Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4719
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Book Part Citation - Scopus: 1A Recycling Route of Plastics Via Electrospinning: From Daily Wastes To Functional Fibers(Walter de Gruyter GmbH, 2019) Isık, Tuğba; Horzum,N.; Demir, Mustafa MuammerSince large-scale plastic production has begun in the 1940s, plastics have been produced and used globally, bringing many advantages to modern life. The consumption of plastics has increased exponentially due to their low cost, chemical resistance, lightness, durability and ability to combine with other materials. However, plastic materials represent high tonnage in urban wastes, and it is known that these plastics discarded at the end of their useful life by filling the landfill sites. Electrospinning is a well-established and versatile technique for the fabrication of submicron fibers. In addition, it is a promising approach for the recycling of waste polymers without using complex methodologies. In this chapter, utilization of electrospinning approach for the recycling of daily wastes will be discussed. The literature about the daily wastes of both synthetic materials and natural/agricultural materials will be analyzed, and the applications of these materials will be given in detail. © 2019 Walter de Gruyter GmbH, Berlin/Boston. All rights reserved.Article Citation - WoS: 8Citation - Scopus: 10Impact of Simulated Inflammation and Food Breakdown on the Synergistic Interaction Between Corrosion and Wear on Titanium(Elsevier, 2024) Lima, A.R.; Pinto, A.M.P.; Toptan, F.; Alves, A.C.This paper investigates the impact of lactic acid and phosphoric acid additives in artificial saliva (AS), simulating inflammation and food breakdown, on the electrochemical and tribo-electrochemical behavior of titanium. The results showed that, unlike lactic acid, phosphoric acid significantly reduced corrosion resistance, mainly due to local damage and heterogeneities on the passive film. Non-additivated AS caused greater wear volume loss, with mechanical wear identified as the main mechanism. However, when additives were present, a synergistic interplay between corrosion and wear was observed. The study concludes that prolonged exposure to food breakdown could accelerate material degradation in titanium. © 2024 Elsevier LtdArticle Citation - Scopus: 10Development of Lightweight Geopolymer Composites Containing Perlite and Vermiculite(International OCSCO World Press, 2023) Korniejenko, Kinga; Pławecka, Kinga; Bulut, Alperen; Şahin, Baran; Azizağaoğlu, Göksu; Figiela, BeataPurpose: The aim of this work was to prepare and characterise geopolymer composites containing lightweight aggregates-perlite and vermiculite. Design/methodology/approach: The geopolymer matrix was prepared on the basis of fly ash, sand and a 6M sodium hydroxide solution with sodium silicate. The properties of the materials were tested 28 days after the preparation of the samples. The following research methods were used to characterise the composites: compressive and flexural strength tests, microstructural tests using a scanning electron microscope, and thermal conductivity were measured. Findings: The results obtained showed a slight effect of the additives on the strength properties. Lightweight aggregates are characterised by good coherence with the matrix material. Their addition allowed to reduce the density and lowered the thermal conductivity of the materials. The results obtained indicate that the proposed additives can improve the properties of the geopolymer composite for use in the construction industry. Research limitations/implications: Further research should focus on geopolymer composites with perlite and involve fire-resistant and water-absorption tests. Practical implications: The production of lightweight building materials brings a number of benefits, such as reducing the density of building elements and, at the same time, the entire structure, which results in a reduction in their weight, as well as lower transport costs. Such elements have better thermal and acoustic insulation, reflected in the parameters of buildings. An additional advantage is the reduced environmental impact through better insulation properties, lower fuel consumption during transport, etc. Originality/value: The density of the material can be reduced by using lightweight aggregates or obtaining porous material in the foamed process. In the case of geopolymer composites, a number of studies related to foamed materials have been provided, but there is only a few previous research connected with lightweight aggregates such as perlite and vermiculite. © by International OCSCO World Press. All rights reserved. 2023.Conference Object Citation - WoS: 1Citation - Scopus: 1Assessment of Separation and Agglomerationt Tendency of Non-Metallic Inclusions in an Electromagnetically Stirred Aluminum Melt(Springer international Publishing Ag, 2023) Li, Cong; Dang, Thien; Gokelma, Mertol; Zimmermann, Sebastian; Mitterecker, Jonas; Friedrich, BerndPresence of non-metallic inclusions (NMIs) reduces surface quality and mechanical properties of aluminum products. The development of good NMIs removal practices relies on the understanding of inclusion behaviors with respect to separation and agglomeration particularly in the turbulent flow. In the scenario of electromagnetically induced recirculated turbulent flow, the concerned behaviors of inclusions with different sizes have rarely been investigated experimentally. In the presented study funded by AMAP Open Innovation Research Cluster, reference materials were prepared with uniformly distributed NMIs (SiC and MgAl2O4) via an ultrasoundinvolved casting route. Reference materials were charged into an aluminum melt where turbulent flow was promoted via electromagnetic force. Microscopical analysis shows non-significant agglomeration tendency of SiC, MgAl2O4, and TiB2 inclusion. Time-weight filtration curve, PoDFA, and Spark Spectrometer results suggest a strong dependence of separation rate on particle size. Analytical models were established to estimate the collision rate of particles and to evaluate separation probability of different sized particles.Conference Object Citation - WoS: 2Citation - Scopus: 1The Influence of the Casting Speed in Horizontal Continuous Casting of Aluminium Alloy En Aw 6082(Springer, 2021) Obalı, Akın; Dilek, Kerem Ahmet; Akdi, Seracettin; Ürk, Deniz Kavrar; Gökelma, MertolVertical direct chill (VDC) casting is commonly used to produce slabs and billets from wrought aluminium alloys. The fact that the VDC is not a continuous process and moulds must be prepared for the next batch decreases the productivity of the process. Alternatively, horizontal direct chill (HDC) casting simplifies the process and allows a continuous production. The casting speed in the HDC casting is easier to control and can be optimized for different alloys by changing the speed. This study focuses on investigating the effects of casting speed on the macrostructure of 6082 aluminium billets with 60 mm diameter. A demo-scale casting unit was used and the casting speed was changed from 310 to 385 mm/min. Changes in surface condition, macrocracks, microporosity, and diameter of the billets were investigated. Surface quality of the billets became better with the increasing casting speed, while diameter of the billet expands. Furthermore, centreline cracks appear at the casting speed of 355 mm/min. © 2021, The Minerals, Metals & Materials Society.Book Citation - Scopus: 19Advanced Sensor and Detection Materials(John Wiley and Sons Inc., 2014) Tiwari, Ashutosh; Demir, Mustafa MuammerPresents a comprehensive and interdisciplinary review of the major cutting-edge technology research areas-especially those on new materials and methods as well as advanced structures and properties-for various sensor and detection devices. The development of sensors and detectors at macroscopic or nanometric scale is the driving force stimulating research in sensing materials and technology for accurate detection in solid, liquid, or gas phases; contact or non-contact configurations; or multiple sensing. The emphasis on reduced-scale detection techniques requires the use of new materials and methods. These techniques offer appealing perspectives given by spin crossover organic, inorganic, and composite materials that could be unique for sensor fabrication. The influence of the length, composition, and conformation structure of materials on their properties, and the possibility of adjusting sensing properties by doping or adding the side-groups, are indicative of the starting point of multifarious sensing. The role of intermolecular interactions, polymer and ordered phase formation, as well as behavior under pressure and magnetic and electric fields are also important facts for processing ultra-sensing materials. The 15 chapters written by senior researchers in Advanced Sensor and Detection Materials cover all these subjects and key features under three foci: 1) principals and perspectives, 2) new materials and methods, and 3) advanced structures and properties for various sensor devices. © 2014 Scrivener Publishing LLC. All rights reserved.Conference Object Development of Graphene Nanoplatelets Reinforced Aluminium Matrix Nanocomposites by a Combination of Semi-Solid Stirring and Ultrasonic Treatment(European Conference on Composite Materials, 2016) Kandemir, Sinan; Aydoğan, YücelGraphene Nanoplatelets (GNPs) consisting of graphene layers with a thickness less than 100 nm have recently emerged as a promising reinforcement type owing to their excellent physical and mechanical properties to improve mechanical properties of alloys beyond ceramic nanoparticles. Although there are numerous studies on GNPs reinforced polymer matrix composites in the literature, the number of studies related to the incorporation of GNPs in metal matrices is limited. It is a challenging task to incorporate and uniformly distribute GNPs into liquid metals due to their poor wettability and large surface-to-volume ratio. The purpose of this study is to effectively disperse GNPs into liquid aluminium. 0.5 wt.% GNPs with an average thickness of 50-100 nm and size of 5 ?m were first incorporated into A360 aluminium alloy under semi-solid stirring, and then the composite was ultrasonically treated in fully liquid state. The microstructural investigation of the nanocomposites by optical and scanning electron microscopy may suggest that relatively uniform distribution and effective deagglomeration of GNPs in the matrix were achieved. The hardness of the GNPs reinforced nanocomposites increased in comparison with that of semi-solid stirred and ultrasonically processed A360 alloy without reinforcement, indicating the potential of GNPs for strengthening metals. © 2016, European Conference on Composite Materials, ECCM. All rights reserved.Conference Object Reversible Energy Transfer Between a Single Defect in Hbn and Graphene(OSA - The Optical Society, 2019) Özçeri, Elif; Arı, Ozan; Balcı, Sinan; Kocabaş, Coşkun; Ateş, SerkanWe present a reversible energy transfer between a single defect in hBN and graphene. Dynamic control of Fermi level of graphene results in switching on and off single photon emission from a single quantum emitter. © OSA 2019 © 2019 The Author(s)