Loading...
Search for:
gheiratmand--tayebeh
0.144 seconds
Synthesis of FeNiCoTi powder alloy by mechanical alloying and investigation of magnetic and shape memory properties
, Article Journal of Superconductivity and Novel Magnetism ; Volume 25, Issue 6 , March , 2012 , Pages 1893-1899 ; 15571939 (ISSN) ; Madaah Hosseini, H. R ; Sharif University of Technology
Springer
2012
Abstract
FeNiCo base powder alloy with nominal composition Fe-27Ni-17Co-4Ti (wt%) was prepared from elemental powders by mechanical alloying. The structure of milled powders was characterized by XRD and SEM. The effect of nanosize structure on magnetic properties and shape memory behavior was studied using VSM and DSC. After milling for 240 minutes by high energy vibrational ball mill under argon atmosphere, supersaturated solid solution formed with mean crystallite size of ∼20 nm. Results of VSM examinations showed that by milling for 240 minutes saturation magnetization and intrinsic coercivity reached 304 emu/gr and 21 Oe, respectively. XRD analyses made it clear that transformation from BCC to...
Finemet nanocrystalline soft magnetic alloy: Investigation of glass forming ability, crystallization mechanism, production techniques, magnetic softness and the effect of replacing the main constituents by other elements
, Article Journal of Magnetism and Magnetic Materials ; Volume 408 , 2016 , Pages 177-192 ; 03048853 (ISSN) ; Madaah Hosseini, H. R ; Sharif University of Technology
Elsevier
2016
Abstract
Finemet soft magnetic alloy has been in the focus of interest in the last years due to its high saturation magnetization, high permeability and low core loss. The great quantity of papers has been devoted to the study of its structural and magnetic properties, confirms this claim. This paper reviews the different researches performed on Finemet up to now. The criteria that should be satisfied in order to have the high glass forming ability in an alloy and also the techniques applied for production of Finemet ribbons, powders and bulk samples have been explained. In addition, the mechanism of devitrification, nanocrystallization and magnetic softness in this applicable magnetic alloy has been...
Experimental Study of the Aging Effect on the Oxidation Catalyst Performance as an Emission Control Device for 4-stroke Gasoline Carburetor Motorcycles
, M.Sc. Thesis Sharif University of Technology ; Hamzehlouyan, Tayebeh (Supervisor)
Abstract
There are more than one million motorcycles in the city of Tehran that are responsible for significant amounts of various air pollutants emissions such as carbon monoxide and hydrocarbons. Oxidation catalysis, as the exhaust aftertreatment system of motorcycles, can reduce the emission of CO and hydrocarbon pollutants. The efficiency of these catalysts under typical operating conditions of vehicle exhaust gas has been studied in the literature. However, due to the specific features of motorcycles exhaust gas in Tehran, such as ultra-rich combustion, low air to fuel ratio (lambdas as low as 0.6-0.7), different exhaust gas composition and significant amount of lubricating oil consumption,...
Synthesis and Evaluation of a Three-Way Catalyst for CO, Hydrocarbon and Nitrogen Oxide Emission Control in CNG-Fueled Vehicles
, M.Sc. Thesis Sharif University of Technology ; Hamzehlouyan, Tayebeh (Supervisor)
Abstract
According to the reports of the Tehran Air Quality Control Company, mobile sources are responsible for the emission of 70-85% of air pollutant in this metropolis. Over the past decades, compressed natural gas (CNG) is known as a cleaner fuel and a suitable alternative to gasoline and diesel fuels in the transportation section in some countries. However, methane emissions from natural gas vehicles is a significant challenge because it is a potent greenhouse gas and plays important role in global warming. In addition, because of another pollutant emissions from these vehicles, exhaust gas treatment is a crucial issue. Using Three-Way catalysts (TWC) is the conventional method in order to...
Experimental Study of the Three-Way Catalyst Aging in a Reactor System
, M.Sc. Thesis Sharif University of Technology ; Hamzehlouyan, Tayebeh (Supervisor)
Abstract
Due to the significant role of vehicles in air pollution in Tehran and other metropolitan areas of the country, continuous monitoring and ensuring the quality and durability of automotive after-treatment catalysts based on valid standard methods is essential. One of the methods for evaluating the performance and durability of automotive after-treatment catalysts is using a reactor system that provides test conditions using simulated exhaust gas. In this method, the catalyst sample is exposed to a stream of simulated exhaust gases, and a specific aging cycle is performed by controlling the catalyst's operating conditions, including temperature and air-to-fuel ratio in the exhaust gas. The...
Kinetic Study of Selective Catalytic Reduction of over a Cu/Zeolite Catalyst for Emission Control from Diesel Engines
, M.Sc. Thesis Sharif University of Technology ; Hamzehlouyan, Tayebeh (Supervisor)
Abstract
Urban air pollution has become a significant environmental concern in recent times. NOx recognized as a criterion pollutant, is especially problematic. In 2021, the Tehran Air Quality Control Company reported that the ambient concentration of NOx in Tehran was around 50 ppb, which surpasses both the initial and final targets recently established by the World Health Organization (40 ppb and 10 ppb, respectively). To control and predict NOx emissions from diesel engines, A detailed selective catalytic reduction (SCR) model has been developed to describe the global kinetic reactions within the catalyst. This model incorporates two types of sites for high- and low-temperature NH3...
Modification of Three-Way Catalyst (Twc)Formulation for Gasoline Vehicles with the Goal of Improving Its Thermal Stability
, M.Sc. Thesis Sharif University of Technology ; Hamzehlouyan, Tayebeh (Supervisor)
Abstract
Vehicle exhaust gas catalysts play a significant role in air pollution control. In order to solve the problems of cold start and limited supply of precious metals, new studies have focused on the development of three-way catalysts for gasoline vehicles with small amounts of precious metals and increase thermal stability. Different metal ions, especially rare earth metals, due to different physical and chemical properties, show different reinforcing effects on the properties of ceria-zirconia-based materials. Previous studies have shown that the enhancing effect of these materials and the ceria-zirconia ratio on catalyst activity and stability, as well as studies on thermal stability at 1050...
Evaluation of Zeolite-Based Catalysts for Selective Catalytic Reduction of Nox As Part of Diesel After-Treatment System
, M.Sc. Thesis Sharif University of Technology ; Hamzehlouyan, Tayebeh (Supervisor)
Abstract
Urban air pollution has emerged as a significant environmental concern in recent times. NOx is classified as a criterion pollutant. In 2021, the Tehran Air Quality Control Company reported that the ambient concentration of this pollutant in Tehran is around 50 ppb which exceeds both the initial and final target recently established by the World Health Organization (40 ppb and 10 ppb, respectively). Diesel vehicles are the primary contributor to NOx emissions in Tehran. To control NOx emissions from diesel engines, Selective Catalytic Reduction (SCR) systems are used according to Euro 4 and Euro 5 standards. Considering the novelty of this technology within the nation, it is critical to...
Fabrication of FINEMET bulk alloy from amorphous powders by spark plasma sintering
, Article Powder Technology ; Volume 289 , 2016 , Pages 163-168 ; 00325910 (ISSN) ; Madaah Hosseini, H. R ; Davami, P ; Sarafidis, C ; Sharif University of Technology
Elsevier
2016
Abstract
Finemet bulk soft magnetic alloy was fabricated by spark plasma sintering of the milled ribbons. The amorphous melt-spun ribbons were milled for 36min by high energy vibrational mill and then sieved to separate particles smaller than 125μm. The size distribution of particles was determined by a laser diffraction particle size analyzer. Spark plasma sintering was carried out at super-cooled liquid region for short times of 7 and 21min. The structure of bulk samples was characterized using X-ray diffraction, scanning electron microscopy, differential scanning calorimetry and transmission electron microscopy techniques. The magnetization and coercivity of samples were measured using SQUID...
Iron-borosilicate soft magnetic composites: the correlation between processing parameters and magnetic properties for high frequency applications
, Article Journal of Magnetism and Magnetic Materials ; Volume 429 , 2017 , Pages 241-250 ; 03048853 (ISSN) ; Madaah Hosseini, H .R ; Seyed Reihani, S. M ; Sharif University of Technology
Elsevier B.V
2017
Abstract
Iron-borosilicate soft magnetic composites are suitable magnetic materials for high temperature and high frequency applications. In this research two different techniques have been applied to fabricate these composites: uniaxial pressing following by sintering and spark plasma sintering. Different processing parameters including the content of borosilicate, the amount of compaction pressure and the size of iron particles have been evaluated through the study of microstructure and magnetic properties. The microstructural observations showed that the borosilicate is distributed on the iron grain boundaries enhancing the resistivity and causing the loss of eddy currents. Increasing the...
, M.Sc. Thesis Sharif University of Technology ; Hamzehlouyan, Tayebeh (Supervisor) ; Khorasheh, Farhad (Supervisor)
Abstract
Diesel oxidizing catalysts (DOCs) based on precious metals of Platinum and Palladium are among the most important and most widely used catalysts in the exhaust aftertreatment system of diesel cars. DOCs are used to oxidize CO and hydrocarbons to reduce their emissions to the environment. In spite of the excellent performance of DOCs, sulfur exposure can lead to their deactivation. Sulfur is mainly in the form of SO2 at the combustion chamber exit, which can be further oxidezed to SO3 on the DOC. The deactivation impact of SO2 and SO3 on DOCs are different, with SO3 leadig to higher degrees of deactivation. In this study, a kinetic model for SO2 oxidation on a bimetallic Pt-Pd-based catalyst...
Investigation the structural and magnetic properties of FINEMET type alloy produced by mechanical alloying
, Article Advanced Materials Research ; Vol. 970, issue , 2014 , p. 252-255 ; Siyani, S. M ; Hosseini, H. R. M ; Davami, P ; Sharif University of Technology
2014
Abstract
In this research, FINEMET alloy with composition of Fe73.5Si13.5B9Nb3Cu1 was produced by mechanical alloying from elemental powders. The effect of milling time on the magnetic and structural properties of alloy has been investigated using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometery. The results showed that milling for 53 hr leads to the formation of Fe supersaturated solid solution which includes Si, B and Nb atoms with mean crystallite size of ~30 nm. The shift of the main peak of Fe to the higher angles indicated that Si and B atoms dissolve in the Fe solid solution, at primary stage of mechanical alloying, up to the...
Examination of Activity of Three-Way Catalysts Toward CO and Hydrocarbon Emission Reduction from Tehran Gasoline Taxis
, M.Sc. Thesis Sharif University of Technology ; Hamzehlouyan, Tayebeh (Supervisor) ; Hosseini, Vahid (Co-Supervisor)
Abstract
Air pollution is one of the main environmental problems in Iran's metropolises, especially in the city of Tehran. Taxis have a significant contribution to pollution due to the long distances they travel during the day. Due to the fact that the operation of automotive three-way catalysts is a function of their operating conditions, and considering the different fuel composition in Iran and the specific conditions of engine performance, exhaust gas composition can be different from similar cases abroad. A commercial three-way catalyst was tested to evaluate its performance under conditions relevant to the exhaust gas of Tehran's taxis fleet. In this study, CO and C3H6 were considered as the...
Improving the Photocatalytic Activity of Bismuth-Based Semiconductors Via Plasmonic Effects for Degradation of Non-Biodegradable Pollutants
, M.Sc. Thesis Sharif University of Technology ; Hamzehlouyan, Tayebeh (Supervisor) ; Ghasemi, Shahnaz (Supervisor)
Abstract
The ever-growing population and the rapid industrialization in recent years have left the world with serious environmental problems such as the shortage of water resources and pollution of existing resources. This shortage and pollution not only increase the mortality rate in certain regions of the globe but could cause the industry to falter. To address this problem, water treatment facilities are a logical and possible solution. Recently, water treatment using photocatalysis has attracted much attention. This process, which requires only a semiconductor (photocatalyst) and sunlight, has low energy consumption and does not produce harmful by-products (two problems traditional water...
The effect of mechanical milling on the soft magnetic properties of amorphous FINEMET alloy
, Article Journal of Magnetism and Magnetic Materials ; Volume 381 , 2015 , Pages 322-327 ; 03048853 (ISSN) ; Madaah Hosseini, H. R ; Davami, P ; Gjoka, M ; Song, M ; Sharif University of Technology
Elsevier
2015
Abstract
The effect of milling time on the magnetic properties of FINEMET amorphous ribbons has been investigated using X-ray diffraction, Mössbauer spectroscopy, thermo-magnetic measurements, transmission electron microscopy and SQUID magnetometery. Ribbons were melt-spun at a wheel speed of 38 ms-1 and then mechanically milled for different periods up to 45 min. The results showed that the partially crystallization of the amorphous powder occurs during milling. TEM observations confirmed the formation of small volume fraction of the crystalline phase with ∼9 nm crystallite size in the amorphous matrix for the ribbon milled for 45 min. Thermo-magnetic measurements indicated the enhancement of the...
Investigation the Correlation Between Nanocrystallization and Consolidation Mechanisms and Their Effect on Magnetic Properties of Bulk Finemet Type Alloys
, Ph.D. Dissertation Sharif University of Technology ; Madaah Hosseini, Hamid Reza (Supervisor) ; Davami, Parviz (Supervisor)
Abstract
Finemet soft magnetic alloys in the form of toroidally winded ribbons are not suitable for industrial applications where a large volume of magnetic materials is required. Production of Finemet bulk alloy by powder metallurgy techniques is an applicable method to produce complex component with isotropic magnetic properties which are the same as ribbons. In this research, Finemet bulk magnetic alloy with composition of has been produced by consolidation of amorphous powders obtained by milling of melt-spun ribbons. At the all stages, the structure and magnetic properties were studied using X-ray diffraction, differential scanning calorimetry, transmission electron microscopy, scanning...
Kinetic Modeling of Hydrothermal Aging of an Oxidation Catalyst with Wiremesh Structure as Part of the Motorcycle Emission Control System
, M.Sc. Thesis Sharif University of Technology ; Hamzehlouyan, Tayebeh (Supervisor) ; Khorasheh, Farhad (Supervisor)
Abstract
Diesel oxidation catalysts (DOCs) containing precious metals such as platinum and palladium are crucial components of the after-treatment system for exhaust gas purification in diesel vehicles and motorcycles. These catalysts aid in reducing the emission of pollutants into the environment by oxidizing carbon monoxide (CO) and hydrocarbons (HCs). However, their efficiency in removing environmental pollutants diminishes over time due to various deactivation mechanisms, especially by sintering. Given the significant contribution of motorcycles to CO and HC emissions, especially in least-developed countries, experimental and simulation studies on fresh and aged DOCs are essential for the optimal...
Photocatalytic Degradation of Organic Pollutants in the Presence of Nanocomposites Based on Graphitic Carbon Nitride under Visible Light Illumination
, M.Sc. Thesis Sharif University of Technology ; Hamzehlouyan, Tayebeh (Supervisor) ; Rahman Setayesh, Shahrbanoo (Co-Supervisor)
Abstract
The susceptible light-harvesting and tremendous reduction capability along with the potentiality (photo)electrochemical merits of the thiospinels like CuCo2S4 (CCS) bring forth appreciably an advancement in efficacious photocatalytic reactions. However, scant oxidation potential originated from 3p orbitals of sulfur atoms puts a damper on their performance and is even conducive to self-oxidation. In this research, the surfactant/template free of hierarchical CCS thiospinels was synthesized using solvothermal sulfidation of the affordable glycerate-based CuCo-alkoxide and successfully was embedded with Z-scheme V2O5 deposited on wrinkled g-C3N4 lamella (VO-UCN) in the interest of developing...
Evaluation of the Effect of the Presence of Activated Carbon Powder on the Microbial Removal of Azomethyl Red Dye by Klebsiella Bacteria
,
M.Sc. Thesis
Sharif University of Technology
;
Yaghmaei, Soheila
(Supervisor)
;
Bagheri Lotfabad, Tayebeh
(Supervisor)
Abstract
Synthetic azo dyes are one of the most common environmental pollutants in wastewater due to their many uses in various industries such as textile, printing, food, cosmetics, etc. In this project, the bacterial removal method is used to remove azo methyl red dye, and according to the functional groups on the surface of activated carbon, its effect on the efficiency and rate of the microbial removal process of azo methyl red dye is investigated. For this purpose, dye removal tests for each dye concentration (0.1 to 6 mM) in three separate series, as (1) dye removal in the presence of bacteria, (2) dye removal in the presence of activated carbon, and (3) dye removal was investigated in the...
Effect of annealing on soft magnetic behavior of nanostructured (Fe 0.5Co0.5)73.5Si13.5B 9Nb3Cu1 ribbons
, Article Journal of Alloys and Compounds ; Vol. 582, issue , 2014 , pp. 79-82 ; Hosseini, H. R. M ; Davami, P ; Gjoka, M ; Loizos, G ; Aashuri, H ; Sharif University of Technology
2014
Abstract
The effects of relaxation and nanocrystallization on magnetic properties of (Fe0.5Co0.5)73.5Si13.5B 9Nb3Cu1 ribbons have been investigated. Ribbons were melt-spun at wheel speed of 38 m/s and then annealed at different temperatures. The results indicated that the relaxation processes shift the Curie temperature of amorphous phase to the higher temperatures. It was also found that through crystallization phenomena the saturation magnetization increases due to the super-exchange between Fe and Co atoms in the crystalline phase. A slight variation in magnetization was observed at ~700 °lC during heating due to the ordering transition in FeCo system. At early stage of crystalline phase...