Search for: deposits
Total 657 records
Mechanism of Al-Si codeposition on In738LC through single-step diffusion process, Article International Journal of Surface Science and Engineering ; Volume 11, Issue 1 , 2017 , Pages 1-11 ; 1749785X (ISSN) ; Abdi, M ; Rastegari, S ; Sharif University of Technology
The out-of-pack cementation method was applied to coat the Nickel-based super alloy IN738LC with Si-modified aluminide. Different mixtures of the pack containing pure Al, Si, alumina powders as an inert filler, and NH4Cl as a halide salt activator were used for co-deposition at 950 and 1,050°C. The results showed although the amount of subhalide vapour pressures of Al and Si were equal at 1,050°C, Al atoms diffused only after Si atoms had been deposited. Before heat treatment, the coating thickness formed by the pack containing 2.3 wt.% Al was 6 μm more than that containing 3.5 wt.% Al. After heat treatment, thickening coatings formed within the pack containing 2.3 wt.% Al was less than that...
Mechanistic study to investigate the effects of different gas injection scenarios on the rate of asphaltene deposition: An experimental approach, Article Fuel ; Volume 262 , 2020 ; Zanganeh, P ; Kord, S ; Ayatollahi, S ; Amiri, A ; Sharif University of Technology
Elsevier Ltd 2020
Asphaltene deposition during enhanced oil recovery (EOR) processes is one of the most problematic challenges in the petroleum industry, potentially resulting in flow blockage. Our understanding of the deposition mechanism with emphasis on the rate of the asphaltene deposition is still in its infancy and must be developed through a range of experiments and modelling studies. This study aims to investigate the rate of asphaltene deposition through a visual study under different gas injection scenarios. To visualise the asphaltene deposition, a high-pressure setup was designed and constructed, which enables us to record high-quality images of the deposition process over time. Present research...
Modeling particle deposition in the respiratory system during successive respiratory cycles, Article Scientia Iranica ; Volume 27, Issue 1 B , February , 2020 , Pages 215-228 ; Saidi, M. S ; Hosseini, V ; Sharif University of Technology
Sharif University of Technology 2020
This study uses a 5-lobe symmetric model to investigate total, lobar and generational particle deposition fractions in the lungs during successive cycles. It was found that for the particle size between 0.05 and 2 μm and the tidal volumes greater than 1000 ml, the effect of successive cycles helped predict more deposition fraction per cycle up to about 16% than that of a single cycle. The mentioned range of tidal volumes corresponds to light or heavy physical activities. Therefore, it can be understood that people, when physically active, exposed to particulate matter within the mentioned size range are at higher health risk as compared to both the resting state and the same state...
Electrophoretic deposition of titanium dioxide nano-powders films in isopropanol as a solvent, Article International Journal of Modern Physics B ; Volume 22, Issue 18-19 , 2008 , Pages 2989-2994 ; 02179792 (ISSN) ; Roushan Afshar, M ; Sharif University of Technology
World Scientific Publishing Co. Pte Ltd 2008
In this study, titanium dioxide nano powders were electrophoretically deposited on the stainless steel in Isopropanol and Triethanolamine as a solvent and dispersant, respectively. The effects of deposition parameters including deposition voltage (5 to 20 V) and deposition time (5 to 60 s) on the microstructure and surface topography were examined by scanning electron microscope (SEM) and scanning probe microscope (SPM), respectively. In addition, the effects of these deposition parameters on packing density were investigated. This research revealed that substrate surface is fully covered with increasing deposition voltage and deposition time. Therefore packing density of deposited films is...
The effect of oxidation of macroporous silicon on carbon nanotubes growth by TCVD method, Article Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry ; Volume 37, Issue 6 , 2007 , Pages 489-492 ; 15533174 (ISSN) ; Iraji zad, A ; Taghavi, N. S ; Reyhani, A ; Sharif University of Technology
Carbon nanotubes (CNTs) were grown on deposited Ni on macroporous silicon by thermal chemical vapor deposition (TCVD) method using CH4 as the reaction gas. Macroporous silicon was fabricated by electrochemical etching of P-type silicon in organic electrolytes. The effect of oxidation of porous silicon (PS) on growth rate, morphology and structure of CNTs has been studied. The SEM micrographs and Raman spectra indicated that the nanotubes grown on the oxidized PS are more homogeneous and regular than those grown on the pristine PS and growth rate of CNTs grown on oxidized PS higher than those grown on pristine PS. In addition, the CNTs grown on the non-oxidized PS have different morphology...
A new design of continuous coaxial nozzle for direct metal deposition process to overcome the gravity effect, Article Progress in Additive Manufacturing ; 2021 ; 23639512 (ISSN) ; Movahhedy, M. R ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH 2021
In the metal deposition process, the performance of the nozzle is crucial to the quality of clad. Continuous coaxial nozzles are broadly used in this process for repairing two- and three-dimensional parts, because it can create a homogeneous distribution of powder particles. In addition, an inert gas can be applied using this type of nozzles which shields powder particles and laser interaction zone, and prevents the surface from oxidizing at high process temperatures. However, when this type of nozzle is tilted from the vertical axis for cladding non-horizontal surfaces, the effect of gravity on powder particles affects the uniformity of powder distribution at the nozzle outlet. This matter...
Design and Implement of Gas Distribution and Control System for Deposition of Nano-Structure through NFCVD, M.Sc. Thesis Sharif University of Technology ; Rashidian, Bizhan
For realization of nanosale photonic device required by the future system, electron beams, and scanning probe microscopes have been used to control the site on the subtrate. However, these techniques have a fatal disadvantage because they cannot deal with insulators and Diffraction of light, limiting their application.To overcome this difficulties, we design and implement near-field optical chemical vapor deposition, which enables the fabrication of nanometer-scale structure, while controlling their position. To guarantee that an optical near field is generated sufficiently, we fabricated a sharped W-tip by electrochemical etching. The separation between the W-tip and the substrate was kept...
Asphaltene deposition in different depositing environments: Part 2. Real oil, Article Energy and Fuels ; Vol. 28, Issue. 6 , 2014 , Pages 3594-3603 ; ISSN: 08870624 ; Panuganti, S. R ; Taghikhani, V ; Pishvaie, M. R ; Chapman, W. G ; Sharif University of Technology
This paper is a continuation of our previous paper (part 1; 10.1021/ef401857t), which discussed the roles of different phenomena effecting the deposition of asphaltene from model oil systems and before the onset of asphaltene precipitation. The study in this paper is to understand the depositional tendency of asphaltene using a quartz crystal microbalance with dissipation (QCM-D) measurements and their corresponding modeling for real crude oil systems with emphasis after the onset of asphaltene precipitation
Effect of pH and carbon nanotube content on the corrosion behavior of electrophoretically deposited chitosan-hydroxyapatite-carbon nanotube composite coatings, Article Ceramics International ; Volume 39, Issue 5 , July , 2013 , Pages 5393-5402 ; 02728842 (ISSN) ; Ghorbani, M ; Sharif University of Technology
In the first stage, chitosan (CH)-hydroxyapatite (HA)-multiwalled carbon nanotube (MWCNT) composite coatings were synthesized by electrophoretic deposition technique (EPD) on 316L stainless steel substrates at different levels of pH and characterized by X-ray diffraction (XRD), Raman spectroscopy, FTIR and field emission scanning electron microscopy (FESEM). A smooth distribution of HA and MWCNT particles in a chitosan matrix with strong interfacial bonding was obtained. In the next stage, effects of pH and MWCNT content of the suspension on the corrosion behavior and deposition mechanism were studied. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) curves...
Modeling and optimization of asphaltene deposition in porous media using genetic algorithm technique, Article Society of Petroleum Engineers - International Oil and Gas Conference and Exhibition in China 2010, IOGCEC, 8 June 2010 through 10 June 2010 ; Volume 1 , June , 2010 , Pages 479-491 ; 9781617388866 (ISBN) ; Kharrat, R ; Ghazanfari, M. H ; Bagheri, M. B ; Sharif University of Technology
Different models have been proposed for deposition of asphaltene on reservoir rocks that due to complexity of asphaltene nature, most of them have not been productive. Here, a reliable model is proposed which despite of previous models, considers the change in asphaltene saturation in the core. The obtained experimental data in the laboratory was used for model validation. In this work, a series of core flooding tests was carried out in presence of connate water at different solvent-oil volume ratios. Pressure drop was measured at three different terminals along the core. The obtained experimental data as well as mass balance equations, momentum equation, asphaltene deposition and...
Vapor assisted deposition of alkaline doped perovskites: Pure phase formation of CsxMA1−xPbI3, Article Electrochimica Acta ; Volume 259 , 2018 , Pages 485-491 ; 00134686 (ISSN) ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
Elsevier Ltd 2018
Alkaline doping (Cs, Rb) in CH3NH3PbI3 (MAPbI3) is known to enhance the stability of perovskite solar cells. The films are usually deposited using anti-solvent method, which is tricky and not applicable for large scale deposition. Besides, in case of CsxMA1−xPbI3 the amount of Cs must be carefully controlled to prevent CsI phase formation. Herein, we report an atmospheric pressure vapor assisted solution process (AP-VASP) for the growth of Cs doped MAPbI3 perovskite films that features highly uniform morphology, pin-hole free films, large grain size, as well as being scalable. The CsxMA1−xPbI3 films are formed by the reaction of Cs doped PbI2 films with MAI vapor in a simple oven. We...
Direct growth of nickel-cobalt oxide nanosheet arrays on carbon nanotubes integrated with binder-free hydrothermal carbons for fabrication of high performance asymmetric supercapacitors, Article Composites Part B: Engineering ; Volume 172 , 2019 , Pages 41-53 ; 13598368 (ISSN) ; Shahrokhian, S ; Hosseini, H ; Sharif University of Technology
Elsevier Ltd 2019
A high performance asymmetric supercapacitor (ASC)has been fabricated by using nickel oxide-cobalt oxide nanosheets (NiO–CoO NSs), which were directly grown on carbon nanotubes (CNTs)and hydrothermal carbon spheres (HTCs)as positive and negative electrodes, respectively. Both electrode materials are binder-free prepared by using a catalytic chemical vapour deposition (CVD)approach followed by a facile hydrothermal method for cathode and a one-step environmental-friendly route called hydrothermal carbonization for anode. Using NiO–CoO NSs@CNTs and HTCs, which were directly grown on Ni foam, not only leads to a very small equivalent series resistance, but also provides an impressive capacitive...
Graphene oxide sheets involved in vertically aligned zinc oxide nanowires for visible light photoinactivation of bacteria, Article Journal of Alloys and Compounds ; Vol. 612 , 2014 , pp. 380-385 ; ISSN: 09258388 ; Rahighi, R ; Akhavan, O ; Moshfegh, A ; Sharif University of Technology
Vertically aligned ZnO nanowires (NWs) hybridized with reduced graphene oxide sheets (rGO) were applied in efficient visible light photoinactivation of bacteria. To incorporate graphene oxide (GO) sheets within the NWs two different methods of drop-casting and electrophoretic deposition (EPD) were utilized. The EPD method yielded effective penetration of the positively charged GO sheets into the NWs to form a spider net-like structure, whereas the drop-casting method resulted in only a surface coverage of the GO sheets on top of the NWs. The electrical connection between the EPD-incorporated sheets and the NWs was checked by monitoring the electron transfer from UV-assisted photoexcited ZnO...
Development of electrophoretically deposited hydroxyapatite coatings on anodized nanotubular TiO2 structures: Corrosion and sintering temperature, Article Applied Surface Science ; Vol. 301 , May , 2014 , pp. 250-257 ; ISSN: 01694332 ; Batmanghelich, F ; Afshar, A ; Dolati, A ; Mortazavi, G ; Sharif University of Technology
Hydroxyapatite (HA) coatings in and onto anodized TiO2 nanotube arrays were presented and prepared by electrophoretic deposition technique (EPD). Coatings were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). EPD proved to be an innovative and versatile technique to coat HA on and into nanotubular structures of TiO2 with enhanced adhesion between nanotubes and HA particles provided by mechanical interlocking. After EPD of HA on TiO2 layer, samples were sintered at 400 °C, 600 °C and 800 °C for 2 h in an Ar atmosphere. Effect of EPD processing parameters on thickness of the deposits and rate of deposition was elucidated for HA coatings on the nanotubular TiO2...
Pt and Pd as catalyst deposited by hydrogen reduction of metal salts on WO3 films for gasochromic application, Article Applied Surface Science ; Volume 273 , May , 2013 , Pages 261-267 ; 01694332 (ISSN) ; Mahdavi, S. M ; Iraji Zad, A ; Sharif University of Technology
In this study, tungsten oxide films were deposited by pulsed-laser deposition (PLD) technique. The as-deposited films were annealed at 250 °C in air for 1 h. The surface morphology, microstructure, crystalline phase, and chemical composition of the films were characterized by SEM, XRD and XPS techniques. Pt nanoparticles were deposited onto the tungsten oxide films through a two-step process. First of all, a layer of PtCl2 was coated on the WO3 surface by drop-drying the PtCl2 solution onto the WO3 surface at 60 °C. Consequently, the reduction of the PtCl2 into the metallic Pt nanoparticles was performed at 200 °C. In this study, the effect of the temperature during hydrogen reduction of...
Effect of geometry, joule heating, and critical current on the responsivity of MOD superconducting transition edge sensors, Article Journal of Superconductivity and Novel Magnetism ; Volume 26, Issue 4 , April , 2013 , Pages 831-834 ; 15571939 (ISSN) ; Moftakharzadeh, A ; Kokabi, A ; Vesaghi, M. A ; Fardmanesh, M ; Sharif University of Technology
By fabrication of several bolometric detectors on the YBCO film made of Metal-Organic Deposition (MOD) and the effect of pattering and film parameters on the optical responsivity of transition edge sensors is investigated. The low cost nonfluorine (MOD) method has been applied to fabricate YBCO thin films with different patterning parameters. The measurement results of the optical responsivity versus modulation frequency up to 100 KHz for these devices are reported
Electrophoretic deposition of titania nanoparticles in different alcohols: Kinetics of deposition, Article Journal of the American Ceramic Society ; Volume 94, Issue 8 , 2011 , Pages 2354-2361 ; 00027820 (ISSN) ; Ghorbani, M ; Sharif University of Technology
The suspension of titania nanoparticles in different alcohols (methanol, ethanol, and butanol) was prepared and triethanolamine (TEA) was used as a dispersant. The suspensions were characterized by different tests such as sedimentation, zeta potential, and Fourier transform infrared spectroscopy. The electrophoretic deposition (EPD) was performed at various voltages and times. EPD from butanolic suspension (0.8 g/L TEA) showed the slowest kinetics, because of the low electrophoretic mobility of titania nanoparticles in it (2.40 × 10-5 cm2·(V·s)-1). Also, it was observed that at low voltages (5, 10, and 20 V), the EPD kinetics from methanolic suspension (0 g/L TEA) was the fastest; however,...
Modeling formation damage due to asphaltene deposition in the porous media, Article Energy and Fuels ; Volume 25, Issue 2 , February , 2011 , Pages 753-761 ; 08870624 (ISSN) ; Tohidi, B ; Jamialahmadi, M ; Rashtchian, D ; Sharif University of Technology
Asphaltene deposition in a reservoir severely reduces the effective permeability and results in a reduction in oil production. The main term in asphaltene deposition modeling in the porous media is pore surface deposition. Previous models do not describe the effects of different parameters (i.e., concentration, velocity, and temperature) on the pore surface deposition term. We report the results of a series of experiments carried out to study the effects of the above parameters on the surface deposition term using an accurate thermal method. Based on these data, a new expression for the surface deposition term has been developed and implemented in asphaltene deposition modeling. The...
Synthesis and characterization of electrochemically grown CdSe nanowires with enhanced photoconductivity, Article Journal of Materials Science: Materials in Electronics ; Volume 26, Issue 3 , March , 2015 , Pages 1395-1402 ; 09574522 (ISSN) ; Irajizad, A ; Azarian, A ; Ashiri, R ; Sharif University of Technology
Springer New York LLC 2015
CdSe nanowires were grown in polycarbonate track etched membrane with pore diameter of 80 nm by an electrochemical deposition technique. The mechanism of the growth was studied during the potentiostatic deposition of nanowires. X-ray photoelectron spectroscopy and energy dispersive spectrometry results showed binding of fragments and fraction of atoms for the CdSe nanowires. Microstructure and morphology of synthesized CdSe nanowires were observed by scanning electron microscopy. Optical spectrophotometry technique was used to determine the energy band gap of CdSe nanowires. It was found that the nanowires were resistive in the dark and exhibited a pronounced visible light photoconductivity....
A two-level undercut-profile substrate for chemical-solution-based filamentary coated conductors, Article IEEE Transactions on Applied Superconductivity ; Volume 26, Issue 3 , 2016 ; 10518223 (ISSN) ; Lundeman, J. H ; Hansen, J. B ; Mishin, O. V ; Zhao, Y ; Mohajeri, R ; Grivel, J. C ; Sharif University of Technology
A recently developed two-level undercut-profile substrate (2LUPS), containing two levels of plateaus connected by a curved wall with an undercut profile, enables self-forming filaments in a coated conductor during physical line-of-sight deposition of buffer and superconducting layers. In the present study, the 2LUPS concept is applied to a commercial cube-textured Ni-5at.%W tape, and the surface of the 2LUPS coated with two Gd2Zr2O7 buffer layers using chemical solution deposition is examined. Except for narrow regions near the edge of upper plateaus, the plateaus are found to be covered by strongly textured Gd2Zr2O7 buffer layers after dip coating and sintering