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Öğe B4C takviyeli alüminyum kompozit malzemelerin yarı katı karıştırma yöntemi ile üretimi ve karakterizasyonu(Trakya Üniversitesi Fen Bilimleri Enstitüsü, 2015) Yakut, Rifat; Taşkın, Nilhan ÜrkmezYüksek dayanımlı alüminyum esaslı kompozit malzeme üretiminde düşük yoğunlukları, yüksek ergime sıcaklıkları, üstün mukavemet özellikleri ve yüksek elastiklik modülüne sahip olmaları nedeniyle takviye malzemesi olarak çoğunlukla B4C ve SiC seramik tozları tercih edilmektedir. Ancak, SiC ve B4C nin ıslatma problemleri sebebiyle Al içerisine karıştırılması oldukça güç olmaktadır. Bu çalışmada, SiC ve B4C? nin ısıl işlem ile alüminyum tarafında ıslatılabilirlikleri arttırılmaya çalışılmış, iki farklı alüminyum alaşımı (AA5754 ve AA7075) kullanılarak, farklı takviye oranlarına sahip hibrit alüminyum kompozitler üretilmiştir. Üretim yöntemi olarak, homojen dağılım sağlama ve sıvı yöntemlerle yapılan çalışmalarda karşılaşılan sorunların çözüldüğü doğrudan yarı katı karıştırma yöntemi uygulanmış ve karıştırma işlemini takiben düşük basınç altında katılaştırma ile farklı takviye oranlarında AA5754/B4C, AA7075/B4C kompozitleri ile AA7075/SiC/B4C hibrit kompozitleri üretilmiştir. Üretilen kompozit malzemelerin karakterizasyonu için mekanik testler(sertlik, üç noktadan eğme ve basma testleri) uygulanmış, takviye malzemeleri ile matris malzemeleri arasında kimyasal veya mekanik bağ oluşturup oluşturmadığı ve takviye matris ara yüzeyinde oluşan reaksiyon ürünlerinin tespit edilmesi amacıyla mikroyapı (SEM, EDS, XRD) analizleri ve porozite tespiti için yoğunluk ölçümleri yapılmıştır. Yapılan test ve analizler sonucunda takviye tozlarına uygulanan ısıl işlem ile takviye yüzeyinde reaksiyon ürünleri oluştuğu, alüminyum tarafından ıslatılabilirliklerinin arttığı ve takviye ile matris arasında hem mekanik hem de kimyasal bağ oluştuğu görülmüştür.Öğe The Effects of Different Reinforcement Ratios on Wear Behaviors in EN AW 5754 (AlMg3)/SiCp Composite Materials Produced with the Squeeze Casting Method(2022) Taskin, Vedat; Yakut, Rifat; Taşkın, Nilhan Ürkmez; Kılıç, CumaIn this study, SiCp particles were reinforced at volumetric ratios of 5%, 10%, 15% and 20% into the EN AW 5756 (AlMg3) metal matrix composite by using the squeeze casting method. The squeezing process was carried out for 10 seconds under a pressure of 80 MPa. The changes in the wear behaviors and friction coefficients of the EN AW 5754/SiCp composite samples were examined under1.0 N force, 5000 cycles and with a 0.04 m/s sliding speed. As a result of the experiments, it was found that the friction coefficient value increased from the non-reinforced alloy to the 10% SiCp-reinforced composite, while it then decreased in the 15% and 20% SiCp-reinforced composites. Moreover, the amount of wear in the composite material increased as the ratio of the reinforcement increased, and the highest wear occurred in the 10% SiCp-reinforced composite. This wear rate decreased in the 15% reinforced composite and then increased in the 20% reinforced composite. The deformation wear statuses of the composite materials that were used in the experiments were examined by conducting SEM (Scanning Electron Microscopy) and EDS (Energy-Dispersive Spectrometry) analyses. In these examinations, it was observed that the 5% and 10% SiCp reinforcements did not show a homogeneous distribution in the matrix, but the 15% and 20% SiCp reinforcements were homogeneously distributed in the matrix material.Öğe THE EFFECTS OF WELDING PRESSURE AND REINFORCEMENT RATIO ON WELDING STRENGTH IN DIFFUSION-BONDED AlMg3/SiCp COMPOSITES(2020) Taşkın, Nilhan Ürkmez; Yakut, Rifat; Alp, EnginIn this study, using the diffusion welding method, welded joints were created with AlMg3/SiCp composite materials, and the mechanical strengths of these joints were examined. The AlMg3/SiCp composite specimens were cut out of plates produced directly with the semi-solid stir-squeeze casting method and contained 10% SiCp and 20% SiCp reinforcement. To examine the effects of reinforcement ratios on joint strength, specimen couples with the same and different reinforcement ratios were created. To examine the effects of different welding pressures on joint strength, by keeping the welding temperature constant at 580°C, welding was performed under 3 different pressures as 1.5 MPa, 2.5 MPa and 3.5 MPa. By determining the mechanical strengths of the welded joints that were formed by shear test, the effects of reinforcement ratios and welding pressures on joint strength were investigated. As a result of the shear tests applied on the welded specimens, in the specimens that were diffusion-welded, welding quality decreased based on increasing reinforcement ratios, but as the amount of pressure and application duration increased, joint strength increased. As the SiC ratio increased in the joint zones, diffusion became difficult, and weak joints were obtained. The microscopic structure of the joint zone was examined by using optical microscopy and scanning electron microscopy (SEM). It was seen that diffusion welding could be successfully performed in bonding SiCpreinforced aluminium composites if the suitable welding pressure and duration are selected.Öğe PRODUCTION OF AA7075/B4C COMPOSITE MATERIALS BY THE SEMI-SOLID STIRRING METHOD(2019) Yakut, Rifat; Taşkın, Nilhan ÜrkmezAA7075 aluminum alloy was reinforced with B4C particles to producealuminum composite materials. In the production of AA7075/B4C compositematerials, the semi-solid mixing method was used for homogenousreinforcement dispersion and low-pressure solidification. For determinationof the mechanical properties of the obtained samples, three-point bending,compression and hardness tests were performed. Additionally, themicrostructure, reinforcement matrix interface and chemical structure of theproduced composite material were investigated by scanning electronmicroscopy (SEM), energy dispersive X-ray spectrometry (EDS) and X-raydiffraction (XRD) analyses. As a result, it was observed that, by using thesemi-solid mixing method, the reinforcing powders could be distributedhomogeneously into the matrix, both chemical and mechanical bondingcould be facilitated between the matrix and the reinforcing material, and thismixing technique could be easily used in production of particle-reinforcedmetal composites. As the reinforcement rate increased, bending strengthincreased, but there was a reduction in comparison to the non-reinforcedaluminum alloy. As the reinforcement rate increased, compressive strengthwas observed to decreased, while the mean hardness value increased.
