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Kuvars ve metakaolen katkısının jeopolimerlerin özellikleri üzerine etkisi
(2017) Aydın, Tuna
Yapılan bu çalışmada jeopolimer malzemelerin mikroyapı özellikleri üzerine kuvars ve metakaolen katkısının etkileri incelenmiştir. Bu doğrultuda, numunelerin üretiminde kullanılan uçucu kül Soma Termik Santrali uçucu külü olup, karışımlarda, alkali aktifleştirici olarak; sodyum silikat solüsyonu (SS) ve sodyum hidroksit (NaOH) kullanılmıştır. Hazırlanan harçlar, 280 mm 70 mm 70 mm'lik çelik kalıplarda ve vibrasyon yöntemiyle şekillendirilmiştir. Ardmdan numuneler 24 saat süre ile 75 oC'de laboratuvar tipi etüvde termal olarak kürlenmiştir. Sonuç olarak, standart bünyeye kıyasla kuvars ve metakaolen içeren numunelerde yoğunluklarda artış tespit edilmiştir. Buna bağlı olarakta toplam porozite değerlerinde düşüş tespit edilmiştir. Eğme ve basma mukavemet değerlerinde de standart bünyeye kıyasla artış olmuştur.
AZ91 magnezyum alaşımının sol-jel yöntemiyle hidroksiapatit kaplanması
(2017) Albayrak, Sevda; Çinici, Hanifi; Çalın, Recep; Cömert, Canser
Bu çalışmada amaç; biyomedikal uygulamalarda kullanılmak üzere mevcut biyomalzemelerden daha hafif, biyolojik saldırılara karşı dirençli ve kemik yapısına benzer, doku ile uyumlu bir malzeme üretebilmektir. Hafiflik biyomalzeme uygulamalarında son derece önemlidir, çünkü paslanmaz çelik ve bunun gibi ağır metalik alaşımlar vücutta kullanıldığında implant çevresindeki dokulara zarar vererek enfeksiyona sebep olabilmektedir. AZ91 Mg alaşımının hafifliği büyük bir avantaj olsa da vücutta kullanmak için yeterli mukavemete sahip değildir ve biyolojik ortamda bozunmaktadır. AZ91 Mg alaşım tozları 320 °C sıcaklık ve 275 MPa basınçta sıcak pres yöntemi ile preslendikten sonra, yeterli dayanımı sağlamak ve bozunmasını engellemek amacıyla sol-jel ve dip coating metoduyla yüzeyi farklı daldırma sayılarında hidroksiapatit ile kaplanmış ve 400 °C'de sinterlenmiştir. Kaplanan numunelerin yüzey morfolojileri SEM; faz yapıları ise XRD ile incelenmiştir
Investigation of wear resistance of the porcelain tile bodies by solid particle impingement using alumina particles
(SPRINGER, 2020) Aydin, Tuna; Bican, Osman; Gumruk, Recep
Wear resistance is of great importance for many industries related with minerals. The particles seen in these industries may cause erosion. These particles may have various sizes, shapes, and hardness, and may also impact the surface at various angles and speeds. Wear resistance is also important for the ceramic tile industry because the materials, which are also used in building facades, must withstand all kinds of weather conditions. In this study, the wear resistance of the porcelain tile bodies was investigated by solid particle impingement using alumina particles. The effects of technological, mechanical, and microstructural properties on wear resistance were also investigated. It was determined that the technological, mechanical, and microstructural properties were improved with the addition of spodumene, which also caused that the wear rates were reduced.
Effects Of The Boriding Process And Of Quenching And Tempering After Boriding On The Microstructure, Hardness And Wear Of AISI 5140 Steel
(WORLD SCIENTIFIC PUBL CO PTE LTD, 2020) Bican, Osman; Bayca, Salih Uğur; Ocak-Araz, Şule; Yamaneli, Bünyamin; Taniş, Naci Arda
An investigation was made on the effects of the boriding process and of quenching and tempering after boriding on the microstructure, hardness and wear of AISI 5140 steel. In this study, a new boriding agent (Baybora (R)-1) developed for the solid boriding method was used. It was observed that the wear resistance of the borided samples increased by about four times, but the wear resistance of the sample subjected to quenching and tempering after boriding increased by only about two times. Thus, it was determined that quenching and tempering after boriding worsen wear resistance.
Microstructure evolution and hardness of MWCNT-reinforced Sn-5Sb/Cu composite solder joints under different thermal aging conditions
(PERGAMON-ELSEVIER SCIENCE LTD, 2020) Dele-Afolabi, T. T.; Hanim, M. A. Azmah; Calin, R.; Ilyas, R. A.
In this work, multi-walled carbon nanotubes (MWCNTs) reinforced Sn-5Sb/Cu composite solder joints were synthesized and the effects of MWCNTs addition on the microstructure evolution and hardness of the Sn-5Sb solder alloy during various thermal aging conditions were investigated. After conducing a thorough microstructural analysis, the SbSn and Cu6Sn5 intermetallic compounds (IMCs) were observed in the beta-Sn matrix of the composite solder joints subjected to reflow soldering while the latter was also present at the solder/Cu interface. However, after subjecting the composite solder joints to isothermal aging, the Cu3Sn IMC emerged between the Cu6Sn5 IMC at the solder/Cu interface and the Cu substrate. With the promising properties exhibited by MWCNTs as a reinforcement material, experimental results showed that MWCNTs refined the bulk solder microstructure and inhibited growth of the interfacial IMC layer in the Sn-5Sb-xCNT/Cu samples. In general, the composite sample reinforced with 0.05 wt% MWCNTs showed the least IMC layer thickness and diffusion coefficient in the ranges of 2.6-11.99 mu m and 1.07 x 10(-14 )-14.9 x 10(-14) cm(2)/s respectively. Meanwhile, the strengthening mechanism triggered by MWCNTs addition was clearly evident in the MWCNT-reinforced Sn-5Sb/Cu as superior hardness values within a range of 20.6-15.3 HV were registered for the as-soldered and aged composite solder joints with 0.05 wt% MWCNTs reinforcement.
Mixed Alkali and Mixed Alkaline-Earth Effect in Ceramic Sanitaryware Bodies Incorporated with Blast Furnace Slag
(SPRINGER, 2020) Aydin, Tuna; Casin, Eray
Raw materials and energy are among the most important costs in ceramic sanitaryware production. With the decrease in raw material sources and increasing costs of energy in recent years, researches on alternative raw materials and energy have started to gain importance. In this study, blast furnace slag and spodumene were used to reduce both energy and raw material costs. In standard vitreous china ceramic sanitaryware, a maximum of 15% blast furnace slag and 4% spodumene was used instead of sodium feldspar. In this study, the effects of CaO, MgO, and Li2O on microstructure, technological properties such as flexure strength, water absorption, porosity, bulk density; and also, thermal properties such as sintering analysis were investigated by using a non-contact optical dilatometer and thermal expansion. The dry strength and flexure strength of fired samples increased. The increase in dry strength was approximately 47%. The increase in flexure strength was approximately 67%. The reduction in the thermal expansion coefficient values was approximately 17%, which is also important in terms of stability of the final product. As a result, the use of blast furnace slag and spodumene will result in a reduction in both energy and raw material costs. The spodumene and BFS provided a reduction in sintering temperature at a rate of approximately 60 degrees C. The flue gas emissions may also reduce because flue gas emissions are higher as the temperature inside the furnace is higher. The spodumene and blast furnace slag addition provide a decrease in the peak of sintering temperatures so that flue gas emissions will reduce. [GRAPHICS] .
Tailored pore structures and mechanical properties of porous alumina ceramics prepared with corn cob pore-forming agent
(WILEY, 2021) Dele-Afolabi, T. T.; Hanim, M. A. Azmah; Ojo-Kupoluyi, O. J.; Calin, R.; Zuhri, M. Y. M.
In this work, the effects of porosity and different particle sizes of pore-forming agent on the mechanical properties of porous alumina ceramics have been reported. Different grades of porous alumina ceramics were developed using corn cob (CC) of different weight contents (5, 10, 15, and 20 wt%) and particle sizes (<63 mu m, 63-125 mu m and 125-250 mu m) as the pore-forming agent. Experimental results showed that total porosity and pore cavity size of the porous alumina ceramics increased with rising addition of CC pore former. Total porosity increased with increasing particle size of CC with the Al2O3-(<63)CC(5)sample exhibiting the lowest total porosity of 41.3 vol% while the highest total porosity of 68.1 vol% was exhibited by the Al2O3-125-250CC20. The particle size effect of CC on the mechanical properties revealed that diametral tensile strength and hardness of the porous alumina ceramics deteriorated with increasing particle size of CC pore former. The Al2O3-(<63)CC(5)sample exhibited the highest diametral tensile strength and hardness of 25.1 MPa and 768.2 HV, respectively, while Al2O3-(125-250)CC(20)exhibited the lowest values of 1.1 MPa and 35.9 HV. Overall, porous alumina ceramics with the smallest pore sizes under each particle size category exhibited superior mechanical properties in their respective categories.
The effect of cement raw mix waste dust on porcelain tile properties
(Springer, 2019) Aydin, Tuna; Paksoy, Cigdem
Nowadays, the recycling of industrial waste is one of the priority issues. Recycling studies related with reducing the negative effects of wastes on the environment are becoming increasingly important. It was believed that nothing was beyond recycling, and manufacturers should take greater responsibility for their part in the waste economy to apply cyclical solutions to an expanding breadth of new product categories. Cement raw mix contains silicate, alumina, iron oxide, and limestone. Raw mix contains SiO2, Al2O3, CaO, Fe2O3, MgO, Na2O, and K2O in higher ratio. The high presence of these oxides in the raw mix powder makes raw powder an alternative source of raw material for porcelain tile compositions. In this study, raw mix dust was used instead of sodium feldspar in a standard porcelain tile composition, at a rate of 1, 5, 10, and 15% by weight. The specimens were sintered at 1210 A degrees C. Flexural strength, firing shrinkage, water absorption, porosity, and other technological properties were investigated. It has been determined that the body containing 1% of the raw mix powder improved its physical and mechanical properties compared to the standard body.
The development of porcelain foams lighter than water for heat isolation application
(Springer, 2019) Aydin, Tuna
In this study, technological and heat isolation properties of porous ultra-lightweight porcelain foams were investigated. Traditional construction materials such as brick show good durability against environmental conditions. Bricks are also a good alternative compared to pumice blocks and autoclaved aerated concrete which are largely used as construction materials. Bricks are also more economical than the other construction materials. But they also have poorer thermal insulation properties. Among the construction material, XPS shows the best heat isolation properties. XPS (extruded polystyrene foam) is a polymeric material. Although XPS shows best heat insulation property, it easily flames. The aim of this study is developing porous porcelain isolation materials lighter than water by using a replication method and relatively better thermal isolation properties than the other construction materials.
Addition of cement kiln dust in ceramic wall tile bodies
(Springer, 2019) Aydin, Tuna; Tarhan, Muge; Tarhan, Baran
The volume of wastes generated from heavy industries, such as cement and steel industries, is increasing, and the cost of landfill disposal grows daily. Economical and eco-friendly areas of recycle are being developed to stop the growth of these waste products. Cement kiln dust (CKD) is a waste product in the cement industry. It contains very fine grains like cement in addition to finer particles of lime, silica, alumina and iron. These particles contain high concentrations of sulphates and alkalis. The aim was to study the effects of using CKD as an alternative source of CaO in ceramic wall tile production. Ceramic tiles compositions in different ratios were prepared with CKD (15 mass% max) rather than calcite. All shaped samples were sintered at 1150 degrees C. Optical dilatometer was used to evaluate sintering behaviour. Physical properties, such as linear firing shrinkage, bulk density, flexural strength and water absorption, were also measured. The bodies containing CKD showed a decrease in moisture expansion and were whiter than the body of a standard composition. This study showed that CKD is an effective CaO source in ceramic tile production.
A New Method for Colemanite Waste Processing
(Pleiades Publishing Inc, 2019) Bayca, Salih Uğur
In this study, two extraction methods were used sequentially. In the first stage, colemanite process waste was subjected to scrubbing and decantation, and colemanite concentrate was obtained. In the second stage, leaching and filtration processes were carried out on the colemanite concentrate, and pure boric acid was obtained. Colemanite process waste (CPW) contains colemanite, calcite, quartz and others minerals. The boron oxide percentage of CPW was increased by the scrubbing method. Thus, impurities of the CPW were decreased. Scrubbed CPW is referred to as colemanite concentrate (CC). Boric acid extraction was investigated by the leaching of the colemanite concentrate in sulfuric acid solutions. The characterization of colemanite concentrate was determined by X-ray diffraction (XRD) analysis and X-ray fluorescence (XRF) analysis. The leaching parameters in this study were solid/liquid ratio, stirring speed, acid concentration, and reaction temperature. It was observed that the dissolution efficiency increased with increasing reaction temperature and with decreasing solid/liquid ratio and acid concentration. CPW is a problem for the environment; however, in this study, this CPW was converted into a valuable product (boric acid).
Synthesis of nickel nanothorn particles by the hydrothermal method
(Taylor & Francis Inc, 2019) Bayca, Salih Uğur; Altınok, Haydar; Akçay, Aysun
In this study, an investigation was performed of the preparation of nickel nanothorn particles by the hydrothermal synthesis method. The effects of parameters were investigated on the particle shape and size, which were determined by scanning electron microscope (SEM) analysis. The synthesis parameters were hydrazine concentration, heating temperature in autoclave, heating time in autoclave, nickel sulfate concentration, pH, NaCl concentration. The phases contained in the synthesized samples were analyzed by X-ray powder diffraction (XRD) analysis, nickel purity of samples were analyzed by X-ray fluorescence (XRF), and the magnetic properties of the nickel particles were measured by a magnetic hysteresis test. The results showed that nickel nanothorn particles were successfully produced without any surfactant by simple hydrothermal synthesis. As the hydrazine concentration was increased, the thorn length of the nickel particles also increased.
Impact of different isothermal aging conditions on the IMC layer growth and shear strength of MWCNT-reinforced Sn-5Sb solder composites on Cu substrate
(Elsevier Science Sa, 2019) Dele-Afolabi, T. T.; Hanim, M. A. Azmah; Ojo-Kupoluyi, O. J.; Calin, R.
In this study, the effect of multi-walled carbon nanotubes (MWCNTs) reinforcement on the intermetallic compound (IMC) layer growth and shear strength of Sn-5Sb-xCNT/Cu composite solder joints subjected to different isothermal aging conditions has been investigated. A series of plain and composite lead-free solder systems (Sn-5Sb-xCNT; x = 0, 0.01, 0.05 and 0.1 wt%) was successfully developed through the powder metallurgy method. Isothermal aging process was performed on the solder/Cu joints at 120 degrees C, 150 degrees C and 170 degrees C temperatures in order to investigate the evolution of the interfacial IMC layers and the shear strength property. Experimental results showed that the thickness of the total IMC layer increased with rising aging temperature. While the Cu3Sn IMC maintained a layer-type morphology for all aging conditions, morphology of the Cu6Sn5 IMC transformed from a scallop-type to a layer-type after aging at intermediate (150 degrees C) and high (170 degrees C) temperatures. Given the potential of MWCNTs as a reinforcement material, significant suppression in IMC layer growth was demonstrated by the composite solder joints relative to the plain counterpart. Comprehensive investigation on the growth kinetics showed that the presence of MWCNTs in the composite solder joints was effective in slowing down the diffusion mechanism responsible for IMC growth. Overall, the Sn-5Sb-0.05CNT composite solder joint exhibited the lowest diffusion coefficient within the range of 0.09 x 10(-14)-1.03 x 10(-14) cm(2)/s and 0.95 x 10(-14)-9.8 x 10(-14) cm(2)/s for Cu6Sn5 and Cu3Sn IMC layers respectively. Moreover, the strengthening effect of the MWCNTs reinforcement was well marked in the composite solder joints as the maximum shear strength within a range of 24.2-15.2 MPa was exhibited by the Sn-0.01CNT/Cu composite solder joint subjected to reflow soldering and isothermal aging conditions. (C) 2019 Elsevier B.V. All rights reserved.
Optimization of Leaching Parameters of Aluminum Hydroxide Extraction from Bauxite Waste Using the Taguchi Method
(Wiley, 2018) Bayca, Salih U.; Kisik, Hakan
In this study, the statistical optimization of the leaching parameters of aluminum hydroxide extraction from bauxite waste (red mud) was investigated. The extraction parameters were solid-to-liquid ratio, base concentration, reaction temperature, leaching time, and stirring speed. Optimum experimental conditions were carried out by the Taguchi method. A higher dissolution rate was found to give better performance characteristics. The most important parameter was determined using the statistical analysis of variance. (c) 2017 American Institute of Chemical Engineers
The Effect of Nepheline Syenite Addition on Pyroplastic Deformation of Sanitarywares
(Int Inst Science Sintering (I I S S), 2018) Aydin, Tuna; Kunduraci, Nazim; Akbay, Atamer
Nepheline syenite is used instead of feldspars as fluxing in ceramics. In this study, three ceramic bodies were prepared. Nepheline syenite was substituted by Na feldspar in the ratio of maximum 30 wt.%. The pyroplastic deformation was evaluated together with technological properties, including linear shrinkage, water absorption and strength. Phase and microstructural characteristics were also investigated. Results showed that the addition of nepheline syenite provided a decrease in viscosity. The decrease in viscosity caused an increase in the tendency for pyroplastic deformation in bodies containing nepheline syenite; however, this result shows that bodies containing nepheline syenite can be sintered at a lower temperature than the standard body. The addition of nepheline syenite also decreased water absorption and increased strength.
Development of porous lightweight clay bricks using a replication method
(Australian Ceramic Society, 2018) Aydin, Tuna
This study focused on porous lightweight clay bricks as a construction material as opposed to autoclaved aerated concrete and pumice blocks. Traditional clay bricks exhibit good stability against environmental conditions and are an economical alternative compared to other construction materials. Furthermore, clay bricks have better mechanical properties than autoclaved aerated concrete and pumice blocks but poorer thermal insulation properties; hence, their use in buildings is becoming increasingly unfavourable. This study focused on developing porous lightweight clay bricks with relatively better thermal insulation properties using a replication method.
The Effects of Nitrogen Gas on Microstructural and Mechanical Properties of TIG Welded S32205 Duplex Stainless Steel
(Mdpi, 2018) Basyigit, Aziz Baris; Kurt, Adem
Duplex stainless steels are gaining greater interest due to their increasing amounts of application fields. Accordingly, there is a need for awareness of problems associated with improper microstructural distributions such as delta-ferrite (delta-ferrite), austenite and other important intermetallic phases that may form in these steel weldments. Since delta-ferrite versus austenite ratio profoundly influences corrosion and mechanical properties, optimum delta-ferrite ratios must be kept approximately within 35-65 vol % and balance austenite to maintain satisfactory corrosion and mechanical properties on welding of these steels. Cooling rates of welds and alloying elements in base metal are the major factors that determine the final microstructure of these steels. In this work, 3 mm thickness of 2205 duplex stainless-steel plates were TIG (Tungsten Inert Gas) welded with various amounts of nitrogen gas added to argon shielding gas. Specimens were joined within the same welding parameters and cooling conditions. As nitrogen is a potential austenite stabilizer and an interstitial solid solution hardener, the effects of nitrogen on mechanical properties such as hardness profiles, grain sizes and microstructural modifications are investigated thoroughly by changing the welding shielding gas compositions. Increasing the nitrogen content in argon shielding gas also increases the amount of austenitic phase while delta-ferrite ratios decreases. Nitrogen spherodized the grains of austenitic structure much more than observed in delta-ferrite. The strength values of specimens that welded with the addition of nitrogen gas into the argon shielding gas are increased more in both austenitic and delta-ferritic structure as compared to specimens that welded with plain argon shielding gas. The addition of 1 vol % of nitrogen gas into argon shielding gas provided the optimum phase balance of austenite and delta-ferrite in S32205 duplex stainless-steel TIG-welded specimens.
Significant effect of rice husk and sugarcane bagasse pore formers on the microstructure and mechanical properties of porous Al2O3/Ni composites
(Elsevier Science Sa, 2018) Dele-Afolabi, T. T.; Hanim, M. A. Azmah; Norkhairunnisa, M.; Sobri, S.; Calin, R.; Ismarrubie, Z. N.
Porous alumina systems are suitable for application in wide-ranging industrial processes that require extreme service conditions such as high temperatures and corrosive mediums due to their remarkable thermal and chemical stability. Given the inherent brittleness of ceramics and their high sensitivity to thermo-mechanical loading, large-scale production of porous alumina components is constrained. In this study, the reinforcement of porous alumina ceramics with nickel (Ni) particles has been reported. Plain and Ni-reinforced porous alumina ceramics were developed through the powder metallurgy method with agro-waste materials from rice husk (RH) and sugarcane bagasse (SCB) as the pore-forming agents (PFAs). Experimental results showed that the formation of a stable Ni3Al2SiO8 spinelloid phase in the RH-graded composites actuated the emergence of a relatively refined microstructure while on the other hand, microstructural defects such as dislocated grains and localized voids were observed for the SCB-graded counterparts due to the presence of poorly crystallized NiAl2O4 spinel phase. Generally from the mechanical strength characterization, an inverse relationship was established between the mechanical properties and Ni reinforcement which agrees well with the Griffith's model. Moreover, the strengthening effect of the Ni3Al2SiO8 spinelloid phase was well marked in the RH-graded composites as maximum hardness, tensile and compressive strengths of 167.3HV, 12.6 MPa and 55.3 MPa respectively were achieved for the composite reinforced with 2 wt% Ni. (c) 2018 Elsevier B.V. All rights reserved.
Tensile strength and corrosion resistance properties of porous Al2O3/Ni composites prepared with rice husk pore-forming agent
(Elsevier Sci Ltd, 2018) Dele-Afolabi, T. T.; Hanim, M. A. Azmah; Norkhairunnisa, M.; Sobri, S.; Calin, R.; Ismarrubie, Z. N.
The mechanical performance and chemical stability of porous alumina materials operating under harsh service conditions are of utmost importance in understanding their operational behavior if they are to stand the test of time. In the present study, the joint effect of nickel (Ni) reinforcement and rice husk (RH) pore-forming agent (PFA) on the tensile strength and the corrosion resistance properties of composite porous alumina ceramics was studied. To exploit the potential of this new porous alumina system, plain and Ni-reinforced porous alumina samples (Al2O3-xNi-RH; x = 2, 4, 6 and 8 wt%) were developed through the powder metallurgy technique. Comprehensive investigation on the tensile strength properties of the developed porous alumina ceramics showed that relative to the plain sample (tensile strength and elastic modulus; 6.1 MPa and 1201 MPa), the presence of highly stable Ni3Al2SiO8 spinelloid promoted the tensile strength enhancement (12.6-6.4 MPa) and the elastic modulus decline (897-627 MPa) of the composite samples. Similarly, corrosion resistance test was performed on the composite porous alumina samples in both 10wt% NaOH and 20wt% H2SO4 hot aqueous solutions. Overall, the composite samples demonstrated superior chemical stability in NaOH solution as compared with the plain sample. On the other hand, the composites were more prone to attack in H2SO4 solution, except for the Al2O3-2Ni-10RH composite sample which maintained its superiority over the plain counterpart.
Agro-waste shaped porous Al2O3/Ni composites: Corrosion resistance performance and artificial neural network modelling
(Elsevier Science Inc, 2018) Dele-Afolabi, T. T.; Hanim, M. A. Azmah; Norkhairunnisa, M.; Sobri, S.; Calin, R.; Ismarrubie, Z. N.
In the present study, an analysis on the combined effect of nickel (Ni) reinforcement and pore former type in characterizing the corrosion behavior of composite porous alumina ceramics was performed. In order to showcase the potential of the new porous ceramics, pore-forming agents (PFAs) from rice husk (RH) and sugarcane bagasse (SCB) were used in shaping the plain and composite porous alumina samples having sample formulation of Al2O3-xNi-PFA; x = 0, 2, 4, 6 and 8 wt%. Results showed that the emergence of a highly stable Ni3Al2SiO8 spinelloid phase in the RH-graded composites enhanced their chemical stability in the corrosive mediums (10 wt% NaOH and 20 wt% H2SO4) relative to the plain and the corresponding SCB-graded counterparts. An artificial neural network (ANN) model has been developed for predicting the corrosion behavior of the plain and composite porous alumina ceramics based on the experimental data. The developed ANN model satisfactorily predicted the percent mass losses of the porous ceramics in strong alkali and strong acid solutions with coefficient of determination (R-2) of approximately 0.99.

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