Browsing by Author "Seker, Ulvi"

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Effect of Pumice Powder on Mechanical, Thermal, and Water Absorption Properties of Fiberboard Composites
(Lukasiewicz Research Network - Lodz institute of Technology, 2023) Koyuncu, Menderes; Ulay, Goksel; Seker, Ulvi
Composites were produced using medium-density fiberboard (MDF) flour with pumice powder which was mixed at various ratios by the hand lay-up technique. Mechanical properties, such as tensile and three-point bending strengths, were determined by ASTM D3039 and ASTM D790 respectively. The best three-point bending and tensile strength properties were maximum values obtained from composites containing 20wt% pumice powder (pp) and 50wt% pumice powder (pp) respectively. It is observed that the water absorption rate into the composites decreases with an increase in the pumice powder-to-ratio. The composite filled with 50wt%pumice powder absorbed the least amount of water compared to the other composites. All composites were characterized by scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FTIR), and differential scanning calorimetry analysis (DSC). SEM images revealed a near-homogeneous surface partly free of defects and holes. However, lateral profile images showed the presence of MDF flour particles agglomerated and a considerable number of bubbles and cavities that could interfere with the mechanical properties of the composites. The results of the mechanical, and thermal properties suggested that pumice powder epoxy composites with MDF flour can increase their tensile, three-point-bending strength, and glass transition temperature for the pure MDF flour composite.
The Effects of a Tool's Chemical Composition on Its Performance When Turning Inconel 718 With Ceramic Inserts
(Assoc Mechanical Engineers Technicians Slovenia, 2007) Altin, Abdullah; Taskesen, Ahmet; Nalbant, Muammer; Seker, Ulvi
The effects of a cutting tool's chemical composition on wear and tool life are investigated. A series of experiments was carried out using silicon-nitrite-based (Si, Al, O, N) and whisker-reinforced ceramic tools (Al2O3+SiCw) that have two different geometries (square and circular) and three different ISO qualities. For the ceramic tools, a high level of aluminum and germanium caused built-up edge (BUE) formation, while notch wear is considered as a cause of high copper and oxygen levels in whisker-reinforced ceramic tools. Four different tools with two qualities showed the best performance at a cutting speed of 200 m/min. The fact that the whisker-reinforced square-type ceramic tools are subjected to plastic deformation is attributed to the high oxygen level in the cutting tool's structure. (C) 2007 Journal of Mechanical Engineering. All rights reserved.