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    Tribological and Corrosion Properties of Ni-SiC (FGM) Coatings

    , M.Sc. Thesis Sharif University of Technology Daneshpour, Mohammad Javad (Author) ; Ghorbani, Mohammad (Supervisor)
    Ni-SiC nanocomposite coatings are considered as corrosion resistant coatings with better tribological properties. In order to get superior properties, the amount of added particles should be increased. But high concentration of particles has some drawbacks such as low adhesion to substrate, probability of cracking in coating due to heat expansion coefficient difference between substrate and coating and also embrittlement of coating and low elasticity. In this study, the possibility of producing Ni-SiC nanocomposite coatings with FGM structure was investigated. SiC particles concentration was 5 to 80 g/l and the current density was between 3 to 5 A/dm¬2. The pH of bath and temperature was... 

    Investigation of Vanadium Dopant and SiO2 Prelayer on the Self-Cleaning Property of TiO2 Coatings by Sol-Gel Dip Coating Method

    , M.Sc. Thesis Sharif University of Technology Namkhah, Yalda (Author) ; Faghihi Sani, Mohammad Ali (Supervisor)
    Because of limitation of titania coating that can act as self-cleaning surface under UV light irradiation, introduction of transition metal ions into titania lattice can decrease band gap energy of titania in order to activate the coating under visible light irradiation. In this research, by using vanadium element and silica prelayer, a titania coating was deposited on the soda-lime glass substarte to produce self-cleaning surface. The scope of coating was to increase the photocatalytic activity and hydrophilicity of vanadium doped titania coating on the soda-lime glass and silica coated glass by sol-gel dip coating method. XRD and FTIR analysis were done on the powders with different... 

    An Investigation on Photocatalytic Behavior of N-doped and N-V-doped TiO2 Thin Film, Coated on Glass Surface by Sol-gel Dip Coating Method

    , M.Sc. Thesis Sharif University of Technology Khatibnezhad, Hediyeh (Author) ; Faghihi Sani, Mohammad Ali (Supervisor)
    In this study, the photocatalytic activity and hydrophilicity of coat improved using Nitrogen and Vanadium elements as dopant in TiO2 coating. By using vanadium and nitrogen elements and silica prelayer, a titania coating was deposited on the soda-lime glass substrate by sol-gel dip coating method to produce self-cleaning surface. XRD and FTIR analyses were done on the powders after heat treating at in 450˚C for 30 min. XPS analysis was done for investigation of N replacement in titania structure. The band-gap energy of formed anatase was derived using UV-Vis analysis. The coating morphology and thickness were also investigated by SEM. Hydrophilicity of coatings was determined by measuring... 

    Investigation on Effective Parameters in Ceramic Coating on Titanium Substrate by PEO Method in Galvano Static Condition

    , M.Sc. Thesis Sharif University of Technology Fazeli Tehrani, Alimohammad (Author) ; Faghihi Sani, Mohammad Ali (Supervisor)
    During this research, ceramic coatings on titanium substrate were prepared by plasma electrolytic oxidation process at a constant current density. Effect of different parameters such as frequency, current density, additives and time on the characteristics of the coated samples was studied. Composition, structure and elemental distribution of the coatings were studied by XRD, SEM and wave-length dispersive spectroscopy (WDS), respectively. Various tests were carried out to calculate the amount of coatings porosity. Pin-On-Disk method was used to evaluate erosion resistance of coatings. Corrosion and erosion-corrosion behaviors of the coatings were studied in 3.5wt% sodium chloride aqueous... 

    Electroplating and characterization of Cr–Al2O3 nanocomposite film from a trivalent chromium bath [electronic resource]

    , Article Anti-Corrosion Methods and Materials ; Vol 61, No 4, 2014, 205-214 Salehi Doolabi, M. (Mohsen) ; Sadrnezhaad, Khatiboleslam ; Salehi Doolabi, Davood ; Sharif University of Technology
    The main aim of this study was to improve current efficiency and to obtain thicker coatings via aluminum oxide (Al2O3) addition to the chromium (Cr) (III) bath. Design/methodology/approach ‐ Pure Cr and nanocomposite Cr–Al2O3 coatings were electrodeposited from Cr (III) bath onto cathode copper substrates by conventional method. Dependence of current efficiency to current density, Al2O3 content and particle size were investigated. Findings ‐ Current efficiency increased with Al2O3 amount and decreased with Al2O3 particle size. Maximum current efficiency was achieved at 25 A/dm2 for pure Cr and 30 A/dm2 for composite coatings. Al2O3 bath content, current density and stirring rate increased... 

    Application of sol-gel technique to synthesis of copper-cobalt spinel on the ferritic stainless steel used for solid oxide fuel cell interconnects

    , Article Journal of Power Sources ; Vol. 266, issue , 2014 , pp. 79-87 ; ISSN: 03787753 Paknahad, P ; Askari, M ; Ghorbanzadeh, M ; Sharif University of Technology
    The conductive CuCo2O4 spinel coating is applied on the surface of the AISI 430 ferritic stainless steel by the dip-coating sol-gel process and it is evaluated in terms of the microstructure, oxidation resistance and electrical conductivity. The results show that the CuCO2O 4 coating forms a double-layer scale consisting of a Cr, Fe-rich subscale and Cu-Co spinel top layer after 500 h in air at 800 °C. This scale is protective, acts as an effective barrier against Cr migration into the outer oxide layer and alleviates the cathode Cr-poisoning. The oxidation resistance is significantly enhanced by the protective coating with a parabolic rate constant of 5.8 × 10-13 gr2 cm-4 s -1, meanwhile... 

    Corrosion resistance enhancement of Ni-P-nano SiO2 composite coatings on aluminum

    , Article Applied Surface Science ; Vol. 303 , 2014 , Pages 125-130 ; ISSN: 01694332 Sadreddini, S ; Afshar, A ; Sharif University of Technology
    In this study, the influences of different concentrations of SiO 2 nano sized particles in the bath on deposition rate, surface morphology and corrosion behavior of Ni-P-SiO2 Composite coatings were investigated. The deposition rate of coating was influenced by incorporation of SiO2 particles. The microstructure was investigated with field emission scanning electron microscopy (FESEM). The amount of SiO 2 was examined by Energy Dispersive Analysis of X-Ray (EDX) and amount of SiO2 nanoparticles co-deposited reached a maximum value at 4.5 %wt. Corrosion behavior of coated aluminum was evaluated by electrochemical impedance spectroscopy (EIS) and polarization techniques. The results... 

    Erratum: Effects of crimping on mechanical performance of nitinol stent designed for femoral artery: Finite element analysis

    , Article Journal of Materials Engineering and Performance ; Vol. 23, issue. 4 , 2014 , pp. 1511- ; ISSN: 1059-9495 Nematzadeh, F ; Sadrnezhaad, S. K ; Sharif University of Technology
    [No abstract available]  

    Effect of content silver and heat treatment temperature on morphological, optical, and electrical properties of ITO films by sol-gel technique

    , Article Journal of Nanoparticle Research ; Volume 16, Issue 9 , September , 2014 ; ISSN: 13880764 Mirzaee, M ; Dolati, A ; Sharif University of Technology
    Silver-doped indium tin oxide thin films were synthesized using sol-gel dip-coating technique. The influence of different silver-dopant contents and annealing temperature on the electrical, optical, structural, and morphological properties of the films were characterized by means of four-point probe, UV-Vis spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and X-ray photoelectron spectroscope (XPS). XRD analysis confirmed the formation of cubic bixbyte structure of In2O3with silver nanoparticles annealed at 350 °C. XPS analysis showed that divalent tin transformed to tetravalent tin through oxidization, and silver nanoparticles embedded into ITO... 

    Experimental fatigue lifetime of coated and uncoated aluminum alloy under isothermal and thermo-mechanical loadings

    , Article Ceramics International ; Volume 39, Issue 8 , December , 2013 , Pages 9099-9107 ; 02728842 (ISSN) Azadi, M ; Farrahi, G. H ; Winter, G ; Eichlseder, W ; Sharif University of Technology
    This paper presents the fatigue lifetime of an aluminum-silicon-magnesium alloy, widely used in diesel engine cylinder heads, both with and without a thermal barrier coating (TBC) system. The coating system in this study consists of two layers including a 150 μm thick metallic bond coat and a zirconium oxide top coat 350 μm thick. These coating layers were applied on the substrate of A356.0 alloy by air plasma thermal spraying. The isothermal fatigue tests were conducted in low cycle fatigue (LCF) regime at various temperatures. Out-of-phase thermo-mechanical fatigue (OP-TMF) tests were also performed at different maximum temperatures and constraint factors. Experimental results demonstrate... 

    Poly(basic ionic liquid) coated magnetic nanoparticles: High-loaded supported basic ionic liquid catalyst

    , Article Comptes Rendus Chimie ; Volume 16, Issue 10 , 2013 , Pages 906-911 ; 16310748 (ISSN) Pourjavadi, A ; Hosseini, S. H ; AghayeeMeibody, S. A ; Hosseini, S. T ; Sharif University of Technology
    A novel poly(ionic liquid) (PIL) coated magnetic nanoparticle was synthesized by distillation-precipitation-polymerization of 1-vinyl-3- ethyl imidazolium in the presence of surface modified magnetic nanoparticles. The resulting catalyst was used as magnetic heterogeneous base catalyst for the synthesis of 4H-benzo[b]pyrans in water. The separation of the catalyst from the reaction mixture was readily achieved by simple magnetic decantation and the catalyst could be easily recycled without appreciable loss of catalytic activity. Because of polymer layers coated the surface of the magnetic nanoparticles, the catalyst has a high loading level of ionic liquid  

    Fe doped Ni-Co spinel protective coating on ferritic stainless steel for SOFC interconnect application

    , Article International Journal of Hydrogen Energy ; Volume 38, Issue 27 , 2013 , Pages 12007-12014 ; 03603199 (ISSN) Jalilvand, G ; Faghihi Sani, M. A ; Sharif University of Technology
    In an attempt to reduce the oxidation and Cr evaporation rates, various protective coating layers with a nominal composition of NiCo 2-xFexO4 (x = 0, 0.5, 1) were deposited on the SUS 430 ferritic stainless steel substrate, as interconnect for solid oxide fuel cell application, by sol-gel dip coating method. Then, the coated samples were soaked at 750 C for 2.5 h in N2 and subsequently for 2.5 h in air. Phase composition and microstructure of the coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Moreover, long-term isothermal oxidation experiment and area specific resistance (ASR) measurement were also carried out on the coated samples. Results... 

    Morphology of nanodroplets on structured surfaces

    , Article Journal of Physics D: Applied Physics ; Volume 46, Issue 21 , May , 2013 ; 00223727 (ISSN) Vahid, A ; Moosavi, A ; Sharif University of Technology
    We report different morphologies of nanodroplets over various topographical features of the supporting substrates. The effects of different parameters such as the profile of the disjoining pressure, droplet size and the geometrical parameters are studied and discussed. Also, the effects of a coating layer on the surface of the substrate are determined. It is demonstrated that the nanodroplets at some positions are not stable and gradually move to more stable positions so that the system has less energy. For grooves this results in a series of morphology diagrams of the nanodroplets over the grooves as a function of the grooves' width and the liquid volume  

    Green's functions of a surface-stiffened transversely isotropic half-space

    , Article International Journal of Solids and Structures ; Volume 49, Issue 23-24 , 2012 , Pages 3282-3290 ; 00207683 (ISSN) Eskandari, M ; Ahmadi, S. F ; Sharif University of Technology
    Green's functions of a transversely isotropic half-space overlaid by a thin coating layer are analytically obtained. The surface coating is modeled by a Kirchhoff thin plate perfectly bonded to the half-space. With the aid of superposition technique and employing appropriate displacement potential functions, the Green's functions are expressed in two parts; (i) a closed-form part corresponding to the transversely isotropic half-space with surface kinematic constraints, and (ii) a numerically evaluated part reflecting the interaction between the half-space and the plate in the form of semi-infinite integrals. Some limiting cases of the problem such as surface-stiffened isotropic half-space,... 

    Sol-gel derived hydroxyapatite coating on TiB 2/TiB/Ti substrate

    , Article Surface Engineering ; Volume 28, Issue 7 , August , 2012 , Pages 526-531 ; 02670844 (ISSN) Esfahani, H ; Dabir, F ; Taheri, M ; Sohrabi, N ; Toroghinejad, M. R ; Sharif University of Technology
    The low erosion resistance of titanium and its alloys has prevented their widespread application as joint implants. In addition, one essential requirement for the implants to bond with the living bone is the formation of a bone-like apatite on their surfaces in the host body. To enhance the erosion resistance of the surface, a diffused layer of TiB2 was formed at 1000uC on the commercial pure titanium. Hydroxyapatite was then coated on the boronised titanium by means of dip coating in a sol-gel solution. In order to confirm the biocompatibility of the specimens, they were soaked in a simulated body fluid for several days. The surface morphology of the specimens after exposure was studied by... 

    Solid phase extraction of trace amounts of Pb(II) in opium, heroin, lipstick, plants and water samples using modified magnetite nanoparticles prior to its atomic absorption determination

    , Article Journal of the Iranian Chemical Society ; Volume 9, Issue 2 , 2012 , Pages 171-180 ; 1735207X (ISSN) Karimi, M. A ; Hatefi Mehrjardi, A ; Mohammadi, S. Z ; Mohadesi, A ; Mazloum Ardakani, M ; Hormozi Nezhad, M. R ; Kabir, A. A ; Sharif University of Technology
    A new, simple, fast and reliable solid-phase extraction method has been developed for separation/preconcentration of trace amounts of Pb(II) using dithizone/sodium dodecyl sulfate-immobilized on alumina-coated magnetite nanoparticles, and its determination by flame atomic absorption spectrometry (FAAS) and graphite furnace atomic absorption spectrometry (GFAAS) after eluting with 4.0 mol L -1 HNO 3. Optimal experimental conditions including pH, sample volume, eluent concentration and volume, and co-existing ions have been studied and established. Under the optimal experimental conditions, the preconcentration factor, detection limit, linear range and relative standard deviation of Pb(II)... 

    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... 

    Electrodeposition of Ni/WC nano composite in sulfate solution

    , Article Materials Chemistry and Physics ; Volume 129, Issue 3 , 2011 , Pages 746-750 ; 02540584 (ISSN) Mohajeri, S ; Dolati, A ; Rezagholibeiki, S ; Sharif University of Technology
    Metal matrix composite coatings have gained great attention due to their exclusive properties. They have shown the properties of a metallic host material modified by addition of a second phase. In electrodeposition of Ni/WC nano composite, nickel was deposited on the substrates by DC electrodeposition in Watt's based bath containing nickel sulfate, nickel chloride, boric acid and sodium dodecyl sulfate. WC content in the coating was determined by different parameters such as current density, powder content and surfactant amount. Mechanism of electrodeposition was analyzed by cyclic voltammetry and was confirmed by Guglielmi model. Surface morphology was studied by scanning electron... 

    Tribological properties of Ni–P–SiO2 nanocomposite coating on aluminum

    , Article Colloid Journal ; Volume 77, Issue 5 , September , 2015 , Pages 628-634 ; 1061933X (ISSN) Sadreddini, S ; Afshar, A ; Jazani, M. A ; Sharif University of Technology
    Maik Nauka Publishing / Springer SBM  2015
    In this study, the effects of different concentrations of SiO2 nanosized particles in the bath on deposition rate, surface morphology and wear behavior of Ni–P–SiO2 composite coatings were investigated. The rate of coating deposition was influenced by the incorporation of SiO2 particles. The observations of microstructural morphology were performed with field emission scanning electron microscopy. The amount of deposited SiO2 was examined by X-ray energy dispersive analysis. The results showed that for the coating produced at 12.5 g/L of nanoparticles, the amount of co-deposited SiO2 nanoparticles and microhardness reached their maximal... 

    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...