Yazar "Uslu, Emin" seçeneğine göre listele
Listeleniyor 1 - 13 / 13
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Cu İLAVESİNİN ALÜMİNYUM ALAŞIMLARININ KOROZYON ÖZELLİKLERİNE ETKİSİNİN İNCELENMESİ(E-Journal of New World Sciences Academy, 2017) Çatar, Recep; Uslu, Emin; Çolak, MuratAlüminyum döküm alaşımları başta ağırlık/dayanım oranının yüksek olması gibi korozyon dayanımı, yüksek termal iletkenlik, iyi işlenebilirlik süneklik gibi birçok avantajlı özelliği sahiptir. Bu sebeple birçok endüstriyel alanda kullanılmakta ve özellikle otomotiv sektöründe kullanımı her geçen gün daha da artmaktadır. Ancak kullanım yerine bağlı olarak alaşıma çeşitli alaşım ilaveleri ile belirli özelliklerinin artması beklenmektedir. Bu yönde çalışmalar artan ihtiyaç ve kalite beklentileri doğrultusunda devam etmektedir. Al alaşımına Cu ilavesi ile mekanik özelliklerin artırmakla birlikte korozyon direncinde azalmaya neden olmaktadır. Bu çalışmada, ticari saflıkta (%99.8 Al) Alüminyum alaşımına farklı oranlarda (%2-%6-%8) Cu ilave edilerek kum kalıba döküm yöntemi ile Al-Cu alaşımları üretilmiştir. Çalışmada spektrometro ile kimyasal bileşim belirleme, yoğunluk ölçümleri, mikro yapı ve SEM incelemeleri ile elektrokimyasal davranışları incelenmiştir. Cu ilavesinin alüminyum alaşımlarının korozyon özelliklerine etkisi; %3.5 NaCI çözeltisi içerisinde potansiyodinamik polarizasyon yöntemi ile araştırılmıştır. Deneyler sonucunda, Cu ilavesi arttıkça Al alaşımının korozyon direncini azaldığı tespit edilmiştir.Öğe Design and Production of 2-Axis Shaking Table(Bayburt University, 2020) Tayfur, Bilal; Uslu, Emin; Can, Ömer; Cihan, Ahmet; Öztekin, ErtekinToday, many analytical methods developed to predict the behavior of structures under dynamic effects and software based on these methods have been developed and presented to the service of engineers. However, it is not possible for these softwares to predict some possible damages in the structures with absolute accuracy. At this point, shaking tables can sometimes be used to reveal the dynamic behavior of the scaled models of the structures. However, these devices often have high costs. Within the scope of this study, a 2-axis (X and Y) shaking table has been developed. The device, which has a table size of 70x70 cm, has a ± 25 cm stroke length and is designed to be able to apply both cyclic and predefined earthquake movements. Unlike common biaxial systems; Thanks to the developed joint system, equal distribution of the loads on both axes is ensured. The parts of the system that require real-time management are written in C, and the computer interface software is written in C#. The drive system is provided by servo motors for stable operation of the system under high weights. As a result of the experiments carried out after the production, it has been observed that the error margin of the system remains below 1 percent.Öğe Determination of mechanical properties of polymer matrix composites reinforced with electrospinning N66, PAN, PVA and PVC nanofibers: A comparative study(Elsevier, 2021) Uslu, Emin; Gavgali, Mehmet; Erdal, Mehmet Okan; Yazman, Sakir; Gemi, LokmanFiber-reinforced polymer matrix composites are widely used in many structural applications thanks to their exceptional properties. In recent years, the use of electrospinning nanofibers with unique properties as reinforcement agents has attracted a great deal of attention in improving the performance of these composites. Although there are many promising studies on this subject in the literature, there are still many issues that need to be investigated. In this study, an experimental research reporting on the production and mechanical properties of two-phase polymer matrix composites reinforced with various types of thermoplastic nanofibers is presented. Nanofiber mats were produced from N66, PAN, PVA, and PVC polymers by electrospinning technique. Composites were obtained by embedding these nanofibers into epoxy resin by using vacuum infusion process. Mechanical properties of the composites were determined by performing tensile tests and the results were compared. The morphologies of nanofibers and the fracture surfaces of the composites were examined with SEM. Finally, statistical evaluations were carried out using mechanical data. According to tensile test results, the best ultimate tensile strength of 38.04 +/- 3.7 MPa, elongation of 2.46 +/- 0.4 % and toughness of 532 +/- 137 kJ/m(3) were obtained from N66 nanofiber composite, while PVA nanofiber composite was the most favorable in terms of Young's modulus (2.40 GPa). It was observed that the polymer type significantly affected the performance of the composite. In addition to the best mechanical properties, N66 composite was found to be more stable and reproducible than other specimens. Due to the good impregnation of nanofibers, it was conclusively determined that the use of vacuum infusion process is suitable for the production of these materials.Öğe The effect of cooling plate, mechanical vibration, and grain refinement on the microstructure and hardness of A380 produced by sand mold(Taylor & Francis Ltd, 2024) Uslu, Emin; Tigli, Ahmet; Colak, MuratThe mechanical properties of aluminium alloys can be increased by controlling the grain size and morphology of the alloy. In these studies, mechanical vibration, cooling slope plate (CSP), and grain refiner were applied on sand mould casting using A380 alloys. The hardness, and microstructure of the cast samples are investigated. These processes lead to the refinement of grain structures and a decrease in the tendency for dendritic structure formation. The Effect of the solidification time (modulus) on the microstructure is investigated. It was determined that the solidification time varies depending on the section thickness, which affects the SDAS values. It was observed that the lowest SDAS values were in CSP and the highest values were in grain refiners added casting. The lowest hardness value was recorded at CSP casting. Meanwhile, the grain refiner added vibration casting exhibits the highest hardness.Öğe Evaluation of Fe Content on the Fluidity of A356 Aluminum Alloy by New Fluidity Index(Springer Int Publ Ag, 2024) Durmus, Melek; Dispinar, Derya; Gavgali, Mehmet; Uslu, Emin; Colak, MuratElements that are deliberately added to aluminum alloys or are incorporated into the alloy later depending on the production process affect the final product properties. In addition, liquid metal cleaning is important in minimizing undesirable elements. Considering the production process, one of the most harmful impurities that is likely to pass into the alloy via diffusion for aluminum is the element, Fe. It is known that this is due to the fact that although Fe is highly soluble in liquid aluminum and its alloys, it has very little solubility in solids. Depending on the Fe content, mechanical properties, porosity and fluidity properties are affected in aluminum alloys. In this study, stainless and carbon steel rods were dipped into the melt at 700 degrees C and 750 degrees C for 1, 2 and 5 h. Castings were performed before and after degassing. Four-channel fluidity mold with different section thickness was used in the trials. Additionally, microstructure characterization was performed under varying casting conditions. Fluidity Index was proposed which is a single value measured from all fluidity values in different sections. When the results were examined, it was determined that the diffusion material, holding time, casting temperature and liquid metal cleanliness had an effect on the fluidity. Due to the increase in diffusion time, a decrease in fluidity was observed in both carbon steel and stainless steel. It was found that fluidity was significantly reduced when using stainless steel.Öğe Experimental Investigation of Springback of DC Series Steel Sheet in V-Bending Process(Bayburt University, 2019) Uslu, Emin; Tosun, NihatSheet materials, which are commonly used in sectors such as automotive and whitewares, are usually formed by applying bending operations. The most important problem encountered in bending processes is springback. Springback problem arising from elastic behavior of the material complicates the assembly of manufactured part due to dimensional differences and causes financial loss. For this reason, it is required to properly estimate the springback behavior to provide the dimensional integrity and cost savings of the shaped parts as a result of the bending operations. In this study, the springback behavior of DC series sheet metals forming by V bending was experimentally investigated the different process parameter of material quality, thickness, rolling direction and die angle. The sheet metals have the quality of DC01, DC04 and DC05 and the thickness of 1, 1.5 and 2 mm. The V-bending dies have 60, 90 and 120o angles. From the experimental studies, it is seen that the behavior of springback changes depending on the die and the process parameters.Öğe Importance of Melt Cleaning Parameters on Reliability of Tensile Properties in A356 Alloy(Springer Int Publ Ag, 2025) Tigli, Ahmet; Uslu, Emin; Colak, Murat; Dispinar, DeryaThis study examines how melt treatment and pouring temperature affect the microstructure and mechanical properties of A356 aluminum alloy. Samples were cast under degassed, non-degassed, and upgassed conditions at 725, 750, and 775 degrees C. Melt quality was assessed using the reduced pressure test (RPT) and the bifilm index (BI), while microstructural features were analyzed via SEM and EDS. Tensile testing and Weibull statistics were used to evaluate mechanical performance and variability. Results showed that by improper degassing the reproducibility of mechanical properties decreased regardless of hydrogen content of the melt. When bifilm index (BI) was high (> 50 mm), the ductility was lowered and caused greater variability in strength and elongation. SEM confirmed large oxide films in samples, linked to the brittle fracture. The work also highlighted the importance of melt cleaning parameters for the reliability of cast aluminum alloys regardless of the hydrogen content.Öğe Investigation of Liquid Metal Cleanliness Control Methods Applied to Aluminum Alloys(Bayburt University, 2022) Tokatlı, Mehmet; Uslu, Emin; Çolak, Murat; Yüksel, ÇağlarIn industry, aluminum is produced from ore (primary aluminum) and scrap materials (secondary aluminum). The use of secondary aluminum is very common in the casting industry, with its contribution to the country's economy through recycling, as well as to the competitive market and the manufacturer. However, the advantage of secondary aluminum depends on the cleaning of factors such as inclusions, impurities, hydrogen gases, oxide films in the structure. Liquid metal cleaning is very important in the use of aluminum through recycling, and there are various alternatives for cleaning in industrial applications. Various test techniques are also used to check the suitability of the applied cleaning process and to determine whether it is efficient. In this study, the test methods used for the importance of liquid metal quality in the casting of aluminum alloys and the suitability of the cleaning method were evaluated. In addition, the use of the methods and their comparison with each other are given. As a result, current test methods are discussed depending on foundry practice.Öğe Joule heating of carbon fiber in hybrid composites with glass fibers: Investigation of electro-thermal and vibration characteristics(Elsevier, 2025) Uslu, Emin; Yilmaz, Galip; Uyar, MehmetThis study explores the innovative dual-purpose use of carbon fiber, functioning both as a structural and a heating element, expanding its potential in hybrid composites. A prototype composite was fabricated using the vacuum infusion process, featuring a single carbon fiber layer at the core for dual-purpose and two outer layers of glass fiber. Electrical heating tests revealed a stable relationship between voltage, resistance, power, and temperature, demonstrating efficient heat generation as the voltage increased. Thermal imaging confirmed uniform heat distribution with minor variations. Free vibration tests evaluated the composite's dynamic behavior under various electro-thermal conditions. Results showed that increasing temperature reduced the natural frequencies, particularly in the second vibration mode. Changes in Rayleigh damping coefficients at higher temperatures highlighted the composite's sensitivity to thermal inputs. These findings underline the potential of hybrid composites for advanced applications like turbine blades and aerospace components, where multifunctionality, self-heating, and vibration control are critical.Öğe A new approach for high-quality production of UHMWPE by applying powder vibration densification before sintering(Elsevier, 2023) Yilmaz, Galip; Uslu, EminDue to its extreme viscosity, UHMWPE powder requires elevated pressure and temperature settings to ensure a fully solid structure. But a gentle process is vital for reliability in certain applications, such as prosthetic liners. A unique type of large gap, not mentioned in the literature, has been observed to resist closing more than regular gaps due to the number of particles forming a shield against pressure. As a solution, a mechanical vibration treatment of the particles before heating was used to eliminate these particular large gaps. Optimum vibration parameters were found, and the samples' final solid density and mechanical properties increased. The particles' dimensions and coefficient of friction were measured, and their vibration-dependent characteristics were discussed. A custom-made microscope apparatus was used to observe the vibration-induced densification of the particles and the gaps resisting closing.Öğe A novel perspective for Lactobacillus reuteri: Nanoencapsulation to obtain functional fish fillets(Elsevier, 2019) Ceylan, Zafer; Uslu, Emin; Ispirli, Humeyra; Meral, Raciye; Gavgali, Mehmet; Yilmaz, Mustafa Tahsin; Dertli, EnesEnrichment of food products with beneficial Lactic Acid Bacteria (LAB) is an important methodology used to develop functional food products. Lactobacillus reuteri E81 was successfully nanoencapsulated into poly (vinyl alcohol)-based nanofibers for its application to the surface of fish fillets. The Scanning Electron Microscopy analysis confirmed the nanoencapsulation of L. reuteri E81 in electrospun nanofibers (LRNF) that had an average diameter of 381.83 +/- 130.69 nm. LAB growth in rainbow trout fillets and fatty fish (mackerel) and were found to be 2.92 and in the range of 3.27 and 2.66 log CFU/g, respectively. Importantly, the antioxidative characteristics of fish fillets significantly increased following their coating with LRNF. The results revealed a significant increase in the inhibition of free radicals in the samples treated with nanoencapsulated L. reuteri as compared to control group fish fillet samples. DPPH activity significantly increased to 40.24%, 44.96%, 44.97 in mackerel samples treated with nanoencapsulated L. reuteri (MLR) and increased to 19.76%, 20.87%, 21.46% in rainbow samples treated with nanoencapsulated L. reuteri (RLR). MLR samples exhibited the highest ABTS radical-scavenging activity (1631 mu mol TEAC/g). FRAP value of MLR samples was found to be 1.70 times higher than the control group samples.Öğe Si VE Cu ELEMENTLERİ İÇEREN ALÜMİNYUM DÖKÜM ALAŞIMLARININ KOROZYON ÖZELLİKLERİNİN BELİRLENMESİ VE KARŞILAŞTIRILMASI(E-Journal of New World Sciences Academy, 2017) Uslu, Emin; Çatar, Recep; Çolak, MuratOtomotiv sanayinde birçok parçanın üretiminde malzeme seçeneği olarak alüminyuma duyulan ilgi ile birlikte kalite beklentileri de artmakta, maliyetlerinin düşmesi beklenmektedir. Alüminyumun en belirgin özelliği ağırlıkça hafif olması, yüksek korozyon dayanımı ve alaşımlandırılarak yapı çeliklerinden bile daha fazla mukavemet değerleri kazandırılabilmesidir. Alüminyum içerisine belli oranlarda farklı alaşım elementleri katılarak çeşitli standartlarda alaşımlar oluşturulmuştur. Ülkemizde de uluslararası standartlar baz alınarak Seydişehir Eti Alüminyum fabrikası çeşitli alüminyum döküm alaşımlarını primer külçe olarak üretmektedir. Bu çalışmada kum kalıba döküm yöntemiyle üretilen Etial 140, Etial 160, Etil 171 ve Etial 220 alüminyum döküm alaşımlarının korozyon davranışları incelenmiştir. Korozyon deneyleri %3,5 NaCI çözeltisi içerinde potansiyodinamik polarizasyon yöntemi ile araştırılmıştır. Farklı standartta alaşımların korozyon dirençleri tespit edilerek alüminyum alaşımına ilave edilen alaşım elementlerinin korozyon direncine etkisi değerlendirilmiştir. Çalışmada kum kalıba döküm, mikro yapı inceleme, SEM analizi, elektrokimyasal test teknikleri kullanılmıştır. Sonuçlar incelendiğinde, alaşımların kimyasal içeriğine bağlı olarak korozyon dirençlerinin değiştiği gözlemlenmiştir.Öğe Solidification analysis for variable thickness aluminum castings: simulation and chill design insights(Iop Publishing Ltd, 2023) Yilmaz, Galip; Colak, Murat; Uslu, EminManufacturing high-quality casting parts with complex geometries requires high engineering skill and precision. One essential quality concern is isolated hot spots within the castings, often in thick sections. Each hot spot must be consistently fed or mitigated through directional solidification techniques. The impact of various mold sands and the geometry of chill parts on solidification direction was investigated using specialized casting and general-purpose simulation programs. A parametric optimization method was employed to analyze directional solidification to adjust the geometry of the chill parts. The results indicate that employing diverse mold sands to enhance cooling in the thick sections was a viable strategy for achieving directional solidification in parts where the feeding pathway is obstructed due to changes in cross-section. Furthermore, the study revealed that intricate details in the chill part's geometry are not critical; however, a minimum volume (or weight) was necessary for adequate directional solidification. Lastly, an easily applicable mathematical model has been developed to determine the required volume of chill parts to ensure successful directional solidification.
