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    Preparation of uniform TiO2 nanostructure film on 316L stainless steel by sol-gel dip coating

    , Article Applied Surface Science ; Volume 255, Issue 20 , 2009 , Pages 8328-8333 ; 01694332 (ISSN) Barati, N ; Sani, M. A. F ; Ghasemi, H ; Sadeghian, Z ; Mirhoseini, S. M. M ; Sharif University of Technology
    Sol was prepared by the mixing of tetra-η-butyle titanat, ethyl aceto acetate, and ethanol in an optimized condition. Polished 316L specimens were coated with the sol by dip-coating method. The influences of drying condition, withdrawal speed, calcination temperature, addition of dispersant, and pH of sol on TiO2 nanostructure coating were investigated. Choosing of alcohol as drying atmosphere hindered the crack formation. The relation between coating thickness and withdrawal speed was evaluated. The optimum temperature to create a uniform distribution of nanoparticles of anatase was derived as 400 °C. Average roughness of coating was found about 10.61 nm by AFM analysis. Dispersant addition... 

    Nanostructural Coating of Al2O3 on NiTi Alloy Via Electrochemical Method for Improvement of Biomedical and Surface Properties

    , M.Sc. Thesis Sharif University of Technology Mahloujchi, Raziyeh (Author) ; Sadrnezhaad, Khatiboleslam (Supervisor)
    Nitinol alloy is important and increasingly used in medicine and industry due to its unique properties such as shape memory and superelasticity. Plasma Electrolytic Oxidation (PEO) is a relatively new method which in electrical discharge occurrence and formation of small plasma arcs on the anode surface and the electrochemical and thermochemical reactions in plasma environment prepare ceramic coating on the substrate. This method is taken into consideration because of its simplicity and effectiveness in the preparation of oxide ceramic coatings with porous structure on the surface of certain metals and alloys to improve their corrosion and wear properties. In this study, to improve the... 

    Preparation and Characterization of ZrO2 Antistatic Coatings on Glass

    , M.Sc. Thesis Sharif University of Technology Naderi, Armaghan (Author) ; Dolati, Abolghasem (Supervisor) ; Afshar, Abdollah (Supervisor)
    In this study, the zirconia antistatic coating was synthesized by dip coating sol-gel route on glass substrate. The solution contains ZrCl4 as precursor and isopropanol as solvent to synthesize zirconium oxide. The effects of environmental humidity and solution concentration on the coating characterization were analyzed. MPTS and primer binder were added as binding agents in the solution to observe the effect of binding agents on the coating adhesion. Solution stability and antistatic coating characterization were analyzed by zita potential test, FTIR spectroscopy, EDX analysis, FESEM and AFM microscopy, pencil hardness test, thickness test, antidust ability and spectrophotometer. The... 

    Preparation and Characterization of Inhibitor Loaded Nanodiamond for Anticorrosion Coating

    , M.Sc. Thesis Sharif University of Technology Rahmani, Pooria (Author) ; Shojaei, Akbar (Supervisor) ; Pirhadi, Nahid (Co-Supervisor)
    In recent years, nanodiamond (ND) has been used as reinforcement in polymeric nanocomposites in order to improve mechanical properties, thermal conductivity, etc. The surface of nanodiamond has several functional groups which make it appropriate adsorbent. In this study, nanodiamond was modified with dodecylamine corrosion inhibitor and was utilized (1wt %) in epoxy based nanocomposite. Fourier transform infrared spectroscopy (FTIR) analysis was used to confirm the surface modification of Nanodiamond. In order to estimate the loading amount of corrosion inhibitor, thermogravimetric analysis was investigated. FE-SEM analysis demonstrated nanoparticle dispersibility in epoxy matrix. Regarding... 

    Synthesis of Antibacterial Hydroxyapatite/Titania-Silver Coating on Titanium Substrate Using Sol-Gel Method

    , M.Sc. Thesis Sharif University of Technology Azadeh, Mohsen (Author) ; Afshar, Abdollah (Supervisor)
    With the increase in the average age of the world's population, osteoporosis is a worldwide incidence. This disease, along with natural disasters, are important factors in the occurrence of fractures in various bones of the body. One of the methods for solving this problem and replacing with broken body bones is the use of metal implants with hydroxyapatite-based coatings. One of the common problems with using implants in the body is the infection in the adjacent parts of the implant. To overcome this problem, several studies have been carried out on the use of hydroxyapatite coatings with metal ions or antibacterial oxide compounds. In the present study, the influence of factors such as the... 

    Study on the Properties of the Cationic Antistatic Polyurethane-based Coating

    , M.Sc. Thesis Sharif University of Technology Khodadoust, Yasaman (Author) ; Dolati, Abolghasem (Supervisor)
    In this study, cationic polyurethane resin was synthesized by use of the reflux technique under N2 atmosphere. At first TDI was reacted with GMS to form prepolymer with terminal –NCO, also DBTDL was used as catalyst. This prepolymer was then reacted for chain-lengthening with N-methyl diethanolamine compound containing tertiary nitrogen atoms. The chain-lengthened product was then converted into an ammonium compound or cationic compound, by reacting with HCl as reactive hydrogen containing compound. The structure of product was studied by FT-IR spectroscopy. Then the cationic product was used as adduct resin with commercial tow-components polyurethane with proportion of 25%wt, 50%wt and... 

    Functional Design of a Coating System for the Telescope Mirrors, A Recognition to Telescope of Iranian National Observatory

    , M.Sc. Thesis Sharif University of Technology Mahdizadeh, Sajjad (Author) ; Moshfegh, Alireza (Supervisor) ; Khosroshahi, Habib (Co-Advisor)
    Functional design of coating system for the primary mirror of the Iranian National Observatory (INO) is done. This telescope has a 3.4 m primary mirror in diameter, made of Zerodur from Schott. Although similar coating systems are in use since years ago, this is the first attempt to design a system for such a large surface case in Iran. Systematic approach led us first to clarify and identifying the design requirements. Lower limit of 80% for reflectance on all wavelength range from 325-1000 nm, thickness of 100 nm with un-uniformity of 5 nm, adhesion enough to pass the selotape test and surface roughness of less than 8 nm. Study of the available methods for coating and selection of the best... 

    The Investigation of Effective Parameters in Coating on Aluminized Steel by Plasma Electrolytic Oxidation Process

    , M.Sc. Thesis Sharif University of Technology Jafarniya, Vahid (Author) ; Faghihi Sani, Mohammad Ali (Supervisor)
    Plasma electrolytic oxidation process (PEO) is now recognized as a relatively new method in surface engineering. In this process, formation of micro arcs resulted from electric discharges on the surface of the specimen in the appropriate electrolyte, is used to ionize the gas layer which has enshrouded the specimen. In the present study, ceramic coating on aluminized steel was produced by PEO process and the effects of the influential parameters were comprehensively investigated. For this purpose, coating on the aluminized steel with dimension of 25×30 mm² was produced under different condition of processing time from 1 to 15 minutes, current density from 10 to 20 A/dm², frequency from 50 to... 

    Synthesis of Super Hydrophobic and Anti-Wear Coating with SiO2 and SiC Nano Particles on Glass Surface )

    , M.Sc. Thesis Sharif University of Technology Zahmatkesh Saredorahi, Amir Hossein (Author) ; Dolati, Abolghasem (Supervisor)
    In this research we developed a superhydrophobic and anti-wear coating on a glass substrate using SiO2 nanoparticles to form a transparent superhydrophobic thin film and SiC nanoparticles to improve the wear resistance of coating.
    Silica nanoparticles were produced via a simple sol gel method from Tetraethylorthosilicate (TEOS) as precursor. Hexamethyldisilazane (HMDS) and Tetramethylclourosilane (TMCS) were used as hydrophobic inducing agents and at last SiC nanoparticles were dispersed in the solution in order to provide wear resistance. The final results indicate the contact angle (CA) of water droplet on the surface was about 158° and sliding angle (SA) lower than 9°. Studying the... 

    Smart Coating Incorporated with Inhibitor-Enclosed Nanocontainers for Corrosion Protection of Steel

    , Ph.D. Dissertation Sharif University of Technology Ebrahim Fathabadi, Hadi (Author) ; Ghorbani, Mohammad (Supervisor)
    In this thesis a smart anticorrosive pH-responsive coat was developed with layer by layer (LbL) technique in the assembly of SiO2/CTAB/PSS/HMTA/PSS/PEI/PSS. SiO2 nanoparticles were prepared from Matland Company (Iran) with average size of 24 nm. At first, the corrosion inhibition of HMTA for API 5L Grade B steel in 3.5 wt.% NaCl solution was investigated. Tafel polarization technique showed the optimum concentration of HMTA was 0.08 M with 92% corrosion inhibition efficiency as the morphology of coverage and adsorption on the steel surface was confirmed by SEM and EDS. AFM results showed the roughness of the surface decreased from 241 nm to 56 nm that is attributed to HMTA adsorption on the... 

    Preparation of Composite Coating with ZrO2 Nanoparticles on Aluminum 5052 Alloy Using Plasma Electrolytic Oxidation

    , M.Sc. Thesis Sharif University of Technology Amiri Yarahmadi, Hossein (Author) ; Ghorbani, Mohammad (Supervisor)
    Plasma Electrolytic Oxidation (PEO) method was used for the preparation of ceramic coatings on Aluminum 5052 substrate in a silicate-based electrolyte containing different concentrations of ZrO2 nanoparticles. Before the addition of nanoparticles into the electrolyte, determining process parameters including current density, coating time, and frequency were examined carefully. After studying corrosion behavior, thickness, and coating morphology in different circumstances, the frequency of 50Hz, the current density of 150mA/cm2, and the coating time of 20 minutes were chosen as the optimum parameters. After that and with the usage of those parameters, ZrO2 nanoparticles were added to the... 

    Fabrication of Oleophobic Coating

    , M.Sc. Thesis Sharif University of Technology Rahimi, Amir Mohammad (Author) ; Mousavi, Ali (Supervisor) ; Nouri Borujerdi, Ali (Supervisor)
    Wettability is the cause of many interactions today and is definitely effective in almost all processes where liquid and solid phases are in contact. Wetting controls by surface engineering can accelerate the process in the industry or improve the quality of daily life. Therefore, the fabrication of complex surfaces with a specific purpose and different wettability has attracted the attention of researchers. In this thesis, silica nanoparticles were synthesized to create roughness and reduce contact between surfaces and liquids at first. Then, using chemical compounds to reduce the surface energy, a transparent (94.20%) superhydrophobic and oleophobic coating was created on the glass. The... 

    Influence of pulse parameters on electrocodeposition of Cr-Al2O3 nanocomposite coatings from trivalent chromium bath

    , Article International Heat Treatment and Surface Engineering ; Volume 6, Issue 4 , December , 2012 , Pages 178-184 ; 17495148 (ISSN) Salehi Doolabi, M ; Sadrnezhaad, S. K ; Salehi Doolabi, D ; Asadirad, M ; Sharif University of Technology
    Cr and Cr-Al2O3 coatings were electrodeposited from Cr(III) bath with both pulsating and direct current onto copper substrates. Pulsating current resulted in homogeneous films of higher Al2O3 content and lower particle agglomeration than the direct current. Differences were more tangible at shorter duty cycles and pulse frequencies. Pulsating current improved both microhardness and corrosion resistance. The presence of alumina nanoparticles resulted in greater current efficiency, higher film microhardness and better corrosion resistance. Maximum current efficiency, highest microhardness and densest electrodeposited coatings were achieved at current density of 20 A dm-2, duty cycle of 40% and... 

    A study on the mechanism of electrodeposition of Ni/SiC composite coatings using impedance technique

    , Article ECS Transactions ; Volume 41, Issue 44 , 2012 , Pages 47-57 ; 19385862 (ISSN) ; 9781607683452 (ISBN) Sohrabi, A ; Dolati, A ; Electrodeposition; Sensor ; Sharif University of Technology
    Ni/SiC nanocomposite coatings were electrodeposited using Watts type bath and different SiC particle size. The electrodeposition behavior of Ni/SiC nanoelectrocomposites was studied using electrochemical techniques such as impedance spectroscopy (EIS) and voltammetry. In this study it was shown that SiC particles modify the EIS diagram and voltammograms as well as surface morphology of electrodeposited layers. Experimental results showed that SiC particles not only affect the formation of intermediate species and decrease charge transfer resistance but also increase the nucleation sites for nickel electrodeposition and thus affect the microstructure of electrodeposited Ni/SiC nanocomposites.... 

    Self-cleaning TiO2 nanofilms on FTO glass: Influence of electrophoretic deposition and UV irradiation conditions

    , Article Journal of Nano Research ; Volume 30 , 2015 , Pages 39-49 ; 16625250 (ISSN) Horandghadim, N ; Ghorbani, M ; Dolati, A ; Sharif University of Technology
    Trans Tech Publications Ltd  2015
    In this research, anatase TiO2 nano-particles were electrophoretically deposited on the FTO glass. This investigation was focused on the self-cleaning property of TiO2 coatings and the effects of different parameters on this characteristic such as: applied voltages during electrophoretic depositions and durations of UV irradiation. Electrophoretic depositions of suspensions were performed in different voltages of 10, 30 and 60 V (for 10 s) at room temperature. TiO2 coatings were sintered in 450oC for 1 hr. The phase transformation of TiO2 films was considered using XRD. Morphology, average particle size and the thickness of TiO2 films was analyzed using FESEM microscope. The photocatalytic... 

    Synthesis parameters effect on the final morphology of the layered double hydroxide (LDH)

    , Article Protection of Metals and Physical Chemistry of Surfaces ; Volume 53, Issue 3 , 2017 , Pages 460-465 ; 20702051 (ISSN) Imanieh, I ; Afshar, A ; Sharif University of Technology
    Maik Nauka Publishing / Springer SBM  2017
    Smart coatings which prevent corrosion by several mechanisms recently have been carefully planned. One of these mechanisms is the use of ion exchangers like LDH in the coating network. Since the morphology is the most important properties for the applications that the surface plays an important role, LDH morphology was evaluated in this study. For this purpose, the LDH contain a kind of green inhibitor was synthesized and after evaluating its performance it was examined morphologically by changing significant parameters like MII/MIII, pH, aging time and temperature. It is found that, high ratio of the MII/MIII cause thinner layer of LDH. The pH also has special effect on the surface... 

    Communication - Co-electrodeposition of Ni/SiO2(CH2)3SH composite: Modified Guglielmi’s model and mechanism of nucleation

    , Article Journal of the Electrochemical Society ; Volume 164, Issue 13 , 2017 , Pages E472-E474 ; 00134651 (ISSN) Fazlolahzadeh, O ; Rouhollahi, A ; Dolati, A ; Ghahramanifard, F ; Sharif University of Technology
    Electrochemical Society Inc  2017
    This work studies the influence of surface modification of silica nanoparticles by mercaptopropyl trimethoxysilane on silica weight percent in Ni coating during electrodeposition. Results showed SiO2(CH2)3SH particles were embedded in the Ni coating up to 11%. Also, modified Guglielmi’s model and mechanicsm of nucleation of Ni-SiO2(CH2)3SH composite were studied. © 2017 The Electrochemical Society. All rights reserved  

    Determination of the scattered fields of an SH-wave by an eccentric coating-fiber ensemble using DEIM

    , Article International Journal of Engineering Science ; Volume 46, Issue 11 , 2008 , Pages 1136-1146 ; 00207225 (ISSN) Sarvestani, A. S ; Mohammadi Shodja, H ; Delfani, M. R ; Sharif University of Technology
    To date, the existing theories pertinent to the determination of the scattered fields of an inhomogeneity have been limited to certain topological symmetries for which the method of wave-function expansion is widely used. In the literature the wave-function expansion method has also been employed to the case involving concentric coated fiber. An alternative approach is the dynamic equivalent inclusion method (DEIM) proposed by Fu and Mura [L.S. Fu, T. Mura, The determination of elastodynamic fields of an ellipsoidal inhomogeneity. ASME J. Appl. Mech. 50 (1983) 390-396.] who found the scattered field of a single spheroidal inhomogeneity. The pioneering work of Eshelby [J.D. Eshelby, The... 

    An FGM coated elastic solid under thermomechanical loading: A two dimensional linear elastic approach

    , Article Surface and Coatings Technology ; Volume 200, Issue 12-13 , 2006 , Pages 4050-4064 ; 02578972 (ISSN) Shodja, H. M ; Ghahremaninejad, A ; Sharif University of Technology
    A thin coating made of linear elastic functionally graded material (FGM) perfectly bonded to an elastic substrate is considered. This work which is of particular interest to tribological community is devoted to the determination of the thermal and mechanical stresses due to mixed normal and tangential Hertzian surface pressure. The thermomechanical properties of the FGM coating are assumed to vary exponentially through the thickness. Solutions for temperature rise and stresses are obtained by use of Fourier transform technique. The influences of coating thickness, Peclet number and friction coefficient on temperature rise and stresses in the FGM coating are investigated. Comparative studies... 

    Effects of Additives on Chromium Coating in Trivalent Chromium Bath

    , M.Sc. Thesis Sharif University of Technology Ebrahimi, Ghasem (Author) ; Dolati, Abolghasem (Supervisor)
    In this work, effects of different additives on trivalent Chromium bath and Chromium coating has been investigated. Malonic acid wich had been used as a complexing agent of the bath improved current efficiancy and coating quality obviously. Effects of Magnesum, zinc, Tin, Aluminium sulfates, Molybdic acid, TiO2 nano particles, Sodium hypophospite, formaldehead and mixtures of these compositions on hexavalent Chromium concentration of the bath were also studied. Concentration of Cr6+ ion decreased by 18 ppm due to adding these materials. Using Ti/ TiO2/ RuO2 Anode also could decrease Cr6+ concentration by 78 ppm. Remarkable results had been recorded in current efficiency and coating...