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Total 74 records

    The Corrosion Behavior of Sulfur Concrete in Persian Gulf Sea Water

    , M.Sc. Thesis Sharif University of Technology Haghipour, Amir (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    In this project sulfur concretes were prepared. The optimum of casting temperature, weight percent of sulfur cement and weight percent of filler were analyzed, so that better corrosion resistance could be found. It is observed, the optimum sulfur is 15% for sulfur concrete samples with 21% sulfur cement; the optimum filler is 10-15% with 18% sulfur cement and finally the optimum filler is 10% for concrete samples with 15% sulfur cement. The casting temperature for concrete with 15-21% sulfur cement is in the interval of 127-150°C could be achieved. By applying the relation between the optimum filler percent and the content of sulfur cement and choosing a suitable temperature for casting... 

    Electrodeposition of the Ni-P by Pulse Plating

    , M.Sc. Thesis Sharif University of Technology Kazerooni, Amir (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    Ni-P alloy coatings were electrodeposited using pulse current in a watt type bath in various conditions. The influences of different parameters were investigated and optimized for the highest amount of coating hardness using the Design Of Experiment (DOE) method. The optimized deposition parameters were current density 23.7 A/dm2, duty cycle 75%, frequency equal to 188 Hz, temperature equal to 70ºC and 17.5 gr/l of H3PO3. The DOE prediction of hardness for the optimized coatings was between 700 and 750 the achieved micro-hardness was about 725.8 HV. It was obtained that an increase of the current density will improve micro-hardness, decreases P content and increase deposition rate. Also, the... 

    Protection of Steel Rebar in Concrete with Zinc Based Coatings in Persian Gulf

    , M.Sc. Thesis Sharif University of Technology Attar, Morteza (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    Reinforced concrete is one of the most important structural materials used in the construction industry worldwide. Nevertheless, certain physical and chemical factors in the service environment can contribute to its deterioration and failure. One of the most significant factors is the reinforcing steel bar (rebar) corrosion. In order to minimize the rebars corrosion, different kinds of coatings were investigated and evaluated by scientists. In this investigation comparative studies were performed on two different kinds of coated rebars (zinc-rich epoxy and polyamide epoxy coated rebars) and uncoated rebar. In order to evaluate these reinforced concretes, the adhesion, durability, thickness... 

    Effects of Additives on Chromium Coating in Trivalent Chromium Bath

    , M.Sc. Thesis Sharif University of Technology Ebrahimi, Ghasem (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    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... 

    Wear-Resistant Nickel-Titanium Nitride Composite Coating by Electrochemical Method

    , M.Sc. Thesis Sharif University of Technology Parhizkar, Nafise (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    Metal matrix nanocomposites contains ceramic ultrafine particles in a metal matrix, are used to improve the mechanical properties such as hardness and wear of coatings. For developing metal matrix nanocomposites, there are many methods. Electrochemical deposition process is one of these methods that have some advantages like uniform depositions on substrates with complex shapes, low cost, good repeatability and reducing waste. In this project, for increasing the hardness and wear resistance of nickel, composite coatings of nickel - titanium nitride was created by using electrochemical deposition of Watts bath contained titanium nitride particles. In order to increase the amount of... 

    CNT Modified Coatings for Glucose Sensing

    , M.Sc. Thesis Sharif University of Technology Partovi, Parisa (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    This research describes a new and relatively general method to grow well-aligned carbon nanotubes (CNTs) on cobalt-deposited stainless steel by thermal chemical vapor deposition (CVD) of ethylenediamine precursor. The CNTs are vertically aligned at high density over large areas on the surface. Different effective parameters in growth of carbon nanotubes, as type of substrate, surface treatment, temperature of growth , feeding carbon supplies have been studied. Finally, aligned carbon nanotubes have been prepared by 100-150 nm diameter and 9µ length. CoOx•nH2O–MWCNTs nanocomposites were successfully synthesized, using a cathodic electrochemical reduction of H2O2 to deposit cobalt... 

    Gold Electroless from Sulfite-thiosulfate Bath

    , M.Sc. Thesis Sharif University of Technology Jahanianfar, Hooman (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    Gold coatings due to their unique properties, use in a wide range of applications.Decorative coatings of gold for centuries, has been considered.However, few studies have been done on the properties of this metal, this metal is shown not only in terms of decorating, but in the industry also has a wide range of applications. In this project non-cyanide electroless bath based on binary complex sulfite-thiosulfate was prepared and metal ion concentration of the complex components, temperature, time, pH and addition of amino acids, optimzed bystability, qualityand rate of coating. The main aim of optimizing bathsis optimize the thickness and appearance of the coating.It was found that by... 

    Deposition of Nanostructure Antimony Doped Tin Oxide (ATO) on Glass By Sol-Gel

    , M.Sc. Thesis Sharif University of Technology Royaei, Neda (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    Antimony Doped tin oxide as a conductive film has found a wide range of applications and sol-gel method has so advantageous with respect to another methods for preparing ATO thin films. In this study, ATO thin film has been synthesized using a solution containing metal salts of tin chloride and antimony chloride. The microstructure of the obtained films was studied by applying scanning electron microscopy (SEM) and X-ray diffraction patterns (XRD). In diffraction patterns of the acquired ATO layers which was deposited from a sol containing SnCl4.5H2O and SnCl2.2H2O with Sb concentration of 15%mol and layers which was deposited from a sol containing SnCl4.5H2O with Sb concentration of 15%mol... 

    , M.Sc. Thesis Sharif University of Technology Shokrani, Mohammad (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    In recent years, different of nanoparticles as oil additives has been investigated in many studies . These research show that nanoparticles are deposited on the surface friction and improve tribology properties of base oil and also significant reduction of wear and friction caused by the nanoparticles. Compared with metal and metal oxide nanoparticles , carbon nanotubes (CNT) due to the high thermal conductivity and high aspect ratio , is an excellent candidate as the nanoparticle is dispersed . For preparing useful oil it is essential to stabilize nanoparticles in fluid that will not settle over long time . Oils containing nanoparticles by increasing the heat transfer coefficient... 

    Cathodic Protection of Underground Pipeline by Polyurethane Coating

    , M.Sc. Thesis Sharif University of Technology Rajabpour, Foroud (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    Selection of appropriate coating system is the most important subject in corrosion control of buried pipelines. Corrosion control of buried pipelines is achieved by using a combination of barrier coatings and cathodic protection (CP). Applying barrier coating can decrease the protection current of CP. However, at the coating holidays the pipeline act as cathode generating hydroxyl ion and hydrogen electrochemically. Therefore the selected coating should be compatible with the alkaline condition.This research focuses on evaluating of an epoxy-tar and a urethane-tar based coating. Coatings performance has been tested by accelerated corrosion test methods (i.e. Salt spray according to ASTM... 

    Investigation and Fabrication of Cr2O3 Thin Film Coating on Soda Lime and Low Carbon Steel Substrate

    , M.Sc. Thesis Sharif University of Technology Sarhadi, Neda (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    Chromium oxide coatings (Cr2O3) have been widely used due to their remarkable properties in corrosion, wear, optical and mechanical applications. So far, several methods have been used to prepare Cr2O3 thin films. In this study, the chromium oxide was produced by the sol-gel method and dip coated on the low carbon steel and glass substrates. In this context, we encountered with the problem of incoherency of the Cr2O3 ceramic coating to the steel substrates. It is highly likely that this problem be due to causes such as: a) thermal stresses due to the difference between the thermal expansion coefficients of the substrate and the coating, b) incoherent substrate/coating interface due to their... 

    Synthesis and Investigation on the Properties of Silica-Graphene Oxide Nanocomposite Coating

    , M.Sc. Thesis Sharif University of Technology Afzali, Neda (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    The investigations on hydrophobic surfaces have attracted lots of intrests in science and technology. Silica sols have been used extensively in the area of producing hydrophobic coatings. On the other hand, carbon-based materials have attracted of a great deal of scientific interest in recent years. The purpose of this research is synthesis and investigation on the properties of Silica- Graphene Oxide nanocomposite coating.Graphene Oxide synthesized by using Hummer’s method. Silica nanoparticles were prepared using sol-gel process and tetraethylorthosilicate (TEOS) as precursor. The surface hydroxyl groups of silica nanoparticles are replaced with Methyl groups by treatment with... 

    The Effect of Surfactant Agents on the Superhydrophobic Properties of Silica Coatings Synthesis by Sol-gel

    , M.Sc. Thesis Sharif University of Technology Ziaee, Hamed (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    The purpose of this research is producing one phase silica superhydrophobic coating by sol-gel method and drying temperature less than 200 degrees. For preparing micrometer and nanometer scaled hierarchical structure based on silica, TEOS precursor and Fumed Silica nanoparticles were used by density of 43/30 cc/lit and 6/52 gr/lit in order to provide desired roughness in the range of 40 nm. Moreover, HMDS surface modifying agent was used for reducing the surface energy of coating, which is not a danger to the environment in comparison to the same substances. The best Contact Angle is 155 degree and the best Sliding Angle is less than 5 degree. For instance, it was created with the... 

    The Comparison Between TiN and Hard Chromium Coatings

    , M.Sc. Thesis Sharif University of Technology Ghominejad , Hanieh (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    This research focuses on finding an appropriate method for increasing wear and corrosion resistance of hard coating TiN PVD and chromium. The substrate was made up of 42CrMo4 (DIN) steel (used for marine industries) and coated by TiN Arc PVD process and hard chromium electro-deposition. The results of these two coatings are compared and the better coating which is TiN Arc PVD is suggested. To find the best method for coating, several test studies are organized such as: the mechanical and tribological properties of TiN PVD and hard chromium coatings for wear and corrosion resistance applications are organized. The potentiodynamic polarization technique was used to measure the corrosion rate... 

    , M.Sc. Thesis Sharif University of Technology Baradaran Mohajeri, Saha (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    Electrodeposition of composite coatings containing nano particles is very important because this technique is simple and economic. In this research, in order to produce a coating with high hardness and wear resistance, Ni-Co/WC nano composite was co-deposited. Watt’s based bath containing cobalt and tungsten carbide was used and parameters such as preparation of solution, concentration of ingredients and current density were controlled and adjusted. Surface morphology, microstructure and mechanical properties of coatings were studied by SEM and AFM microscopes. Mechanism of electrodeposition was investigated by cyclic voltametry, cronoamperometry and cronopotentiometry techniques and... 

    Nickel Nano Particles Pulse Electrodeposition

    , M.Sc. Thesis Sharif University of Technology Afsari, Maryam (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    Syntheses of coats including nickel nano-particles by electrodeposition have been
    investigated for over 10 years. A method of testing according to surface reply was chosen
    to reveal the effect of each pulse parameters (including duty cycle, frequency, average
    current density, off time (toff) and on time (ton)) and the effect of saccharin concentration
    on electroplating cathode efficiency, nanostructure. Pulse electroplating test of nickel was
    composed by 30 tests. Pulse electroplating with relatively high peak current density was
    employed and saccharine was added to increase deposition and rate of nickel nucleation on
    surface. According to the results of cathode... 

    Enhanced Photocatalytic Activity of Nano-scaled TiO2 Co-doped with N and Ag by Sol-gel Method

    , M.Sc. Thesis Sharif University of Technology Azimi, Zahra (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    Transparent coatings with self-cleaning property in visible light spectrum, UV radiation resistance and antimicrobial are highly desirable. Titanium dioxide (TiO2) is used in this research has been widely studied as an efficient photocatalyst by researchers. In this research enhanced visible-light photocatalytic activity is gained with N and Ag co-doped titania. All samples were annealed at 450℃. Finally AgI was loaded TiO2 coating and the results were investigated. Peaks of XRD pattern wereattributed to different diffraction planes of anatase TiO2. Morphology of coatings were analyzed with using FE-SEM. Nano granis size of TiO2 and AgI loaded TiO2 were observed in FE-SEMimages. Nitrogen... 

    Electrodeposition of Ag-Pd Alloy for Enhancing Corrosion Resistance

    , M.Sc. Thesis Sharif University of Technology Yari, Mohammad Hossein (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    Silver is a resistant metal against the oxidation under normal atmospheric conditions, but it reacts readily with sulfur bearing species in the environment and corrodes. Alloying silver with more noble elements, such as Palladium, is a promising approach for increasing corrosion resistance against the sulfur pollutants. The purpose of this research is to develop a plating bath for deposition of Silver-Palladium alloy with acceptable appearance and higher corrosion resistance than pure silver. For this purpose, a bath based on thiosulfate complexing agent was investigated. In this solution, with a bath containing 10 mM of each cation, deposits with palladium content of 6, 11 and 14 % were... 

    Synthesis of ZnO and ZnO-TiO2 Nanocoatings by Sol-Gel Methode and Study in Their Antibacterial and Photocatalyst Properties

    , M.Sc. Thesis Sharif University of Technology Nournia, Shayan (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    The goal of this study is synthesis of nanocoating on basis of ZnO by Sol-Gel method and evaluation of their antibacterial and photocatalyst properties changes by different values of TiO2. For this purpose in both method of synthesis contents of TiO2 hase been changed from 0-25 molar percent. Dip coat method has been used for coating from sol with 1.4 mm/s withdrawal speed and 2 minute immersion time. After each step of coating samples has been dried at 150oC for 10 minute and for increasing thickness this process has been repeated 4 times. In first method zinc acetate dihydrate in 0.1 M final concentration and titanium tetraisopropoxide are sol precursors at in situ way of synthesis. In... 

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

    , M.Sc. Thesis Sharif University of Technology Khodadoust, Yasaman (Author) ; Dolati, Abolghasem (Supervisor)
    Abstract
    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...