Search for: formation-mechanism
Total 21 records
Synthesis of "(aminomethyl)phosphonic acid-functionalized graphene oxide", and comparison of its adsorption properties for thorium(IV) ion, with plain graphene oxide, Article Radiochimica Acta ; 2021 ; 00338230 (ISSN) ; Outokesh, M ; Ahmadi, S.J ; Zahakifar, F ; Sharif University of Technology
De Gruyter Open Ltd 2021
The current study presents a simple and scalable method for the synthesis of (aminomethyl)phosphonic acid-functionalized graphene oxide (AMPA-GO) adsorbent. The chemical structure of the new material was disclosed by different instrumental analyses (e.g. FTIR, Raman, XPS, AFM, TEM, XRD, CHN, and UV), and two pertinent mechanisms namely nucleophilic substitution and condensation were suggested for its formation. Adsorption experiments revealed that both AMPA-GO and plain GO have a high affinity toward Th(IV) ions, but the AMPA-GO is superior in terms of adsorption capacity, rate of adsorption, selectivity, pH effect, etc. Indeed, the AMPA-GO can uptake Th(IV) nearly instantaneously, and...
Chatter Phenomena Prediction in Two-dimensional Milling Process from Chip Formation by Using Finite Element Method, M.Sc. Thesis Sharif University of Technology ; Movahhedy, Mohammad Reza
Chattering in cutting process is one of the destructive phenomena in machining, which results in ripple of workpiece surfaces. In this phenomenon, the displacement of the tool tip moves towards instability and the tool vibration continues. Eventually, the tool jumps or breaks out with relatively large shear forces, which leads to a reduction in the rate of production and machining. Since machining processes are very widespread, phenomenological studies of chatter have progressed in the field of modeling and empirical experiments. Research in the field of modeling is mainly intended to examine the dynamics of the tool in two ways: analytic and finite element. In these methods, there are...
Article Polymer (United Kingdom) ; Volume 54, Issue 21 , 2013 , Pages 5586-5594 ; 00323861 (ISSN) ; Ghorbani, M ; Shojaei, A ; Sharif University of Technology
Homogeneous and fairly monosized microspherical structures of polyaniline has been synthesized using a simple soft template method with β-naphthalene sulfonic acid (β-NSA) as both the surfactant and dopant, and ammonium persulfate (APS) as the oxidant at 2-5 C. The morphology of PANI-NSA was successfully controlled from nanotubes to microsphere, by changing the synthesis conditions (i.e. pH, the concentration of surfactant and monomer, and temperature). Some mechanistic aspects of the formation of nanotubes and hollow spheres have been discussed precisely based on SEM, TEM, DLS, FTIR and UV-visible results. Moreover, synthesis was performed under acidic environment to obtain further...
Work hardening of Duratherm 600 cobalt superalloy using repetitive corrugation and straightening process, Article Russian Journal of Non-Ferrous Metals ; Volume 51, Issue 1 , February , 2010 , Pages 59-61 ; 10678212 (ISSN) ; Paimozd, E ; Hashemi, S. M ; Sharif University of Technology
In this paper, the effect of repetitive corrugation and straightening (RCS) process on hardness of Duratherm 600 superalloy has been investigated. To do so, the RCS was carried out until 25 cycles using multiple teeth corrugative setup that the rotation of sample with 90° between cycles was utilized. The results show that the increasing of cycle number enhances the value of hardness. Also, the microstructures of samples are an evidence of slipbands formation during RCS showing the applied strain on the material. As a result, the increasing of hardness can be attributed to formation of subgrains, LAGBs and hcp martensitic plates at large strains
ZnO quantum dots-graphene composites: Formation mechanism and enhanced photocatalytic activity for degradation of methyl orange dye, Article Journal of Alloys and Compounds ; Volume 663 , 2016 , Pages 738-749 ; 09258388 (ISSN) ; Outokesh, M ; Tayebi, M ; Shafikhani, A ; Şengör, S. S ; Sharif University of Technology
The current study demonstrates homogenous decorating of zinc oxide quantum dots (QDs) onto graphene oxide (GO) surface via simple chemical method. The AFM image exhibited that the prepared graphene was 0.8 nm thick and hence practically monolayer. Average size of the ZnO QDs was estimated by transmission electron microscopy around 3 nm. Instrumental and chemical analyses demonstrated formation of a strong bond between ZnO QDs and GO, through C-O-Zn and C-Zn bridges. The UV-visible spectra displayed that the introduction of graphene sheets to ZnO QDs resulted in higher absorption intensity of UV as well as widening of adsorption window toward visible light for ZnO-Graphene due to chemical...
M.Sc. Thesis Sharif University of Technology ; Koochakzadeh, Mohammad Ali ; Yousefi, Reza
Prediction of shear plane angle is a way for prediction of the mechanism of chip formation, machining forces and so on. In this study, Merchant, Corrected Merchant, Lee and Shaffer, Lee and Shaffer with Built up Edge, Corrected Lee and Shaffer and Slip line theories are used for prediction of shear plane angles and cutting forces in machining of Al/SiCp metal matrix composite. The experimental cutting forces are compared with the calculated cutting force based on shear plane angles extracted from Merchant, Corrected Merchant, Lee and Shaffer, Lee and Shaffer with Built up Edge, Corrected Lee and Shaffer and Slip line theories. The variation of these cutting forces with cutting speed, feed...
M.Sc. Thesis Sharif University of Technology ; Akbari, Javad
Today, titanium and its alloys are the most widely used metals in manufacturing of biomedical implants. But unfortunately, most of bulk (nonporous) titanium alloys implants are facing problems such as stress shielding. If titanium is produced in such a way that has sufficient amount of porosity on the surface and inside of the sample, it provides sufficient space for connection and proliferation of new bone tissues and transmission of body fluids. However, machining of porous titanium causes pore closing. Due to the importance of recognizing the machining mechanism of materials such as porous titanium for manufacturing of implants, in this study micromachining of porous titanium with the...
Article TMS Annual Meeting, 14 February 2010 through 18 February 2010, Seattle, WA ; 2010 , Pages 37-47 ; 9781617822933 (ISBN) ; Shayesteh Zeraati, A ; Naser Zoshki, H ; Yousef Sani, M. R ; Sharif University of Technology
In this paper, the effect of aluminum content on the formation mechanism, volume fraction, morphology and particle size distribution of graphite has been investigated. Addition of aluminum on ductile iron causes some fundamental changes in iron-carbon phase-diagram and as a result, improves the graphite formation during eutectic transformation. The results reveals that aluminum compounds have been formed in the core of graphite nodules, thus aluminum plays an important role in the formation of graphite nodules. Furthermore, it is indicated that an increase in the aluminum content also leads to an increase in the number of graphite nodules and a decrease in the nodules size. By using EPMA,...
The effect of aluminium content on morphology, size, volume fraction, and number of graphite nodules in ductile cast iron, Article Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications ; Volume 224, Issue 3 , 2010 , Pages 117-122 ; 14644207 (ISSN) ; Naser Zoshki, H ; Kiani Rashid, A. R ; Yousef Sani, M. R ; Sharif University of Technology
The effect of aluminium content on the formation mechanism, volume fraction, morphology, and particle size distribution of graphite has been investigated. Addition of aluminium to ductile iron causes some fundamental changes in iron-carbon phase diagrams and, as a result, improves graphite formation during eutectic transformation. Results reveal that aluminium compounds have been formed in the core of graphite nodules; thus aluminium plays an important role in the formation of graphite nodules. Furthermore, it is indicated that an increase in the aluminium content also leads to an increase in the number of graphite nodules and a decrease in the nodule size. By using electron probe...
Article Journal of Materials Science: Materials in Electronics ; Volume 28, Issue 6 , 2017 , Pages 4606-4612 ; 09574522 (ISSN) ; Nemati, A ; Sharif University of Technology
Barium hexaferrite (BaFe12O19) nanoparticles were synthesized by sol–gel auto-combustion route. Prepared samples were sintered at 950 and 1100 °C with Fe3+/Ba2+ = 12 and 20 mol ratio. The formation mechanism of barium hexaferrite was investigated by using X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses. In addition, the effect of temperature and Fe3+/Ba2+ mole ratio on BaFe12O19 formation and magnetic properties, and the effect of increasing the Fe3+/Ba2+ upon gel ignition and subsequent phase development were investigated. Finally the magnetic behavior was monitored with VSM. DSC studies showed that pure barium hexaferrite phase was formed from maghemite...
Article Atomization and Sprays ; Volume 28, Issue 8 , 2018 , Pages 751-762 ; 10445110 (ISSN) ; Kashanj, S ; Olyaei, G ; Sharif University of Technology
Begell House Inc 2018
Here, we experimentally investigated the effects of skewness and velocity difference of two Newtonian colliding jets on the formation of a special oscillating liquid sheet pattern with periodic fragmentation, called fishbone, for four liquid sheet regimes known as the triple chain, double chain, close rim, and open rim. We expressed the ranges of the skewness and the velocity difference, where the fishbone pattern was formed for every four regimes. The formation of this special pattern was attributed to the instability of the liquid rim in the past studies. We qualitatively studied the upward and downward directions of the rims branched from the liquid sheet. Besides, the size variations of...
Contribution of water-in-oil emulsion formation and pressure fluctuations to low salinity waterflooding of asphaltic oils: A pore-scale perspective, Article Journal of Petroleum Science and Engineering ; Volume 203 , 2021 ; 09204105 (ISSN) ; Sakhaei, Z ; Salehinezhad, R ; Mahani, H ; Riazi, M ; Sharif University of Technology
Elsevier B.V 2021
During the low salinity waterflooding (LSWF) of a viscous asphaltic oil reservoir, fluid-fluid interactions have a large influence on the fluid flow, pore-scale events, and thus oil recovery efficiency and behavior. In-situ water-in-oil (W/O) emulsion formation is a consequence of crude oil and brine interfacial activities. Despite the published studies, the pore-scale mechanisms of W/O emulsion formation and the role of injected brine salinity, injection rate, and pore-scale heterogeneity on emulsion formation and stability requires a deeper understanding. To address these, a series of static and dynamic micro-scale experiments were performed. The salinity dependent oil-brine interactions...
Electrodeposition of long gold nanotubes in polycarbonate templates as highly sensitive 3D nanoelectrode ensembles, Article Electrochimica Acta ; Volume 75 , 2012 , Pages 157-163 ; 00134686 (ISSN) ; Ghorbani, M ; Dolati, A ; Sharif University of Technology
Electrodeposition of long and well-defined gold nanotubes in polycarbonate (PC) templates is still a major concern due to pore blockage problems. In the present study, we introduce a novel method for electrodeposition of long gold nanotubes within the pores of PC templates for the first time. In order to deposit gold atoms onto the pore walls preferentially, pore walls were functionalized with a coupling agent. Short and thin Ni nanotubes were then electrodeposited at the bottom of the pores. Gold nanotubes were subsequently electrodeposited at constant potentials and low solution concentrations. The morphology of nanotubes was characterized by electron microscopy and their formation...
Effects of initial precursor and microwave irradiation on step-by-step synthesis of zinc oxide nano-architectures, Article Materials Letters ; Volume 67, Issue 1 , 2012 , Pages 342-345 ; 0167577X (ISSN) ; Samberg, J. P ; Ghorbani, H ; Kajbafvala, E ; Sadrnezhaad, S. K ; Sharif University of Technology
ZnO nano-architectures were produced with the aid of a fast, simple and low cost microwave-assisted synthesis method. Solid semispherical ZnO nanoparticles on the order of 600 nm in diameter along with rice-like ZnO nanorods 95 nm thick were produced from butanol, triethanolamine (TEA), and zinc acetate dihydrate. Solid spherical ZnO nano-architectures with an average diameter of 250 nm were produced from the same starting materials in addition to NaOH. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to characterize the ZnO nano-architectures as well as the precursor. This method is cheap, fast and simple; capable of producing large quantities...
Synthesis and characterization of ultrasound assisted "graphene oxide-magnetite" hybrid, and investigation of its adsorption properties for Sr(II) and Co(II) ions, Article Applied Surface Science ; Volume 353 , 2015 , Pages 350-362 ; 01694332 (ISSN) ; Outokesh, M ; Moradi, S ; Doram, A ; Sharif University of Technology
Magnetite nanoparticles with a size distribution of 15-21 nm were synthesized and decorated onto surface of graphene oxide by ultrasound assisted precipitation. Size and size distribution of the obtained M-GO hybrid were appreciably finer than the hybrids prepared by stirring method. M-GO is a superparamagnetic material with saturation magnetization of 31 emu g-1. The Langevin equation was successfully applied for estimation of size of Fe
3O 4 nanoparticles in M-GO hybrid, with maximum error of 17.5%. The study put forward a formation mechanism for M-GO, based on instrumental analyses. Adsorption isotherms of Sr2+ and Co2+ ions, which were fitted by Langmuir monolayer...
(WO3)x-(TiO2)1-x nano-structured porous catalysts grown by micro-arc oxidation method: Characterization and formation mechanism, Article Materials Chemistry and Physics ; Volume 124, Issue 1 , 2010 , Pages 203-207 ; 02540584 (ISSN) ; Moshfegh, A. Z ; Golestani Fard, F ; Molaei, R ; Sharif University of Technology
Very recently, we fabricated (WO3)x-(TiO 2)1-x layers via micro-arc oxidation process under different applied voltages. Morphological and topographical studies, accomplished by SEM and AFM techniques, revealed that the pores size as well as the surface roughness increased with the voltage. Phase structure and chemical composition of the layers were also investigated by XRD and XPS and the results showed the grown layers consisted of titanium and tungsten oxides. It was found that WO3 dispersed in the TiO2 matrix and also doped into the TiO2 lattice. In addition, optical properties of the synthesized layers were studied employing a UV-vis spectrophotometer. Band gap energy of the layers was...
Article Journal of Alloys and Compounds ; Volume 497, Issue 1-2 , May , 2010 , Pages 325-329 ; 09258388 (ISSN) ; Zanganeh, S ; Kajbafvala, E ; Zargar, H. R ; Bayati, M. R ; Sadrnezhaad, S. K ; Sharif University of Technology
Through a fast, simple, low cost, surfactant-free and convenient microwave-assisted route, narcis-like ZnO nanostructures (10-15 nm size) with flower diameters in the range of 1-2.5 μm were synthesized. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and room temperature photoluminescence (PL) measurements were used to characterize the produced ZnO nanostructures. The principle raw materials - ammonium hydroxide (NH4OH) and zinc acetate dihydrate [Zn(CH3COO)2·2H2O] - were both inexpensive. The method was fast, simple and surfactant-free capable of producing larger quantities of zinc oxide...
Supercritical synthesis of a magnetite-reduced graphene oxide hybrid with enhanced adsorption properties toward cobalt & strontium ions, Article RSC Advances ; Volume 6, Issue 17 , 2016 , Pages 13898-13913 ; 20462069 (ISSN) ; Outokesh, M ; Sharif University of Technology
Royal Society of Chemistry 2016
The current study presents a supercritical synthesis of magnetite-reduced graphene oxide (M-RGO) in methanol media, in which Fe3O4 nanoparticles are simultaneously formed, surface modified and decorated on the surface of the reduced graphene oxide. Simulations using density functional theory, which were performed using the M06-2x/cc-pVDZ level of theory, indicate that upon adsorption of a Fe3O4 cluster on the graphene, the overall charge on the graphene surface becomes about -0.0236e, indicating charge transfer from the Fe3O4 cluster to the graphene surface. Instrumental and chemical analyses exhibited the formation of strong bonds between Fe3O4 and graphene, through C-O-Fe and C-Fe bridges....
Shed light on submerged DC arc discharge synthesis of low band gap gray Zn/ZnO nanoparticles: Formation and gradual oxidation mechanism, Article Advanced Powder Technology ; Volume 29, Issue 5 , 2018 , Pages 1246-1254 ; 09218831 (ISSN) ; Poursalehi, R ; Naseri, N ; Sharif University of Technology
Elsevier B.V 2018
Synthesis of colloidal metal oxides with controllable size and morphology is burgeoning field of research in nanoscience. Low band gap gray Zn/ZnO colloidal nanoparticles were fabricated by plasma-liquid interaction of DC arc discharge in water. Scanning electron microscopy, X-ray diffraction and UV–vis spectroscopy were employed for morphology, crystal structure and optical characterizations respectively. Optical emission spectroscopy was used to investigate the plasma properties during the synthesis and formation mechanism of nanoparticles. Nanoparticles with different size and shape were fabricated only by adjusting discharge current during synthesis without introducing any chemical...
Article Advanced Engineering Materials ; Volume 21, Issue 7 , 2019 ; 14381656 (ISSN) ; Azarniya, A ; Abdollah zadeh, A ; Madaah Hosseini, H. R ; Ramakrishna, S ; Sharif University of Technology
Wiley-VCH Verlag 2019
The growing industrial needs for the development of strong load-bearing materials by powder metallurgy and casting technologies has led to recent progress in the synthesis of in situ hybrid aluminium matrix composites (AMCs). Unlike their conventional counterparts, this class of engineering materials and their physicomechanical properties are sparsely investigated with no satisfactorily systematic approach and are not reviewed up to now. This is why providing an overview summarizing the formation mechanisms of in situ phases and mechanical properties of hybrid AMCs can systematically guide the research path in this field. The present review strives to categorize hybrid AMCs based on their...