Yazar "Gürü, Metin" seçeneğine göre listele

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    Alüminyum üretim teknolojilerindeki gelişmeler, çevreye etkisi ve uygulama alanları
    (2021) Çakanyıldırım, Çetin; Gürü, Metin
    Alüminyum yaşantımızın pek çok alanında kullandığımız cazip özellikleri sebebi ile vazgeçilmez bir malzemedir. Bu çalışmada alüminyumun özellikleri, sektördeki yeri, üretim teknolojisi, üretimdeki enerji ihtiyacı, çevreye etkisi ve tarihsel serüveni ana hatları ile incelenmektedir. Alüminyumun dünya kabuğunun %8’ini oluşturan boksit minerali halinde doğadan alınmaktadır. Kullanılmakta olan ve geliştirilen yeni yöntemler ile tüketiciye hem ekonomik fırsatlar hem de geniş bir ürün yelpazesi sunulmaktadır. Bu özelliklerine ek olarak düşük yoğunluk, iletkenlik, işlenebilirlik gibi konularda sunduğu avantajlarda bu mineralin önemini artırmaktadır. Ekonomik Kalkınma ve İşbirliği Örgütü (OECD) ülkelerindeki 33 kg/kişi.yıl tüketim miktarına oranla düşük olan Türkiye alüminyum üretimi son yıllardaki farkındalık ile yıllık kişi başına 10 kg sınırını zorlamaktadır.
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    An approach to the usage of polyethylene terephthalate (PET) waste as roadway pavement material
    (Elsevier, 2014) Gürü, Metin; Çubuk, M. Kürşat; Arslan, Deniz; Farzanian, S. Ali; Bilici, İbrahim
    This study investigates an application area for Polyethylene Terephthalate (PET) bottle waste which has become an environmental problem in recent decades as being a considerable part of the total plastic waste bulk. Two novel additive materials, namely Thin Liquid Polyol PET (TLPP) and Viscous Polyol PET (VPP), were chemically derived from waste PET bottles and used to modify the base asphalt separately for this aim. The effects of TLPP and VPP on the asphalt and hot mix asphalt (HMA) mixture properties were detected through conventional tests (Penetration, Softening Point, Ductility, Marshall Stability, Nicholson Stripping) and Superpave methods (Rotational Viscosity, Dynamic Shear Rheometer (DSR), Bending Beam Rheometer (BBR)). Also, chemical structures were described by Scanning Electron Microscope (SEM) equipped with Energy Dispersive Spectrometer (EDS) and Fourier Transform Infrared (FTIR) techniques. Since TLPP and VPP were determined to improve the low temperature performance and fatigue resistance of the asphalt as well as the Marshall Stability and stripping resistance of the HMA mixtures based on the results of the applied tests, the usage of PET waste as an asphalt roadway pavement material offers an alternative and a beneficial way of disposal of this ecologically hazardous material. © 2014 Elsevier B.V.
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    Atık Polietilen Pirolizinin Dizel Motor Ve Emisyon Parametrelerine Etkisinin İncelenmesi
    (2019) Bilici, İbrahim; Gürü, Metin; Keskin, Ali İhsan
    Plastik malzemelerin kullanılmasının artışıyla birlikte Polietilen (PE) nin de kullanımı da bütün dünyada artmıştır. Bu yüksek miktardaki PE doğal bozulmama özelliğinden dolayı çevresel problemleri de beraberinde getirmektedir. Fakat bu PE sıvı yakıtlara dönüştürülebildiği için çevresel ve ekonomik olarak fayda sağlayabilir. Bu deneysel çalışmada PE dizel yakıt katkısına dönüştürülerek polimer bazlı yakıtların dizel motorlarda eksoz emisyonu ve performans paramatereleri incelenmiştir. PE atıklar termal piroliz yöntemiyle yakıta dönüştürülmüştür. PE atık katkılı yakıt %5, %10 ve %20 oranlarında dizel yakıt ile karıştırılarak herhangi bir modifikasyon gerçekleştrilmeden test edilmiştir. Genel olarak motor performans ve eksoz emisyon değerleri dizel yakıtlar ile benzer özellikler göstermiştir. Spesifik yakıt tüketimi (SFC) değeri PE oranının artmasıyla hafif düzeyde artış göstermiştir. Karbonmonoksit (CO) ve azot oksit (NOx) değerleri de dizel yakıt ile karşılaştırıldığında artma eğilimi göstermiştir.
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    Bor bileşiklerinin alev geciktirici ve yüksek sıcaklığa dayanıklı pigment olarak uygulanabilirliği
    (Ulusal Bor Araştırma Enstitüsü, 2016) Yılmaz Aydın, Duygu; Gürü, Metin; Ayar, Barış; Çakanyıldırım, Çetin
    Sanayileşme ve teknolojik gelişmeler arttıkça; geniş uygulanabilirliğe sahip, çevre dostu, toksik olmayan, yüksek sıcaklığa ve aleve dayanıklı, fonksiyonel malzeme arayışı da artmaktadır. Bor tüm bu ihtiyaçlara cevap verebilecek stratejik öneme sahip, gelişen sanayi ve teknolojik ilerlemelerin temel girdi maddelerinin başında gelen vazgeçilmez mineral kaynaklarından biridir. Ham ve rafine ürünler dışında genellikle yüksek teknoloji gerektiren metotlar ile rafine bor ürünleri kullanılarak dünyada ticari amaçla üretilen özel bor bileşikleri mevcuttur. Bu özel bor bileşiklerinin her biri farklı sektörlerde belirli amaçlar için kullanılmaktadır. Özel bor bileşiklerinin kullanım amaçlarından biri de alev geciktirici olarak kullanılabilirliğidir. Alev geciktirici katkı maddeleri, yanmanın başlamasını ve ilerlemesini engelleyerek, bazı durumlarda can ve mal güvenliğini, bazı durumlarda da çevreyi korumaya yardımcı olurlar. Yanıcı malzemelerin, daha geç tutuşmalarını sağlayabilmek ve yanmanın ilerlemesini önemli derecede azaltabilmek, alev geciktirici katkı maddelerinin ilavesi ile gerçekleşebilir. Borlu bileşikler alev geciktirici olarak yaygın kullanım alanı bulmuştur. Borlu bileşikler ahşap, selülozik yalıtım, PVC ve tekstil malzemelerine katılarak bu malzemelere güç tutuşurluk özelliği kazandırırlar. Bu çalışmada alev geciktiriciler üzerinde genel bir inceleme yapılmış, borlu bileşiklerin alev geciktirici etkisi yapılan çalışmalar üzerinden gösterilmiştir
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    Co-Mn/TiO2 catalyst to enhance the NaBH4 decomposition
    (Ulusal Bor Araştırma Enstitüsü, 2016) Özsaçmacı, Gözde; Çakanyıldırım, Çetin; Gürü, Metin
    Developing catalyst to create a feasible system for NaBH4 hydrolysis would increase the widespread use of clean energy producing fuel cell system. However, transfer difficulties such as; three phase reaction mechanism and reactant-side product solubility problems limit the promising properties of the hydrolysis systems. In this study Co1-xMnx bimetallic catalyst was produced and adhered on TiO2 support by co-reducing method. Optimum NaOH concentration for the catalyst and reaction conditions was determined before the studies. In the experiments it was proved that only 40 mg of Co0.7Mn0.3/TiO2 catalyst is highly active to decompose NaBH4 at 20 °C. SEM-EDX results revealed that the catalyst homogeneity and active sites existence are valid after reaction. Released hydrogen was collected by inverse burette apparatus and maximum hydrogen generation rate was calculated as 43.6 at 20 °C. Investigations resulted that the reaction obeys first order kinetic on the basis of NaBH4and the activation energy is 38.7 kJ.mol-1
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    Comparison of the curing kinetic behavior for two epoxy resin systems containing EPIKOTE 828-EPIKURE 3090 and DURATEK KLM 606a-DURATEK KLM 606b
    (2007) Tüzün, Fatma Nihal; Gürü, Metin; Akyüz,Yüksel
    The aim of the study is to determine the optimum cure temperatures and kinetics for two different epoxy resin systems without using solvent. Two resin systems consist of EPIKOTE 828® epoxy resin-EPIKURE® 3090 polyamidoamine curing agent and DURATEK® KLM 606A epoxy resin-DURATEK®KLM 606B polyamide curing agent. The ratio of resin to curing agent was kept as 1:1 for both the systems. Curing temperatures of both the systems were determined and kinetic parameters were calculated with respect to the experimental results following nth-order kinetics. Then, a series of isothermal temperatures was applied to the resin systems in order to assess the cure process in terms of conversion, time, and temperature by using differential scanning calorimeter (DSC). The test results of both systems show that the rate of degree of cure for EPIKOTE 828® epoxy resin-EPIKURE® 3090 polyamidoamine curing agent system is approximately 10 times higher than that of DURATEK® KLM 606A epoxy resin-DURATEK® KLM 606B polyamide curing agent system at 230°C. © 2007 Society of Plastics Engineers.
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    Conversion of KCl into KBH4 by mechano-chemical reaction and its catalytic decomposition
    (Springer New York LLC, 2017) Bilen, Murat; Gürü, Metin; Çakanyıldırım, Çetin
    Production of KBH4, in the presence of KCl, B2O3 and MgH2 by means of a mechanical reaction and a dehydrogenation kinetic, constitute the main parts of this study. Operating time and reactant ratio are considered as two parameters for the mechanical reaction to obtain the maximum yield. The production process was carried out in a ball milling reactor, and the product residue was purified with ethylene diamine (EDA) and subsequently characterized by Fourier Transform Infrared Spectroscopy (FT-IR) and x-ray Diffraction (XRD) analyses. Optimum time for mechano-chemical treatment and reactant ratio (MgH2/KCl) were obtained as 1000 min and 1.0, respectively. Synthesized and commercial KBH4 were compared by hydrolysis tests in the presence of Co1?xNix/Al2O3 heterogeneous catalyst. Hydrogen generation rates, activation energy and order of the KBH4 decomposition reaction were obtained as 1578 mLH2min?1g?1catalystmLH2min?1gcatalyst?1, 39.2 kJ mol?1 and zero order, respectively.
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    Decomposition of NaBH4 with self-regeneration of carbon-supported CoCl2 catalyst
    (Taylor and Francis Inc., 2017) Çakanyıldırım, Çetin; Gürü, Metin
    In this study, economically favorable CoCl2 catalysts at four different amounts were supported on activated carbon (AC) for NaBH4 dehydrogenation. Supported catalyst could achieve hydrogen release for 2,060 cycles, which is equivalent to 103 days of uninterrupted operation. Slow and continuous hydrogen release was observed in all experiments. Even 1 g of NaBH4 can carry 1.2 L of hydrogen, and in hydrolysis process, it liberates 2.5 L of hydrogen that indicates the decomposition of water. EDX analysis and reverse burette measurements show that CoCl2 could be homogeneously distributed on and permanently joined to the support surface. Kinetic investigation of the dehydrogenation reaction fits zero order kinetics, and activation energy was calculated to be 48 kJ/mol. © 2017 Taylor & Francis Group, LLC.
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    Farklı destekler ile hazırlanan sentetik Co-Mn-Pt katalizörünün NaBH4 hidroliz performansı ve kinetik değerlendirmesi
    (GAZI UNIV, FAC ENGINEERING ARCHITECTURE, 2022) Çakanyıldırım, Çetin; Gürü, Metin
    Bu çalışmada Co0,92-xMn0,08Ptx/TiO2 ve Co0,92-xMn0,08Ptx/Al2O3 nano katalizörleri sentezlenmiştir. Destekli katalizörlerin üretilmesinde impregnasyon tekniği kullanılmıştır. Katalizörlerin hidroliz yöntemi ile NaBH4’ü parçalararak yüksek hızda hidrojen üretme yetenekleri belirlenmiştir. Katalizörlerin özelliklerinin belirlenmesi için geçirimli ve taramalı electron mikroskopları (TEM ve SEM), X-ışını difraktometresi (XRD), yüzey alanı ölçüm ve gözenek dağılımı (Brunauer Emmett Teller) analizleri, enerji dağılım spektroskopisi (EDX) ve hidroliz testleri gerçekleştirilmiştir. Testler destek ile aktif bileşenin birbiri ile iyi bir uyum içinde ve sıkıca tutunmuş halde olduğunu göstermiştir. TiO2 destek ile aktivitenin daha yüksek olduğu ve 22? sıcaklıkta 40 mg Co0,85Mn0,08Pt0,07/TiO2 katalizör ile gerçekleştirilen hidroliz testlerinde 5 mL (0,525 M) NaBH4 çözeltisinin hidrojen üretim hızı 6.250 mL H2/min.gkat olarak bulunmuştur. Değişik NaOH, NaBH4 miktarları ve sıcaklıklarda kinetik çalışmalar yapılmıştır. Hidroliz tepkimesi için uygun NaOH miktarı 0,15 M olarak tespit edilmiştir. Tepkime hızı üzerinde katalizör miktarının etkin, NaBH4 miktarına göre ise sıfırıncı dereceden kinetiğe sahip olduğu belirlenmiştir. Co0,85Mn0,08Pt0,07 içerikli katalizörlerin TiO2 ve Al2O3 destekleri için sırasıyla 34,19 ve 40,02 kJ/mol aktivasyon enerjisine sahip olduğu tespit edilmiştir.
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    Nano Mineralojik Akışkanların Termofiziksel Özelliklerinin Deneysel Olarak İncelenmesi
    (2019) Karakaya, Uğur; Gürü, Metin; Sözen, Adnan; Aydın, Duygu Y.; Bilici, İbrahim
    Bu çalışmada bentonit, diatomit, sepiyolit ve klinoptilolit malzemeleri içeren nanoakışkanların termofiziksel özellikleri belirlenmiştir. Spex tipi yüksek enerjili öğütücü kullanılarak 50 nm boyutunda nano parçacıklar üretilmiştir. Bu nano parçacıklar kullanılarak kütlece % 2 mineralojik malzeme ve kütlece % 0,5 Sodyum Dodesil Benzen Sülfonat içeren nanoakışkanlar 5 saat ultrasonik karıştırma sonucunda hazırlanmıştır. Termofiziksel özelliklerden olan ısıl iletkenlik, özgül ısı ve viskozite ölçümleri deneysel olarak gerçekleştirilmiştir. Mineral nanoakışkanlar içerisinde en büyük ısıl iletkenlik ve özgül ısı artışının bentonit içeren nanoakışkan ile elde edilmiştir. Bentonit içeren naoakışkanın askıda bulunan nano parçacık miktarının daha fazla olması nedeniyle diğer mineralojik nanaoakışkanlara göre ısıl iletkenlik ve özgül ısı diğerlerinin daha yüksek olduğu sonucuna varılmıştıır. Nanoakışkanlar içerisinde bulunan nano parçacıkların oluşturduğu parçacık-parçacık etkileşimi nedeniyle akışa karşı oluşan direncin arttığı, sonuç olarak saf suya kıyasla viskozitenin arttığı gözlemlenmiştir.
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    Oxidative desulfurization of cayirhan lignites by permanganate solution
    (2008) Gürü, Metin; Tüzün, Fatma Nihal; Selek Murathan, Ayşe; Asan, Abdurrahman; Kıyak, Tülin
    Unless important developments record new and renewable energy sources, the role of fossil fuels as an energy resource goes on. It is possible to detect sulfur, heavy metals, and tracer elements such as arsenic and selenium by decreasing calorific value of coals. Sulfur oxides, which are the main pollutants in atmosphere, are irritative to humans and plants, and erosion occurs on buildings. Although there are high lignite reservoirs, high sulfur content limits the efficient use of them. In this research, it is aimed to convert combustible sulfur in coal to non-combustible sulfur form in the ash by oxidizing it with permanganate solution. During this research, the effect of two different parameters of potassium permanganate concentration, processing time, and mean particle size were investigated at constant room temperature and shaking rate. The conversion of combustible sulfur to non-combustible sulfur form was achieved optimally with 0.14 M potassium permanganate solution, 0.1 mm mean particle size at 16 h of treatment time, and the combustible sulfur amount was decreased by 46.37% compared to undoped conditions.
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    Processing of fireproof and high temperature durable particleboard from rice husk
    (Walter de Gruyter GmbH and Co. KG, 2015) Gürü, Metin; Karabulut, Ahmet F.; Aydın, Mustafa Yasir; Bilici, İbrahim
    The aim of this study is the recovery of rice husk waste by researching usability in industry as an alternative to wood. In this study urea formaldehyde resin was used mainly as binding agent for wood-panel used in industry. For the preparation of composite material, ground powder rice husks were mixed with urea formaldehyde resin used in different proportions (65/50, 75/50, 80/50, 85/50, 95/50 by mass of filler/binder). Each particleboard produced in 393.15 K and 9.8 MPa pressure was tested by means of three point bending strength, shore hardness and limited oxygen index (LOI) tests. Particleboard made with 75/50 paddy husk/urea formaldehyde composition material formed of 11.40 MPa specimens showed the highest strength. Limited oxygen index value increased by increasing the filler material usage. The highest LOI value was recorded as 40%. Besides, fire point of particleboards which have the best three point bending strength has been analyzed at environmental atmosphere and 493.15 K has been measured as fire point. The results of the tests showed that this material maybe used instead of wooden plate. The usage of agricultural wastes like these in processing of particleboard will give economically benefits and slow down waste products. © 2015 by De Gruyter 2015.
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    Processing of urea-formaldehyde-based particleboard from hazelnut shell and improvement of its fire and water resistance
    (Wiley Blackwell, 2009) Gürü, Metin; Aruntaş, Yılmaz; Tüzün, Fatma Nihal; Bilici, İbrahim
    The purpose of this study was to manufacture urea-formaldehyde-based particleboard from hazelnut shell and eliminate its disadvantages such as flammability, water absorption, swelling thickness by using fly ash and phenol-formaldehyde. Synthesized urea-formaldehyde and grained hazelnut shells were blended at different ratios ranging from 0.8 to 3.2 hazelnut shell/urea-formaldehyde and dried at 70°Cinanoven until constant weight was reached. In addition, other parameters affecting polymer composite particleboard from hazelnut shell and urea-formaldehyde were investigated to be the amount of fly ash, amount of phenol formaldehyde and the effects of these parameters on bending stress, limit oxygen index, water absorption capacity and swelling in the thickness. The optimization results showed that the maximum bending strength was 4.1N/mm2, at urea-formaldehyde ratio of 1.0, reaction temperature of 70°C, reaction time of 25 min, hazelnut shell/urea- formaldehyde resin of 2.4 and mean particle size of 0.1 mm. Although the limited oxygen index and smoke density of composite particleboard without fly ash has 22.3 and 1.62, with fly ash of 16% (w/w) according to the filler has 38.2 and 1.47, respectively. Water absorption and increase in the swelling thickness exponentially decreased with increasing phenol formaldehyde. Copyright © 2009 John Wiley & Sons, Ltd.
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    Production of Ti-Fe based MgAl2O4 composite material by pressureless infiltration method
    (Gazi University, 2015) Bilici, İbrahim; Gürü, Metin; Tekelì, Süleyman
    In spite of their high temperature and corrosion resistance, ceramics show a brittle nature under applied loads and this limits their usage areas. In order to compensate the weakness of ceramics with metals, which have high ductility, the production of ceramic-metal composite materials has been recently started. In the present study, a ceramic-metal composite material was produced by means of pressureless infiltration method using spinel oxide (MgAl2O4) and Ti-Fe alloy. Atmospheric conditions, Ti-Fe/MgAl2O4 ratio, infiltration temperature and time were chosen as an experimental parameter. The experimenral results showed that a passivating oxide layer on the surface of the Ti-Fe alloy was observed in ambient atmosphere at 1600 degrees C for 120 minutes and therefore no reaction took place between the spinel and Ti-Fe alloy. Whereas, the Ti-Fe alloy was successfully infiltrated under argon atmosphere at 1550 and 1600 degrees C for 30, 60 and 120 minutes. The infiltrated Ti-Fe composites were characterized using SEM equipped with EDS. The hardness values of the Ti-Fe/MgAl2O4 composite increased up to 22.5 % Ti-Fe amount and further increase in the Ti-Fe amount led to a decrease in the hardness.
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    Role of NaCl in NaBH4 production and its hydrolysis
    (2013) Bilen, Murat; Gürü, Metin; Çakanyıldırım, Çetin
    This study explains completely feasible route to synthesize NaBH 4 by means of mechano-chemical reaction, in which NaCl, B 2O3 and MgH2 were utilized. Optimum reaction conditions were investigated by different values of reactant ratio and duration to reach 95% NaBH4 purity. In addition, commercial NaBH4 was hydrolyzed with CoI2 supported on activated carbon (AC). Intermediate steps of the studies were traced by means of FT-IR, XRD, SEM and EDX analyses. Activation energy of the catalyst was searched at distinct reaction temperatures and found as 36 kJ/mol. Optimum working time for ball-milling reactor and reactant ratio (MgH2/NaCl) were obtained as 1000 min and 1.0, respectively. © 2013 Elsevier Ltd. All rights reserved.
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    Solid phase synthesis of anhydrous zinc borate from zinc and boron oxide and utilization as a flame retardant in dye and textile
    (Gazi University, 2014) Ayar, Barış; Gürü, Metin; Çakanyıldırım, Çetin
    Durability of materials against flame and stability at high temperatures are very important in order to increase the field of use. Non-flammability is not the only requirement; these materials should not have toxic gas products during the burning, also. Anhydrous zinc borate was chosen as flame retardant due to its advantages, such as; light weight, high melting point, low thermal expansion, and intrinsic smoke suppression and corrosion resistance properties. For the synthesis, metallic zinc and anhydrous boron oxide powders were mixed in the attritor working at 600 rpm. Powder product was sintered under atmospheric conditions according to the phase change temperature that was determined by TGA-DSC analyses. Synthesized zinc borate was grinned up to nanometer size by Spex type grinder. Zinc borate was introduced in binder to decrease the flammability. The properties of the produced materials were determined and compared by LOI, TGA-DSC, SEM and oven according to the zinc borate ingredients.