Browsing by Author "Kir D."

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Characterization of hot pressed CuAl–TiC composites with different TiC grain sizes
(2016-07-01) Islak S.; Çelik E.; Kir D.; Özorak C.
In this study, the CuAl–TiC composite materials were produced using hot pressing process. Effect of TiC grain size (0.2, 4 and 20 μm) on some properties of these materials was investigated experimentally. Production of CuAl–TiC composites was carried out under pressure of 35 MPa, at 700°C, and for a sintering time of 5 minutes. SEM-MAP studies showed that the TiC grains were relatively homogeneously distributed in the CuAl matrix. Microstructure analysis revealed that the composite materials consist of Cu, Al, Cu9Al4, CuAl2 and TiC phases. With the decreasing of TiC grain size, the hardness, transverse rupture strength, relative density and sintered density of composites increased.
Effect of sintering temperature on electrical and microstructure properties of hot pressed Cu-TiC composites
(2014-01-01) Islak S.; Kir D.; Buytoz S.
In this study, Cu-TiC composites were successfully produced using hot pressing method. Cu-TiC powder mixtures were hot-pressed for 4 min at 600, 700 and 800 °C under an applied pressure of 50 MPa. Phase composition and microstructure of the composites hot pressed at different temperatures were characterized by X-ray diffraction, scanning electron microscope, and optic microscope techniques. Microstructure studies revealed that TiC particles were distributed uniformly in the Cu matrix. With the increasing sintering temperature, hardness of composites changed between 64.5 HV0.1 and 85.2 HV0.1. The highest electrical conductivity for Cu-10 wt.% TiC composites was obtained for the sintering temperature of 800 °C, with approximately 68.1% IACS.
Effect of the cBN content and sintering temperature on the transverse rupture strength and hardness of cBN/diamond cutting tools
(2012-09-24) Islak S.; Kir D.; Çelik H.; Çelik E.
The aim of this work was to investigate the effect of cBN content and sintering temperature on the transverse rupture strength (TRS) of cBN/diamond cutting tools produced by hot pressing. The segments containing different cBN content were manufactured under 35 MPa pressure at 600, 650 and 700 °C with a 3 minutes sintering time. The TRS of segments were determined using three-point bending test. Microstructure and phase composition of fracture surface of segments were determined by scanning electron microscopy (SEM), and X-ray diffraction (XRD) analysis. The obtained results show that the TRS of the segments with cBN were higher than that of the segments with diamond.
Effect of the TiC content on microstructure and thermal properties of Cu-TiC composites prepared by powder metallurgy
(2014-01-01) Buytoz S.; Dagdelen F.; Islak S.; Kok M.; Kir D.; Ercan E.
Copper matrix with an individual addition of TiC particles was prepared by means of powder metallurgy and hot pressing process, and the effect of TiC addition on microstructure, thermal properties, and electrical conductivity of Cu-TiC composites was investigated. The TiC quantity was changed as 1, 3, 5, 10, and 15 Cu (in mass%), and Cu-TiC powder mixtures were hot-pressed for 4 min at 700 °C under an applied pressure of 50 MPa. Microstructure studies revealed that TiC particles were distributed uniformly in the Cu matrix. Thermal Analysis result showed that there were two exothermic peaks and with rising TiC rate, oxidation amount of Cu composite decreased. With the increasing addition of TiC, hardness of composites changed between 58.6 HV0.1 and 87.8 HV 0.1. The highest electrical conductivity for Cu-TiC composites was obtained in the Cu-1 mass% TiC composite, with approximately 81.2 % IACS. © 2014 Akadémiai Kiadó, Budapest, Hungary.
Investigation of the usability of cubic boron nitride cutting tools as an alternative to diamond cutting tools
(2013-12-01) Islak S.; Kir D.; Çelik H.
Diamond and cubic boron nitride cBN cutting segments were produced using hot pressing technique for this study to be used in cutting natural stone. cBN grains were added to bronze powder, the chosen matrix, at a rate of 0%, 20%, 40%, 60%, 80%, and 100% (according to percentage by weight). Segments were produced under a pressure of 35 MPa, at a sintering temperature of 600°C, over a sintering time of 3 minutes. The cutting properties of the produced segments were determined by cutting Ankara andesite. A Scanning Electron Microscope SEM and an X-Ray Diffractometer XRD were used to analyse the microstructure, phase compound, and wear surfaces of each segment type.
Microstructure and mechanical properties of PM Fe-Cu-Al2O3 alloys
(2013-01-01) Çelik E.; Islak S.; Kir D.; Ilkiliç C.
The purpose of this study was to investigate the effect of Cu addition on the microstructure and mechanical properties of Fe-Cu-Al2O3 alloys produced using hot-pressing method. Copper powder was added to iron powder at 5 wt.%, 10 wt.% and 15 wt.% rates. Production of Fe-Cu-Al2O3 alloys was carried out under pressure of 35 MPa, at 750, 800 and 850 °C, and for a sintering time of 4 minutes. Microstructure phase composition, relative density, hardness, and transverse rupture strength of the alloys were investigated. Phase composition and microstructure of the alloys were characterised by optical microscopy, X-ray diffraction and scanning electron microscope (SEM-EDS) techniques. The transverse rupture strength (TRS) of the samples was assessed by means of a three-point bending test. Hardness of Fe-Cu-Al2O3 alloys changed between 57 HB and 110 HB depending on the amount of Cu and sintering temperature. Results show that the TRS of the alloys decreased together with the increase in the amount of copper, while it increased with increasing sintering temperature.
Wear characteristics of circular cBN/diamond saws produced by hot pressing
(2014-01-01) Islak S.; Kir D.; Çelik H.
This study describes the investigation of wear characteristics of circular cBN/diamond saws produced by hot pressing. In order to determine the usability of cBN instead of diamond, cBN and diamond grains were added to the bronze matrix. Production of the saws was performed at a sintering temperature of 600-700 °C for a sintering time of 3 minutes. Sawing tests were carried out to determine the wear characteristics of the saws by sawing natural stone. It is concluded that cBN together with diamond could be added to the matrix with a concentration of 12 (the rest of concentration of 30 is diamond) and that the saws will have more wear if this concentration is exceeded. After sawing, SEM analyses of the saws indicate that there were more fractures and wear in cBN grains in comparison to the diamond grains. The results concluded that cBN can be used to saw softer natural stones, or can be added to the matrix together with diamond. © Carl Hanser Verlag, München Materials Testing.