Browsing by Author "Yalamac, E"

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    Effects of Surface Finishing on the Mechanical Properties of Induction Welded Iron Based Sintered Compacts
    (CARL HANSER VERLAG) Çavdar, U; Yalamac, E; Gülsahin, I
    In this study, iron based sintered parts were welded by high frequency induction welding. The effects of surface roughness on the mechanical properties of induction welded samples were investigated. Polished and unpolished samples were welded and mechanically tested by three point bending test. The hardness of the samples increased from the base material towards the weld metal. The weld metal, heat affected zone and the base material of the samples were investigated by light microscopy. In contrast to the polished samples, corrosion attack was registered in the welded region of unpolished samples. According to the results, the welding duration affects the mechanical properties. However, the surface finishing process was the dominant factor for the bending strength of the welded samples.
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    Growth of the Fe2B layer on SAE 1020 steel employed a boron source of H3BO3 during the powder-pack boriding method
    (ELSEVIER SCIENCE SA) Türkmen, I; Yalamac, E
    In this study, an alternative powder-pack boriding mixture containing H3BO3 as boron source was prepared and used for boriding of SAE 1020 steel. The boriding treatment was carried out in the temperature range of 850-950 degrees C for a treatment time ranging from 4 to 12 h. The generated boride layers were characterized by different experimental techniques such as optical microscope, SEM, XRD analysis and the Daimler-Benz Rockwell C indentation test. The powder-pack boriding mixture was analyzed by TGA and DTA methods and the possible chemical reactions that may be occurred during boriding were investigated. Furthermore, the growth kinetics of the boride layer forming on SAE 1020 steel substrates was investigated. A regression model based on a full factorial design was used to estimate the boride layers' thicknesses as a function of the boriding parameters. A single phase boride layer with saw-tooth morphology was formed on the steel samples. The value of boron activation energy for SAE 1020 steel was estimated as 183.15 kJ/mol. The comparisons were made between the empirical values of the boride layers' thicknesses with estimated ones. The contour diagrams were plotted for estimating the thickness of boride layer as a function of the temperature and time. (C) 2018 Elsevier B.V. All rights reserved.
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    English
    (0301-4797) Sutcu, M; Ozturk, S; Yalamac, E; Gencel, O
    ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
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    Preparation and characterization of anorthite ceramics from sugar production solid waste: a statistical analysis of grinding parameters
    (SPRINGER) Kaya, VS; Sutcu, M; Yalamac, E
    The purpose of the study was to investigate the possibility of using press filter cake (PFC) waste from sugar production in the preparation of anorthite ceramics. In this study, at first step, the properties of anorthite ceramic compositions produced using different proportions of press filter cake (PFC) as calcium oxide source and chamotte as aluminosilicate source were investigated. A single anorthite phase was obtained in samples containing high PFC ratios sintered at high temperature. In the second step, the PCH-35 (35% PFC plus 65% chamotte) ceramic composition was statistically analyzed to examine grinding parameters and sintering temperatures. This composition was ground and sintered at different parameters to investigate the effects on physical, mechanical, and morphological properties on anorthite ceramics. The results indicated that the anorthite phase formed in the powders sintered at 1200 degrees C and 1300 degrees C after grinding was the major phase. With increasing sintering temperature, grinding speed, and time, the samples exhibited lower porosity, higher bulk density, and compressive strength. With the sintering of the samples at 1200 degrees C, the percentage of apparent porosity decreased from 49.95 to 25%, while the bulk density value increased from 1.36 to 2.03 g/cm(3) with increasing grinding speed and time. When the samples were sintered at 1300 degrees C, the percentage of apparent porosity decreased from 49.59 to 0.33%, while the bulk density value increased from 1.33 to 2.54 g/cm(3) with increasing grinding speed and time. The compressive strength results (from 26 to 82 MPa) increased due to body densification with the effect of increasing sintering temperature, grinding speed, and time.