curing at 60 °C and 100 °C for 3 days. The flexural and compressive strength (CS) values of 3, 28 and 90 days were obtained for the samples whose curing period was completed. According to the mechanical strength results, influence of capillary water absorption, porosity, water absorption and density and freeze-thaw from durability tests were carried out. After experimental tests, Scanning Electron Microscope (SEM) and Energy-dispersive X-ray Spectroscopy (EDS) images were utilized to determine microstructures of the samples. As a result of the study, it was determined that the highest strengths were obtained at the curing temperature of 60 °C. Also, it was seen that mechanical strengths and durability decreased with the increase in the BW ratio in the mixtures.
AtıfScopus31WoS28OpenAlex33İncele - MakaleAçık Erişim2022Scopus SJRQ1Newly synthesized NiCoFeCrW High-Entropy Alloys (HEAs): Multiple impacts of B4C additive on structural, mechanical, and nuclear shielding properties
Gul, Ali Oktay; Kavaz, Esra; Basgoz, Oykum; Guler, Omer; ALMisned, Ghada; Bahceci, Ersin; Albayrak, M. Gokhan; Tekin, H.O.
High-Entropy Alloys (HEAs) are regarded as potential structural materials for fusion and next-generation fission reactors, which will be required to fulfil growing nuclear energy demands. In this study, a HEA-composite was synthesized by adding B4C to an HEA containing Ni. The microstructure of the obtained HEA-composite was examined and the changes in its mechanical properties were revealed. Additionally, the nuclear radiation shielding properties of the Ni-containing HEA, and the HEA-composite are investigated using experimental and theoretical methods. Our initial findings showed that with the addition of 2.5% B4C to the alloy, the hardness increased more than two times. The addition of B4C to the HEA matrix resulted in a more than 90% and a nearly twofold increase in compressive strength. The shielding qualities of gamma-ray and neutron radiation were investigated using experimental and theoretical approaches. Our findings demonstrated that increasing the B4C reinforcement considerably enhanced the composite material's neutron attenuation capabilities. On the other hand, no significant change in the gamma-ray shielding characteristics of HEA and HEA-composite samples was observed. The gamma-ray shielding characteristics of HEA and HEA-composite samples were compared to those of other alloy shields and commercial products. Our findings indicate that both HEA and HEA-composite samples exhibit superior gamma-ray shielding characteristics when compared to the control samples. It can be concluded that increasing B4C reinforcement may be a multifunctional tool in terms of improving the mechanical properties as well as neutron attenuation properties for advanced applications in nuclear radiation facilities and next-generation fission reactors. Additionally, due to their promising material features and higher gamma-ray shielding capabilities compared to other kinds of alloys and commercial shields, HEAs may be beneficial materials.
AtıfScopus33OpenAlex31İncele - MakaleAçık Erişim2022Scopus SJRQ1High-temperature and abrasion resistance of self-compacting mortars incorporating binary and ternary blends of silica fume and slag
Yön, Merve Şahin; Arslan, Furkan; Karatas, Mehmet; Benli, Ahmet
Researchers from all over the world have recently developed an interest in the utilization of waste materials in the concrete industry. Using silica fume (SF) and ground granulated blast furnace slag (S) to manufacture self-compacting mortars (SCMs) could be a step toward sustainable waste management and produce the unique fresh qualities needed for SCMs. This research evaluates the abrasion and high-temperature resistance of SF and S based SCMs. A total of 14 mixtures were designed by partially replacing SF and S with Portland cement (PC) including control, binary and ternary mixtures. Binary mixtures were obtained by replacing cement by SF and S at replacement rates of 5, 10, 15 and 20 % and 10, 20, 30 % by weight respectively. Ternary mixtures were determined at the rates of 5, 10, 15 and 20 % SF and 10 and 20 % S respectively. The flexural strength and compressive strength of SF and S based binary and ternary water curing SCMs samples were determined at the age of 7, 28 and 90 days at room conditions. SCMs specimens were exposed to high temperatures after 90-day water curing. Water absorption, apparent porosity, sorptivity and abrasion resistance of 28-day water cured SCMs samples was also determined. The fresh and rheological properties of SCMs was evaluated by conducting mini-slump flow and viscosity tests. Cost analysis of the SCMs were also performed. The experimental results exhibited that the flowability of SCMs mixes containing SF was reduced with the increasing rate of SF compared to control while the workability of S incorporated SCMs mixes increased with the increase of S in comparison to control mixtures. Late- age of compressive strength above 70 MPa was achieved for 20 % SF incorporated binary mixture and 15 %SF and 10 % S incorporated ternary mixture. The ternary mixture with 15 % SF and 10 % S also exhibited the best abrasion resistance and the lowest sorptivity. Overall, it can be concluded from the mechanical characteristics and abrasion resistance that ternary combination of S with SF content of especially above 10 % and can be used to manufacture self-compacting mortar with a smaller carbon footprint.
AtıfScopus60WoS56OpenAlex62İncele - MakaleAçık Erişim2022Scopus SJRQ2Investigation of the Effects of Deformation Aging Applied to AA 7075 Aluminum Alloy on Mechanical and Metallographic Properties
Taşgın, Yahya; Ergin, Ramazan
Aging is quite important in improving the mechanical properties of aluminum alloys. One of the most widely used Al alloys is AA7075 aluminum alloy. Since AA7075 aluminum alloys contain aluminum-zinc-magnesium-copper, various aging processes have been applied to improve their mechanical qualities, and as a result, they have become commercially available. When this aluminum alloy series with increased strength is subjected to any thermal effect in industrial use, the loss of mechanical properties can be reduced by applying deformation aging. In this study, the effect of deformation aging on the mechanical properties of commercially available aluminum alloy has been determined and the relationship between mechanical properties and microstructure examined. Deformation aging was applied to 7075 Al alloy in our study by cooling in air, water and oil at temperatures of 120–180 °C for 2–24 hours. Structural differences were revealed by examining the effects of heat treatment on the mechanical properties and machinability properties of the alloy. As a result of the study, it was observed that metallographic precipitation occurred in the AA7075 Al alloy, and accordingly, intermetallic phases were formed. It is thought that various nanoscale fine precipitates occurring in the matrix of this alloy can also prevent dislocation movements. The study has positive effects on the mechanical properties of the material.
AtıfScopus9WoS6OpenAlex8İncele - MakaleYalnız künye2022Scopus SJRQ2Characterization of the mechanical and thermal properties of rape short natural-fiber reinforced thermoplastic composites
Kısmet, Yılmaz; Dogan, Akar
In this study, the effects of filler amounts were studied on the mechanical and thermal properties of high-density polyethylene (HDPE), polystyrene (PS) and polyoxymethylene (POM) polymers reinforced with short rape fibers. HDPE-rape, POM-rape and PS-rape fiber composite materials were prepared with different fiber contents and their tensile, flexural, Izod impact and TGA/DTA properties were examined. When tensile and Izod impact properties were compared, it was observed that an increase in the amount of filling in HDPE-based composites did not cause any significant changes in these peoperties, while they were decreased for POM- and PS-based composites. On the contrary to tensile and impact strengths, when the three-point flexural properties were examined, it was observed that the strength values of all these materials increased with increasing the amount of fillers. However, a pronounced increase was observed in the three-point flexural strength of the HDPE-based composite materials. The flexural strength of 30 wt% rape-reinforced HDPE composite was found to be twice that of the pure HDPE. The results of TGA and DTA analyses revealed that the reinforcement element started to burn before the matrix material and therefore burning was delayed in these thermoplastics. As a result, the mechanical properties of HDPE composite materials improved with rape reinforcement. In this way, by using approximately 30 wt% natural filling material in a polymeric matrix, an environmentally friendly material, as well as, significant advantages in cost can be obtained. Graphic abstract: [Figure not available: see fulltext.].
AtıfScopus25WoS25OpenAlex33İncele - MakaleAçık Erişim2021Scopus SJRQ1Thermoset powder coating wastes as filler in LDPE – Characterization of mechanical, thermal and morphological properties
Kismet, Yilmaz; Dogan, Akar; Wagner, Manfred H.
In this study, three different electrostatic powder coating wastes of thermoset structure were used as fillers for low-density polyethylene (LDPE). The mechanical, thermal, and morphological properties of these composites materials are reported. The thermoset powder coating wastes were hydrolyzed using water and alcohol, and then 10%, 20%, and 30% by weight of the deactivated wastes were mixed with LDPE, first in a mechanical dry mixer, and subsequently homogenized by melt compounding in an extruder at about 160 °C. Standard tensile test bars and plate-shaped samples were produced from these homogeneous compounds by injection molding. The effects of adding hydrolyzed powder coating wastes on the properties of LDPE were determined by mechanical, thermal, and morphological tests. Tensile strength and perforation threshold of the sample filled with powder coating wastes decreased to some extent compared to un-filled sample. However, an increase in izod impact and bending strengths has been observed. The results of this investigation demonstrate that powder coating wastes with thermoset structure can be used as fillers in LDPE.
AtıfScopus13WoS15OpenAlex16İncele - MakaleYalnız künye2021Scopus SJRQ2Radiation shielding and mechanical properties of Bi2O3–Na2O–TiO2–ZnO–TeO2 glass system
Sayyed, M.I.; Askin, Ali; Zaid, M.H.M.; Olukotun, S.F.; Khandaker, Mayeen Uddin; Tishkevich, Daria I.; Bradley, D.A.
Recently, heavy metal oxides (HMO) based glass systems attracted great attention to the scientific community to be used as an alternative to the conventional lead, lead composites and concrete based materials for protection of harmful radiation. In this work, we report the role of Bi2O3 on the mechanical and radiation shielding properties of Bi2O3–ZnO–TiO2–Na2O–TeO2 glass system as well as its mechanical behaviour. The mechanical properties of the glasses were calculated using Makishima-Mackenzie model and different shielding factors have been calculated using Monte Carlo simulation via Geant4 code and also using Phy-X software. The mechanical properties based on Makishima-Mackenzie model depend on the values of packing density (Vi) and dissociation energy (Gi) of the oxide constituents. The simulated values of the mass attenuation coefficient showed a good agreement between both approaches. The mass attenuation coefficient (MAC) at 0.284 MeV of the glass with 5 mol% of Bi2O3 is equal to 0.2083 cm2/g, at 0.662 MeV its equal to 0.0785 cm2/g, while at 1.33 MeV, its MAC is 0.0501 cm2/g. The transmitted percentage of the photons through the proposed glasses was found to rise with increasing the energy of the photon, while decreasing with rising the thickness of the glass sample. The transmission factor (TF) revealed that the greater the thickness of the glass, the lower the TF, and the better the shield. Also, the radiation protection efficiency of the glasses was enhanced with the addition of the Bi2O3. The glass sample with composition of 15Bi2O3–10ZnO–5TiO2–5Na2O–65TeO2 possesses the highest effective atomic number among the studied compositions and showed the lowest half value layer. From the obtained data, Bi2O3 seems to be a strong candidate for enhancing the gamma radiation attenuation factors in the bismuth-based tellurite glasses.
AtıfScopus77OpenAlex78İncele - MakaleYalnız künye2021Scopus SJRQ1Effect of waste textile dye adsorbed almond shell on self compacting mortar
Cemalgil, Selim; Onat, Onur; Tanaydın, Mehmet Kayra; Etli, Serkan
The aim of the current experimental study is to investigate the effect of waste textile dye absorbed almond shell on fresh and mechanical characteristics of self-compacting mortar (SCMs). In this context, eight SCMs were designed by substituting Violet Dye Solution adsorbed Almond shell (VDSA) at the rate of 0%, 2.5%, 5.0%, 7.5%, 10.0%, 12.5%, 15.0% and 17.5% as a cement on weight basis including the control mix. To measure the rheological properties of SCMs, mini slump and V-Funnel tests were conducted. A total of 72 beams of 40x40x160 mm3 dimension specimens were casted and immersed in water curing at the end of the 7, 28 and 56 days to determine the mechanical parameters. 48 cubes of 50x50x50 mm3 dimensions were casted and kept in the curing tank to determine durability characteristics such as porosity, sorptivity and specific gravity. Quantitative analyses are also performed by using Scanning Electron Microscopes (SEM), X-ray Diffraction Analysis (XRD), Energy-Dispersive X-ray Spectroscopy (EDS) and Fourier Transform Infrared (FTIR). The experimental results indicated that as the content of VDSA enchases, a remarkable enhancement in flexural strength at early days age and 28 days age strength. Whereas, increasing the content of VDSA resulted in a considerable decrease in compressive strength higher than 5%.
AtıfScopus20WoS16OpenAlex26İncele - MakaleYalnız künye2020Scopus SJRQ1Mechanical, thermal, and morphological properties of powder coating waste reinforced acetal copolymer
Kismet, Yilmaz; Wagner, Manfred H.
The present study investigates the individual effects of three different thermosetting waste materials, used as fillers, on the mechanical, thermal and flow properties of acetal copolymers (POM). Different amounts ranging from 5% to 30% by weight of hydrolyzed powder coating recyclates were mixed as filler material in POM. The matrix and the fillers were first dry-mixed and then compounds were prepared through melt extrusion. The resulting compounds were cooled, granulated, and then standard tensile test bars were produced through use of an injection-molding machine. We investigated the mechanical and thermal properties of test specimens, and tensile strength, bending strength and impact strength were evaluated as a function of type and amount of filler material in the POM matrix. In addition, the change in melt flow index of POM/filler mixtures was determined, before and after extrusion. Furthermore, the morphology of the specimens was examined via electron microscopy. The results of this investigation are encouraging and present an innovative approach to reutilize hydrolyzed electrostatic powder coating wastes with thermoset structures as fillers in acetal copolymers.
AtıfScopus10WoS8OpenAlex13İncele - MakaleYalnız künye2020A RESEARCH FOR BACTERIAL SELF-HEALING IN METAKAOLIN BASED GEOPOLYMER MORTARS
Yilmazer Polat, Berivan; Uysal, Mucteba; Korkmaz, Volkan
Cement production is a polluting process for nature. For this reason, new types of concrete which can be produced with recycled materials and without cement continue to be investigated. On the other hand; cracks in structural elements reduce the strength and durability of a building. Extending service life of buildings has eliminated the cost of rebuilding and thus, contributed to both the economy and the ecosystem. Due to this, research on crack healing in Portland cement concretes with various bacteria is continuing for some time. However, there are not enough studies in literature regarding the improvement of metakaolin-based geopolymer mortars produced without using cement by urolytic bacteria. The parameters of temperature, pH and void ratio of bacterial geopolymer mortar affect the viability of bacteria. For example, pH value of the medium required for the survival of bacteria is, generally around nine. During the production of geopolymer concrete, a sudden increase in high alkali environment occurs due to use of activators. This reduces the survival rate of bacteria added to the mixture during the production of geopolymer mortar. In this study, the most suitable environment for geopolymer mortar, and the conditions for the bacteria to survive until the end of the curing process for the mortar to be strengthened were investigated. Analyses on the effects of urolytic bacteria and geopolymer mortar healing process on mechanical strength of the mortar were conducted. Sporosarcina Pasteurii were used for the self healing process. Various mixtures of geopolymer mortars were cured under different environmental conditions to observe changes in their mechanical strength and water absorption capacity. As the result of the study, the most suitable mixture ratio and curing medium were identified. It was observed that the nutrient, ensuring the life cycle of the urolytic bacteria, had no negative effect on the mechanical strength of mortar and reduced capillary water absorption of the mortar. This study is a specific text in the literature that analyzes bacterial curing conditions and the effect of improving geopolymer mortar.
AtıfScopus14İncele - MakaleYalnız künye2019Scopus SJRQ3Utilizing hydrolyzed powder recyclates as filler in polystyrene; [Verwendung von hydrolisierten Pulverlackrecyclaten als Füllstoff in Polystyrol]
Kismet, Y.; Wagner, M.H.
In the present study, hydrolyzed powder coating wastes were used as filler materials in polystyrene compounds, and the effect on the mechanical properties, melt flow index and density of polystyrene compounds were investigated. Epoxy/polyester, epoxy and polyurethane systems with thermoset structure were used as powder coating recyclates. After separately hydrolyzing these wastes, 5 %, 10 %, 20 % and 30 % by weight were homogeneously mixed with polystyrene, initially mechanically and subsequently with an extruder in the melt at 180 °C. The resulting compounds were cooled and granulated, and by use of an injection molding machine at 180 °C to 200 °C, standard tensile test bars were produced. Tensile strength, bending strength and izod impact strength of the test bars were measured and the variations of the mechanical properties of the polystyrene compounds as a function of the type and amount of filler were examined. In addition, melt flow index and density of the compounds were determined. Furthermore, the bonding mechanism of filler and matrix material was examined by electron microscopy.
AtıfScopus2WoS2OpenAlex3İncele - MakaleAçık Erişim2018Scopus SJRQ4The effect of hygrothermal aging on the glass and carbon reinforced epoxy composites for different stacking sequences
Dogan, Akar; Arman, Yusuf
The present paper examines the effects of hygrothermal aging on the reinforced epoxy composites. The roles of reinforcement types and stacking sequence on the mechanical properties of composites under hygrothermal aging are investigated. Four different composite materials with different stacking sequence were produced. Unidirectional E-glass and carbon fabrics with an areal density 300 gr/m2 as reinforcement and epoxy as matrix were used. Composites were manufactured using vacuum-assisted resin infusion molding. In order to determine the mechanical properties of the composites, specimens were prepared according to the ASTM standards. The aging process was carried out in climatic test cabin at a temperature of 90oC and a humidity of 90%. As a result of the tests, while the tensile strength of the glass reinforced composites decreased with aging time, no significant change was observed for carbon and hybrid composites. On the other hand, the tensile strength decreased in the transverse direction for all types of composites. XPS analysis was used to understand the distribution of atoms on the surface of specimens.
AtıfScopus22WoS19OpenAlex23İncele - MakaleYalnız künye2018Scopus SJRQ2Mechanical and flow properties of blends of polypropylene and powder coating recyclates with and without addition of maleic anhydride
Kismet, Yilmaz; Wagner, Manfred H.
In this research, from 10% to 40% by weight of hydrolyzed powder coating recyclates were used as filler in polypropylene (PP). Firstly, PP and filler were dry-mixed and then, in order to get a homogeneous mixture, were extruded at 180°C. The resulting compounds were cooled and granulated, and by use of an injection molding machine at 180–200°C, standard tensile test bars were produced. Tensile stress, three-point bending strength, and izod impact strength of these specimens containing different types of filler and different filler concentrations were tested. The results are presented, and the effects of type and content of hydrolyzed powder coating waste on the mechanical properties of polypropylene are discussed. Also, the change in melt flow index of polypropylene as a function of filler content is analyzed. Furthermore, the bonding mechanism of filler and matrix material was examined by electron microscopy.
AtıfScopus12WoS10OpenAlex13İncele