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    Evaluation of electrical breakdown of anodic films on titanium in phosphate-base solutions

    , Article Surface and Coatings Technology ; Volume 186, Issue 3 , 2004 , Pages 398-404 ; 02578972 (ISSN) Afshar, A ; Vaezi, M. R ; Sharif University of Technology
    Titanium is a highly reactive metal, so that whenever it is exposed to air or other environments containing available oxygen, a thin layer of oxide is formed on the surface. This layer increases the corrosion resistance of titanium. The formation of the oxide film can be electrochemically performed by anodizing. In this research, anodizing of titanium was performed in phosphate-base solutions such as H3PO4, NaH2PO 4·2H2O and Na2HPO4 at 9.75 mA/cm2 and 35 °C under galvanostatic conditions. The potential-time curves in the above mentioned solutions show that the anodic films formed on Ti are compact and their thickness depends on the solution type and concentration. The SEM and XRD studies... 

    Anodizing of titanium in NaOH solution and its corrosion resistance in PBS physiologic solution

    , Article Scientia Iranica ; Volume 10, Issue 3 , 2003 , Pages 361-366 ; 10263098 (ISSN) Afshar, A ; Vaezi, M. R ; Sharif University of Technology
    Sharif University of Technology  2003
    Titanium is a highly reactive metal with an inclination to compose with oxygen. In order to increase its corrosion resistance and application, therefore, a thin layer of titanium oxide is produced on the surface by chemical and electrochemical methods. In the present research, titanium has been anodized in 20 M of NaOH solution under potentiostatic conditions at constant voltages of 25 and 35 V. The microstructure of the anodic layers has been studied by the use of a Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD). The results indicated that the structure of the anodic layers is amorphous with low porosity and that thickness increases with an increase in anodizing voltage. The... 

    Comparison of the corrosion resistance of alkaline- and acid-anodized titanium

    , Article Materials Performance ; Volume 54, Issue 1 , 2015 , Pages 51-55 ; 00941492 (ISSN) Karambakhsh, A ; Ghahramani, S ; Afshar, A ; Malekinejad, P ; Sharif University of Technology
    National Assoc. of Corrosion Engineers International  2015
    The process of self-color anodizing of titanium is done in acidic and alkaline solutions, and anodic films of different colors are formed. Results of this work show that the corrosion rate of titanium decreased after the application of an anodizing layer  

    Preparation and Characterization of Ternary Mixed Oxide Containing IrO2,RuO2,TiO2 on Platinum Coated Titanium Anode

    , M.Sc. Thesis Sharif University of Technology Ali Asghari, Sepideh (Author) ; Ghorbani, Mohammad (Supervisor) ; Davami, Parviz (Supervisor)
    Ruthenium based-oxide coatings on Titanium anodes are widely used as DSA (Dimensionally Stable Anode) for chlorine and chlorate production. Coatings consisting of composition of highly conductive oxide of noble metals (Ru, Ir and Pt) make them as long lasting anodes in chlor-alkali technology.In this work, a newly anode by a ternary coating of IrO2, RuO2, and TiO2 on the Pt-coated Ti was developed through thermal decomposition of iridium and titanium and ruthenium inorganic salts dissolved in n-pentane. The effect of deposition parameters such as current density, time, different condition of baking, heating, mole ratio and pulling up the samples was investigated to find out reasonable... 

    The effect of additives on anode passivation in electrorefining of copper

    , Article Chemical Engineering and Processing: Process Intensification ; Volume 46, Issue 8 , 2007 , Pages 757-763 ; 02552701 (ISSN) Ojaghi Ilkhchi, M ; Yoozbashizadeh, H ; Sadegh Safarzadeh, M ; Sharif University of Technology
    In copper electrorefining process, some additives are added to the electrolyte to improve the morphology of cathode deposits as well as the quality of products. In the present investigation, the effects of thiourea, glue and chloride ions (as additives) on the passivation of industrial copper anodes under high current densities have been reported. Experiments were conducted at 65 °C; using a synthetic electrolyte containing 40 g/l Cu2+ and 160 g/l H2SO4. Results obtained from chronopotentiometry experiments showed that increasing the concentration of chloride ion leads to increase in passivation time. The results also indicated that from a certain level on, namely 2 ppm, the increase in... 

    A Study on Properties of Composite Coating with Al2O3 Base Prepared by Hard Anodizing with ZrO2 Nanoparticles

    , M.Sc. Thesis Sharif University of Technology Motamen, Ali (Author) ; Afshar, Abdollah (Supervisor)
    In this study anodized none composite and composite film containing ZrO2 nanoparticles were prepared on 1050 Al Alloy using hard anodizing method in sulfuric and oxalic acid mixed solution by pulse Currents. The microstructure and properties of the film were studied by field emission scanning electron microscopy with EDS analyzer and XRD diffraction and friction wear test were performed to evaluate the mechanical properties of coating . Results indicate that the composite film with ZrO2 nanoparticles have reduced friction coefficient with high micro hardness friction coefficient of composite film can be small as 0.16 which is much smaller than that 0.39 of none composite film. Micro hardness... 

    Sulfide stress corrosion cracking and hydrogen induced cracking of A216-WCC wellhead flow control valve body

    , Article Case Studies in Engineering Failure Analysis ; Volume 1, Issue 3 , 2013 , Pages 223-234 ; 22132902 (ISSN) Ziaei, S. M. R ; Kokabi, A. H ; Nasr Esfehani, M ; Sharif University of Technology
    The wellhead flow control valve bodies which are the focal point of this failure case study were installed in some of the upstream facilities of Khangiran's sour gas wells. These valve bodies have been operating satisfactorily for 3 years in wet H2S environment before some pits and cracks were detected in all of them during the periodical technical inspections. One failed valve body was investigated by chemical and microstructural analytical techniques to find out the failure cause and provide preventive measures. The valve body alloy was A216-WCC cast carbon steel. During investigation many cracks were observed on the inner surface of the valve body grown from the surface pits. The results... 

    Electricity generation from petrochemical wastewater using a membrane-less single chamber microbial fuel cell

    , Article 2012 2nd Iranian Conference on Renewable Energy and Distributed Generation, ICREDG 2012 ; 2012 , Pages 23-27 ; 9781467306652 (ISBN) Marashi, S. K. F ; Kariminia, H. R ; Sharif University of Technology
    Microbial fuel cells (MFCs) represent a new method for simultaneous wastewater treatment and biological electricity generation. In this study, petrochemical wastewater with 8000 mg/l of chemical oxygen demand was examined in a membrane-less single chamber MFC. Effects of wastewater concentration as substrate for microbial oxidation, and anode material (stainless steel or carbon brush) were investigated as designing parameters  

    Electrochemical degradation of clindamycin by anodic oxidation on SnO2-Sb coated titanium anodes

    , Article Environmental Engineering and Management Journal ; Volume 17, Issue 2 , February , 2018 , Pages 343-355 ; 15829596 (ISSN) Gholami, M ; Davoudi, M ; Farzadkia, M ; Esrafili, A ; Dolati, A ; Sharif University of Technology
    Gheorghe Asachi Technical University of Iasi, Romania  2018
    Degradation of Clindamycin phosphate (CMP) was studied in aqueous solutions by an anodic oxidation process under galvanostatic conditions. The electrolysis cell consisted of a Ti/SnO2-Sb anode, prepared by dip-coating technique, and a 316 stainless steel cathode, both of which had a surface area of 6 cm2. The effects of critical factors, including CMP concentration, current density, initial pH, and the supporting electrolyte were evaluated. The electrochemical oxidation of CMP was controlled by mass transport within the studied range. The kinetic analysis indicated that the degradation reactions followed pseudo-first-order equation. The rate of CMP decay, as well as that of COD removal,... 

    Electrocatalytic oxidation of ethanol on flexible three-dimensional interconnected nickel/gold composite foams in alkaline media

    , Article Electroanalysis ; Volume 31, Issue 3 , 2019 , Pages 504-511 ; 10400397 (ISSN) Hatamie, A ; Rezvani, E ; Sedighian Rasouli, A ; Simchi, A. R ; Sharif University of Technology
    Wiley-VCH Verlag  2019
    In this work, a porous and flexible three-dimensional (3D) nickel/gold nanoparticle electrode (NiF/AuNPs) is presented as an efficient electrocatalyst for ethanol oxidation in alkaline media. The 3D nanocomposite electrode consists of interconnected porous nickel foam (NiF) with large pores (500±200 μm diameter) surrounded by interconnected struts (∼100 μm) that are decorated with gold nanoparticles (AuNPs, 37±8 nm) through in-situ electrochemical deposition. The catalytic performance of the 3D electrode was evaluated by different electrochemical methods. An enhancement in the performance (about 253 %) and a remarkable decline in onset potential (about ∼0.63 V) in comparison with pristine... 

    Synthesis of anodized TIO2 nanotube arrays as ion sieve for lithium extraction

    , Article ChemistrySelect ; Volume 5, Issue 33 , 2020 , Pages 10339-10345 Taghvaei, N ; Taghvaei, E ; Askari, M ; Sharif University of Technology
    Wiley-Blackwell  2020
    Titanium type lithium ion-sieve nanotubes synthesized by the hydrothermal method were extensively explored over recent years due to its promising properties. However, on account of nanotubes′ tangled structure impeding the lithium adsorption in the interior nanotube walls, unalterable dimensions of the synthesized nanotubes, and a long period of annealing, the anodizing technique was proposed. It is shown that lithium uptake and adsorption capacity is improved because of easier mass transfer during the ion exchange process. This work focuses on a novel anodizing method for nanotube ion-sieve synthesis. The optimum anodizing condition was discovered by altering anodizing voltage, time, and... 

    Effect of anode position on the incorporation of nano/microparticles during the PEO coating on AZ31B

    , Article Applied Surface Science Advances ; 2021 , Volume 6 ; 26665239 (ISSN) Esmaeili, M ; Asgari, M ; Daneshmand, H ; Karimi, M ; Sabour Rouhaghdam, A ; Sharif University of Technology
    Elsevier B.V  2021
    In this study, the influence of the sample position (anode) on the incorporation of nano/micro alumina particles on the AZ31B magnesium alloy substrate was investigated by plasma electrolytic oxidation (PEO) coating. For characterized this effect, Scanning electron microscopy (SEM), potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and pin-on-disk test were used to the evolution of the microstructure, corrosion resistance, and the wear behavior of the films. Based on the obtained results, the effect of the anode position from vertical to horizontal is dependent on particle size and it can be influenced only on the incorporation of nanoparticles. The... 

    Study the failure of casted copper anode: The formation of bumps defects on the surface of the anode during casting

    , Article Engineering Failure Analysis ; Volume 138 , 2022 ; 13506307 (ISSN) Reza Shojaei, M ; Reza Khayati, G ; Javad Khorasani, S. M ; Assadat Yaghubi, N ; Sharif University of Technology
    Elsevier Ltd  2022
    Copper anode (∼98%) is widely used to produce the cathode (99.995 wt%) in electrorefining process. These anodes sometimes become problematic from the production line due to the presence of bumps/holes on their surface. To find the reason of this defect, chemical composition of the three casted anodes was determined by the quantmeter analysis. Also, the microscopic and phase analysis were done by FESEM, EDS, XRD, and XRF for three types of anodes bump. The chemical analysis of anodes confirmed a high level of sulfur and oxygen, which have a key role in the formation of bumps. The results confirmed the presence of impurities including Cu2S, BaSO4, CaCO3 and MgCO3, which cause the formation of... 

    Pure commercial titanium color anodizing and corrosion resistance

    , Article Journal of Materials Engineering and Performance ; Volume 20, Issue 9 , 2011 , Pages 1690-1696 ; 10599495 (ISSN) Karambakhsh, A ; Afshar, A ; Ghahramani, S ; Malekinejad, P ; Sharif University of Technology
    In order to improve titanium corrosion behavior, we can increase the thickness of oxide layer on titanium surface during anodizing process and by electrochemistry. In this research, self-color anodizing of Ti in sulfuric acid was done, and anodizing layers were created in different colors. The highest value of chromaticity was 37.8 for the anodized sample in 10 V, and the lowest value was 8.6 at 15 V. The oxide layer thickness was calculated by optical method (light refraction). The anodic film thickness increased by increasing the anodizing voltage. The highest thickness of anodic film was 190 nm in sulfuric acid solution for the anodized sample in 80 V. Corrosion resistance of anodized Ti... 

    A non-catalytic vapor growth regime for organohalide perovskite nanowires using anodic aluminum oxide templates

    , Article Nanoscale ; Volume 9, Issue 18 , 2017 , Pages 5828-5834 ; 20403364 (ISSN) Tavakoli, M. M ; Waleed, A ; Gu, L ; Zhang, D ; Tavakoli, R ; Lei, B ; Su, W ; Fang, F ; Fan, Z ; Sharif University of Technology
    Royal Society of Chemistry  2017
    In this work, a novel and facile synthesis process to fabricate single crystalline organometal halide perovskite nanowires has been successfully developed. Nanowires were grown in a high density ordered array from metal nanoclusters inside anodic aluminum oxide templates using a non-catalytic chemical vapor deposition method. Specifically, perovskite NWs were grown as a result of the reaction between methylammonium iodide (MAI) and the Pb/Sn (Pb or Sn) metal in anodic aluminum oxide templates under optimal conditions. The characterization results show that there is a reaction zone at the interface between the perovskite material and metal, at the bottom of the anodic aluminum oxide... 

    Anodizing behavior and electrochemical evaluation of accumulative roll bonded Al and Al-SiC composite

    , Article Surface and Coatings Technology ; Volume 408 , 2021 ; 02578972 (ISSN) Ebadi, M ; Alishavandi, M ; Paydar, M. H ; Sharif University of Technology
    Elsevier B.V  2021
    Accumulative roll bonded (ARBed) AA1050 and Al-2 vol% SiCp (AMC) samples were anodized in an H2SO4 electrolyte to improve corrosion resistance. The SEM images revealed that the anodic oxide's morphology is significantly dependent on the microstructure of the ARBed bare samples, owing to high internal energy that accelerates Al consumption during anodizing process. Potentiodynamic polarization measurements and EIS evaluation showed that anodic oxide improves the corrosion resistance of both ARBed AA and AMC samples; however, the electrochemical behavior of the processed samples changed due to the formation of a complex oxide structure comprising of twisted pore channels and attack routes. ©... 

    Cathodic Protection of Concrete by Zinc Sacrificial Anode in Persian Gulf Sea Water

    , M.Sc. Thesis Sharif University of Technology Cheraghali, Behrouz (Author) ; Dolati, Abolghasem (Supervisor)
    Many of the major structure over coastal waters in the Kish Island due to the aggressive condition are showing signs of reinforcement corrosion. Recent advances in the development of anodes make it practical to use zinc galvanic cathodic protection to protect this structure in this area. Five anode systems were tested on several samples as, (1) zinc metal spray applied by arc-spraying on the concrete, (2) a zinc foil with conductive adhesive backing, (3) a system of zinc mesh and grout jacket, (4) a system of zinc mesh and compression panels, and (5) a bulk zinc. These anodes are set up to comparison the effects of potential and current over the zinc galvanic cathodic protection during 4... 

    Aluminum Production by Alumina Electrolysis Method with Using Inconel 617 Inert Anode

    , M.Sc. Thesis Sharif University of Technology Vakil, Mohammad Mahdi (Author) ; Halali, Mohammad (Supervisor)
    In this study, the performance of Inconel 617 anode as an inert anode in aluminum electrolysis process was studied. To carry out the research, first, an electrolyte was produced using NaF, KF, AlF3 and Al2O3 with a molar ratio of sodium and potassium fluoride to aluminum fluoride of 1.33. Next, aluminum electrolysis cell was made using Inconel 617 anode and cathode and the aforementioned electrolyte. To evaluate the Inconel 617 anode, the performance of the electrolysis cell in different conditions of temperature, anode-cathode distance, and excess potential was investigated in a period of one hour. Using anode mass measurements, cell potential and current density and scanning electron... 

    Electrodeposition of Ni-Fe-Co alloy nanowire in modified AAO template

    , Article Materials Chemistry and Physics ; Volume 91, Issue 2-3 , 2005 , Pages 417-423 ; 02540584 (ISSN) Saedi, A ; Ghorbani, M ; Sharif University of Technology
    Anodic aluminum oxide (AAO) was used as a template to prepare highly ordered Ni-Fe-Co alloy nanowire arrays. This membrane was fabricated with two-step anodizing method. It is found that there is an optimum barrier thickness to obtain a successful electrodeposition in pores of AAO. The thickness of barrier layer can be modified by additional electrochemical process after completing the anodizing step. Barrier layer thinning can create a rooted structure at the bottom side of the AAO pores and the electrodeposited nanowire arrays. The triple Ni-Fe-Co alloy was deposited in AAO membrane by ac voltage in a simple sulfate bath. The composition of nanowires shows anomalous deposition features... 

    SnO2 nanowires on carbon nanotube film as a high performance anode material for flexible Li-ion batteries

    , Article Journal of Nanostructures ; Volume 8, Issue 3 , 2018 , Pages 288-293 ; 22517871 (ISSN) Abnavi, A ; Faramarzi, M. S ; Sanaee, Z ; Ghasemi, S ; Sharif University of Technology
    University of Kashan  2018
    Today, Li-ion batteries (LIBs) are the most common rechargeable batteries used in electronic devices. SnO2 with theoretical specific capacity of 782 mAh/g is among the best anode materials for LIBs. In this report, Threedimensional SnO2 nanowires (NWs) on carbon nanotube (CNT) thin film (SnO2 / CNT) is fabricated using a combination of vacuum filtration and thermal evaporation techniques. The resulting 3D heterostructure SnO2/CNT was characterized by X-ray diffraction, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). This fabricated SnO2/CNT electrode has been tested as a flexible and binderfree anode for LIB, which exhibits high initial discharge/charge...