Search for: cobalt-alloys
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    Sintering of biocompatible P/M Co-Cr-Mo alloy (F-75) for fabrication of porosity-graded composite structures

    , Article Materials Science and Engineering A ; Volume 472, Issue 1-2 , 2008 , Pages 338-346 ; 09215093 (ISSN) Dourandish, M ; Godlinski, D ; Simchi, A ; Firouzdor, V ; Sharif University of Technology
    Manufacturing of complex-shaped bimetals utilizing two-color powder injection molding (2C-PIM) and three-dimensional printing (3DP) processes, which basically involve sintering of a powder/binder mixture, has been attracted a great interest. This article addresses sintering of biocompatible Co-Cr-Mo alloy for manufacturing stepwise porosity-graded composite structures. Such composite structures provide strength at the core and a porous layer for the tissue growth. To evaluate the process, two grades of gas atomized Co-Cr-Mo powder with an average particle size of 19 and 63 μm were used. Isothermal and non-isothermal sintering behavior of the loose powders under hydrogen and argon... 

    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  

    A study on the kinetic of the electrodeposited Co-Ni alloy thin films in sulfate solution

    , Article Materials Chemistry and Physics ; Volume 102, Issue 2-3 , 2007 , Pages 118-124 ; 02540584 (ISSN) Dolati, A ; Sababi, M ; Nouri, E ; Ghorbani, M ; Sharif University of Technology
    The electrodeposition of cobalt, nickel and Ni-Co alloys was studied by electrochemical techniques. Cyclic voltammetry and current transient measurements were used to characterize the Co-Ni system in other to obtain the nucleation and growth mechanism. The cyclic voltammetry results clearly showed that electrodeposition of cobalt, nickel and Co-Ni alloy is diffusion-controlled process with a typical nucleation mechanism. The redox potentials of the Co and Ni are shifted to more cathodic potentials in the Co-Ni alloy system. In addition, the current transients revealed that nucleation mechanism is instantaneous with a typical three-dimensional (3D) nucleation and growth process. The number of... 

    Mössbauer and magnetic studies of iron-zeolite and iron-cobalt zeolite catalysts used in synthesis gas conversion

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 20, Issue 3 , 2007 , Pages 263-274 ; 1728-144X (ISSN) Oskoie, M ; Lo, C ; Sharif University of Technology
    Materials and Energy Research Center  2007
    Medium-pore (diameter - 6A) zeolites such as ZSM-5 and silicalite impregnated with Group VIII metals provide selective catalytic pathways for the conversion of synthesis gas to gasoline or olefins. Mössbauer and magnetic studies on these catalysts containing iron or iron plus cobalt are reported. The zeolites were impregnated with metal nitrate solutions, reduced, and carbided to yield showed Fe3+ type spectra. The ZSM-5 (14.7 % Fe) and Silicalite (13.6 % Fe) samples exposed to H2 (450 C) showed an approximate 85% reduction to the metallic state. The carbided ZSM-5 (14.7 % Fe) revealed a spectrum of Hagg carbide (Fe5C2), an active component of the catalyst. The used catalysts showed mixtures... 

    Corrosion behaviour of Ni-Co alloy coatings at Kish Island (marine) atmosphere

    , Article Bulletin of Materials Science ; Vol. 37, issue. 3 , May , 2014 , p. 713-719 Sharifi, K ; Ghorbani, M ; Sharif University of Technology
    In this study, the corrosion behaviour of Ni-Co alloys with low Co content, electroplated on steel substrate in sulphate bath, was investigated. The morphology of coatings was studied by optical and SEM microscopy. The corrosion products were analyzed using EDX. The results showed that Ni-1%Co coatings had a better corrosion resistance 0.30, 0.92 and 3.75 mpy for atmospheric, salt spray and polarization tests, respectively. These are 0.41, 1.20 and 5.40 mpy for pure nickel coatings that indicate the least corrosion resistance. Surface analysis revealed the presence of oxides, sulphides and chlorides in corrosion products  

    Hot ductility of a Fe-Ni-Co alloy in cast and wrought conditions

    , Article Materials and Design ; Volume 32, Issue 5 , 2011 , Pages 2956-2962 ; 02641275 (ISSN) Yazdani, M ; Abbasi, S. M ; Momeni, A ; Karimi Taheri, A ; Sharif University of Technology
    The hot ductility of Fe-29Ni-17Co alloy was studied in both cast and wrought conditions by hot tensile tests over temperature range of 900-1250°C and at strain rates of 0.001-1s-1. Over the studied temperature range, the wrought alloy represented higher elongation and reduction in area as compared to the cast alloy. Dynamic recrystallization was found responsible for the higher hot ductility of the wrought alloy and the improvement of hot ductility of the cast alloy at high temperatures. At temperature range of 1000-1150°C the wrought alloy exhibited a hot ductility drop while a similar trough was not observed in case of the cast alloy. It was also found that at temperatures of 1150-1250°C... 

    Efficient electrocatalytic oxidation of water and glucose on dendritic-shaped multicomponent transition metals/spongy graphene composites

    , Article Electrochimica Acta ; Volume 386 , 2021 ; 00134686 (ISSN) Nourmohammadi Khiarak, B ; Mohammadi, R ; Mojaddami, M ; Rahmati, R ; Hemmati, A ; Simchi, A ; Sharif University of Technology
    Elsevier Ltd  2021
    To improve the efficiency of electrochemical processes for environmental remediation, we present a new type of hybrid nanomaterials based on leaf-like copper-based quaternary transition metals and spongy monolayer graphene. To demonstrate the functionality of the hybrid electrocatalyst, fast and competent electrooxidation of water and glucose is shown. The mechanism of improved catalysis is ascribed to the synergetic catalytic effect of quaternary Cu-Ni-Fe-Co alloy with dendritic morphology along with the highly conductive and spongy structure of the graphene monolayer. It is shown that water oxidation can be performed at a low overpotential of 315 mV to reach a current denisty of 100 mA... 

    Hot deformation behavior of Fe-29Ni-17Co alloy

    , Article Transactions of Nonferrous Metals Society of China (English Edition) ; Volume 23, Issue 11 , 2013 , Pages 3271-3279 ; 10036326 (ISSN) Yazdani, M ; Abbasi, S. M ; Taheri, A. K ; Momeni, A ; Sharif University of Technology
    Hot compression tests were carried out on a Fe-29Ni-17Co alloy in the temperature range of 900 °C to 1200 °C and at strain rates of 0.001-1 s-1. Dynamic recrystallization was found responsible for flow softening during hot compression. The flow behavior was successfully analyzed by the hyperbolic sine equation and the corresponding material constants A, n and α were determined. The value of apparent activation energy was determined as 423 kJ/mol. The peak and steady state strains showed simple power-law dependence on the Zener-Hollomon parameter. The dynamic recrystallization kinetics was analyzed using Avrami equation and the corresponding exponent was determined to be about 2.7. This... 

    A comparison between the corrosion resistances of High Velocity Oxy Fuel (HVOF) sprayed coatings and hard chromium coatings

    , Article Materials Science Forum, 1 September 2010 through 3 September 2010, Seoul ; Volume 673 , 2011 , Pages 173-178 ; 02555476 (ISSN) ; 9783037850183 (ISBN) Saghi Beyragh, M. R ; Khameneh Asl, S ; Vasfpour, R ; Tazesh, F ; Khallagi, P ; Sharif University of Technology
    HVOF-sprayed coatings (WC-17%Co) and hard chromium coatings corrosion resistances have been compared through electrochemical polarization test in 3.5% NaCl solution. WC-17%Co alloy coatings were deposited on mild steel substrates by High Velocity Oxy-Fuel (HVOF) spray process. The layers of standard and crack free hard chromium coatings were prepared by using Direct Current (DC) and Pulse Current (PC) electroplating process on the mild steel substrates. Hard chromium coatings was characterized as a reference material, to verify whether HVOF-sprayed coatings are suitable as a hard chromium coatings replacement. The microstructure of the coatings was examined by OM, SEM and XRD. Standard hard... 

    The effect of current density on microstructural homogeneity, hardness, fracture toughness and electrochemical behavior of electrodeposited Cu-0.5Co/WC nano-composite coating

    , Article Scientia Iranica ; Volume 24, Issue 6 , 2017 , Pages 3505-3511 ; 10263098 (ISSN) Khaleghpanah, Sh ; Abachi, P ; Dolati, A ; Sharif University of Technology
    The Cu-0.5Co/WC nano-composite coating was synthesized on CP-copper substrate using Direct Current (DC) electrodeposition method. In this work, it was tried to increase the hardness of surface without considerable degradation of copper's particular physical properties such as electrical conductivity. The effect of current density on microstructural homogeneity, hardness, fracture toughness, and electrochemical behavior of coating was investigated. The copper plates with the purity of 99.99% were used as electrodes. The electrolyte consists of tungsten carbide particles (30 g/l), copper sulfate (200 g/l), sulfuric acid (50 g/l), cobalt sulfate (50 g/l), and Sodium Dodecyl Sulfate (SDS) (0.3... 

    Probabilistic assessment of creep-fatigue crack propagation in austenitic stainless steel cracked plates

    , Article Engineering Fracture Mechanics ; Volume 200 , 2018 , Pages 50-63 ; 00137944 (ISSN) Vojdani, A ; Farrahi, G. H ; Mehmanparast, A ; Wang, B ; Sharif University of Technology
    Elsevier Ltd  2018
    This study investigates the effects of uncertainties in the prediction of creep-fatigue crack propagation in 316L(N) austenitic stainless steel plates containing a semi-elliptical surface defect. Different parameters in geometry, material behavior and test condition are considered as random variables in probabilistic assessments. Monte-Carlo sampling method is employed to estimate the probability distribution of desired outputs such as propagated crack sizes, stress intensity factors and creep rupture life. It is shown that, the standard deviation of the predicted crack sizes in both through-wall direction and along the surface of the plate will be increased by increasing the time (hence the... 

    On the controllability of phase formation in rapid solidification of high entropy alloys

    , Article Journal of Alloys and Compounds ; Volume 748 , 2018 , Pages 679-686 ; 09258388 (ISSN) Jafary Zadeh, M ; Aitken, Z. H ; Tavakoli, R ; Zhang, Y. W ; Sharif University of Technology
    Elsevier Ltd  2018
    The demonstration of high entropy alloys (HEAs), or more generally multi-principal-element alloys (MPEAs), which display a greater resistance to softening at elevated temperatures and embrittlement at cryogenic temperatures, has offered an accessible alternative alloying process for materials scientists and engineers. Although solidification is a fundamental process in synthesis of alloys which strongly affects their microstructure and properties, a firm understanding of this process in HEAs is scarce. Here, using molecular dynamics (MD) simulations, we study the rapid solidification of the multi-principal-element CoFeNiPd alloy as a prototypical single-phase HEA. Our simulations reveal an... 

    Cyclic oxidation characteristics of HVOF thermal-sprayed NiCoCrAlY and CoNiCrAlY coatings at 1000 °C

    , Article Journal of Alloys and Compounds ; Volume 746 , 25 May , 2018 , Pages 509-519 ; 09258388 (ISSN) Feizabadi, A ; Salehi Doolabi, M ; Sadrnezhaad, S. K ; Rezaei, M ; Sharif University of Technology
    Elsevier Ltd  2018
    Thermal-sprayed MCrAlY coatings have become widespread in various industries such as power plants, aeronautics, and oil and gas firms. High-temperature oxidation behavior of these coatings is therefore of significance. Spraying of two prevalent MCrAlY powders (NiCoCrAlY and CoNiCrAlY) on Hastelloy substrate by high velocity oxygen and fuel method and exposing them to 1000 °C air for resolving of their cyclic oxidation behavior are presented in this paper. The coatings were characterized by x-ray diffraction, scanning electron microscopy and energy-dispersive x-ray spectroscopy. The obtained oxidation kinetic indicated that at 1000 °C, the thermally sprayed NiCoCrAlY coating has greater... 

    Effects of lithium excess and Ni content on the electrochemical performance of Li1+x (Ni0.45-xMn0.4Co0.15) O2 lithium-ion cathode materials in stoichiometric state

    , Article Materials Research Express ; Volume 6, Issue 8 , 2019 ; 20531591 (ISSN) Tolouei, A ; Kaflou, A ; Sadrnezaad, S. K ; Sharif University of Technology
    Institute of Physics Publishing  2019
    In Li-ion batteries, application of active materials can enhance the kinetics of the charge-discharge process, reduce the costs and improve the safety of the system. In this work, the effect of nickel content and lithium excess in Li1+x (Ni0.4-xMn0.5Co0.1) O2 compounds on the electrochemical performance of the lithium-ion battery cathode have been studies. For this purpose, three compounds of NMC in the stoichiometric state were synthesized via co-precipitation as the cathode active material. XRF and EDS analyses indicate that precursors and oxide compounds are well synthesized. The final compound of synthesized cathodes was obtained by ICP analysis. XRD results also suggest that the... 

    Flexible and mechanically durable asymmetric supercapacitor based on nico-layered double hydroxide and nitrogen-doped graphene using a simple fabrication method

    , Article Energy Technology ; Volume 7, Issue 5 , 2019 ; 21944288 (ISSN) Mehrabimatin, B ; Gilshteyn, E. P ; Melandsø Buan, M. E ; Sorsa, O ; Jiang, H ; Iraji zad, A ; Shahrokhian, S ; Nasibulin, A. G ; Kallio, T ; Sharif University of Technology
    Wiley-VCH Verlag  2019
    A high-performing, lightweight, and flexible asymmetric supercapacitor (ASC) using NiCo-layered double hydroxide (NiCo LDH) supported on 3D nitrogen-doped graphene (NG) as a positive electrode and NG as a negative electrode is demonstrated. Highly conductive NG provides fast electron transfer and facilitates (dis)charging of NiCo LDH deposited on it. The composite electrode of NiCo LDH@NG exhibits a high specific capacitance of 1421 F g −1 at 2 A g −1 . Moreover, the as-obtained hybrid electrode shows an excellent rate capability with a specific capacitance of 1397 F g −1 at a high current density of 10 A g −1 , which is about 98% of the capacitance obtained at 2 A g −1 . The flexible ASC... 

    Oxidation behavior and electrical properties of de-siliconized aisi 430 alloy with mn1.5co1.5o4 coating for solid oxide fuel cell interconnect

    , Article Oxidation of Metals ; Volume 93, Issue 3-4 , 2020 , Pages 401-415 Bakhshi Zadeh, A ; Salmani, S ; Faghihi Sani, M. A ; Abdoli, H ; Jalili, N ; Sharif University of Technology
    Springer  2020
    Abstract: The effect of de-siliconization on the oxidation behavior of AISI 430 stainless steel used for solid oxide fuel cell interconnect application was investigated. De-siliconization treatment was conducted via heating steel parts in an H2 environment. The de-siliconized substrates were then coated with a Mn1.5Co1.5O4 spinel coating, using wet spray method. For comparison, a similar coating process was applied on the as-received AISI 430 stainless steel specimens. Oxidation kinetics of coated interconnects were evaluated at 700, 800 and 900 °C in air. Results showed that the de-siliconization surface treatment decreased oxidation rates, with kinetic rates (g2 cm−4 s−1) of 4.39 × 10−14... 

    The oxidative desulfurization process performed upon a model fuel utilizing modified molybdenum based nanocatalysts: Experimental and density functional theory investigations under optimally prepared and operated conditions

    , Article Applied Surface Science ; Volume 527 , 2020 Hasannia, S ; Kazemeini, M ; Rashidi, A ; Seif, A ; Sharif University of Technology
    Elsevier B.V  2020
    CoMo/reduced graphene oxide (rGO) catalyst was synthesized for the oxidative desulfurization process (ODS) of dibenzothiophene (DBT) in n-decane. Parameters including total metal (Co and Mo) loading, Co/Mo and CA (citric Acid)/Mo molar ratios were investigated toward achieving optimum conditions. The catalysts were characterized by the XRD, ICP, FTIR, Raman Spectroscopy, BET-BJH, NH3-TPD, XPS, and TEM methods. The product sulfur content was measured by the ICP-OES while the product was evaluated using FTIR and 1H NMR analyses. All experimental stages were designed using Design-Expert software. High BET area, acidity, uniform particle size, and Co-promoter played key roles in this... 

    An optimal analytical solution for maximizing expected battery lifetime using the calculus of variations

    , Article Integration ; Volume 71 , March , 2020 , Pages 86-94 Jafari Nodoushan, M ; Ejlali, A ; Sharif University of Technology
    Elsevier B.V  2020
    The exponential growth in the semiconductor industry and hence the increase in chip complexity, has led to more power usage and power density in modern processors. On the other hand, most of today's embedded systems are battery-powered, so the power consumption is one of the most critical criteria in these systems. Dynamic Voltage and Frequency Scaling (DVFS) is known as one of the most effective energy-saving methods. In this paper, we propose the optimal DVFS profile to minimize the energy consumption of a battery-based system with uncertain task execution time under deadline constraints using the Calculus of Variations (CoV). The contribution of this work is to analytically calculate the... 

    In situ synthesis of quasi-needle-like bimetallic organic frameworks on highly porous graphene scaffolds for efficient electrocatalytic water oxidation

    , Article Chemical Communications ; Volume 56, Issue 21 , 2020 , Pages 3135-3138 Nourmohammadi Khiarak, B ; Hasanzadeh, M ; Mojaddami, M ; Shahriyar Far, H ; Simchi, A ; Sharif University of Technology
    Royal Society of Chemistry  2020
    We present enhanced electrocatalytic activity of three-dimensional graphene scaffolds by decoration with one-dimensional CoxNi1-x MOF nanostructures (0 ≤ x ≤ 1). The decreased overpotential and fast kinetics of the oxygen evolution reaction as compared with the existing materials are shown. The developed bimetallic MOF/3DG composites have great potential to be used in electrocatalytic water oxidation. This journal is © The Royal Society of Chemistry  

    Electrodeposited Ni-Co alloy-particle composite coatings: A comprehensive review

    , Article Surface and Coatings Technology ; Volume 382 , 2020 Safavi, M. S ; Tanhaei, M ; Ahmadipour, M. F ; Ghaffari Adli, R ; Mahdavi, S ; Walsh, F. C ; Sharif University of Technology
    Elsevier B.V  2020
    Electrodeposited composite and nanocomposite layers have attracted considerable attention as engineering coatings, due to their favourable tribological properties and corrosion resistance. Ni[sbnd]Co alloy matrix composite coatings are particularly significant due to their extensive and developing industrial applications. Ceramic nanoparticles are commonly incorporated into the Ni[sbnd]Co alloy matrix to further improve their properties, opening new windows for industrial applications. This review aims to comprehensively assess the influence of operating parameters (including the type of current control, plating bath conditions, particle loading and size) on the deposit properties....