Loading...
Search for:
surface-treatment
0.009 seconds
Total 75 records
Surface modification of carbon steel by ZnO-graphene nano-hybrid thin film
, Article Surface and Coatings Technology ; Volume 363 , 2019 , Pages 1-11 ; 02578972 (ISSN) ; Ghorbani, M ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Application of corrosion resistant coatings is one of the most widely used means of protecting steel. Zinc coated (galvanize) steel, is well known for galvanic protection of steel substrates and nowadays, particular attention has been paid to the coupling of graphene oxide (GO) with metallic materials, in order to lessen corrosion rate. In this research, an isopropanol supercritical reducing environment prepared to make zinc ions bond directly with graphene oxides, to form a button shape hybrids of ZnO-Graphene (ZnOG). The hybridized bonding between zinc and graphene oxide is confirmed by Fourier Transform Infra-Red analysis. And the morphology revealed, using a Field Emission Scanning...
Investigating the effects of amino acid-based surface modification of carbon nanoparticles on the kinetics of insulin amyloid formation
, Article Colloids and Surfaces B: Biointerfaces ; Volume 176 , 2019 , Pages 471-479 ; 09277765 (ISSN) ; Yahyazadeh, A ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Surface functionality of nanoparticles has been pivotal in defining interactions of nanoparticles and biomolecules. To explore various functionalities on the surface of nanoparticle through a facile procedure, various carbon-based nanoparticles, modified with a specific natural amino acid, were synthesized; the amino acids were chosen in order that almost all classes of amino acids were included. After characterizations of the nanoparticles using several spectroscopic methods, the effects of surface modification of nanoparticles were examined against amyloid formation, exploiting insulin as a model amyloidogenic polypeptide. Although most amino acids afforded carbon nanoparticles, only...
Effect of combined shot peening and ultrasonic nanocrystal surface modification processes on the fatigue performance of AISI 304
, Article Surface and Coatings Technology ; Volume 358 , 2019 , Pages 695-705 ; 02578972 (ISSN) ; Karimbaev, R ; Maleki, E ; Unal, O ; Pyun, Y. S ; Amanov, T ; Sharif University of Technology
Elsevier B.V
2019
Abstract
In this study, the fatigue performance of AISI 304 subjected to shot peening (SP), ultrasonic nanocrystal surface modification (UNSM) and the combination of SP + UNSM processes was systematically assessed by rotary bending fatigue (RBF) tester at different stress levels. The purpose of combining SP and UNSM processes is to find out whether SP following UNSM process can further improve the fatigue life of AISI 304 in comparison with the SP and UNSM processes alone. Interestingly, the fatigue strength of AISI 304 was deteriorated by the combination of SP + UNSM processes in comparison with the UNSM process alone, but the combination of SP + UNSM processes demonstrated a higher fatigue strength...
Wettability alteration of calcite rock from gas- repellent to gas-wet using a fluorinated nanofluid: A surface analysis study
, Article Journal of Natural Gas Science and Engineering ; Volume 83 , 2020 ; Shafiei, Y ; Shayesteh, M ; Dehghan Monfared, A ; Ghazanfari, M. H ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Wettability alteration analysis form gas-repellent to gas-wet with the aid of chemical agents has been subjected of numerous studies. However, fundamental understanding of the effect of surface tension of liquid on repellency strength, the change in the intermolecular forces due to the adsorption of nanoparticles onto the rock surfaces, and exposure of treated rock in brine are not well discussed in the available literature. In this study, X-ray diffraction, Atomic Force Microscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were applied to characterize the treated and fresh samples. Dynamic and static contact angle measurements were then combined with six methods...
CaTiO3/α-TCP coatings on CP-Ti prepared via electrospinning and pulsed laser treatment for in-vitro bone tissue engineering
, Article Surface and Coatings Technology ; Volume 401 , 2020 ; Esfahani, H ; Sheikhi, M ; Mohammadi, M ; Sharif University of Technology
Elsevier B.V
2020
Abstract
In this study, the in-vitro bone regeneration ability of commercial pure titanium (CP-Ti) surface modified via electrospun polyvinylidene/hydroxyapatite (PVP/HA) masking and subsequent Nd-YAG pulsed laser treatment was investigated. The ratio of HA to PVP played a significant role in achieving a perfect homogenous mask on the CP-Ti. In the laser treatment process, the parameter of area scanning speed (ASS) had an important influence on the final surface morphology. A favorable range was defined for this parameter where these two conditions were satisfied: no PVP remaining and no severe substrate melting. Within a favorable range of ASS, as decreasing ASS exchanged the surface structure from...
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...
Surface modification of exchange-coupled Co/NiO x magnetic bilayer by bias sputtering
, Article Applied Surface Science ; Volume 252, Issue 2 , 2005 , Pages 466-473 ; 01694332 (ISSN) ; Akhavan, O ; Moshfegh, A. Z ; Jafari, G. R ; Kavei, G ; Sharif University of Technology
Elsevier
2005
Abstract
We have investigated the effect of bias voltage on sheet resistance, surface roughness and surface coverage of Co/NiO x magnetic bilayer. In addition, interface topography and corrosion resistance of the Ta/Co/Cu/Co/NiO x /Si(1 0 0) system have been studied for Co layers deposited at an optimum bias voltage. Atomic force microscopy (AFM) and four point probe sheet resistance (Rs) measurement have been used to determine surface and electrical properties of the sputtered Co layer at different bias voltages ranging from 0 to -80 V. The Co/NiO x bilayer exhibits a minimum surface roughness and low sheet resistance value with a maximum surface coverage at Vb=-60 V resulted in a slight increase of...
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
Reducing ion migration in methylammonium lead tri-bromide single crystal via lead sulfate passivation
, Article Journal of Applied Physics ; Volume 127, Issue 18 , April , 2020 ; Parikh, N ; Kumari, H ; Pandey, M. K ; Kumar, M ; Prochowicz, D ; Kalam, A ; Tavakoli, M. M ; Yadav, P ; Sharif University of Technology
American Institute of Physics Inc
2020
Abstract
Surface passivation of organic-inorganic halide perovskites (OIHPs) is a crucial step to annihilate the surface defects and to control the deteriorated ion migration phenomenon. Here, we study the role of lead sulfate (PbSO4) as an effective passivator in OIHP single crystals (SCs). Using impedance spectroscopy, we evaluate the ion migration and electrical properties of lead sulfate-passivated methylammonium lead tri-bromide (MAPbBr3) SCs. We found that the low-frequency impedance response that is assigned to the ionic motion in the MAPbBr3 SC is strongly affected by the inorganic PbSO4 surface treatment. The activation energy corresponding to the ion migration of MAPbBr3 SC is increased...
The effect of multiple surface treatments on biological properties of Ti-6Al-4V alloy
, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Vol. 45, issue. 10 , 2014 , p. 4588-4593 ; Amini, P ; Asgari, S ; Sharif University of Technology
Abstract
In this research, the effect of various surface treatments including laser processing, grit blasting and anodizing on chemical structure, surface topography, and bioactivity of Ti-6Al-4V was investigated. Six groups of samples were prepared by a combination of two alternative laser processes, grit blasting and anodizing. Selected samples were first evaluated using microanalysis techniques and contact roughness testing and were then exposed to in vitro environment. Scanning electron microscopy was used to characterize the corresponding final surface morphologies. Weight measurement and atomic absorption tests were employed for determination of bioactivity limits of different surface...
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...
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...
The effects of combination of severe plastic deformation and Shot Peening surface treatment on fatigue behavior of 6082 aluminum alloy
, Article Russian Journal of Non-Ferrous Metals ; Volume 56, Issue 2 , 2015 , Pages 206-211 ; 10678212 (ISSN) ; Irani, M ; Karimi Taheri, A ; Sharif University of Technology
Abstract
In this paper, the effects of Equal Channel Angular Pressing process (ECAP) followed by Shot Peening process (SP) on the fatigue properties of 6082 aluminum alloy are investigated. Several samples of the alloy are ECAPed and SPed and then their mechanical behavior are characterized using tensile, micro-hardness, and fatigue tests. The results indicate that shot peening and then polishing the specimen after one-pass ECAP is an effective method to improve the fatigue life of the alloy. Moreover, by increasing the number of ECAP passes before shot peening, a local work softening occurs at the subsurface layer, leading to a significant decrease in the fatigue life of the alloy. The results of...
Energy aspects and workpiece surface characteristics in ultrasonic-assisted cylindrical grinding of alumina-zirconia ceramics
, Article International Journal of Machine Tools and Manufacture ; Volume 90 , 2015 , Pages 16-28 ; 08906955 (ISSN) ; Tawakoli, T ; Akbari, J ; Sharif University of Technology
Abstract
Ultrasonic assisted grinding is a novel method for improving the grinding process of difficult-to-cut materials. In the present research a novel setup has been designed and manufactured for utilizing ultrasonic vibrations in external cylindrical grinding. The designed ultrasonic head vibrates a rotating workpiece in axial direction. An alumina-zirconia ceramic (AZ90) has been selected as the workpiece material. Energy aspects and workpiece surface characteristics of ultrasonic assisted cylindrical grinding (UACG) and conventional cylindrical grinding (CG) processes have been analytically modeled and corresponding grinding experiments have been performed. The combined kinematics of the...
Study of nanocrystallization in FINEMET alloy by active screen plasma nitriding
, Article Journal of Alloys and Compounds ; Volume 491, Issue 1-2 , 2010 , Pages 487-494 ; 09258388 (ISSN) ; Madaah Hosseini, H. R ; Memarzadeh Lotfabad, E ; Roostaie, S ; Sharif University of Technology
2010
Abstract
The nanocrystallization process of amorphous Fe73.5Si13.5B9Nb3Cu 1 was investigated by active screen plasma nitriding (ASPN) treatment at temperatures ranging from 410 °C to 560 °C for 3 h in two gas mixtures of 75% N2-25% H2 and 25% N2-75% H2 at 5 mbar atmosphere. The amorphous ribbons were then annealed under vacuum at the same time and temperatures mentioned above. The structure of the samples was analyzed using various techniques such as X-ray diffraction (XRD), atomic force microscopy (AFM) and differential scanning calorimetry (DSC). Microhardness measurements, electrical resistivity and Vibrating Sample Magnetometer (VSM) were used to study mechanical, electrical and magnetic...
Self cleaning TiO2 coating on polycarbonate: Surface treatment, photocatalytic and nanomechanical properties
, Article Surface and Coatings Technology ; Volume 204, Issue 9-10 , 2010 , Pages 1562-1568 ; 02578972 (ISSN) ; Taghavinia, N ; Keshavarz Alamdari, E ; Sharif University of Technology
Abstract
A developed route to form TiO2 self cleaning coatings on polycarbonate substrates is reported. TiO2 coatings on plastics may find widespread application in auto and construction industries if possess desired photocatalytic and mechanical properties. A chemical surface treatment method was used to create hydrophilic groups on the surface. X-ray photoelectron spectroscopy showed the treatment led to the oxidation of surface groups. TiO2 deposition was based on wet coating using an anatase sol of TiO2 nanoparticles of 30 nm size. The sol was synthesized using a sol-gel route. A pre-coat of peroxotitanium complex was employed to improve adhesion and inhibit the substrate degradation. The coating...
Effective surface modification of MnFe2O4@SiO2@PMIDA magnetic nanoparticles for rapid and high-density antibody immobilization
, Article Applied Surface Science ; Volume 426 , 2017 , Pages 1023-1029 ; 01694332 (ISSN) ; Soleimani, M ; Ghahremanzadeh, R ; Vossoughi, M ; Esmaeili, E ; Sharif University of Technology
Abstract
The present study is aimed at the synthesis of MnFe2O4@SiO2@PMIDA in terms of highly efficient sensing platform for anti-prostate specific membrane antigen (PSMA) immobilization. Superparamagnetic manganese ferrite nanoparticles were synthesized following co-precipitation method and then SiO2 shell was coated on the magnetic core with tetraethyl orthosilicate (TEOS) through a silanization reaction to prevent oxidation, agglomeration and, increase the density of OH groups on the surface of MnFe2O4. Subsequently, MnFe2O4@SiO2@PMIDA obtained as a result of the reaction between N-(phosphonomethyl)iminodiacetic acid (PMIDA) and MnFe2O4@SiO2. The reactive carboxyl groups on the surface of magnetic...
Fabrication and characterization of low-cost, bead-free, durable and hydrophobic electrospun membrane for 3D cell culture
, Article Biomedical Microdevices ; Volume 19, Issue 4 , 2017 ; 13872176 (ISSN) ; Saidi, M. S ; Kashaninejad, N ; Kiyoumarsioskouei, A ; Trung Nguyen, N ; Sharif University of Technology
Abstract
This paper reports the fabrication of electrospun polydimethylsiloxane (PDMS) membranes/scaffolds that are suitable for three-dimensional (3D) cell culture. Through modification the ratio between PDMS and polymethylmethacrylate (PMMA) as carrier polymer, we report the possibility of increasing PDMS weight ratio of up to 6 for electrospinning. Increasing the PDMS content increases the fiber diameter, the pore size, and the hydrophobicity. To our best knowledge, this is the first report describing beads-free, durable and portable electrospun membrane with maximum content of PDMS suitable for cell culture applications. To show the proof-of-concept, we successfully cultured epithelial lung...