Loading...
Search for:
anodic-oxidation
0.007 seconds
Total 30 records
Fabrication and Photoelectrochemical Characterization of Ordered Nanotube Arrays of TiO2 for Solar Cell Application
, Ph.D. Dissertation Sharif University of Technology ; Iraji zad, Aazam (Supervisor) ; Dolati, Abolghasem (Supervisor) ; Taghavinia, Neima (Co-Advisor)
Abstract
In this research we focus on study and fabrication of ordered nanotube arrays of titanium oxide and their applications in photoelectrochemical cell. Nanotubular films of titanium oxide have been fabricated using anodization method. Short-length nanotubes, less than one micrometer, have been synthesized in aqueous electrolyte containing deionized water, hydrofluoric acid and phosphoric acid. To get Micron-length nanotubes, we have employed organic electrolyte containing ethylene glycol, deionized water and fluoride ammonium. After fabrication, the photo-catalytic activity of nanotubular structures was evaluated by measuring the rate of degradation of in methylene blue aqueous solution. The...
Aluminum Production by Alumina Electrolysis Method with Using Inconel 617 Inert Anode
, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad (Supervisor)
Abstract
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...
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) ; 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
Abstract
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...
Electrophoretic encapsulation for slow release of vancomycin from perpendicular TiO2 nanotubes grown on Ti6Al4V electrodes
, Article Materials Research Express ; Volume 6, Issue 12 , 2019 ; 20531591 (ISSN) ; https://iopscience.iop.org/article/10.1088/2053-1591/ab6c98 ; Ahmadi Seyedkhani, S ; Sadrnezhaad, S. K ; Sharif University of Technology
Institute of Physics Publishing
2019
Abstract
Ordered perpendicular TiO2 nanotubes (TNT) with 405 to 952 nm length and 60 to 90 nm diameter were grown via 40 to 120 min anodization of Ti6Al4V flat substrates. The samples were called TNT-40, -60, -80, -100, and -120. Vancomycin was loaded on the bare and anodized electrodes by separate immersion and electrophoretic (EP) deposition procedures. EP loading resulted in storage capacity of 5221.86 μg cm-2 for TNT-80 which was much higher than 1036.75 μg cm-2 of immersed sample. Drug release comprised of three stages: (i) burst release (78% for the bare, and 23% for the TNT-80 sample), (ii) gradual transport (21% for the bare, and 64% for the TNT-80 sample), and (iii) equilibrium. Transfer...
Electrophoretic encapsulation for slow release of vancomycin from perpendicular TiO2 nanotubes grown on Ti6Al4V electrodes
, Article Materials Research Express ; Volume 6, Issue 12 , 2019 ; 20531591 (ISSN) ; Ahmadi Seyedkhani, S ; Sadrnezhaad, S. K ; Sharif University of Technology
Institute of Physics Publishing
2019
Abstract
Ordered perpendicular TiO2 nanotubes (TNT) with 405 to 952 nm length and 60 to 90 nm diameter were grown via 40 to 120 min anodization of Ti6Al4V flat substrates. The samples were called TNT-40, -60, -80, -100, and -120. Vancomycin was loaded on the bare and anodized electrodes by separate immersion and electrophoretic (EP) deposition procedures. EP loading resulted in storage capacity of 5221.86 μg cm-2 for TNT-80 which was much higher than 1036.75 μg cm-2 of immersed sample. Drug release comprised of three stages: (i) burst release (78% for the bare, and 23% for the TNT-80 sample), (ii) gradual transport (21% for the bare, and 64% for the TNT-80 sample), and (iii) equilibrium. Transfer...
Room temperature selective sensing of aligned Ni nanowires using impedance spectroscopy
, Article Materials Research Express ; Volume 7, Issue 2 , 24 February , 2020 ; Fardindoost, S ; Iraji Zad, A ; Almasi Kashi, M ; Sharif University of Technology
Institute of Physics Publishing
2020
Abstract
Room temperature gas sensing behavior of arrayed one-dimensional (1D) nickel nanowires (Ni NWs) are investigated using impedance spectroscopy. Ni nanowires synthesized via electrochemical deposition method based on anodic aluminum oxide (AAO) templates. Their structural characterization verified by scanning electron microscopy (SEM), x-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) analysis. Impedance spectroscopy as an essential technique utilized to understand the mechanism of gas interaction with the wires through the changes in their electronic behavior. Bode and Nyquist plots with the real and imaginary impedances are plotted versus frequency range of 500 Hz...
Bioinspired TiO2/chitosan/HA coatings on Ti surfaces: Biomedical improvement by intermediate hierarchical films
, Article Biomedical Materials (Bristol) ; Volume 17, Issue 3 , 2022 ; 17486041 (ISSN) ; Ahmadi Seyedkhani, S ; Eslami Saed, A ; Sadrnezhaad, S. K ; Seza, A ; Sharif University of Technology
Institute of Physics
2022
Abstract
The most common reasons for hard-tissue implant failure are structural loosening and prosthetic infections. Hence, in this study, to overcome the first problem, different bioinspired coatings, including dual acid-etched, anodic TiO2 nanotubes array, anodic hierarchical titanium oxide (HO), micro- and nanostructured hydroxyapatite (HA) layers, and HA/chitosan (HA/CS) nanocomposite, were applied to the titanium alloy surfaces. X-ray diffraction and FTIR analysis demonstrated that the in situ HA/CS nanocomposite formed successfully. The MTT assay showed that all samples had excellent cell viability, with cell proliferation rates ranging from 120% to 150% after 10 days. The HO coating...
Effect of pulse current parameters on the mechanical and corrosion properties of anodized nanoporous aluminum coatings
, Article Materials Chemistry and Physics ; Volume 183 , 2016 , Pages 490-498 ; 02540584 (ISSN) ; Ahmadi, Sh ; Afshar, A ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
In this study, the effects of pulse current parameters on corrosion resistance and mechanical properties of anodized coatings were evaluated. Hardness measurements, polarization and electrochemical impedance spectroscopy tests were employed to investigate the mechanical properties and corrosion behavior of these coatings. Also, field emission scanning electron microscopy (FE-SEM) was used to analyze the surface morphology and microstructure of the coatings. It was found that the properties of anodized coatings were dependent on various parameters, among which, time, temperature and pulse current parameters (current density limit, frequency and duty cycle) were optimized. Analysis of Variance...
Synthesis of titanium oxide nanotubes and their decoration by MnO nanoparticles for biomedical applications
, Article Ceramics International ; Volume 45, Issue 15 , 2019 , Pages 19275-19282 ; 02728842 (ISSN) ; Mahmoudi, P ; Zamanian, A ; Mozafari, M ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In this study, apatite formation ability on TiO2 nanotubes (TNTs) synthesized by anodizing process were compared with TNTs decorated by MnO nanoparticles. The MnO nanoparticles used for decoration process were fabricated via thermal decomposition method. At first, it was strived to find the optimal condition of anodizing process and the effect of applied voltages (15 V, 20 V, and 25 V) and process times (15 min, 20 min, and 25 min) on the diameter of the synthesized TNTs was investigated. Results of microscopic characterizations showed that the completely uniform structure of nanotubes with a diameter in the range of about 100–130 nm was achieved after 20 min of anodizing process at an...
Influence of PEO and mechanical keying on the strength of AA 5052 alloy/polypropylene friction stir spot welded joints
, Article International Journal of Adhesion and Adhesives ; Volume 92 , 2019 , Pages 65-72 ; 01437496 (ISSN) ; Skeldon, P ; Zhou, X ; Ghorbani, M ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
A study has been carried out of the effect of plasma electrolytic oxidation (PEO)on the strength of AA 5052 alloy/polypropylene joints prepared using friction stir spot welding (FSSW). The joint strengths were determined using lap-shear tests and failure modes were investigated using scanning electron microscopy. Comparisons were made between control joints prepared with the alloy in the as-rolled condition or the as-rolled condition with a mechanical key and with PEO-treated alloy, with or without a mechanical key. Mechanical keying alone, provided by infiltration of polymer into holes of either 3 or 4.5 mm diameter drilled in the alloy, yielded enhancements of the joint strength by a...
Effect of an anodizing pre-treatment on AA 5052 alloy/polypropylene joining by friction stir spot welding
, Article Materials Science and Engineering B: Solid-State Materials for Advanced Technology ; Volume 245 , 2019 , Pages 107-112 ; 09215107 (ISSN) ; Skeldon, P ; Zhou, X ; Hashimoto, T ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
A study has been carried out of the effect of an anodizing pre-treatment in a sulphuric acid electrolyte on the strength of AA 5052 alloy/polypropylene joints prepared using friction stir spot welding. Lap-shear tests were used to determine the joint strength. Comparisons were made with joints pre-treated using sand blasting. The failed specimens were examined by scanning and transmission electron microscopy. Anodizing improved the strength of the joints by a factor of about 6 compared with sandblasting. For the anodizing pre-treated joints, melted polymer infiltrated deeply within the nanoporous anodic film, forming a strong polymer-film bond. Joint failure occurred by ductile tearing of...
2-D microflow generation on superhydrophilic nanoporous substrates using epoxy spots for pool boiling enhancement
, Article International Communications in Heat and Mass Transfer ; Volume 113 , April , 2020 ; Moosavi, A ; Rad, S. V ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
We conduct an experimental investigation on the pool boiling enhancement in DI water on nanoporous surfaces. The surfaces are modified by anodic oxidation, and cavities with 2 mm diameter and pitches between 2.5 and 5 mm applied on them using EDM method filled with a two-part epoxy with low thermal conductivity properties. The capillary wicking action of the superhydrophilic nanoporous oxide layer enhances the rewetting and spreading of the liquid to dry-spots during boiling. The epoxy disks remain wet and prevent merging bubbles during the pool boiling experiment and a 2-D microflow is induced toward dried regions with synergic effects of nanoporous surface absorption, create a considerable...
On the growth sequence of highly ordered nanoporous anodic aluminium oxide
, Article Materials and Design ; Volume 27, Issue 10 , 2006 , Pages 983-988 ; 02613069 (ISSN) ; Nasirpouri, F ; Iraji zad, A ; Saedi, A ; Sharif University of Technology
Elsevier Ltd
2006
Abstract
Anodic aluminium oxide films were fabricated by well known two-step anodizing process in oxalic acid electrolyte. The ordering characteristics (ordered pore domains, average pore diameter size and through-pore arrangement) of anodic aluminium oxide films, obtained in different growth sequences, were identified by microscopic analysis such as ex situ contact-mode atomic force microcopy and scanning electron microscopy. Flattened areas in which some pits are seen mostly cover the electropolished surface of aluminium. Single anodizing of aluminium produces a broad distribution of nanopore size, whereas induces a highly ordered hemispherical pattern, which plays the ordered nucleation sites for...
Facile synthesis of petal-like NiCo/NiO-CoO/nanoporous carbon composite based on mixed-metallic MOFs and their application for electrocatalytic oxidation of methanol
, Article Applied Catalysis B: Environmental ; Volume 244 , 2019 , Pages 802-813 ; 09263373 (ISSN) ; Shahrokhian, S ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Porous carbon template decorated with mixed transition metals/metal oxides with tunable architecture is becoming increasingly important and attractive as a kind of novel electrode materials. In this way, mixed-metallic metal-organic frameworks (MOFs) provide an opportunity for fabrication of homogeneous mixed metals/metal oxides distribution in the porous carbon frame without any carbon precursor additive. Also, structures, dimensions and electrochemical performance of MOFs can be readily manipulated by simply tuning the metals molar ratio. In this study, we demonstrate the design and fabrication of petal-like NiCo/NiO-CoO metal/metal oxides with a rational composition embedded in 3D...
Anodizing behavior and electrochemical evaluation of accumulative roll bonded Al and Al-SiC composite
, Article Surface and Coatings Technology ; Volume 408 , 2021 ; 02578972 (ISSN) ; Alishavandi, M ; Paydar, M. H ; Sharif University of Technology
Elsevier B.V
2021
Abstract
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. ©...
Modification of nanostructured anodized aluminum coatings by pulse current mode
, Article Surface and Coatings Technology ; Volume 278 , 2015 , Pages 48-55 ; 02578972 (ISSN) ; Afshar, A ; Sharif University of Technology
Elsevier
2015
Abstract
In this study, the effects of pulse current mode on corrosion resistance and mechanical properties of anodized coatings were explored. Thickness and hardness measurements, polarization and electrochemical impedance spectroscopy were employed to take mechanical and corrosion behaviors of the anodized coatings into consideration. Also, field-emission scanning electron microscopy (FE-SEM) was utilized to characterize the surface morphology of the coatings. It was shown that in short anodizing times, coating thickness is controlled by the heat concentrated on coating. Although at prolonged anodizing times, the coating thickness is affected by average current density. Hardness measurements showed...
Hydroxyapatite based and anodic titania nanotube biocomposite coatings: fabrication, characterization and electrochemical behavior
, Article Surface and Coatings Technology ; Volume 287 , 2016 , Pages 67-75 ; 02578972 (ISSN) ; Mohammadi, I ; Sadrnezhaad, S. K ; Sharif University of Technology
Elsevier
2016
Abstract
The main challenges of biological implants are suitable strength, adhesion, biocompatibility and corrosion resistance. This paper discusses fabrication, characterization and electrochemical investigation of anodized Ti6Al4V without and with a hydroxyapatite (HA) layer, HA/TiO2 nanoparticles (NPs) and HA/TiO2 nanotubes (HA/anodized). X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS) were used to characterize and compare properties of different samples. Dense HA with uniform distribution and 12.8 ± 2 MPa adhesive strength enhanced to 19.2 ± 4 MPa by the addition of TiO2 nanoparticles and enhanced to 23.1 ± 4 MPa by the...
A comparative study of the electrooxidation of ethylene glycol on transition metal electrodes in alkaline solution
, Article Journal of New Materials for Electrochemical Systems ; Volume 15, Issue 4 , 2012 , Pages 255-263 ; 14802422 (ISSN) ; Jafarian, M ; Shahnazi Sangachin, A. A ; Gobal, F ; Sharif University of Technology
2012
Abstract
Electrodes made of group VIII and IB metals were examined for their redox process and electrocatalytic activities towards the oxidation of ethylene glycol in alkaline solutions. The method of cyclic voltammetery (CV) and Open circuit potentials measurement (OCP) was employed. It is found that considerable electrooxidation current are observed for silver and copper but lower anodic overpotential for oxidation is obtained for gold and platinum. Oxide layer produced on the surface of all electrodes in alkaline solution under anodic scan participates in ethylene glycol electrooxidation. Oxidation current observed in the reverse scans for platinum and gold are higher than those observed in...
Electrochemical determinations of 6-mercaptopurine on the surface of a carbon nanotube-paste electrode modified with a cobalt salophen complex
, Article Journal of Solid State Electrochemistry ; Volume 16, Issue 4 , April , 2012 , Pages 1643-1650 ; 14328488 (ISSN) ; Ghorbani Bidkorbeh, F ; Mohammadi, A ; Dinarvand, R ; Sharif University of Technology
2012
Abstract
A mixture of multi-walled carbon nanotube/graphite paste electrode modified with a salophen complex of cobalt was prepared and was applied for the study of the electrochemical behavior of 6-mercaptopurine (MP) using cyclic and differential pulse voltammetry (DPV). An excellent electrocatalytic activity toward the oxidation of MP was achieved, which led to a considerable lowering in the anodic overpotential and remarkable increase in the response sensitivity in comparison with unmodified electrode. Utilizing DPV method, a linear dynamic range of 1-100 μM with detection limit of 0.1 μM was obtained in phosphate buffer of pH 3.0. The electrochemical detection system was very stable, and the...
Al2O3/Si3N4 nanocomposite coating on aluminum alloy by the anodizing route: Fabrication, characterization, mechanical properties and electrochemical behavior
, Article Ceramics International ; 2016 ; 02728842 (ISSN) ; Afshar, A ; Ahmadi, S ; Sharif University of Technology
Abstract
An Al2O3/Si3N4 nanocomposite coating was successfully fabricated on commercial aluminum alloy. Hardness measurements, polarization and electrochemical impedance spectroscopy (EIS) were employed to study the mechanical and corrosion behaviors of the coatings. Field-Emission Scanning Electron Microscopy (FE-SEM) equipped with Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) were utilized to characterize the surface morphology and phase composition of the coatings. Also, coatings abrasive wear properties were evaluated with a modified ASTM G105 standard. FE-SEM image, EDS and XRD analysis revealed the presence of Si3N4 in the coating. Furthermore, the results showed hardness of...