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Öğe Bronz ve dökme demir talaşlarının geri dönüştürülmesiyle prizmatik şekilli makine elemanı üretimi ve mekanik karakterizasyonu(2018) Aslan, Abdullah; Salur, Emin; Aydın, Güneş; Şahin, Ömer Sinan; Karadağ, Hakan Burak; Akdemir, AhmetBu çalışmada küresel grafitli dökme demir (GGG-40) ve Bronz (CuSn10) talaşlarının izostatik sıcakpresleme yöntemiyle geri dönüştürülmesi ile üretilen metal matrisli kompozit malzemelerin (MMK) üretimive mekanik davranışları incelenmiştir. MMK malzemeler 4 farklı karışım oranında 3 farklı sıcaklıkta ve 3farklı basınçta üretilerek üretim parametrelerinin gözeneklilik, sertlik ve eğilme mukavemeti üzerine etkisiincelenmiştir. Prizmatik geometrili olarak üretilen numunelerin öncelikle gözeneklilik ve yoğunluk değerleritespit edilmiştir. Daha sonra Brinell ve Mikro Vickers ve 3 noktadan eğilme deneyleri ile MMKmalzemelerin mukavemeti belirlenmiştir. Optik mikroskopi tekniği ile mikro yapı görüntüleri incelenerektalaşların birleşme mekanizması incelenmiştir. Ayrıca XRD analizi aracılığıyla metalik talaşlar arasında arafaz oluşumu olup olmadığı sorgulanmıştır. Gözeneklilik deneyleri neticesinde %20 mertebelerindegözeneklilik elde edilmiştir. Aşırı plastik deformasyon gösteren CuSn10 sebebiyle mukavemeti artanCuSn10 talaşları sertlik değerini Bulk CuSn10 ile kıyaslanabilir seviyelere getirmiştir. Eğilme deneyineticesinde MMK malzemelerin eğilme mukavemetleri bulk CuSn10’dan düşük çıkmıştır. Sonuç olarakmetal talaşların başarılı bir biçimde metal matris kompozit haline getirilebileceği gösterilmiştir.Öğe Effect of micro and nano-sized ZrSiO4 particles on the friction and wear properties of polymer matrix composites(Walter De Gruyter Gmbh, 2022) Sugozu, Banu; Daghan, Behcet; Akdemir, Ahmet; Sugozu, IlkerIn this study, the size effect of zircon (ZrSiO4) on the tribological characteristics of polymer matrix friction composites were investigated. Hence, four friction composites containing micro and nano-sized zircon particles (5 and 10 wt%) were developed and produced using powder metallurgy method. Their wear and friction characteristics were examined using a friction-wear test device. The weight loss and specific wear rate were measured and compared with that obtained for microsized zircon particles. The surfaces of samples were analyzed using a scanning electron microscope, and less wear was observed in the samples containing nano-sized zircon particles. The results revealed that the size of abrasive particles plays a key role in enhancing the friction coefficient and friction stability.Öğe Effect of micro and nano-sized ZrSiO4 particles on the friction and wear properties of polymer matrix composites(Walter De Gruyter Gmbh, 2022) Sugozu, Banu; Daghan, Behcet; Akdemir, Ahmet; Sugozu, IlkerIn this study, the size effect of zircon (ZrSiO4) on the tribological characteristics of polymer matrix friction composites were investigated. Hence, four friction composites containing micro and nano-sized zircon particles (5 and 10 wt%) were developed and produced using powder metallurgy method. Their wear and friction characteristics were examined using a friction-wear test device. The weight loss and specific wear rate were measured and compared with that obtained for microsized zircon particles. The surfaces of samples were analyzed using a scanning electron microscope, and less wear was observed in the samples containing nano-sized zircon particles. The results revealed that the size of abrasive particles plays a key role in enhancing the friction coefficient and friction stability.Öğe Effect of Silica/Graphene Nanohybrid Particles on the Mechanical Properties of Epoxy Coatings(Springer Heidelberg, 2019) Ozcan, Umit Esra; Karabork, Fazliye; Yazman, Sakir; Akdemir, AhmetEpoxy resins are used as coating materials, but the practical use of epoxy coatings in industries is limited due to their weak mechanical properties. In the present paper, different amounts of silica nanoparticles (SiO2) and graphene nanoplatelets (GNPs) were introduced separately and together into an epoxy coating matrix as reinforcements. Graphene, a newly discovered carbon allotrope, has been found to improve the mechanical properties of the polymer composites in which it is dispersed. Silica particles are also known to improve the mechanical properties of composites. In this study, mechanical, physical and thermal properties of the epoxy coatings are considered as multidimensional by the macro- and microanalyses. The experimental results showed that after the addition of GNPs into the epoxy matrix, the flexibility and impact resistance of the coatings increased by 8.3 and 157.1%, respectively, in relation to neat epoxy. The microhardness increased by 53.8% and penetration depth, which is indicative of the scratch resistance, decreased by 29.7%, with the addition of SiO2-GNPs nanohybrid. A remarkable synergistic effect was observed between the GNPs and SiO2, which improved the hardness and the scratch resistance of the epoxy coatings.Öğe Effect of the size on the friction characteristics of brake friction materials: a case study with Al2O3(Emerald Group Publishing Ltd, 2018) Sugoezue, Banu; Daghan, Behcet; Akdemir, AhmetPurpose The purpose of this paper is to study the potential of alumina (Al2O3) in nanometer size in automotive brake friction materials. Design/methodology/approach Four brake linings containing alumina differing in particle size (355 mu m and 80 nm) and various amount (5 and 10 Wt.%) were designed and produced. The hardness, density and porosity of the samples were measured. All samples were tested on a full-scale brake dynamometer with gray cast iron disc to determine the tribological properties. Detailed examinations on the worn surface were analyzed using a scanning electron microscopy. Findings It was concluded that all performance parameters were beneficially affected because of nano alumina. Originality/value This paper emphasizes the importance of nano-composites in the automotive industry and helps industrial firms and academicians working on wear of materials.Öğe The Effect of Ultrasonic Cleaning Upon Mechanical Properties of Metal Matrix Composites(Springer India, 2021) Aslan, Abdullah; Salur, Emin; Gunes, Aydin; Sahin, Omer Sinan; Karadag, Hakan Burak; Akdemir, AhmetThe aim of this study is to produce composite materials by recycling metallic chips, which are found in industry as a large amount of waste. In addition, it is aimed to investigate the effect of ultrasonic cleaning process as the consolidation behavior and mechanical properties of bulk material directly depend on the cleaning of waste metallic chips. In the present investigation, spheroidal graphite cast iron (GGG-40) was employed as reinforcement material in tin bronze (CuSn10) matrix system. GGG-40 and CuSn10 chips were cleaned by ultrasonic agitation in water for 20 and 40 min. Consolidation of the cleaned metallic chips was achieved with a hot press by applying 820 MPa pressure under 450 degrees C, and the cylindrical and prismatic metal matrix composite materials with different reinforcement ratios were successfully produced. Energy-dispersive X-ray and scanning electron microscopy analyses were carried out to determine the amount of the oxide removed from the surfaces of chips. The mechanical properties of the samples were determined by hardness, porosity, compression and three-point bending tests. According to the results of the analyses, it was found that CuSn10 surfaces were cleaned from 20%, 50% and GGG-40 surfaces from 35%, 39% oxides during 20- and 40-min cleaning time, respectively. In addition, the results of the mechanical tests revealed that increased ultrasonic cleaning time improves the consolidation quality of metallic chips and it provides successful covering of GGG-40 chips by the CuSn10 chips as a result of a better structural integrity. New machinery parts with high mechanical properties can be produced as a result of recycling of the metallic chips which are available as waste in industry by appropriate cleaning process and this situation makes this study more innovative, economical and environmentally friendly research.Öğe Effects of nano reinforcing/matrix interaction on chemical, thermal and mechanical properties of epoxy nanocomposites(Sage Publications Ltd, 2021) Yazman, Sakir; Uyaner, Mesut; Karabork, Fazliye; Akdemir, AhmetThis article investigates the impact of addition various types of nanoparticles with different structural, dimensional, and morphological properties on the interphase region formed between the particle/matrix and the curing behavior of the epoxy affect the nanocomposite material properties. For this purpose, epoxy nanocomposites (NCs) were produced by adding multi-walled carbon nanotube (MWCNT) and alumina (Al2O3) nanoparticles (NPs) into the epoxy matrix at different rates (0.5-2.0 wt.%). The effects of the particle/matrix interaction on the properties of the composite have been revealed by chemical, thermal, mechanical analyzes and microstructure investigations. An increase in the absorption density, which reveals the physical interaction of nanoparticles with the epoxy matrix, was observed in Fourier-transform infrared spectroscopy. Absorption vibration peak intensities in nanocomposite samples were at most 1.0 wt.% Al2O3 and 1.25 wt.% CNT added nanocomposites. It was observed that the T-g value increased depending on the number of nanoparticles. The addition of Al2O3 increased T-g values more than CNT. Besides, the mechanical properties of NCs were determined by tensile tests. The highest increase in mechanical properties was achieved by adding 1.25 wt.% CNT and 1.0 wt.% Al2O3, respectively. Mechanical properties tended to decrease at higher addition rates. The shape, size, amount, and distribution of nanoparticles added into the epoxy matrix directly affected the NCs' properties. It has been determined that homogeneously dispersed spherical Al2O3 nanoparticles are more effective than fiber-shaped CNTs in the properties of NCs.Öğe Experimental investigation of fatigue damage formation of hybrid pipes subjected to impact loading under internal pre-stress(Elsevier Sci Ltd, 2017) Gemi, Lokman; Sahin, Omer Sinan; Akdemir, AhmetIn this study, the effect of impact loading upon fatigue behavior of hybrid composite pipes has been investigated. The composite pipes were subjected to tangential pre-stress as 3-48 MPa according to ANSI/AWWA C950 standard than, subjected to low velocity impact at 20 J. The impact pre-damaged pipes then subjected to cyclic loading at 50% sigma ult in accordance with ASTM D 2992-06. It is also observed that increasing the tangential pre-stress decreases impact damage area and increases fatigue life of the pipe. It is also showed that impact pre-damage are not effective on the fatigue life of the pipe at the pre-stress level of 24 MPa. (C) 2017 Elsevier Ltd. All rights reserved.Öğe Fracture toughness (Mode I) characterization of SiO2 nanoparticle filled basalt/epoxy filament wound composite ring with split-disk test method(Elsevier Sci Ltd, 2017) Demirci, Mehmet Turan; Tarakcioglu, Necmettin; Avci, Ahmet; Akdemir, Ahmet; Demirci, IbrahimMatrix cracking which is the major initial form of damage in fiber reinforced polymer composites plays significant role in determining the fracture toughness. The fast crack propagation in polymer matrix causes to decrease the fracture toughness of fiber reinforced polymer (FRP) composite. In order to retard the fast crack propagation in polymer matrix and provide to increase of the fracture toughness of FRP composite, the polymer matrix of FRP composite is modified by filling the different kinds of nano particles. In such a way, the crack propagation leads to retard and dissipate the stress concentration affected to form the fiber cracks along of fibers in composite structure. In this study, basalt fiber was used as reinforcement material in +/-[55]6 filament wound ring composite for creating the alternative to carbon, kevlar and glass fibers, to contribute to the research studies and literature. SiO2 nanoparticles that provides to form the effects of fracture toughness mechanism based on the effect of retarding crack propagation were filled into epoxy matrix to increase the mechanical properties and fracture toughness of +/-[55]6 filament wound BFR/Epoxy ring composite. The split-disk tensile tests of single edge notched and un-notched +/- 155]6 filament wound BFR/Epoxy ring composite specimens were conducted to determine the mechanical properties and mode I fracture toughness. SiO2 nanoparticle addition into epoxy matrix of +/-[55]6 filament wound BFR/Epoxy ring composites has given the results of hoop tensile stress within the range of 27.7-30.3%. The fracture toughness of composite ring specimen was specified by ASTM E 399-12E3 by adapting to the directed mode I crack propagation and compared with each other. An effective increase in mode I fracture toughness of 43%-50% was obtained at 4 wt% addition level of SiO2 nanoparticles. The crack branching in epoxy matrix provided by SiO2 nanoparticle, matrix cracking, debonding, delamination and fiber breakage failures has been observed via microscope and SEM analysis. (C) 2017 Elsevier Ltd. All rights reserved.Öğe Improvement of anti-corrosion performance (surface and near the cut edge) and mechanical properties of epoxy coatings modified with nano, micro and hybrid ZnO particles(Sage Publications Ltd, 2023) Kabaoglu, Emre; Karabork, Fazliye; Balun Kayan, Didem; Akdemir, AhmetComposites were formed by incorporating nano, micro and hybrid-ZnO particles into the epoxy matrix at the same loading levels (3%) and applied at 90 mu m thickness on the galvanized steel substrate using a film applicator in this study. The improvement in anti-corrosion performance and mechanical and physical properties of the composite coatings were evaluated using various tests and techniques such as salt-spray, electrochemical impedance spectroscopy, nanohardness, microscratch, cross-cut, bending, Fourier transform infrared spectroscopy, thermogravimetric and Scanning electron microscopy. The corrosion performance of the composite coatings near the cut edge is discussed in detail as well as on the surface of galvanized steel. The results show that the addition of all ZnO particles has a positive effect on the corrosion resistance and mechanical properties of the coatings. The addition of nano, micro and hybrid ZnO particles increased the hardness of the composites by 52, 37 and 56%, respectively, compared to the neat epoxy. Although the cathodic protection performance is weakened near the cut edge due to the loss of Zn after thermal cutting, high barrier protection was provided with composite coatings, especially micro ZnO/Epoxy composite coating.Öğe Improving electrical and mechanical properties of a conductive nano adhesive(Taylor & Francis Ltd, 2017) Ekrem, Mursel; Ataberk, Necati; Avci, Ahmet; Akdemir, AhmetIn this experimental study, lap shear strength and electrical conductivity of nanohybrid adhesives containing multi-walled carbon nanotubes (MWCNT) and silver (Ag) nanoparticles were investigated. Ag nanoparticles were produced via arc-discharge method in liquid nitrogen. For characterizing the Ag nanoparticles, X-ray diffraction analysis, transmission electron microscopy, and scanning electron microscopy (SEM) were performed. Tensile lap shear properties were determined in accordance with ASTM D 1002-10 standard. Mechanical and the electrical properties of nanohybrid adhesives were compared with neat epoxy adhesive. The best electrical conductivity of nanohybrid adhesive was obtained for the 1% wt MWCNT-2% wt Ag-contained sample. However, the samples which contain 0.5% wt. MWCNT-0.5% wt. Ag nanoparticles reached the highest lap shear strength. The results showed that Ag nanoparticles enhance the conductivity in the presence of MWCNT. It is concluded that the MWCNT act as conductivity bridges among epoxy adhesive and facilitate the electron transfer. As seen in the tensile test results, the ductility of the adhesive was improved by adding the nanoparticles in to the epoxy resin.Öğe Investigation Effect of Zinc Nanoparticles on The Mechanical and Anticorrosion Properties of Epoxy Coatings on Stainless Steel Surface(Gazi Univ, 2021) Apsak, Merve; Akdemir, Ahmet; Karabork, Fazliye; Yazman, SakirIn this study, effects of zinc nanoparticles (ZNPs) on the mechanical properties of epoxy coatings and anticorrosion behavior on the stainless steel were investigated. The nanocomposites (NCs) were obtained by adding ZNPs (0.5, 1.0, 1.5 wt%) to epoxy resin. The first stage in this study, bulk samples were prepared for tensile test and DSC, TGA, FTIR, SEM analysis. The test and analysis were performed separately for samples cured at room temperature for 24 h and postcured at 80 degrees C for 15 h in the oven. The results indicated that both postcuring and adding ZNPs caused an increase in the mechanical properties of the epoxy matrix. Tensile strength increased by 13.2% and 90.2% in the postcured NC (1.0% Zn) and untreated NC (0.5% Zn) respectively. The NCs prepared with the same parameters for the second stage were coated on AISI 304 test panels and the panels were postcured in the oven. The anticorrosive performance of the coatings was studied by an immersion test. According to the corrosion test results, it was observed that the coated steel surface preserves the best rate of 1.0% ZNPs containing epoxy composite. In addition, impact resistance, flexibilities and adhesion properties of the coating were analyzed.Öğe Mechanical properties and microstructure of composites produced by recycling metal chips(Springer, 2018) Aslan, Abdullah; Gunes, Aydin; Salur, Emin; Sahin, Omer Sinan; Karadag, Hakan Burak; Akdemir, AhmetIn this study, the processing and mechanical properties of porous metal matrix composites (MMCs) composed of spheroidal cast iron chips (GGG40) and bronze chips (CuSn10) and formed by hot isostatic pressing were investigated. Bronze chips (CuSn10) were used as a matrix component, and spheroidal cast iron (GGG40) chips were used as a reinforcement component. The MMCs were produced with different CuSn10 contents (90wt%, 80wt%, 70wt%, and 60wt%). The hot isostatic pressing process was performed under three different pressures and temperatures. The produced MMCs were characterized using density tests, Brinell hardness tests, and compression tests. In addition, the consolidation mechanism was investigated by X-ray diffraction (XRD) analysis and scanning electron microscopy. The test results were compared with those for bulk CuSn10 and bulk GGG40. Mechanical tests results revealed that the metallic chips can be recycled by using hot pressing and that the mechanical properties of the produced MMCs were similar to those of bulk CuSn10. XRD and microscopy studies showed that no intermetallic compounds formed between the metallic chips. The results showed that the CuSn10 and GGG40 chips were consolidated by mechanical interlocking.
