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Öğe Effect of PC electrodeposition on the structure and tribological behavior of Ni-Al2O3 nanocomposite coatings(Elsevier Science Sa, 2014) Gül, Harun; Uysal, Mehmet; Akbulut, Hatem; Alp, AhmetIn this study, Ni-Al2O3 metal matrix composite (MMC) coatings were prepared from a modified Watt's type electrolyte by pulse current (PC) plating under current densities varying between 1 and 9 A/dm(2). The tribological tests were performed with a reciprocating ball-on-disk apparatus sliding against a M50 steel ball (empty set 10 mm). The wear tests were carried out at sliding velocities of 50, 100 and 150 mm/s under a constant load. The results compared with our previously published work of DC electrodeposited coatings. The results showed that the electrodeposition method can significantly affect the microstructure and tribological behavior of Ni-Al2O3 nanocomposite coatings. For the same current density, PC electrodeposition creates coatings with higher co-deposited particle content more homogenous particle distribution, higher wear resistance at high sliding distance and improved friction coefficients. The superior dispersion of Al2O3 nanoparticles in PC-coated materials contributed to its increased load bearing capacity. Detailed tribological tests and characterization showed that DC- and PC-coated nanocomposite layers yielded different wear mechanisms depending on the sliding velocity. (C) 2014 Elsevier B.V. All rights reserved.Öğe Effect of surfactant concentration in the electrolyte on the tribological properties of nickel-tungsten carbide composite coatings produced by pulse electro co-deposition(Elsevier Science Bv, 2015) Kartal, Muhammet; Uysal, Mehmet; Gül, Harun; Alp, Ahmet; Akbulut, HatemA nickel plating bath containing WC particles was used to obtain hard and wear-resistant particle reinforced Ni/WC MMCs on steel surfaces for anti-wear applications. Copper substrates were used for electro co-deposition of Ni matrix/WC with the particle size of <1 mu m tungsten carbide reinforcements. The influence of surfactant (sodium dodecyl sulfate, SDS) concentration on particle distribution, microhardness and wear resistance of composite coatings has been studied. The nickel films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of the surfactant on the zeta potential, co-deposition and distribution of WC particles in the nickel matrix, as well as the tribological properties of composite coatings were also investigated. The tribological behaviors of the electrodeposited WC composite coatings sliding against M50 steel ball (empty set 10 mm) were examined on a CSM Instrument. All friction and wear tests were performed without lubrication at room temperature and in the ambient air (relative humidity 55-65%). (C) 2015 Elsevier B.V. All rights reserved.Öğe Preparation and characterization of bronze/SiCp composites produced via current activated sintering method(Elsevier Sci Ltd, 2015) Gül, Harun; Uysal, Mehmet; Alp, Ahmet; Akbulut, HatemIn this study, bronze matrix was reinforced with nickel coated nano SiC particles using mechanical alloying and then subsequent rapid current sintering technique. Mechanical ball milling of bronze matrix composite powders were performed with 1.0, 3.0 and 5.0 vol% SiC nanoparticle reinforcements. The composite powders were cold compacted under constant pressure of 150 MPa. The compacted structures were sintered at atmospheric conditions almost to the full density within 10 min using current sintering, in which the powders were heated by a low voltage and high amperage current and compressed simultaneously to achieve dispersion of nano SIC particles. The samples were sintered at 900 A current to eliminate porosities and agglomeration of particles. The porosity of the produced samples were reduced from 9.49% to 6.13% respectively for the uncoated and coated 5.0 vol% SiC reinforced nanocomposites. Microhardness testing and scanning electron microscopy (SEM) were used for the microstructural characterization of the composites. Rapid sintering was also thought to be an advantage to eliminate volume increment seen under conventional atmospheric sintering conditions. (C) 2015 Elsevier Ltd. All rights reserved.Öğe Preparation of Sn-Co alloy electrode for lithium ion batteries by pulse electrodeposition(Pergamon-Elsevier Science Ltd, 2014) Gül, Harun; Uysal, Mehmet; Çetinkaya, Tuğrul; Güler, Mehmet Oğuz; Alp, Ahmet; Akbulut, HatemSn-Co alloy films for Li-ion batteries were prepared by pulse electrodeposition on the copper foils as current collectors. Nanocrystalline Sn-Co alloy electrodes produced by using a solution containing cobalt chloride and tin chloride at constant electrodeposition conditions (pulse on-time too at 5 ms and pulse off-time toff at 5 ms) with varying peak current densities, Jp have been investigated. The structures of the electroplated Sn-Co alloy thin films were studied to reveal film morphology current density relationships and the effect of the current density parameters on the electrochemical properties. X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM), Brunauer-Emmett-Teller (BET) surface area analyzer and Energy-Dispersive X-ray Spectroscopy (EDS) facilities were used for determination the relationships between structure and experimental parameters. Cyclic voltammetry (CV) tests were carried out to reveal reversible reactions between cobalt tin and lithium. Galvanostatic charge/discharge (GC) measurements were performed in the cells formed by using anode composite materials produced by pulse elect co-deposition. The discharge capacities of these cells were cyclically tested by a battery tester at a constant current in the different voltage ranges between 0.02 V-1.5 V. The results have shown that Sn-Co alloy yielded promising reversible discharge capacities with a satisfactory cycle life for an alternative anode material to apply for the Li-ion batteries. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Öğe Pulse electrocodeposition of Ni/MWCNT nanocomposite coatings(Taylor & Francis Ltd, 2015) Kartal, Muhammet; Uysal, Mehmet; Gül, Harun; Alp, Ahmet; Akbulut, HatemNickel/multiwalled carbon nanotube (MWCNT) metal matrix composite coatings were deposited by pulse electrocodeposition method from a Watt's type electrolyte. The influence of peak current density on the particle codeposition and distribution, the surface morphology, microstructure, microhardness and wear resistance of nanocomposite coatings were studied. Copper substrates were used for electrocodeposition and MWCNTs with the diameter of 50-60 nm and length of 10 mm used as reinforcements. The electrodeposited Ni matrix coatings were characterised by scanning electron microscopy, Raman spectroscopy and X-ray diffraction analysis.Öğe Reciprocating sliding speed effect on the tribological properties of SiCp reinforced Ni MMCs deposited by electroplating(European Conference on Composite Materials, ECCM, 2012) Gül, Harun; Aslan, Serdar; Akbulut, Hatem; Alp, AhmetIn the present work, Ni/SiC metal matrix composite (MMC) coatings were prepared from a modified Watt's type electrolyte containing nano-SiC particles by direct current (DC) plating method to increase wear resistance of Ni. The influence of surfactant content on co-deposition of SiC particles (0.1-1.0 ?m size range) in the matrix, and tribological properties were investigated. The influence of sliding speed on the tribological performances of the coatings was investigated by a reciprocating ball-on disk apparatus. The wear tests were carried out at different sliding speeds by using a constant load. Wear resistances and friction coefficients of Ni/SiC composites were decreased by increasing sliding speed because of temperature-controlled surface oxidation. The change in wear mechanisms by changing surfactant content and sliding speeds were also comprehensively studied and, in general, decreasing surface damage was obtained by increasing sliding speed.Öğe A reciprocating wear study on the effect of surfactant concentration and sliding speed in the electro codeposited Ni/SiCp metal matrix composites(Sage Publications Ltd, 2016) Gül, Harun; Uysal, Mehmet; Akbulut, Hatem; Alp, AhmetIn this present work, Ni/SiC metal matrix composite coatings were prepared from a modified Watt's type electrolyte containing nano-SiC suspended particles by direct current plating method to increase the wear resistance of Ni. The influence of surfactant content on codeposition of SiC particles within the matrix and tribological properties were investigated. A wide particle size range (between 0.1 and 1.0 mu m) was chosen to provide a high load bearing ability for the codeposited layers. The wear tests were carried out at different sliding speeds by using a constant load. The influence of sliding speed on the tribological performances of the coatings has been investigated by using a reciprocating ball-on disk apparatus. Wear resistances and friction coefficients of Ni/SiC composites were decreased by increasing sliding speed due to temperature-controlled surface oxidation. The change in wear mechanisms by changing surfactant content and sliding speeds were also comprehensively studied.Öğe Sn-Ni/MWCNT nanocomposite negative electrodes for Li-ion batteries: The effect of Sn:Ni molar ratio(Pergamon-Elsevier Science Ltd, 2014) Uysal, Mehmet; Gül, Harun; Alp, Ahmet; Akbulut, HatemSince Ni is used to behave as a buffer component in the Sn-based anode materials for the Li-ion batteries, it is aimed to reveal the optimum Sn:Ni ratio to reduce the electrode pulverization emanated from volume increase during the charge/discharge process. MWCNTs were also co-deposited from the suspended MWCNT in the electrolyte to increase buffering effect and conductivity. To reduce irreversible capacity and improve cycle performance of tin electrodes, Sn-Ni/MWCNT three components nanocomposite electrodes were prepared with different Sn:Ni ratio by pulse electrodeposition method using copper substrate as current collector. The morphology and the structures of the Sn-Ni/MWCNT nanocomposites were characterized by scanning electron microscopy (SEM), Xray diffraction (ICED). Raman spectroscopy was used to determine the existence of MWCNT in the Sn-Ni matrix. The electrochemical performance of Sn-Ni/MWNT nanocomposites studied by charge/discharge tests and cyclic voltammetry experiments. Results showed that increasing the amount of co-deposited Ni has a strong effect on the electrochemical performances. The best electrochemical results were obtained in the nanocomposite electrodes with Ni content of 29 wt.% Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Öğe Tribological behavior of copper/MWCNT nanocomposites produced by pulse Electrodeposition(2014) Gül, Harun; Uysal, Mehmet; Akbulut, Hatem; Alp, AhmetCopper coatings containing well-distributed multiwalled carbon nanotubes were obtained by pulse electrodeposition in acidic sulfate bath in order to improve the microhardness and wear resistance of coatings. Multiwalled carbon nanotubes concentration was determined as the most significant factor for the incorporation of multiwalled carbon nanotubes in copper based electrolyte. The amount of embedded multiwalled carbon nanotubes and the microhardness of nanocomposites were found to increase with the increase of multiwalled carbon nanotubes in the electrolyte. The tribological properties of nanocomposites deposited by pulse electrocodeposition technique were studied by reciprocating ball on-disk method. The characterization of the coatings was investigated by scanning electron microscopy and X-ray diffraction facilities. The experimental results indicated that the wear resistance of copper composite is superior to that of pure copper. The friction coeffcient and wear rates decreased with the increase in the concentration of multiwalled carbon nanotubes in the electrolyte.
