Search for: nickel
0.009 seconds
Total 443 records

    Directional solidification of Ni base superalloy IN738LC to improve creep properties

    , Article Materials Science and Technology ; Volume 16, Issue 5 , 2000 , Pages 579-586 ; 02670836 (ISSN) Kermanpur, A ; Varahraam, N ; Engilehei, E ; Mohammadzadeh, M ; Davami, P ; Sharif University of Technology
    IOM Communications Ltd  2000
    The high Cr, Ni base superalloy IN738LC has been directionally solidified on both laboratory and industrial scales using Bridgman and liquid metal cooling (LMC) methods respectively. In the Bridgman experiments, cylindrical rods were grown using a graphite chill with temperature gradient G = 5·0 K mm-1 and a water cooled copper chill with G = 8·5 K mm-1, and a wide range of withdrawal rates of R = 60, 120, 240, 600, and 1200 mm h-1. In the LMC rigs, several turbine blades were grown using a wide range of withdrawal rates of R = 120, 225, 330, 420, and 630 mm h-1. Grain and dendritic structures in both cylindrical and turbine blade specimens were evaluated in longitudinal and transverse... 

    Nickel (II) and iron (II) / Dowex 50W: An effective catalyst for the Baeyer-Villiger oxidation of ketones using molecular oxygen and benzaldehyde

    , Article Journal of Chemical Research - Part S ; Issue 4 , 2000 , Pages 196-197 ; 03082342 (ISSN) Hashemi, M. M ; Beni, Y. A ; Sharif University of Technology
    Scientific Reviews Ltd  2000
    A mixture of Ni(II) and Fe(II) supported on Dowex 50W catalyses Baeyer- Villiger oxidation of ketones using molecular oxygen and benzaldehyde  

    Optimization of a new activated carbon based sorbent for on-line preconcentration and trace determination of nickel in aquatic samples using mixed-level orthogonal array design

    , Article Analyst ; Volume 125, Issue 9 , 2000 , Pages 1649-1654 ; 00032654 (ISSN) Bagheri, H ; Saraji, M ; Naderi, M ; Sharif University of Technology
    Royal Society of Chemistry  2000
    A mini-column was made by packing α-diphenylglyoxime (DPG), a known ligand for complexation with nickel ions, loaded on activated charcoal (AC). Water samples were buffered at the pH range 8-9 and then passed through the column. After the preconcentration step, the column was eluted with 0.2 M nitric acid into the atomic absorption spectrometer (AAS). Mixed-level orthogonal array design (OAD) was used as a chemometric approach to study the effect of various factors on recovery of extraction. Factors such as pH, amount of sorbent, flow rate of sample, concentration and volume of the sample were investigated. Effects of interference ions, i.e., Co, Cu, Bi, Fe(I1), Pt and Pd was also studied.... 

    Electro-catalytic oxidation of methanol on a Ni-Cu alloy in alkaline medium

    , Article Journal of Applied Electrochemistry ; Volume 36, Issue 8 , 2006 , Pages 913-918 ; 0021891X (ISSN) Jafarian, M ; Moghaddam, R. B ; Mahjani, M. G ; Gobal, F ; Sharif University of Technology
    The electro-catalytic oxidation of methanol on a Ni-Cu alloy (NCA) with atomic ratio of 60/40 having previously undergone 50 potential sweep cycles in the range 0-600 mV vs. (Ag/AgCl) in 1 m NaOH was studied by cyclic voltammetry (CV), chronoamperometry (CA) and impedance spectroscopy (EIS). The electro-oxidation was observed as large anodic peaks both in the anodic and early stages of the cathodic direction of potential sweep around 420 mV vs. (Ag/AgCl). The electro-catalytic surface was at least an order of magnitude superior to a pure nickel electrode for methanol oxidation. The diffusion coefficient and apparent rate constant of methanol oxidation were found to be 2.16 × 10-4 cm2 s-1 and... 

    Electrochemical impedance of ethanol oxidation in alkaline media

    , Article Chemical Research in Chinese Universities ; Volume 28, Issue 1 , 2012 , Pages 19-25 ; 10059040 (ISSN) Danaee, I ; Jafarian, M ; Gobal, F ; Sharafi, M ; Mahjani, M. G ; Sharif University of Technology
    Nickel modified NiOOH electrodes were used for the electrocatalytic oxidation of ethanol in alkaline solutions. The electro-oxidation of ethanol in a 1 mol/L NaOH solution at different concentrations of ethanol was studied by ac impedance spectroscopy. Electrooxidation of ethanol on Ni shows negative resistance on impedance plots. The impedance shows different patterns at different applied anodic potential. The influence of the electrode potential on impedance was studied and a quantitative explanation for the impedance of ethanol oxidation was given by means of a proposed mathematical model. At potentials higher than 0.52 V(vs. Ag/AgCl), a pseudoinductive behavior was observed, but at those... 

    A novel efficient magnetic core-zeolitic shell nanocatalyst system: Preparation, characterization and activity

    , Article Chemical Papers ; Volume 69, Issue 6 , 2015 , Pages 856-863 ; 03666352 (ISSN) Padervand, M ; Vossoughi, M ; Janfada, B ; Sharif University of Technology
    De Gruyter Open Ltd  2015
    Analcime shell-nickel ferrite core microspheres were decorated with Pd and Pt nanoparticles with the aid of an ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6). The samples thus prepared were characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), nitrogen adsorption-desorption isotherms, transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) methods. The XRD patterns confirmed the growth of a zeolitic layer on the surface of the magnetic cores. The thermogravimetric analysis (TGA) curve clearly indicated the thermal decomposition of the loaded IL, which confirmed the presence of... 

    Growth behavior of the electrodeposited Co-Ni alloy nanowires

    , Article International Journal of Modern Physics B ; Volume 22, Issue 18-19 , 2008 , Pages 3013-3022 ; 02179792 (ISSN) Ghahremaninezhad, A ; Dolati, A ; Kazemeini, M ; Sharif University of Technology
    World Scientific Publishing Co. Pte Ltd  2008
    The Co-Ni alloy nanowires were electrodeposited into porous anodic aluminum oxide (AAO) templates. At the first, highly ordered AAO templates were synthesized by two-step anodizing of aluminum to increase pore ordering. Arrays of nanowires with diameter about 30 nm and length about 5000 nm were electrodeposited by alternating current. The composition and structure property of nanowires were investigated by EDX, SEM and TEM techniques. It was found that nanowire composition was related to ions concentration in solution and it was shown that at the optimum potential range of electrodeposition (17-19 V), a change at the potential was shown no strong effect on chemical composition of nanowires.... 

    Electrocatalytic oxidation of methane at nickel hydroxide modified nickel electrode in alkaline solution

    , Article Electrochemistry Communications ; Volume 5, Issue 2 , 2003 , Pages 184-188 ; 13882481 (ISSN) Jafarian, M ; Mahjani, M. G ; Heli, H ; Gobal, F ; Heydarpoor, M ; Sharif University of Technology
    Elsevier Inc  2003
    Nickel hydroxide modified nickel electrodes prepared by cycling the potential of a nickel electrode in alkaline solution exhibited electrocatalytic activity for the oxidation of methane in alkaline media. In the presence of methane the oxidation peak current of nickel hydroxide increases while that of the reverse process decreases. This is attributed to the mediation of nickel species, probably β-NiOOH phase, in the process of electrocatalysis. The mechanism of methane oxidation has also been discussed in terms of the formations of intermediates normally encountered in small organics electro-oxidation. It has also been suggested that in the further oxidation of the intermediates, ions in the... 

    Wear and corrosion properties of electroless nickel composite coatings with PTFE and/or MoS 2 particles

    , Article Journal of Coatings Technology Research ; Volume 8, Issue 4 , 2011 , Pages 527-533 ; 15470091 (ISSN) Mohammadi, M ; Ghorbani, M ; Sharif University of Technology
    This study focuses on the effect of co-deposition of PTFE and/or MoS 2 particles on the morphology, wear, and corrosion properties of electroless nickel coating. The composite coating of EN-PTFE-MoS 2 was heat treated at different temperatures for hardness investigations. The surface morphology of coatings was characterized by scanning electron microscopy. Pin-on-disk and potentiodynamic polarization tests were used to study the tribological and corrosion properties of the coatings, respectively. Results of hardness analysis revealed that the hardness of electroless nickel coatings was increased by the heat treatment, and its maximum was gained at 400°C. Wear investigations showed that... 

    , M.Sc. Thesis Sharif University of Technology Baradaran Mohajeri, Saha (Author) ; Dolati, Abolghasem (Supervisor)
    Electrodeposition of composite coatings containing nano particles is very important because this technique is simple and economic. In this research, in order to produce a coating with high hardness and wear resistance, Ni-Co/WC nano composite was co-deposited. Watt’s based bath containing cobalt and tungsten carbide was used and parameters such as preparation of solution, concentration of ingredients and current density were controlled and adjusted. Surface morphology, microstructure and mechanical properties of coatings were studied by SEM and AFM microscopes. Mechanism of electrodeposition was investigated by cyclic voltametry, cronoamperometry and cronopotentiometry techniques and... 

    A copper-free Sonogashira reaction using nickel ferrite as catalyst in water

    , Article Catalysis Communications ; Volume 60 , 2014 , Pages 82-87 ; 15667367 (ISSN) Moghaddam, F. M ; Tavakoli, G ; Rezvani, H. R ; Sharif University of Technology
    The Sonogashira reaction using nickel ferrite nanoparticles as catalyst and under copper-free conditions was investigated in water as a green solvent. Various types of aryl and alkyl halides were successfully coupled with phenyl acetylene under the optimized reaction conditions with very good to excellent yields at a short time. The catalyst is easily recoverable and can be reused for several runs with a good turnover number  

    Synthesis and characterization of chitosan coating of NiFe2O4 nanoparticles for biomedical applications

    , Article Journal of the Iranian Chemical Society ; Volume 13, Issue 11 , 2016 , Pages 2069-2076 ; 1735207X (ISSN) Ramezani, S ; Ghazitabar, A ; Sadrnezhaad, S. K ; Sharif University of Technology
    Springer Verlag  2016
    Nickel ferrite nanoparticle is a soft magnetic material whose appealing properties as well as various technical applications have rendered it as one of the most attractive class of materials; its technical applications range from its utility as a sensor and catalyst to its utility in biomedical processes. The present paper focuses first on the synthesis of NiFe2O4 nanoparticles through co-precipitation method resulting in calcined nanoparticles that were achieved at different times and at a constant temperature (773 k). Afterward, they were dispersed in water that was mixed by chitosan. Chitosan was bonded on the surface of nanoparticles by controlling the pH of media. In order to assess the... 

    Microstructural evolution mechanism during brazing of Hastelloy X superalloy using Ni–Si–B filler metal

    , Article Science and Technology of Welding and Joining ; 2017 , Pages 1-7 ; 13621718 (ISSN) Ghasemi, A ; Pouranvari, M ; Sharif University of Technology
    The paper aims at understanding solidification phenomena and solid state precipitations during diffusion brazing of Hastelloy X nickel base superalloy using a ternary Ni–4.5Si–3.2 B (in wt-%) filler metal. The joint is featured by the formation of Ni-rich solid solution in an isothermal solidification zone, borides/silicide formation during eutectic-type solidification in an athermal solidification zone, on-cooling precipitation of fine nickel silicides in the joint centerline, in situ precipitation of Mo–Cr-rich borides in the diffusion affected zone and grain growth in the heat affected zone. The implication of the phase transformations on the joint properties is discussed. It is shown... 

    3D flower-like nickel cobalt sulfide directly decorated grassy nickel sulfide and encapsulated iron in carbon sphere hosts as hybrid energy storage device

    , Article Applied Surface Science ; Volume 558 , 2021 ; 01694332 (ISSN) Shahi, M ; Hekmat, F ; Shahrokhian, S ; Sharif University of Technology
    Elsevier B.V  2021
    Developing high-performance supercapacitors is of great significance in the area of renewable energies by virtue of having both high energy and power densities. In this work, an innovative strategy is employed for the fabrication of binder-free binary nickel–cobalt-sulfide (NCS) nanosheets (NSs) directly decorated onto the hydrothermal nickel-sulfide (Ni3S2) nanowires (NWs) as the positive electrodes. The NCS/Ni3S2-nickel foam (NF) positive electrodes rendered superior specific capacity of 499.1 mAh.g−1 at 6 A.g−1. Encapsulated iron into the carbon sphere hosts (Fe-HTCSs) are used as the negative counterparts, exhibiting remarkable specific capacitance of 336.6 F.g−1 (at 0.1 A.g−1). The... 

    Nickel ion removal from aqueous solution using recyclable zeolitic imidazolate framework-8 (ZIF-8) nano adsorbent: A kinetic and equilibrium study

    , Article Desalination and Water Treatment ; Volume 103 , 2018 , Pages 141-151 ; 19443994 (ISSN) Roostan, Z ; Rashidi, A ; Borghei, S. M ; Sharif University of Technology
    Desalination Publications  2018
    The adsorption of nickel ions in an aqueous solution system was measured using zeolitic imidazolate framework-8 (ZIF-8) nanoadsorbent. ZIF-8 crystals were synthesized using the hydrothermal method. Nanoadsorbent was characterized by FTIR, XRD, SEM and N2 adsorption analysis. ZIF-8 crystals showed a high surface area of 1303 m2/g and particle size 100–150 nm. The Langmuir and Freundlich isotherms model were used to analyze the data. The sufficiently high R2 value of 0.996 resulted from the Langmuir isotherm model demonstrated the perfect performance of this model. The kinetic data were analyzed using the pseudo-first-order and pseudo-second-order models of types 1–4. Kinetic studies of the... 

    The effect of Si addition and Ta diffusion barrier on growth and thermal stability of NiSi nanolayer

    , Article Microelectronic Engineering ; Volume 85, Issue 3 , 2008 , Pages 548-552 ; 01679317 (ISSN) Kargarian, M ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
    Formation and thermal stability of nanothickness NiSi layer in Ni(Pt 4 at.%)/Si(1 0 0) and Ni0.6Si0.4(Pt 4 at.%)/Si(1 0 0) structures have been investigated using magnetron co-sputtering deposition method. Moreover, to study the effect of Si substrate in formation of NiSi and its thermal stability, we have used Ta diffusion barrier between the Ni0.6Si0.4 layer and the Si substrate. Post annealing treatment of the samples was performed in an N2 environment in a temperature range from 200 to 900 °C for 2 min. The samples were analyzed by four point probe sheet resistance (Rs) measurement, X-ray diffraction (XRD) and atomic force microscopy (AFM) techniques. It was found that the annealing... 

    Influence of solution treatment on precipitation behavior of a Ni-Co alloy

    , Article Scripta Materialia ; Volume 57, Issue 2 , 2007 , Pages 93-96 ; 13596462 (ISSN) Samiee, M ; Asgari, S ; Sharif University of Technology
    The age-hardening behavior and microstructure of selected samples of a Ni-Co alloy were studied using hardness testing, optical microscopy, and scanning and transmission electron microscopy. The final microstructure of the material was found to be sensitive to the temperature of the solution treatment. This approach may be used to optimize the microstructure of the alloy for different applications. © 2007 Acta Materialia Inc  

    Methanol electrooxidation on a nickel electrode modified by nickel-dimethylglyoxime complex formed by electrochemical synthesis

    , Article Journal of Electroanalytical Chemistry ; Volume 588, Issue 1 , 2006 , Pages 155-160 ; 15726657 (ISSN) Nozad Golikand, A ; Asgari, M ; Ghannadi Maragheh, M ; Shahrokhian, S ; Sharif University of Technology
    Elsevier  2006
    Nickel-dimethylglyoxime complex (NiDMG) modified nickel electrode (Ni/NiDMG) showed a catalytic activity towards methanol oxidation in NaOH solution. The modified electrode prepared by the dimethylglyoxime anodic deposition on Ni electrode in the solution containing 0.20 mol L-1 NH4Cl + NH4OH (pH 9.50) and 1.0 × 10-4 mol L-1 dimethylglyoxime. The modified electrode conditioned by potential recycling in a potential range of 100-700 mV (vs. SCE) by cyclic voltammetry in alkaline medium (0.10 M NaOH). The results show that the NiODMG film on the electrode behaves as an efficient catalyst for the electrooxidation of methanol in alkaline medium via Ni(III) species formed on the electrode with the... 

    Electrocatalytic oxidation of methanol on a nickel electrode modified by nickel dimethylglyoxime complex in alkaline medium

    , Article Journal of Power Sources ; Volume 144, Issue 1 , 2005 , Pages 21-27 ; 03787753 (ISSN) Golikand, A. N ; Shahrokhian, S ; Asgari, M ; Ghannadi Maragheh, M ; Irannejad, L ; Khanchi, A ; Sharif University of Technology
    Electrocatalytic oxidation of methanol on a nickel disc electrode coated with nickel dimethyglyoxime complex (NiDMG), conditioned by potential recycling in a potential range of 100-700 mV (versus SCE) is studied by cyclic voltammetry in alkaline medium (0.10 M NaOH). The results show that the NiODMG layer formed at the surface of electrode behaves as an efficient electrocatalyst for the oxidation of methanol in alkaline medium via Ni(III) species with the cross exchange reaction occurring through out the layer at a low concentration of methanol. A plausible mechanism was proposed for catalytic oxidation of methanol at this modified electrode. Moreover, the effects of various parameters such... 

    Nanomechanical properties of functionally graded composite coatings: Electrodeposited nickel dispersions containing silicon micro- and nanoparticles

    , Article Materials Chemistry and Physics ; Volume 121, Issue 3 , June , 2010 , Pages 497-505 ; 02540584 (ISSN) Sohrabi, A ; Dolati, A ; Ghorbani, M ; Monfared, A ; Stroeve, P ; Sharif University of Technology
    Functionally graded composite coatings constitute a class of materials which are mostly used for mechanical and tribological applications. Among these materials, nickel metal deposits with incorporation of SiC particles have excellent mechanical properties due to nickel metal and good tribological properties due to the SiC particles. In this work, nickel coatings containing different sizes of SiC particles, nanoparticles and microparticles (10 nm to 5 μm), were electrodeposited from an additive-free sulfate bath containing nickel ions and SiC particles. The material properties of the coatings were compared to nickel coatings containing microparticles (5 μm). The effect of current density,...