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Experimental analysis and characterization of high-purity aluminum nanoparticles (Al-Nps) by electromagnetic levitation gas condensation (ELGC)
, Article Nanomaterials ; Volume 10, Issue 10 , 2020 , Pages 1-15 ; Halali, M ; Javadi, A. A ; Khanjanpour, M. H ; Sharif University of Technology
MDPI AG
2020
Abstract
The production of high-purity aluminum nanoparticles (Al-NPs) is challenging due to the highly reactive nature of Al metals. Electromagnetic levitation gas condensation (ELGC) is a promising method to produce high-purity metallic particles as it avoids the interaction between molten metal and refractory-lined, which guarantees the removal of impurities such as oxygen (O). In this research, high-purity Al-NPs were successfully fabricated via ELGC process and fully characterized. The effects of power input and gas flow rate on particle size and distribution were analyzed using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), and dynamic light...
Control of High Purity Distillation Columns
, M.Sc. Thesis Sharif University of Technology ; Shahrokhi, Mohammad (Supervisor)
Abstract
Selection of the most appropriate control configuration for two point control strategy in a distillation column is a challenging problem. In the present work, three control configurations namely , and , have been employed to control a high purity distillation column separating the binary mixture of Benzene-Toluene. A simple linear model for the process has been derived via a system identification technique. The uncertainty and performance weights have been defined and have been utilized to design a robust controller based on the μ-synthesis approach. The genetic algorithm is employed and the peak value of μ is minimized in order to obtain appropriate PI controller parameters for each...
Roduction of Solar Grade Silicon by Thermal Refining of Industrial Grade Silicon
, M.Sc. Thesis Sharif University of Technology ; Yoozbashizadeh, Hossein (Supervisor)
Abstract
The photovoltaic (PV) industry is in rapid growth and a large supply of PV feedstock materials must be provided to maintain this growth. Since silicon is still the dominant material for the fabrication of solar cells, low-cost solar-grade silicon (SoG-Si) feedstock is demanded. The most cost-effective and direct approach for producing SoG-Si is to purify and upgrade metallurgical-grade silicon. The major impurities in silicon are Al, Fe and Ca. other impurities present are Cu, Ti , Zn, Ni, Cr, Mn, Cd, B and P. In this study The effects of the acid leaching process parameters, including the particle size of silicon, the acid type (HCl, HNO3, H2SO4, and their combination), tmepreture and the...
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Nasser (Supervisor)
Abstract
High purity Germanium (HPGe) detector is a sub branch of semiconductor detectors which has very good resolution, very little dead time, able tobuild in large dimensions and suitable for any condition that it is using in vast fields from space investigation to radiation therapy. this detector is usually used to detecting gamma radiations furthermore the best resolution can be attained with decreasing leakage current. for analyzing about operation of the HPGe detector, it needs to initiate a model of this detector. in this studing has been used modelGEM-15190,POP-TOP which is built by ortec company. for initiating, it was used liquid nitrogen and accessory equipments like high voltage supply,...
Effect of CO2 partial pressure on the thermal decomposition kinetics of zinc carbonate hydroxide
,
Article
International Journal of Engineering, Transactions B: Applications
;
Volume 24, Issue 3
,
2011
,
Pages 263-268
;
1728-144X (ISSN)
; Halali, M
; Nobari, A. H
;
Sharif University of Technology
Abstract
In this work, the effect of carbon dioxide partial pressure on the calcination kinetics of high purity zinc carbonate hydroxide has been studied. Non-isothermal analysis has been performed on samples at different CO 2 partial pressures by TGA and DTA. It has been found that the calcination behaviour of this material corresponds to the shrinking core model and the reaction mechanism is phase boundary controlled. The calcination reaction of zinc carbonate hydroxide starts at 240 °C. Increasing the carbon dioxide partial pressure can result in an increase in the reaction start temperature of up to 30°C. The activation energy for the reaction is calculated as 180 ± 5 kJ/mol at...
Evaluation the nonlinear response function of a HPGe detector for 59 keV to 10.7 MeV gamma-rays using a Monte Carlo simulation and comparison with experimental data
, Article Journal of Instrumentation ; Volume 16, Issue 7 , 2021 ; 17480221 (ISSN) ; Riazi, Z ; Jokar, A ; Shahabinejad, H ; Vosoughi, N ; Ghasemi, S. A ; Sharif University of Technology
IOP Publishing Ltd
2021
Abstract
Modeling of High Purity Germanium (HPGe) detector on a wide energy range is important in gamma-ray spectroscopy. The precisely modeled detector can be used for proton-induced prompt gamma-ray spectroscopy. In this work, we used both the gamma-rays of calibration sources and prompt gamma-rays emitted in proton capture reactions to model a coaxial p-type HPGe detector using Geant4 Monte Carlo simulation for the gamma-ray energy range of 59–10764 keV. The calibration sources were 137Cs, 241Am, 60Co, 152Eu, and 133Ba, while the prompt gamma-rays were due to the gamma-ray cascades following the 27Al(p,γ)28Si reaction capture at the resonant energies of 992, 1317 and 2483 keV, as well as the...
Development of an Optimal Technique to Construct the Energy Spectrum of the Hpge Detector Using the Output Spectrum of the Nai Detector, with the Help of Soft Computing Algorithms
, M.Sc. Thesis Sharif University of Technology ; Vosoughi, Naser (Supervisor)
Abstract
Gamma ray spectroscopy has a special place in the industrial applications of nuclear radiation. Currently, the most common device for gamma ray detection and spectroscopy is the sodium iodide scintillation detector. Long life and high efficiency and reasonable price of these detectors are the reasons for the development of the use of these detectors in industries and laboratories. But these detectors in the classification of energy sensitive detectors are considered as detectors with low resolution. The presence of broad peaks in the gamma ray spectrum of this detector increases the possibility of interference of peaks related to different energies and makes it difficult to identify the...
Synthesis of wide band gap nanocrystalline NiO powder via a sonochemical method
, Article Ultrasonics Sonochemistry ; Volume 19, Issue 4 , 2012 , Pages 841-845 ; 13504177 (ISSN) ; Hosseini, S. A ; Rezaee, M ; Sadrnezhaad, S. K ; Mohammadyani, D ; Sharif University of Technology
2012
Abstract
A sonochemistry-based synthesis method was used to produce nanocrystalline nickel oxide powder with ∼20 nm average crystallite diameter from Ni(OH)2 precursor. Ultrasound waves were applied to the primary solution to intensify the Ni(OH)2 precipitation. Dried precipitates were calcined at 320 °C to form nanocrystalline NiO particles. The morphology of the produced powder was characterized by transmission electron microscopy. Using sonochemical waves resulted in lowering of the size of the nickel oxide crystallites. FT-IR spectroscopy and X-ray diffraction revealed high purity well-crystallized structure of the synthesized powder. Photoluminescence spectroscopy confirmed production of a wide...
Production of SnO2 nano-particles by hydrogel thermal decomposition method
, Article Materials Letters ; Volume 65, Issue 9 , 2011 , Pages 1249-1251 ; 0167577X (ISSN) ; Barzegar, S ; Ebrahimi, G. R ; Varahram, N ; Sharif University of Technology
Abstract
SnO2 is an important functional material having a wide range of applications in gas sensors and optoelectronic devices. There is a great interest for finding new cost-effective and straight-forward methods for production of these particles. In this research, hydrogel thermal decomposition method (HTDM) is used for production of high purity SnO2 nano-particles. Cost effective reactants and green routs of production are the advantages of polysaccharide based hydrogel as starting material for this method. Visual observations indicated that there is very little tendency for agglomeration in the SnO2 nano-particles produced by this method which can be considered as an advantage for this method...
Analysis and characterization of phase evolution of nanosized BaTiO 3 powder synthesized through a chemically modified sol-gel process
, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 43, Issue 11 , November , 2012 , Pages 4414-4426 ; 10735623 (ISSN) ; Sharif University of Technology
2012
Abstract
In the current research, a cost-effective and modified method with a high degree of reproducibility was proposed for the preparation of fine nanoscale and high-purity BaTiO3. In contrast to the other established methods, in this research, carbonate-free BaTiO3 nanopowders were prepared at a lower temperature and in a shorter time span. To reach an in-depth understanding of the scientific basis of the proposed process, an in-detail analysis was carried out for characterization of nanoscale BaTiO3 particles via differential thermal analysis (DTA)/thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and...
Production of silver nanoparticles by electromagnetic levitation gas condensation
, Article Chemical Engineering Journal ; Volume 168, Issue 1 , March , 2011 , Pages 441-445 ; 13858947 (ISSN) ; Halali, M ; Sharif University of Technology
2011
Abstract
Electromagnetic levitation gas condensation (ELGC) method was used to synthesize silver nanoparticles (NPs). Silver droplets were melted and levitated stably at about 1130°C with appropriate flat coils in a 10mm OD silica tube. High purity argon, nitrogen and helium were employed as carrier gases and cooling media. Morphology and particle size of the products were investigated by scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX) and dynamic light scattering (DLS). The DLS, SEM and TEM studies demonstrated narrow size distribution of spherical shape silver NPs with mean particle size of about 60, 50 and 30nm...
Rapid formation of hydroxyapatite nanostrips via microwave irradiation
, Article Journal of Alloys and Compounds ; Volume 469, Issue 1-2 , 2009 , Pages 391-394 ; 09258388 (ISSN) ; Mohajerani, M ; Mazloumi, M ; Khalifehzadeh, R ; Lak, A ; Sadrnezhaad, S. K ; Sharif University of Technology
2009
Abstract
Hydroxyapatite (HAp) nanostrips were rapidly obtained during a mild microwave heating method. Applying microwave irradiation to Ca(NO3)2·4H2O/CTAB/Na2HPO4 precursor solution, the HAp precipitation process was occurred directly and without common crystallographic transformations including dissolution and slow recrystallization. The cationic surfactant CTAB was used as a soft template to modify nucleation and growth process. TEM investigations showed that the fabricated nanostrips had a width and length of about 10 and 55 nm, respectively. The X-ray diffraction pattern revealed that the fabricated well-crystallized and high purity hydroxyapatite nanostrips had a pattern similar to the bone...
Microstructure and mechanical properties of oxide-dispersion strengthened al6063 alloy with ultra-fine grain structure
, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 42, Issue 3 , 2011 , Pages 816-824 ; 10735623 (ISSN) ; Simchi, A ; Kim, H. S ; Sharif University of Technology
Abstract
The microstructure and mechanical properties of the ultra-fine grained (UFG) Al6063 alloy reinforced with nanometric aluminum oxide nanoparticles (25 nm) were investigated and compared with the coarse-grained (CG) Al6063 alloy (∼2 μm). The UFG materials were prepared by mechanical alloying (MA) under high-purity Ar and Ar-5 vol pct O2 atmospheres followed by hot powder extrusion (HPE). The CG alloy was produced by HPE of the gas-atomized Al6063 powder without applying MA. Electron backscatter diffraction under scanning electron microscopy together with transmission electron microscopy studies revealed that the microstructure of the milled powders after HPE consisted of ultra-fine grains...
Effect of rapid solidification on the microstructure and mechanical properties of hot-pressed Al-20Si-5Fe alloys
, Article Materials Characterization ; Volume 60, Issue 11 , 2009 , Pages 1370-1381 ; 10445803 (ISSN) ; Vahidi, M ; Simchi, A ; Davami, P ; Sharif University of Technology
2009
Abstract
The aim of this work is to study the effect of cooling rate and subsequent hot consolidation on the microstructural features and mechanical strength of Al-20Si-5Fe-2X (X = Cu, Ni and Cr) alloys. Powder and ribbons were produced by gas atomization and melt spinning processes at two different cooling rates of 1 × 105 K/s and 5 × 107 K/s. The microstructure of the products was examined using optical microscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The particles were consolidated by hot pressing at 400 °C/250 MPa/1 h under a high purity argon atmosphere and the microstructure, hardness and compressive strength of the compacts were evaluated....
Mechanical induced reaction in Al-CuO system for in-situ fabrication of Al based nanocomposites
, Article Journal of Alloys and Compounds ; Volume 465, Issue 1-2 , 2008 , Pages 151-156 ; 09258388 (ISSN) ; Simchi, A ; Seyed Reihani, S. M ; Sharif University of Technology
2008
Abstract
Gradual chemical (displacement) reaction between CuO and Al powders during high-energy attrition milling under a high purity argon atmosphere was studied. Differential thermal analysis (DTA), X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques were employed to study the solid-state reaction. It was shown that the solid-state reaction occurred during mechanical alloying (MA) and resulted in the dissolution of copper into the aluminum lattice and formation of nanometric alumina particles. The reinforcement particles were mostly distributed at the grain boundaries of Al matrix with an average crystallite size of about 50 nm. In DTA curve of the milled powders, a small...