Loading...
Search for:
surface-treatment
0.006 seconds
Total 75 records
Fabrication and characterization of graphene-based carbon hollow spheres for encapsulation of organic corrosion inhibitors
, Article Chemical Engineering Journal ; Volume 352 , 2018 , Pages 909-922 ; 13858947 (ISSN) ; Ramazani, S. A. A ; Mahdavian, M ; Taheri, P ; Mol, J. M. C ; Sharif University of Technology
Elsevier B.V
2018
Abstract
In this work, we synthesized carbon hollow spheres (CHSs) using the silica templating method, encapsulated 2-mercaptobenzimidazole (MBI) inhibitor in the CHSs and evaluated their corrosion inhibition performance upon exposure of mild steel to a saline solution containing the released inhibitor. The effects of silica template surface modification on the CHS structure was evaluated, while the structure and morphology of the synthesized CHS was analyzed using field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), Raman spectroscopy and X-ray diffraction (XRD) spectroscopy. Furthermore, thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy...
Graphene oxide in generation of nanobubbles using controllable microvortices of jet flows
, Article Carbon ; Volume 138 , 2018 , Pages 8-17 ; 00086223 (ISSN) ; Akhavan, O ; Madaah Hosseini, H. R ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Spontaneous generation of nanobubbles (NBs) was developed by using a controllable platform of superfast microvortices, based on turbulent jet flows in the presence of graphene oxide (GO) sheets. Very high energy dissipation rates through discharging warm water into cold N2 aqueous solutions resulted in creation of micro/submicro-vortices. Shear stresses in these domains generated gas local supersaturations, leading to the formation of high concentration (∼109 mL−1) of stable NBs. Introducing GO sheets into the microvortex system resulted in effective manipulation of NBs by providing energetically favorable sites for prompt heterogeneous nucleation as well as stronger shear rate fluctuations....
Free radical graft polymerization of 2-hydroxyethyl methacrylate and acrylic acid on the polysulfone membrane surface through circulation of reaction media to improve its performance and hemocompatibility properties
, Article Journal of Membrane Science ; Volume 564 , 2018 , Pages 762-772 ; 03767388 (ISSN) ; Mousavi, S. A ; Abdekhodaie, M. J ; Sadeghi, M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
In this study, a new facile and cost effective method is used to modify polysulfone membrane surface in order to improve the hydrophilicity, antifouling, and blood compatibility. This modification was performed by adding two functional monomers on the dialysis membrane. Polysulfone (PSF) membranes containing polyvinylpyrrolidone were prepared via phase inversion technique. In the next step, free radical polymerization combined with surface polymerization was used to introduce acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) onto the polysulfone membrane surface via circulation of initiator and monomer solutions across the membrane surface, respectively. Various monomer concentrations...
Direct growth of metal-organic frameworks thin film arrays on glassy carbon electrode based on rapid conversion step mediated by copper clusters and hydroxide nanotubes for fabrication of a high performance non-enzymatic glucose sensing platform
, Article Biosensors and Bioelectronics ; Volume 112 , 2018 , Pages 100-107 ; 09565663 (ISSN) ; Khaki Sanati, E ; Hosseini, H ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
The direct growth of self-supported metal-organic frameworks (MOFs) thin film can be considered as an effective strategy for fabrication of the advanced modified electrodes in sensors and biosensor applications. However, most of the fabricated MOFs-based sensors suffer from some drawbacks such as time consuming for synthesis of MOF and electrode making, need of a binder or an additive layer, need of expensive equipment and use of hazardous solvents. Here, a novel free-standing MOFs-based modified electrode was fabricated by the rapid direct growth of MOFs on the surface of the glassy carbon electrode (GCE). In this method, direct growth of MOFs was occurred by the formation of vertically...
Inhibitory effects of functionalized indium doped ZnO nanoparticles on algal growth for preservation of adobe mud and earthen-made artworks under humid conditions
, Article International Biodeterioration and Biodegradation ; Volume 127 , Febraury , 2018 , Pages 209-216 ; 09648305 (ISSN) ; Mallakin, A ; Malekmohammady, F ; Khosravi Nejad, F ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
In this article, indium doped ZnO nanoparticles (alloy nanoparticles) were investigated as inhibitors against algae growth on adobe mud and earthen artworks for surface preservation from destruction caused by micro-organisms under humid conditions, through surface modification and activation run off. Nanoparticles (NPs) were fabricated by physical vapor deposition (PVD) growth mechanism. The fabricated NPs were approximately 20 nm in size. The Chlorella vulgaris and Scenedesmus quadricauda were tested by application of indium doped ZnO nanoparticles (In/ZnO NPs) as inhibitors. As concentrations of NPs increased, the negative impacts of NPs on the algal growth were enhanced and physical...
Effect of initial surface treatment on shot peening residual stress field: analytical approach with experimental verification
, Article International Journal of Mechanical Sciences ; Volume 137 , 2018 , Pages 171-181 ; 00207403 (ISSN) ; Farrahi, G. H ; Mahmoudi, A. H ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Shot peening is the most common surface treatment employed to enhance the fatigue performance of structural metallic materials and often carried out after other surface treatments. This paper mainly focuses on the effects of initial conditions of surface such as initial stress filed and hardness profile on shot peening residual stress field. The residual stress distribution induced by shot peening is obtained using Hertzian contact theory and elastic–plastic evaluation after yielding occurred during impingement and rebound of shots. Elastic plastic calculations are performed using different hardening models considering Bauschinger effect. The present model is able to predict redistribution...
Modelling of conventional and severe shot peening influence on properties of high carbon steel via artificial neural network
, Article International Journal of Engineering, Transactions B: Applications ; Volume 31, Issue 2 , 2018 , Pages 382-393 ; 1728144X (ISSN) ; Farrahi, G. H ; Sharif University of Technology
Materials and Energy Research Center
2018
Abstract
Shot peening (SP), as one of the severe plastic deformation (SPD) methods is employed for surface modification of the engineering components by improving the metallurgical and mechanical properties. Furthermore, artificial neural network (ANN) has been widely used in different science and engineering problems for predicting and optimizing in the last decade. In the present study, effects of conventional shot peening (CSP) and severe shot peening (SSP) on properties of AISI 1060 high carbon steel were modelled and compared via ANN. In order to networks training, the back propagation (BP) error algorithm is developed and data of experimental tests results are employed. Experimental data...
Melt compounding of thermoplastic polyurethanes incorporating 1D and 2D carbon nanofillers
, Article Polymer - Plastics Technology and Engineering ; Volume 56, Issue 7 , 2017 , Pages 732-743 ; 03602559 (ISSN) ; Pedrazzoli, D ; Pircheraghi, G ; Manas Zloczower, I ; Sharif University of Technology
Taylor and Francis Inc
2017
Abstract
Thermoplastic polyurethane nanocomposites incorporating carbon nanotubes and graphene nanoplatelets were prepared through melt blending and compression molding, and the compounding process was optimized taking into account the different physical properties of one-dimensional carbon nanotubes and two-dimensional graphene nanoplatelets. Filler dispersion was further improved in the case of carbon nanotubes by noncovalent surface modification using a specific surfactant. The well-dispersed nanofillers favored enhanced phase separation in the thermoplastic polyurethane, leading to a better microstructure, which is able to improve the load transfer and maximize the tensile and viscoelastic...
The investigation of laser shock peening effects on corrosion and hardness properties of ANSI 316L stainless steel
, Article International Journal of Advanced Manufacturing Technology ; Volume 88, Issue 5-8 , 2017 , Pages 1557-1565 ; 02683768 (ISSN) ; Amini, S ; Mahdavi, S. M ; Sharif University of Technology
Springer London
2017
Abstract
Laser shock peening (LSP) is known as a post processing surface treatment which can improve the mechanical properties of some materials. Shock waves are generated by confining the laser-induced plasma to cause a large pressure shock wave over a significant surface area. In the present study, effects of LSP on the electrochemical corrosion and micro hardness properties of 316L stainless steel alloy were investigated by changing the laser parameters such as the laser spot size, the average number of impacts, and the laser intensity. Since laser parameters do not cover the desired region of LSP, we have to use the proper design of experiment method, in which the D-optimal design of MATLAB was...
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) ; Rouhollahi, A ; Dolati, A ; Ghahramanifard, F ; Sharif University of Technology
Electrochemical Society Inc
2017
Abstract
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
A comprehensive experimental and numerical study on redistribution of residual stresses by shot peening
, Article Materials and Design ; Volume 90 , 2016 , Pages 478-487 ; 02641275 (ISSN) ; Ghasemi, A ; Farrahi, G. H ; Sherafatnia, K ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
Shot peening is one of the most effective surface strengthening treatment technologies in which compressive residual stresses are induced beneath the specimen surface. Effects of various factors on the distribution of residual stress profile induced by shot peening have been investigated by many researchers. However, initial residual stresses are one of the important factors which affect the shot peening residual stress.This study is aimed to present comprehensive numerical and experimental study on the effect of initial residual stresses on the shot peened specimen. Initial residual stresses were induced using a four-point bending rig and grinding. Incremental center hole drilling (ICHD)...
TiO2/nanoporous silicon hybrid contact for heterojunction crystalline solar cell
, Article RSC Advances ; Volume 6, Issue 60 , 2016 , Pages 55046-55053 ; 20462069 (ISSN) ; Razi Astaraei, F ; Mohammadpour, R ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
The conventional solar cell architectures include a p-n junction of c-Si sandwiched by rear and front contacts. The conventional approach features a complex as well as expensive procedure. Here, we propose a new architecture for p-n heterojunction solar cells prepared by a simple and cost-effective procedure. In this regard, (1) a silicon wafer underwent surface treatment through electrochemical anodization. To prepare a stick junction, (2) photoactive TiO2 nanoparticles were deposited over the porous layer by electrophoretic technique. Finally, (3) indium tin oxide (ITO) was sputtered. During the fabrication steps, we examined various anodization times ranging from 6 to 12 min to study the...
An easy method to modify PEDOT:PSS/perovskite interfaces for solar cells with efficiency exceeding 15%
, Article RSC Advances ; Volume 6, Issue 70 , 2016 , Pages 65594-65599 ; 20462069 (ISSN) ; Tajabadi, F ; Shiu, H. S ; Sedighi, R ; Jokar, E ; Gholipour, S ; Taghavinia, N ; Afshar, S ; Diau, E. W. G ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
Herein, we show that surface treatment of PEDOT:PSS films using propionic acid (PA) results in better device performance for the resulting CH3NH3PbI3 perovskite solar cells (PCE > 15%). N2 blow spreading of PA appears critical in enhanced performance. This weak acid treatment leads to no worse roughness, while providing larger perovskite grains
Synthesis and cyto-genotoxicity evaluation of graphene on mice spermatogonial stem cells
, Article Colloids and Surfaces B: Biointerfaces ; Volume 146 , 2016 , Pages 770-776 ; 09277765 (ISSN) ; Akhavan, O ; Shamsara, M ; Daliri, M ; Dashtizad, M ; Farmany, A ; Sharif University of Technology
Elsevier
2016
Abstract
The present study analyzed the dose-dependent cyto- and genotoxicity of graphene oxide and reduced graphene oxide on spermatogonial stem cells (SSCs) for the first time. The results showed that graphene oxide significantly increased oxidative stress at concentrations of 100 and 400 μg/ml, while low concentrations did not have a significant effect. In addition, according to the MTT assay, the cell number decreased in high-concentration (100 and 400 μg/ml) graphene oxide-treated samples compared to untreated cells. However, a reduced graphene-treated sample demonstrated a significant increase in cell number. Moreover, microscopic analysis found high concentrations of graphene nanosheets in...
Characterisation of Ni-Ti intermetallic coatings formed on Cp titanium by diffusion treatment
, Article International Journal of Surface Science and Engineering ; Volume 9, Issue 1 , 2015 , Pages 43-54 ; 1749785X (ISSN) ; Sohi, M. H ; Ghasemi, H. M ; Vafadar, A. Kh ; Sharif University of Technology
Inderscience Enterprises Ltd
2015
Abstract
In order to produce a thick near equi-atomic NiTi intermetallic layer on the surface of titanium plate, layers of nickel with thicknesses of 30 μm and 60 μm were electroplated on commercial pure (Cp) titanium and subsequently were heat treated at 850°C and 900°C. The effects of heat treating temperature and the thickness of electroplated nickel on the evolution of the microstructure and mechanical properties were studied. The results confirm the formation of various intermetallic layers in the coatings that substantially affect their hardness. The optimum condition for the formation of a thick NiTi intermetallic layer on the outer surface of the titanium was diffusion treatment of the sample...
Chromium carbonitride coating produced on DIN 1.2210 steel by thermo-reactive deposition technique: Thermodynamics, kinetics and modeling
, Article Surface and Coatings Technology ; Volume 225 , 2013 , Pages 1-10 ; 02578972 (ISSN) ; Nazari, A ; Khoie, S. M. M ; Khalaj, M. J ; Pouraliakbar, H ; Sharif University of Technology
2013
Abstract
A duplex surface treatment on DIN 1.2210 steel has been developed involving nitriding and followed by chromium thermo-reactive deposition (TRD) techniques. The TRD process was performed in molten salt bath at 550, 625 and 700°C for 1-14h. The process formed a thickness up to 9.5μm of chromium carbonitride coatings on a hardened diffusion zone. Characterization of the coatings by means of scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD) indicates that the compact and dense coatings mainly consist of Cr(C,N) and Cr2(C,N) phase. All the growth processes of the chromium carbonitride obtained by TRD technique followed a parabolic kinetics. Activation energy (Q) for the...
Supramolecular polycaprolactone nanocomposite based on functionalized hydroxyapatite
, Article Journal of Bioactive and Compatible Polymers ; Volume 27, Issue 5 , January , 2012 , Pages 467-480 ; 08839115 (ISSN) ; Shokrollahi, P ; Atai, M ; Omidian, H ; Bagheri, R ; Sharif University of Technology
SAGE
2012
Abstract
Arms bearing ureido-pyrimidinone functional groups with self-association capability (through quadruple hydrogen bonds) were successfully grafted onto hydroxyapatite nanoparticles. The supramolecularly modified nanoparticles (nHApUPy) exhibited enhanced colloidal stability compared to the original hydroxyapatite nanoparticles and were uniformly dispersed in supramolecular polycaprolactone in PCL(UPy)2/HApUPy nanocomposites at different filler loadings. The combined atomic force microscopy, mechanical, and rheological analyses confirmed a high degree of compatibility of HApUPy nanoparticles with the polymer matrix. The temperature dependence of the supramolecular structure in PCL(UPy)2/HApUPy...
The effect of shot peening on fatigue life of welded tubular joint in offshore structure
, Article Materials and Design ; Volume 36 , 2012 , Pages 250-257 ; 02641275 (ISSN) ; H-Gangaraj, S. M ; Farrahi, G. H ; Majzoobi, G. H ; Mahmoudi, A. H ; Daghigh, M ; Yari, A ; Moridi, A ; Sharif University of Technology
2012
Abstract
An offshore structure is exposed to environmental loading and cyclic stress variations throughout its life. This would result in the possibility of fatigue cracking in its members. Cracks in these structures usually initiate around welded areas, then grow progressively from the heat-affected zone to base metal through the thickness of the tubular members. Therefore, fatigue life improvement of offshore structures is of great importance. In this paper, structural analysis of an offshore platform is carried out and the critical joint is specified. The welding process is simulated and the residual stresses due to the welding are determined. Experimental residual stress measurement is carried...
Study of cemented carbonitrides with nickel as binder: Experimental investigations and computer calculations
, Article International Journal of Refractory Metals and Hard Materials ; Volume 31 , 2012 , Pages 164-170 ; 02634368 (ISSN) ; Abachi, P ; Parvin, N ; Pourazrang, K ; Sharif University of Technology
2012
Abstract
Cobalt is the most common binder in cemented carbides industry. However, there are some interests in use of alternatives. The similarity in properties has made nickel the first choice. In the present work, the effect of initial composition on modern hardmetals containing transition metal carbides/carbonitrides that are called "cemented carbonitrides" with nickel as binder was investigated. Change in quantity of additive carbides and tungsten to carbon (C/W) weight ratio through applying metallic tungsten powder in primary powder mixture had some effects on final hardness, transverse rupture strength, and microstructure of studied alloys. Addition of vanadium carbide not more than 0.2 wt.%,...
Palladium nanoparticle deposition onto the WO3 surface through hydrogen reduction of PdCl2: Characterization and gasochromic properties
, Article Solar Energy Materials and Solar Cells ; Volume 95, Issue 8 , August , 2011 , Pages 2335-2340 ; 09270248 (ISSN) ; Fardindoost, S ; Mahdavi, S. M ; Iraji Zad, A ; Tahmasebi G. N ; Sharif University of Technology
2011
Abstract
Nowadays, gasochromic Pd/WO3 coatings as optically switchable materials have become more applicable for hydrogen sensors and smart windows. In this study, WO3 films were prepared by Pulsed Laser Deposition (PLD) and spin-coating sol-gel techniques. For deposition of Pd, first a layer of PdCl2 was obtained via a simple drop-drying process by dropping PdCl2 solution onto WO3 substrates and drying them at room temperature. Then Pd nanoparticles were synthesized via hydrogen gas exposure that causes reduction of the PdCl2 layer. According to Scanning Electron Microscope (SEM) observations before hydrogen reduction, many individual nanoparticles or fractal-like constructions of palladium were...