Browsing by Author "Islak S."

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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 alumina addition on the microstructure properties of plasma-sprayed zirconia-alumina coatings
(2013-01-01) Islak S.
ZrO2/Al2O3 coatings with different amounts of Al2O3 were fabricated on the AISI 304 stainless steel surface using plasma spray process. Phase composition and microstructure of the coatings were characterised using X-ray diffraction and scanning electron microscopy. Lamellae and porous microstructure were obtained in the coatings. In addition, a small amount of unmelted particles, partially melted, and fully melted regions in microstructure of coatings were observed. With the increasing addition of Al2O3, a decrease in the pores was determined. The results indicated that the as-prepared ZrO2/Al2O3 based coatings were mainly composed of ZrO2, Al0.52Zr0.48O1.74, ZrTiO4, Al0.18Zr0.82O1.91, Al2O3, Al2Zr3, Al3Ti and Ti2O3 phases. The microhardness of the coating was as high as 1136 HV0.2, which was 4-5 times of the substrate.
Effect of boron on microstructure and microhardness properties of Mo-Si-B based coatings produced via TIG process
(2016-01-01) Islak S.; Özorak C.; Sezgin C.; Akka M.
In this study, Mo-Si-B based coatings were produced using tungsten inert gas (TIG) process on the medium carbon steel because the physical, chemical, and mechanical properties of these alloys are particularly favourable for high-temperature structural applications. It is aimed to investigate of microstructure and microhardness properties of Mo-Si-B based coatings. Optical microscopy (OM), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the microstructures of Mo-Si-B based coatings. The XRD results showed that microstructure of Mo-Si-B coating consists of Mo, Fe, Mo2B, Mo3Si and Mo5SiB2 phases. It was reported that the grains in the microstructure were finer with increasing amounts of boron which caused to occur phase precipitations in the grain boundary. Besides, the average microhardness of coatings changed between 735 HV0.3 and 1140 HV0.3 depending on boron content.
Effect of boron on microstructure, thermal, and mechanical properties of Ni–B matrix diamond cutting tools
(2024-09-01) Islak S.; Çelik E.; Houssain H.; Danacı H.C.
Effect of sintering temperature and boron carbide content on the wear behavior of hot pressed diamond cutting segments
(2015-08-03) Islak S.; Çelik H.
The aim of this study was to investigate the effect of sintering temperature and boron carbide content on wear behavior of diamond cutting segments. For this purpose, the segments contained 2, 5 and 10 wt.% B4C were prepared by hot pressing process carried out under a pressure of 35 MPa, at 600, 650 and 700 °C for 3 minutes. The transverse rupture strength (TRS) of the segments was assessed using a three-point bending test. Ankara andesite stone was cut to examine the wear behavior of segments with boron carbide. Microstructure, surfaces of wear and fracture of segments were determined by scanning electron microscopy (SEM-EDS), and X-ray diffraction (XRD) analysis. As a result, the wear rate decreased significantly in the 0-5 wt.% B4C contents, while it increased in the 5-10 wt.% B4C contents. With increase in sintering temperature, the wear rate decreased due to the hard matrix.
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 sintering temperature on transverse rupture strength of hot pressed Cu-TiC composites
(2015-01-01) Islak S.
In this study, effect of sintering temperature on transverse rupture strength (TRS) of Cu-TiC composites produced using hot pressing (HP) technique has been studied. Copper matrix composites reinforced with 10 wt.-% TiC particles were produced under a pressure of 50 MPa, at 600, 700 and 800 °C, and for a sintering time of 4 minutes, respectively. The TRS of the composites were determined using three-point bending test. SEM was used to analyze the fractured surfaces of composites. SEM results showed that with increasing sintering temperature, pores and gaps in the fractured surfaces decreased. The ultimate transverse rupture strength of Cu-TiC composites was found to increase with increasing sintering temperature.
Effect of sintering temperature on transverse rupture strength of hot pressed Cu-TiC composites
(2015-01-01) Islak S.; Islak, S
In this study, effect of sintering temperature on transverse rupture strength (TRS) of Cu-TiC composites produced using hot pressing (HP) technique has been studied. Copper matrix composites reinforced with 10 wt.-% TiC particles were produced under a pressure of 50 MPa, at 600, 700 and 800 °C, and for a sintering time of 4 minutes, respectively. The TRS of the composites were determined using three-point bending test. SEM was used to analyze the fractured surfaces of composites. SEM results showed that with increasing sintering temperature, pores and gaps in the fractured surfaces decreased. The ultimate transverse rupture strength of Cu-TiC composites was found to increase with increasing sintering temperature.
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.
Effect on microstructure of TiO2 rate in Al2O3-TiO2 composite coating produced using plasma spray method
(2012-01-01) Islak S.; Buytoz S.; Ersoz E.; Orhan N.; Stokes J.; Hashmi M.S.; Somunkiran I.; Tosun N.
In this study, Al2O3-TiO2 composite coatings were thermally sprayed on the SAE 1040 steel using atmospheric plasma spray (APS) process of mixed different rates micron-sized TiO2 and micron-sized Al2O3 powders. The effects of TiO2 addition on the microstructure, phase compositions and microhardness of the coatings were investigated by using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometry (XRD) and microhardness tester. The results show that the Al2O3-TiO2 composite coatings consists of both fully melted regions and partially melted regions, and the fully melted region has a lamellar-like structure. Phase transformations from mainly stable a-Al2O3 and anatase-TiO2 in the powders to predominant rnetastable y-Al2O3, rutile-TiO2 and Al2TiO5 phase in the Al2O3-TiO2 composite coatings were observed. It was determined that the pore content decreased with the increased in the TiO2 powder rate. The microhardness of the coating layers was 3-4.5 times higher than substrate material. The average microhardness values of the coatings were found to reach 650-860 HV.
Effects of TiC content on transverse rupture strength (TRS) of Cu-TiC composites produced using powder metallurgy (PM) technique
(2015-01-01) Islak S.; Buytoz S.; Eski
Cu-TiC composites have been produced by powder metallurgy technique. Mixtures of Cu-TiC powders corresponding to weight fractions of 1, 3, 5, 10 and 15 wt.% TiC were hot-pressed for 4 min at 700 °C under an applied pressure of 50 MPa. The transverse rupture strength (TRS) of the composites was evaluated by a three-point bending test. SEM were used to analyze the resulting fracture surfaces from the bending test. The TRS decreased rapidly in the 0-5 wt.% TiC contents, while it decreased slowly in the 5-15 wt.% TiC contents. SEM results showed that with the increase in the addition of titanium carbide to copper matrix, pores and gaps were present in the structure.
Electrical and optical properties of ZnO-milled Fe2O3 nanocomposites produced by powder metallurgy route
(2016-03-01) Güler S.; Güler Ö.; Evin E.; Islak S.
In this study, ZnO-Fe2O3 nanocomposites were synthesized by powder metallurgy route and characterized through X-ray diffraction, UV-vis diffuse reflectance spectroscopy, scanning electron microscopy, electrical conductivity measurement device. The amount of Fe2O3 in the ZnO and milling time were varied in order to investigate their influence on the electrical and optical properties of the samples. Powder mixture containing milled and unmilled Fe2O3 at the rates of the 1, 3 and 5 wt% was sintered in vacuum environment. Results show that the conductivities of ZnO-Fe2O3 nanocomposites slightly increased by increasing the Fe2O3 content and these composites have potential materials for photocatalysis. Besides, electrical and optical properties of ZnO-Fe2O3 nanocomposites varied according to status of unmilled Fe2O3 and milled Fe2O3.
Electrical conductivity, microstructure and wear properties of Cu-Mo coatings
(2019-06-01) Islak S.; Çalıgülü U.; Hraam H.R.H.; Özorak C.; Koç V.
In this study, Cu–Mo composite coatings were produced on copper substrate by plasma spray technique. Electrical conductivity, microstructure and wear properties of the composite coatings were investigated. Microstructure and phase composition of the coatings were examined by using optical microscopy (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). The microhardness experiments were also performed by using a microhardness machine. The electrical conductivity properties of the coatings were evaluated with eddy current instruments. Wear tests were performed by pin-on-disc method. Although the electrical conductivities of the coatings are very small compared to the substrate, it has been determined that the coatings exhibit very good tribological property and high hardness in comparison to the substrate.
Investigation of machinability properties of aluminium matrix hybrid composites
(2021-08-01) Okay F.; Islak S.; Turgut Y.
In this study, machinability properties of aluminium matrix boron carbide (B4C) and carbon nanofiber (CNF) reinforced hybrid composite material produced by powder metallurgy in drilling were investigated. In the study, the samples produced with hot pressing technique having 6 different volume rates were used. The drilling operations were performed using drills with 3 point angles (90°–118°–135°) at 30–45-67.5 m/min cutting speed and 0.1–0.15–0.225 mm/rev feed rate. As a result of the experiments, the thrust force, moment, and surface roughness were measured and the delamination factor forming at hole exits was calculated. In addition, the effect of reinforcement rate on the machinability was also investigated. In all drill types, it was determined that as the feed rate increased, the thrust force increased and as the reinforcement rate increased, moment values also increased. Surface roughness values increased with the increased feed rate but decreased as the cutting speed increased. As the drill point angle increased, the surface roughness value decreased but the hole exit damage increased.
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.
Mechanical and corrosion properties of alcu matrix hybrid composite materials
(2019-01-01) Islak S.; Islak, S
In this study, AlCu matrix hybride composites with various ratios of boron carbide (B4C), hexagonal boron nitride (hBN), and graphite (Gr) were produced by using hot-pressing method. The microstructure, density, mechanical and corrosion properties of these composites were investigated. Optical microscopy, scanning electron microscopy, and X-ray diffraction were used to characterize the microstructures, and the experimental densities of the composites were measured using a helium pycnometer. The mechanical properties including the hardness and transverse rupture strength were investigated using hardness and three-point bending tests, respectively. In addition, the hybrid composites were immersed in an aqueous solution of 3.5 wt.-percent NaCl at pH 3 for potentiodynamic and corrosion rate measurements. These tests revealed that a microstructure in which reinforcing particles are almost homogeneously dispersed in the matrix was obtained. Density measurements have shown that very dense and compact hybrid AMCs are produced. The hardness and transverse rupture strength of the composites were significantly increased by particulate addition to the matrix. Depending on the type and amount of reinforcement material, differences in the corrosion resistance of the hybrid composites have been determined. The results show that AlCu-8B4C-2Gr hybrid composite material has the highest corrosion resistance among the composite materials.
Mechanical and corrosion properties of alcu matrix hybrid composite materials
(2019-01-01) Islak S.
In this study, AlCu matrix hybride composites with various ratios of boron carbide (B4C), hexagonal boron nitride (hBN), and graphite (Gr) were produced by using hot-pressing method. The microstructure, density, mechanical and corrosion properties of these composites were investigated. Optical microscopy, scanning electron microscopy, and X-ray diffraction were used to characterize the microstructures, and the experimental densities of the composites were measured using a helium pycnometer. The mechanical properties including the hardness and transverse rupture strength were investigated using hardness and three-point bending tests, respectively. In addition, the hybrid composites were immersed in an aqueous solution of 3.5 wt.-percent NaCl at pH 3 for potentiodynamic and corrosion rate measurements. These tests revealed that a microstructure in which reinforcing particles are almost homogeneously dispersed in the matrix was obtained. Density measurements have shown that very dense and compact hybrid AMCs are produced. The hardness and transverse rupture strength of the composites were significantly increased by particulate addition to the matrix. Depending on the type and amount of reinforcement material, differences in the corrosion resistance of the hybrid composites have been determined. The results show that AlCu-8B4C-2Gr hybrid composite material has the highest corrosion resistance among the composite materials.
Microstructural and Mechanical Properties of Ti-B4C/CNF Functionally Graded Materials
(2022-10-01) Gariba A.M.M.; Islak S.; Hraam H.R.H.; Akkaş M.
This study aims to investigate the microstructural and mechanical properties of titanium (Ti) matrix boron carbide (B4C) + carbon nanofiber (CNF)-reinforced functional-graded materials (FGMs) produced using the powder metallurgy method. B4C was added to the Ti matrix at different rates, namely, 5, 10, and 15% by volume, and CNF was added at a rate of 0.5% by volume. The effect of B4C and CNF on the properties of these composite layers was then investigated. In addition, the mechanical properties of the FGMs were compared with the mechanical properties of non-layered structures. In addition, the microstructural, phase formation, hardness, and transverse rupture strength properties of the samples were investigated in detail. The microstructural investigation revealed that the B4C and CNF were homogeneously distributed throughout the Ti matrix and that the layers had bonded properly. With the addition of B4C and CNF, the hardness of the materials increased significantly. The transverse rupture strengths of the FGMs were higher than those of the non-layered samples (with the exception of pure Ti), indicating that the middle layers increased the toughness of the materials.
Microstructural and Wear Characteristics of High Velocity Oxygen Fuel (HVOF) Sprayed NiCrBSi-SiC Composite Coating on SAE 1030 Steel
(2013-01-01) Buytoz S.; Ulutan M.; Islak S.; Kurt B.; Nuri Çelik O.
In this paper, wear properties of NiCrBSi-SiC coatings were investigated using the ball-on-disk wear test. In experimental study, NiCrBSi-SiC powders were sprayed using a high-velocity oxygen fuel technique on an SAE 1030 steel substrate. Powder mixtures with different weight mixing ratios, NiCrBSi + 10 wt% SiC, NiCrBSi + 20 wt% SiC and NiCrBSi + 40 wt% SiC coatings were prepared. The deposited coatings are compared in terms of their phase composition, microstructure and hardness. It is proved that the degree of mixing of the NiCrBSi and SiC components in the powder has a massive effect on the phase composition, microstructure and hardness of the coatings. Wear tests were conducted on both the uncoated and coated substrates at same normal load, speed, and wear distance. It has been determined that the coated substrates exhibit a very good tribological performance in comparison to the uncoated substrate. The increase in the adhesive wear resistance provided by the coating has been attributed to the presence of a large amount of dispersed Ni and Cr carbide and/or borides in the Ni matrix. © 2013 The Author(s).