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    Effect of current density on DC electrochemical phosphating of stainless steel 316

    , Article Surface and Coatings Technology ; Volume 205, Issue 7 , December , 2010 , Pages 2302-2306 ; 02578972 (ISSN) Oskuie, A. A ; Afshar, A ; Hasannejad, H ; Sharif University of Technology
    2010
    Abstract
    In this study, tri-cation phosphate coating of zinc, calcium and iron was applied electrochemically to stainless steel 316 substrates. Cathodic current was used as an accelerator for the phosphating process. The effects of current density on the microstructures of the coatings and the time necessary for the reduction of the oxide layer have been established. For this purpose, analyses such as chronopotentiometery, SEM, EDS and linear polarization were carried out. Results indicated that higher electrophosphating current densities result in finer crystal size of the coating. This effect is detrimental to the quality of the layer. In addition, chemical analyses of the layer revealed that the... 

    Numerical simulation of electro-deposition process influenced by force convection and migration of ions

    , Article Journal of Electroanalytical Chemistry ; Volume 782 , 2016 , Pages 117-124 ; 15726657 (ISSN) Zahraei, M ; Saidi, M. S ; Sani, M ; Sharif University of Technology
    Elsevier B.V  2016
    Abstract
    Electro-deposition process is one of the main steps in the LIGA procedure to fabricate microstructures. In this paper, one-dimensional modeling of Nickel electro-deposition process is implemented on Rayan and developed for simulation of time-dependence diffusion and migration of charge species with reduction reactions on the cathode surface. This model is proposed by considering governing equations on electro-kinetic phenomena consist of Nernst-Plank equation and Poisson's equation of electric potential. Transport of ions toward the cathode is considered based on the effect of convection, reaction rate, diffusion and migration. The numerical results cover two series of data consisting of... 

    Effect of current density on electrochemical phosphating of stainless steel 316L

    , Article TMS 2009 - 138th Annual Meeting and Exhibition, San Francisco, CA, 15 February 2009 through 19 February 2009 ; Volume 3 , 2009 , Pages 613-620 ; 9780873397407 (ISBN) Oskuie, A. A ; Afshar, A ; Sharif University of Technology
    2009
    Abstract
    In this study two cation coating of calcium and zinc has been developed on stainless steel 316L by electrochemical method. Cathodic current used as an accelerator for phosphating process and the effects of current density on microstructure of the phospahted layer and the time needed for termination of the phosphating process has been evaluated by potential-time, SEM, EDS, etc. Results indicate that higher current densities in electrochemical phosphating will result in heavier phospahted layer with finer crystal size which in turn deteriorates the quality of the layer by its higher porosity. Chemical analysis of the layer reveals that using the electrochemical method for phosphating of... 

    The effects of porosity distribution variation on PEM fuel cell performance

    , Article Renewable Energy ; Volume 30, Issue 10 , 2005 , Pages 1557-1572 ; 09601481 (ISSN) Roshandel, R ; Farhanieh, B ; Saievar Iranizad, E ; Sharif University of Technology
    2005
    Abstract
    Gas diffusion layers (GDL) are one of the important parts of the PEM fuel cell as they serve to transport the reactant gases to the catalyst layer. Porosity of this layer has a large effect on the PEM fuel cell performance. The spatial variation in porosity arises due to two effects: (1) compression of the electrode on the solid landing areas and (2) water produced at the cathode side of gas diffusion layers. Both of these factors change the porosity of gas diffusion layers and affect the fuel cell performance. To implement this performance analysis, a mathematical model which considers oxygen and hydrogen mass fraction in gas diffusion layer and the electrical current density in the... 

    Characterization of pulse reverse Ni-Mo coatings on Cu substrate

    , Article Surface and Coatings Technology ; Vol. 238 , 2014 , pp. 158-164 ; ISSN: 02578972 Surani Yancheshmeh, H ; Ghorbani, M ; Sharif University of Technology
    Abstract
    The effect of pulse reverse current (PRC) method on Ni-Mo coatings electroplated from chloride solution was investigated by various plating parameters such as plating duration, the anodic duty cycle, the anodic current density and the cathodic current density. By increasing the anodic duty cycle and anodic current density, the Mo content of coatings reached 68wt.% and 78wt.%, respectively at cathodic current densities of 500 and 300mAcm-2. The Mo content of coatings increases by the preferential dissolution of Ni on the anodic pulse and also by the replenishment of Mo complexes in the diffusion layer near the substrate surface during the anodic pulse. In comparison with the direct current... 

    Kinetic studies of glucose electrocatalytic oxidation on GC/Ni electrode

    , Article International Journal of Chemical Kinetics ; Volume 44, Issue 11 , 2012 , Pages 712-721 ; 05388066 (ISSN) Danaee, I ; Jafarian, M ; Forouzandeh, F ; Gobal, F ; Sharif University of Technology
    2012
    Abstract
    Nickel-modified glassy carbon electrode (GC/Ni) prepared by galvanostatic deposition was used for the electrocatalytic oxidation of glucose in alkaline solutions where different electrochemical methods were employed. In cyclic voltammetry studies, in the presence of glucose an increase in the peak current of the oxidation of nickel hydroxide is followed by a decrease in the corresponding cathodic current. This suggests that the oxidation of glucose is being catalyzed through mediated electron transfer across the nickel hydroxide layer comprising nickel ions of various valence states. Under the chronoamperometric regime, the reaction followed a Cottrellian behavior and the diffusion... 

    Influence of Substrate, Additives, and Pulse Parameters on Electrodeposition of Gold Nanoparticles from Potassium Dicyanoaurate

    , Article Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science ; Volume 46, Issue 6 , December , 2015 , Pages 2584-2592 ; 10735615 (ISSN) Vahdatkhah, P ; Sadrnezhaad, S. K ; Sharif University of Technology
    Springer Boston  2015
    Abstract
    Gold nanoparticles (AuNPs) of less than 50 nm diameter were electrodeposited from cyanide solution by pulsating electric current on modified copper and indium tin oxide (ITO) films coated on glass. Morphology, size, and composition of the deposited AuNPs were studied by X-ray photoelectron spectroscopy, atomic force microscopy, and field emission scanning electron microscopy. Effects of peak current density, pulse frequency, potassium iodide and cysteine on grain size, and morphology of the AuNPs were determined. Experiments showed that cathode current efficiency increases with the pulse frequency and the iodide ion. Size of the AuNPs increased with the current density. The number of... 

    Ni-P/Zn-Ni compositionally modulated multilayer coatings – part 1: electrodeposition and growth mechanism, composition, morphology, roughness and structure

    , Article Applied Surface Science ; Volume 442 , 2018 , Pages 275-287 ; 01694332 (ISSN) Bahadormanesh, B ; Ghorbani, M ; Sharif University of Technology
    Elsevier B.V  2018
    Abstract
    The Ni-P/Zn-Ni compositionally modulated multilayer coatings CMMCs were electrodeposited from a single bath by switching the cathodic current density. The composition, surface morphology, roughness, layers growth pattern as well as the phase structure of deposits were extensively studied via SEM, EDS, AFM and XRD analysis. Effects of bath ingredients on the electrodeposition behavior were analyzed through cathodic linear sweep voltammetry. Although the concentration of Zn2+ in bath was 13 times higher than Ni2+, the Zn-Ni deposition potential was much nearer to Ni deposition potential rather than that of Zn. Addition of NaH2PO2 to the Ni deposition bath considerably raised the current... 

    Electrooxidation of methanol on NiMn alloy modified graphite electrode

    , Article Electrochimica Acta ; Volume 55, Issue 6 , 2010 , Pages 2093-2100 ; 00134686 (ISSN) Danaee, I ; Jafarian, M ; Mirzapoor, A ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
    Abstract
    Nickel and nickel-manganese alloy modified graphite electrodes (G/Ni and G/NiMn) prepared by galvanostatic deposition were examined for their redox process and electrocatalytic activities towards the oxidation of methanol in alkaline solutions. The methods of cyclic voltammetery (CV), chronoamperometry (CA) and impedance spectroscopy (EIS) were employed. In CV studies, in the presence of methanol NiMn alloy modified electrode shows a significantly higher response for methanol oxidation. The peak current of the oxidation of nickel hydroxide increase is followed by a decrease in the corresponding cathodic current in presence of methanol. The anodic peak currents show linear dependency upon the... 

    Electrocatalytic oxidation of methanol on Ni and NiCu alloy modified glassy carbon electrode

    , Article International Journal of Hydrogen Energy ; Volume 33, Issue 16 , August , 2008 , Pages 4367-4376 ; 03603199 (ISSN) Danaee, I ; Jafarian, M ; Forouzandeh, F ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
    2008
    Abstract
    Nickel and nickel-copper alloy modified glassy carbon electrodes (GC/Ni and GC/NiCu) prepared by galvanostatic deposition were examined for their redox process and electrocatalytic activities towards the oxidation of methanol in alkaline solutions. The methods of cyclic voltammetery (CV) and chronoamperometry (CA) were employed. The cyclic voltammogram of NiCu alloy demonstrates the formation of β/β crystallographic forms of the nickel oxyhydroxide under prolonged repetitive potential cycling in alkaline solution. In CV studies, in the presence of methanol NiCu alloy modified electrode shows a significantly higher response for methanol oxidation. The peak current of the oxidation of nickel...