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    Effects of the hardened nickel coating on the fatigue behavior of CK45 steel: experimental, finite element method, and artificial neural network modeling

    , Article Iranian Journal of Materials Science and Engineering ; Volume 14, Issue 4 , 2017 , Pages 81-99 ; 17350808 (ISSN) Maleki, E ; Kashyzadeh, K. R ; Sharif University of Technology
    Hardened nickel coating is widely used in many industrial applications and manufacturing processes because of its benefits in improving the corrosion fatigue life. It is clear that increasing the coating thickness provides good protection against corrosion. However, it reduces the fatigue life. Thus, applying a thin layer of coated nickel might give an acceptable corrosion protection with minimum loss of the fatigue life. In the present study, the effects of hardened nickel coating with different thicknesses on the fatigue behavior of CK45 mild steel were experimentally investigated. After conducting the experimental tests, we carried out two different modeling approaches of finite element... 

    Fabrication of Ni -P -MoS2 Composite Coating by Electroless Deposition and Evaluation of Its Tribological Properties

    , M.Sc. Thesis Sharif University of Technology Majidian, Maryam (Author) ; Ghorbani, Mohammad (Supervisor) ; Afshar, Abdollah (Supervisor)
    Adding solid lubricant particles such as PTFE, Graphite and MoS2, has major influence on electroless composite nickel coatings in order to make low friction surfaces. Among these lubricants, MoS2 has attracted great attention due to its highest stability under wearing condition. In this work Ni-P-MoS2 composite coatings using MoS2 nano-particles have been made and in the next step, we evaluated tribological properties of these coatings. For exploring these coatings different experiments were utilized, like Scanning Electron Microscope study (SEM), chemical composition analysis exploiting AAS and XRF method, and thickness measurements. Two kinds of surfactants, CTAB and PVP, have been applied... 

    Pulse Electrodeposition of Ni-ZrO2-MoS2 Composite Coatings and Its Tribological Properties

    , M.Sc. Thesis Sharif University of Technology Rajabi Khosh Andam, Mohsen (Author) ; Ghorbani, Mohammad (Supervisor)
    In this study solid lubricants MoS2 nanoparticles with average size 50 nm and hard ZrO2 nanoparticles with average size 51 nm were used in watts bath and Ni/ZrO2-MoS2 composite coatings were prepared by pulse plating technique. Effect of current density, frequency, duty cycle, surfactant type and concentration of particles in the electrolyte on the amount of particles in the coatings were investigated and optimum conditions were determined to create composite coatings. Scanning Electron Microscopy (SEM) and x-ray diffraction (XRD) analysis were performed to study the morphology, structure, chemical composition of coatings. Corrosion testing of coatings by potentiodynamic polarization in... 

    Effect of Intermediate Ni Layer on Glass-Stainless Steel Seal at Solid Oxide Fuel Cell

    , M.Sc. Thesis Sharif University of Technology Fakouri Hassanabadi, Masoud (Author) ; Kokabi, Amir Hossein (Supervisor) ; Nemati, Ali (Co-Advisor)
    In order to prevent deterioration of metallic interconnects in solid oxide fuel cells (SOFC), while interacting with glass-ceramic sealant, a nickel electroplated ferritic stainless steel (UNS 430) was used. After applying a layer of powdered glass (SiO2-B2O3-Al2O3-Na2O-BaO-K2O) with thickness around 300-450 μm on the ferritic stainless steel sheets with dimansion of 0.5 × 60 × 60 mm and 0.5 × 10 × 10 mm, samples were heated at temperatures between 770-850 °C and durations of 1 to 15 hours. To evaluate the effect of the Ni layer, two types of sample (only sanded and only electropolished) were also submitted to the same process, and their results were compared with the coated samples. XRF,... 

    Comparison of isothermal with cyclic oxidation behavior of “Cr-Aluminide” coating on inconel 738LC at 900 °C

    , Article Oxidation of Metals ; Volume 87, Issue 1-2 , 2017 , Pages 57-74 ; 0030770X (ISSN) Salehi Doolabi, M ; Ghasemi, B ; Sadrnezhaad, S. K ; Feizabadi, A ; HabibollahZadeh, A ; Salehi Doolabi, D ; AsadiZarch, M ; Sharif University of Technology
    Springer New York LLC  2017
    A two-step pack cementation technique was used to cover nickel-based IN-738LC superalloy with a Cr-aluminide coating layer. The IN-738LC/Cr-aluminide samples were oxidized at 900 °C for 350 and 700 h, isothermally, and 175 and 350 h, cyclically. Each cycle lasted for 25 h. Effects of the isothermal and the cyclic oxidation on (a) morphology, (b) new-phase formation, (c) weight gain, and (d) oxidation reactions were investigated by scanning electron microscopy, electron dispersive spectroscopy, X-ray diffraction, and weight gain measurements. From results, it was concluded that the oxygen attack was more severe during the cyclic oxidation than the isothermal procedure. Kinetics of 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... 

    Effect of specimen orientation and heat treatment on electroless Ni-PTFE-MoS 2 composite coatings

    , Article Journal of Coatings Technology Research ; Volume 7, Issue 6 , November , 2010 , Pages 697-702 ; 15470091 (ISSN) Mohammadi, M ; Ghorbani, M ; Azizi, A ; Sharif University of Technology
    In this study, the effects of simultaneous co-deposition of polytetrafluoroethylene (PTFE) and MoS 2 particles on tribological properties of electroless nickel (EN) coating were studied. The influences of specimen orientation and heat treatment on EN-PTFE-MoS 2 composite coatings were also investigated. Scanning electron microscopy was used to study the morphology of coatings and the distributions of the lubricant particles in the deposits. Chemical analyses of coatings were done by electron dispersive spectrometry. The phases of the coatings were identified by X-ray diffraction utilizing CuKα radiation. Wear and friction properties of the coatings were also determined by pin-on-disk wear... 

    Electrophoretic deposition of Ni/SiO2 nanocomposite coating: Fabrication process and tribological and corrosion properties

    , Article Journal of Nano Research ; Volume 26 , 6 January , 2014 , Pages 45-51 ; ISSN: 16625250 Isfahani, A. G ; Ghorbani, M ; Sharif University of Technology
    To the best of our knowledge, this work presents the first successful effort to fabricate and study nanostructured Ni-based composite coatings using the electrophoretic deposition method with nanostructured SiO2 particles. In this work, Ni/SiO2 nanoparticle composite coatings were prepared by electrophoretic deposition (EPD) [1] and their hardness, wear and corrosion resistances [2] were examined. After studying the morphology of the coatings and finding the optimum conditions for uniform coating, in order to improve the mechanical properties as well as resistance to corrosion, sintering was performed. The Ni/SiO2 nanocomposite coatings show excellent hardness (∼376 HV), reduced Young's... 

    Elucidation of the structural texture of electrodeposited Ni/SiC nanocomposite coatings

    , Article Journal of Physical Chemistry C ; Volume 116, Issue 6 , January , 2012 , Pages 4105-4118 ; 19327447 (ISSN) Sohrabi, A ; Dolati, A ; Ghorbani, M ; Barati, M. R ; Stroeve, P ; Sharif University of Technology
    Crystallographic texture is one of the most sensitive parameters for controlling the microstructure of electrodeposited layers. In this work, we study the crystallographic texture of electrodeposited nickel-silicon carbide coatings. The nickel coatings containing SiC nanoparticles and microparticles were electrodeposited from an additive-free sulfate bath containing nickel ions and SiC particles. The effect of current density on the codeposited Ni/SiC was studied. The coatings were analyzed with scanning electron microscopy and X-ray diffraction. Pole figure studies were done to characterize the evolved crystallographic texture. The X-ray scans followed by Rietveld analysis using the... 

    Mechanical and electrochemical properties of ultrasonic-assisted electroless deposition of Ni-B-TiO2 composite coatings

    , Article Journal of Alloys and Compounds ; Volume 633 , 2015 , Pages 127-136 ; 09258388 (ISSN) Niksefat, V ; Ghorbani, M ; Sharif University of Technology
    Elsevier Ltd  2015
    Nickel-Boron-Titania (Ni-B-TiO2) composite coatings were successfully obtained on mild steel (St-37) by simultaneous electroless deposition. TiO2 particles were dispersed in a suspension by ultrasonic irradiation. The surface morphology, particle size, elemental composition and phase analysis of the coatings were characterized by scanning electron microscopy (SEM), inductively coupled plasma (ICP) and X-ray diffraction (XRD). The hardness and friction coefficient of as- plated and heat treated Ni-B and Ni-B-TiO2 composite coatings were determined by Vickers diamond indentation and indentation scratch tests and compared with Ni-B coatings. As a result, the hardness (1263 HV) of the as-plated... 

    Characterisation of Ni-Ti intermetallic coatings formed on Cp titanium by diffusion treatment

    , Article International Journal of Surface Science and Engineering ; Volume 9, Issue 1 , 2015 , Pages 43-54 ; 1749785X (ISSN) Khosravi, G ; Sohi, M. H ; Ghasemi, H. M ; Vafadar, A. Kh ; Sharif University of Technology
    Inderscience Enterprises Ltd  2015
    In order to produce a thick near equi-atomic NiTi intermetallic layer on the surface of titanium plate, layers of nickel with thicknesses of 30 μm and 60 μm were electroplated on commercial pure (Cp) titanium and subsequently were heat treated at 850°C and 900°C. The effects of heat treating temperature and the thickness of electroplated nickel on the evolution of the microstructure and mechanical properties were studied. The results confirm the formation of various intermetallic layers in the coatings that substantially affect their hardness. The optimum condition for the formation of a thick NiTi intermetallic layer on the outer surface of the titanium was diffusion treatment of the sample... 

    Investigation and optimization of SDS and key parameters effect on the nickel electroless coatings properties by Taguchi method

    , Article Journal of Coatings Technology Research ; Volume 7, Issue 5 , 2010 , Pages 547-555 ; 15470091 (ISSN) Farzaneh, A ; Ehteshamzadeh, M ; Ghorbani, M ; Vazifeh Mehrabani, J ; Sharif University of Technology
    In this research, the influence of anionic surfactant sodium dodecyl sulfate (SDS), pH, substrate finishing, and annealing temperature on the surface morphology and hardness of the electroless nickel phosphorus (ENi-P) coatings were studied. Taguchi's experimental design method was used. Parameters selected in three levels and L9 from orthogonal robust array design were employed. Surface roughnesses of the deposits were measured using a stylus instrument. Scanning electron microscope and x-ray diffraction analysis were implemented to study surface morphologies and phase composition, respectively. Microhardness of the ENi-P deposits was measured using a microhardness tester at three trials... 

    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,... 

    Spark plasma sintering of a multilayer thermal barrier coating on Inconel 738 superalloy: Microstructural development and hot corrosion behavior

    , Article Ceramics International ; Volume 42, Issue 2 , 2016 , Pages 2770-2779 ; 02728842 (ISSN) Pak Seresht, A. H ; Javadi, A. H ; Bahrami, M ; Khodabakhshi, F ; Simchi, A ; Sharif University of Technology
    Elsevier Ltd 
    In the present work, spark plasma sintering (SPS) process was employed to prepare a nanostructured yttria-stabilized zirconia (8YSZ) coating on a nickel-based superalloy (INCONEL 738) with functionally graded structure. A stack layer of INCONEL 738/NiCrAlY powder/Al foil/NiCrAlY+YSZ powder/YSZ powder was SPSed in a graphite die at an applied pressure of 40 MPa under an vacuum atmosphere (8 Pa). The sintering temperature was ∼1040 °C. For comparison purpose, the air plasma spray (APS) technique was employed to prepare the thermal barrier coating (TBC). Microstructural studies by scanning electron microscopy showed that the SPSed coating was sound and free of interfacial cracks and large... 

    Polybutylene terephthalate-nickel oxide nanocomposite as a fiber coating

    , Article Analytica Chimica Acta ; Volume 863, Issue 1 , 2015 , Pages 20-28 ; 00032670 (ISSN) Bagheri, H ; Roostaie, A ; Sharif University of Technology
    Elsevier  2015
    A highly efficient polybutylene terephthalate (PBT)-based nanocomposite containing nickel oxide nanoparticles was synthesized by electrospinning technique and used as a fiber coating for solid phase microextraction. The influential morphological parameters and capability of the prepared nanocomposite including the NiO content, the coating time, the PBT concentration and applied voltage were considered for optimization. The applicability of the synthesized fiber coating was examined by headspace solid phase micro extraction and gas chromatography mass spectrometry detection of some volatile organic compounds in aqueous samples. Among the synthesized nanocomposites and pristine PBT nanofibers,... 

    Three-dimensional hybrid of iron–titanium mixed oxide/nitrogen-doped graphene on Ni foam as a superior electrocatalyst for oxygen evolution reaction

    , Article Journal of Colloid and Interface Science ; Volume 563 , 15 March , 2020 , Pages 241-251 Mousavi, D. S ; Asen, P ; Shahrokhian, S ; Irajizad, A ; Sharif University of Technology
    Academic Press Inc  2020
    Growing demands for clean and renewable energy technologies have sparked broad research on the development of highly efficient and stable non-noble metal electrocatalysts for oxygen evolution reaction (OER). In this regard, in the present work a three-dimensional Fe2TiO5/nitrogen-doped graphene (denoted as 3D FTO/NG) hybrid electrocatalyst was synthesized via a facile in-situ process using a hydrothermal method. Structural characterization of the prepared nanocomposite is performed by various techniques e.g. field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) analysis, Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy spectra (XPS),...