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    Characterization and Reduction Behavior of Cold-Bonded Composite Pellets for Direct Reduction Using an Organic Binder
    (Springer, 2013) Cevik, E.; Ahlatci, H.; Sun, Y.
    The purpose of this study was to investigate the reduction behavior of cold-bonded composite pellets produced from low-grade hematite iron ore using molasses solution at various concentrations, as well as their physical and chemical properties. Direct-Reduction Iron (DRI) technology makes it possible to assess low-grade iron ores and convert them into scrap at facilities that have electric arc furnaces. The reductant used was coke with fixed carbon of 86.04%. The alkalinity rate was adjusted to 0.7 by adding calcium carbonate. In the composite pellets produced, the 300 N/pellet compression strength recommended in the literature was achieved with a Fe-tot/C-fix ratio of 2.5 and 3 using a 50% concentrated molasses solution. Composite pellets prepared with a Fe-tot/C-fix ratio of 3.5 using a 40% concentrated molasses solution reached a compression strength of 496 N/pellet. The porosity is inversely proportional to the increase in compression strength and binder concentration. Reduction experiments were conducted by applying different temperatures and durations to samples possessing optimum conditions for each Fe-tot/C-fix ratio: the best result was achieved with a 88% reduction rate in composite pellets with a Fe-tot/C-fix ratio of 3.5 at the end of 1 h. Pig iron nuggets were characterized using an optical microscopy (LOM) and a scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS).
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    Effect of Aging Treatment on Surface Roughness, Mechanical Properties, and Fracture Behavior of 6XXX and 7XXX Aluminum Alloys
    (Springer, 2014) Sevim, I.; Sahin, S.; Cug, H.; Cevik, E.; Hayat, F.; Karali, M.
    The effect of aging treatment on the surface roughness and mechanical properties of AA6061 and AA7075 alloys was studied. Microhardness and tensile tests were used to investigae the mechanical properties. X-ray diffraction analysis was used to investigate the surface of the specimens. Furthermore, after tensile tests fractured surfaces were examined with scanning electron microscopy. An atomic force microscope was employed for analysis of the effect of aging treatment on surface roughness. Higher surface roughness with an increase in the volume fraction of the precipitate was revealed.
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    Effect of Magnesium Additions on Composites with Al and Al-12% Si Matrices Strengthened with B4C and Prepared by Infiltration Under Pressure
    (Springer, 2016) Cevik, E.; Sun, Y.; Ahlatci, H.; Turen, Y.
    Metallographic and x-ray phase analyses are used for metal-matrix composites Al - B4C and (Al - 12% Si) - B4C with a volume fraction of 60% boron carbide prepared by infiltrating a pressed workpiece with metal under pressure. It is shown that with introduction of 1 to 4% Mg into a metal matrix composite porosity is reduced from 7 to 1%.
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    EFFECT OF PEAK-AGED HEAT TREATMENT ON CORROSION BEHAVIOR OF THE AA6063 ALLOY CONTAINING Al3Ti
    (Polska Akad Nauk, Polish Acad Sciences, Inst Metall & Mater Sci Pas, 2012) Cevik, E.; Sun, Y.; Ahlatci, H.
    The purpose of this study is to analyse the microstructure and corrosion properties of homogenised and aged AA 6063 aluminium alloys, containing up to 2% Ti, after the conventional casting technique. The microstructure of the homogenised and aged alloys was examined using an optic microscope, and scanning electron microscope. The micro-hardness test was used for the hardness measurements of the investigated alloys. Corrosion tests were performed by suspending samples of certain sizes into 30 gr/l NaCl + 10 ml/l HCl solutions, measuring the mass loss; potentiodynamic polarisation measurements were carried out in the same solution. The microstructure characterization of the investigated alloys shows the Al (matrix), non-shaped dark globular grey-coloured phase and rod-shaped phases formed at the grain boundaries. The non-shaped dark grey-coloured phase is Mg2Si. The rod-shaped phase, formed in the microstructure of the Ti-added AA 6063 alloys, is Al3Ti. The Ti content of the alloy increases, the Al3Ti phase tends to elongate and become plated. The results of the corrosion tests proved that the corrosion rate decreased in alloys containing less than 1% Ti, and the rate of corrosion increased in alloys containing more than 1% Ti, regardless of whether the alloys were homogenised and aged. Another observation was that aging heat treatment improved corrosion resistance.
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    MECHANICAL AND TRIBOLOGICAL BEHAVIOUR OF B4C REINFORCED AlSi12-XMg MATRIX COMPOSITES
    (Scibulcom Ltd, 2015) Cevik, E.; Sun, Y.
    In this study, mechanical and tribological behaviours of composites produced by using pressure infiltration method were investigated. Preforms were prepared by using B4C particles with an average grain size of 45 mu m and a volume rate of 60%. Four different matrixes produced by adding different proportions (0, 1, 2 and 4 wt.%) of Mg to AlSi12 aluminium alloy were melted at 800 degrees C and infiltrated to the preform with a pressure of 8 bars. Results whose microstructure characterisation was conducted by using light optical (LOM) and scanning electron (SEM) microscope were supported with X-ray diffraction (XRD) analyses. With the increasing addition of Mg, hardness values and compressive strength increased. This improvement in mechanical properties improved the wear resistance. While the lowest weight loss was achieved with the addition of 4% Mg in low loads as a result of wear tests, the best wear resistance in high loads was observed in composites produced with the addition of 1% Mg.
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    Mechanical and tribological behaviour of B4C reinforced AlSi12-XMg matrix composites
    (Scibulcom Ltd., 2015) Cevik, E.; Sun, Y.
    In this study, mechanical and tribological behaviours of composites produced by using pressure infiltration method were investigated. Preforms were prepared by using B4C particles with an average grain size of 45 mm and a volume rate of 60%. Four different matrixes produced by adding different proportions (0, 1, 2 and 4 wt.%) of Mg to AlSi12 aluminium alloy were melted at 800°C and infiltrated to the preform with a pressure of 8 bars. Results whose microstructure characterisation was conducted by using light optical (LOM) and scanning electron (SEM) microscope were supported with X-ray diffraction (XRD) analyses. With the increasing addition of Mg, hardness values and compressive strength increased. This improvement in mechanical properties improved the wear resistance. While the lowest weight loss was achieved with the addition of 4% Mg in low loads as a result of wear tests, the best wear resistance in high loads was observed in composites produced with the addition of 1% Mg.