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    Mechanical- activated phase formation of NiTi in the presence of nanoparticles [electronic resource]

    , Article Journal of Nano ; October 2013, Volume 08, Issue 05 Farvizi, M ; Ebadzadeh, T ; Vaezi, M. R ; Simchi, A. (Abdolreza) ; Kim, H. S ; Sharif University of Technology
    Abstract
    Effect of Al2O3 nanoparticles (80 nm) on the grain structure and phase formation in Ni-50Ti system during high-energy mechanical alloying (MA) was studied. While the formation of NiTi B2 phase occurs progressively during MA, it is shown that the hard inclusions cause abrupt phase formation at short milling times, particularly at higher nano-Al2O3 contents. High-resolution transmission electron microscopy showed significant grain refinement in the presence of alumina nanoparticles to sizes less than 10 nm, which precedes the formation of semicrystalline structure and reduces the diffusion length and thus accelerates the phase formation. The composite powder reached steady-state MA condition... 

    Effect of alumina nanoparticles on the microstructure and mechanical durability of meltspun lead-free solders based on tin alloys

    , Article Journal of Alloys and Compounds ; Volume 688 , 2016 , Pages 143-155 ; 09258388 (ISSN) Mehrabi, K ; Khodabakhshi, F ; Zareh, E ; Shahbazkhan, A ; Simchi, A ; Sharif University of Technology
    Elsevier Ltd  2016
    Abstract
    As one of the key technologies for high performance electronic devices, composite solders have been recently developed to improve thermal and mechanical properties of solder joints. In this research, melt spinning was employed to fabricate a lead-free based nanocomposite solder for electronic application materials via introducing Ni-coated Al2O3 nanoparticles (0.1 wt%) into a Sn-Ag-Cu ternary eutectic alloy during rapid solidification. These surface-modified nanoparticles were synthesized by an in situ chemical reduction method. The effect of rapid solidification on the distribution of reinforcing nanoparticles, microstructural evolution, and solderability of the tin alloy were studied.... 

    Electroplating and characterization of Cr–Al2O3 nanocomposite film from a trivalent chromium bath [electronic resource]

    , Article Anti-Corrosion Methods and Materials ; Vol 61, No 4, 2014, 205-214 Salehi Doolabi, M. (Mohsen) ; Sadrnezhaad, Khatiboleslam ; Salehi Doolabi, Davood ; Sharif University of Technology
    Abstract
    The main aim of this study was to improve current efficiency and to obtain thicker coatings via aluminum oxide (Al2O3) addition to the chromium (Cr) (III) bath. Design/methodology/approach ‐ Pure Cr and nanocomposite Cr–Al2O3 coatings were electrodeposited from Cr (III) bath onto cathode copper substrates by conventional method. Dependence of current efficiency to current density, Al2O3 content and particle size were investigated. Findings ‐ Current efficiency increased with Al2O3 amount and decreased with Al2O3 particle size. Maximum current efficiency was achieved at 25 A/dm2 for pure Cr and 30 A/dm2 for composite coatings. Al2O3 bath content, current density and stirring rate increased... 

    KF-Al2O3 promoted synthesis of fully substituted new indeno- and naphtho-fused thiophenes under solvent-free conditions by controlled microwave heating

    , Article Letters in Organic Chemistry ; Volume 4, Issue 8 , 2007 , Pages 576-584 ; 15701786 (ISSN) Moghaddam, F. M ; Saeidian, H ; Mirjafary, Z ; Sadeghi, A ; Sharif University of Technology
    2007
    Abstract
    KF-Al2O3 catalyzes the reaction of arylthioacetamides with α-bromo, ketones to give fully substituted new indeno- and naphtho- fused thiophenes with good yields under solvent-free conditions by controlled microwave heating. A mechanism is proposed for the reaction course. © 2007 Bentham Science Publishers Ltd  

    KF/Al2O3 mediated aza-Michael addition of indoles to electron-deficient olefins

    , Article Letters in Organic Chemistry ; Volume 3, Issue 2 , 2006 , Pages 157-160 ; 15701786 (ISSN) Moghaddam, F. M ; Bardajee, G. R ; Taimoory, S. M. D ; Sharif University of Technology
    2006
    Abstract
    KF/Al2O3 efficiently catalyzes aza-Michael addition of indole and 3-methylindole to a variety of electron-deficient conjugated alkenes such as α,β-unsaturated ketones, amides and nitriles. The N-alkylation adducts are produced in good to excellent yields and relatively in short times. The catalyst can be recycled for subsequent reactions without any appreciable loss of efficiency. © 2006 Bentham Science Publishers Ltd  

    Investigation Ni-P-Al2O3-SiO2 Nano Composite Coating on Aluminum by Electroless

    , M.Sc. Thesis Sharif University of Technology Ghanbari, Amir Ali (Author) ; Afshar, Abdollah (Supervisor)
    Abstract
    Electroless coating is a chemical reduction process which depends on the catalytic reduction. In this study, the influences of different concentrations, stirring rate, pH and heat treatment of Al2O3 and SiO2 Nano sized particles in the bath on deposition rate, hardness, wear resistant, surface morphology and corrosion behavior of the Ni-P-Al2O3-SiO2 composite coatings have been investigated. The microstructure was investigated by field emission scanning electron microscopy (FESEM) and among the nanoparticles SiO2 and Al2O3 have drawn attention due to their high hardness, availability, particles distribution and reduced cost. The amount of Al2O3 and SiO2 was examined by Energy Dispersive... 

    Investigation of the Effects of Various Parameters on Microstructure and Mechanical Properties of Nano-Composite Al-Al2O3 and Al-Sic Produced by Accumulative Roll Bonding

    , M.Sc. Thesis Sharif University of Technology Rezayat, Mohammad (Author) ; Akbarzadeh Changiz, Abbas (Supervisor)
    Abstract
    Accumulative roll bonding has been used as novel method to produce the composite with ultra fine grain microstructure. This method has two steps, impose the particles as reinforcement between the layers by roll bonding process and then distribute the particles in matrix and generat an ultra fine grain microstructure during the ARB passes. In the present work, ARB process was performed to produce the Al/SiC and Al/Al2O3 nano-composites with various particles size and different volume fraction of reinforcement. Microscopic observations such as OM, SEM and TEM and XRD analyses were used to investigate the microstructure of produced composites and the distribution of the particles in matrix... 

    Semiconductor TiO2-Al2O3 thin film gas sensors derived from aqueous particulate sol-gel process

    , Article Materials Science in Semiconductor Processing ; Vol. 27, issue , 2014 , p. 711-718 Mohammadi, M. R ; Sharif University of Technology
    Abstract
    Nanostructured TiO2-Al2O3 films and powders were prepared by a straightforward aqueous particulate sol-gel route. Titanium (IV) isopropoxide and aluminum chloride were used as precursors, and hydroxypropyl cellulose was used as a polymeric fugitive agent in order to increase the porosity. The effect of Al:Ti molar ratio was studied on the crystallization behavior of the products. X-ray diffraction (XRD) revealed that the powders crystallized at 800°C, containing anatase-TiO2, rutile-TiO2 and cubic-Al2O3 phases. Furthermore, it was found that Al2O3 retarded the anatase to rutile transformation. Transmission electron microscope (TEM) image showed that one of the smallest crystallite sizes was... 

    Production of V2C MXene using a repetitive pattern of V2AlC MAX phase through microwave heating of Al-V2O5-C system

    , Article Applied Surface Science ; Volume 542 , 2021 ; 01694332 (ISSN) Ghasali, E ; Orooji, Y ; Azarniya, A ; Alizadeh, M ; Kazem-zad, M ; TouradjEbadzadeh ; Sharif University of Technology
    Elsevier B.V  2021
    Abstract
    The present work focuses on the preparation of V2C MXene from Al-V2O5-C mixture heated in a microwave and etched under HF-based process. In the first stage of process, microwave heating caused the formation of an uncommon periodic pattern of V2AlC-Al2O3 MAX phase. In the second stage of process the aggressive leaching (temperature of 80 °C for 96 h) was performed in HF to remove the interlayer aluminum and Al2O3 particles as impurities. The leaching was not completed at room temperature even after 24 h. XRD and FESEM analyses confirmed the successful formation of V2C MXene and its distorted layer, respectively. HRTEM, XPS and Raman analyses also confirmed a perfect structure of V2C MXene. It... 

    Modeling the Kinetics of Sulfur Oxides Adsorption-desorption on a Pt/γ-Al2O3 Catalyst as Diesel Oxidation Catalyst (DOC)

    , M.Sc. Thesis Sharif University of Technology Farzi, Amir Hossein (Author) ; Hamzeh Louyan, Tayyebeh (Supervisor)
    Abstract
    Sulfur oxides are categorized as one of the most important poisoning and activity-reducer groups acting on the catalytic converters present in the exhaust treatment systems. In the present work, interactions of the SOX species with diesel oxidation catalysts (DOCs) are investigated by implementing a kinetic modeling approach. Experimental data obtained from a catalyst of this type, i.e., Pt/γ-Al2O3, was employed and a multi-step microkinetic model was developed in Matlab 2018b® to proxy the poisoning effect of the adsorption of surface sulfur species and their desorption behavior. The microkinetic model was run to describe the individual SO2 and SO3 adsorption-desorption process using the... 

    Influence of adding a modified zeolite-Y onto the NiMo/Al2O3 catalyst utilized to produce a diesel fuel with highly reduced sulfur content

    , Article Microporous and Mesoporous Materials ; Volume 332 , 2022 ; 13871811 (ISSN) Karami, H ; Kazemeini, M ; Soltanali, S ; Rashidzadeh, M ; Sharif University of Technology
    Elsevier B.V  2022
    Abstract
    In order to make a Na–Y zeolite with Si/Al ratio of 2.27 more acidic with a higher volume of mesopores, a combination of different and consecutive methods including; chemical (i.e.; utilizing different compounds, such as NH4F and EDTA) and thermal/hydrothermal (i.e.; implementing calcination/steaming) methods, were employed for modification and dealumination. The combination of acidic-hydrothermal dealumination method led to a further structural collapse compared to that of the acidic calcination. In comparison with the other dealumination methods, the fluorination strategy (i.e.; utilizing NH4F) resulted in a zeolite with higher crystallinity, acidity, and specific surface area. The... 

    Kinetic Study of Heterogeneous and Homogeneous Catalytic Reactions in Molecular and Ionic Solvents and Their Mixtures

    , Ph.D. Dissertation Sharif University of Technology Khodadadi Moghaddam, Mohammad (Author) ; Gholami, Mohammad Reza (Supervisor) ; Habibi Yangjeh, Aziz (Supervisor)
    Abstract
    Solvatochromic parameters (ETN: normalized polarity parameter, π*: dipolarity/polarizability, β: hydrogen-bond acceptor basicity, α: hydrogen-bond donor acidity) have been determined for binary mixtures of propan-2-ol, propan-1-ol, ethanol, methanol and water with recently synthesized ionic liquid (2-hydroxyethylammonium formate) at 25 ◦C. The applicability of nearly ideal combined binary solvent/Redlich-Kister equation was proved for the correlation of various solvatochromic parameters with solvent composition. Solute-solvent and solvent-solvent interactions were applied to interpret the results. Heterogeneous catalytic hydrogenation of cyclohexene, catalyzed by Pt/Al2O3, was carried out in... 

    Effect of sintering temperature on tribological behavior of Ce-TZP/Al2O3-aluminum nanocomposite

    , Article Journal of Composite Materials ; Volume 49, Issue 28 , December , 2015 , Pages 3507-3514 ; 00219983 (ISSN) Bahrami, A ; Soltani, N ; Pech Canul, M. I ; Sharif University of Technology
    SAGE Publications Ltd  2015
    Abstract
    10Ce-TZP/Al2O3 nanoparticles as reinforcement can be a good substitute in aluminum matrix composites prepared through powder metallurgy. In this work, the effects of sintering temperature on the hardness, friction, and wear characteristics of Al-10Ce-TZP/Al2O3 composites have been investigated. Ce-TZP/Al2O3 nanocomposites were synthesized by the aqueous combustion method. About 7 wt% 10Ce-TZP/Al2O3-aluminum composites in the form of cylindrical samples were prepared at the sintering temperatures of 400°C, 450°C, and 500°C under an applied pressure of 600 MPa for 60 min. The experimental results show that the distribution of Ce-TZP/Al2O3 nanocomposite into the metal matrix is homogenous and... 

    Oxidation of H2S to elemental sulfur over alumina-based nanocatalysts: Synthesis and physiochemical evaluations

    , Article Scientia Iranica ; Volume 23, Issue 3 , 2016 , Pages 1160-1174 ; 10263098 (ISSN) Rezaee, M ; Kazemeini, M ; Fattahi, M ; Rashidi, A. M ; Vafajoo, L ; Sharif University of Technology
    Sharif University of Technology  2016
    Abstract
    In this paper, oxidation of H2S into elemental sulfur over synthesized aluminabased nanocatalysts was physiochemically investigated and the results were compared with a commercial Claus catalyst. The wet chemical, co-precipitation, and spray pyrolysis techniques were employed to synthesize several alumina nanostructures. Then, the SEM, XRD, and ASAP analysis methods were utilized to characterize in order to choose the best nanocatalyst. The sulfur and H2S contents were determined through the standard UOP techniques. Amongst the synthesized materials, Al2o3-supported sodium oxide prepared through the wet chemical, and Al2o3 nanocatalysts via spray pyrolysis methods were the most active... 

    Recovery of drop in heat transfer rate for a rotating system by nanofluids

    , Article Journal of Molecular Liquids ; Volume 220 , 2016 , Pages 961-969 ; 01677322 (ISSN) Zeibi Shirejini, S. R ; Rashidi, S ; Abolfazli Esfahani, J ; Sharif University of Technology
    Elsevier 
    Abstract
    This paper simulates Al2O3-water nanofluid flow and forced convection around a rotating circular cylinder. The governing parameters are Reynolds number (1 ≤ Re ≤ 100), solid volume fraction of nanoparticles (0 ≤ φ ≤ 0.05) and non-dimensional rotation rate (0 ≤ α ≤ 3). The simulations are performed to study the effects of mentioned parameters on the heat transfer rate and fluid flow characteristics. The governing equations including the continuity, momentum, and energy equations are solved with a finite volume method. It is observed that the reduction of heat transfer with increase in rotation rate is in the vicinity of 6.9% and 32% for Re = 5 and 100, respectively at φ = 0.05. Furthermore,... 

    Effect of nanoscaled reinforcement particles on the structural evolution of aluminium powder during mechanical milling

    , Article Powder Metallurgy ; Volume 52, Issue 2 , 2009 , Pages 151-157 ; 00325899 (ISSN) Razavi Hesabi, Z ; Kamrani, S ; Simchi, A ; seyed Reihani, M ; Sharif University of Technology
    2009
    Abstract
    This paper presents experimental results on the synthesis of nanostructured aluminium matrix nanocomposite powders by comilling of nanoscaled SiC and Al2O3 particles and micrometric aluminium powder. The effect of the nanometric reinforcement particles on the mechanical milling (MA) process of the soft matrix was studied by scanning electron microscopy, X-ray diffraction (XRD), transmission electron microscopy, laser particle size analyser and standard metallographic techniques. It was found that at the early stage of milling, the nanoparticles are smeared on the surface of the aluminium powder and thus do not significantly contribute in the MA process. As the milling continues, the hard... 

    , M.Sc. Thesis Sharif University of Technology Bakhshi, Bahare (Author) ; 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... 

    Softening behaviour of alumina reinforced copper processed by equal channel angular pressing

    , Article Materials Science and Technology (United Kingdom) ; Volume 30, Issue 2 , February , 2014 , Pages 220-226 ; ISSN: 02670836 Ranjbar Motlagh, S ; Maghsoudi, M. H ; Serajzadeh, S ; Sharif University of Technology
    Abstract
    In this present work, the softening behaviour of Cu-1·1 wt-%Al2O3 alloy containing nanometric alumina particles was investigated. Single pass equal channel angular pressing was first applied on cylindrical specimens, and then, the deformed samples were subjected to annealing treatments in the temperature range of 700-1000°C. Afterwards, finite element analysis, microstructural observations, Vickers hardness and shear punch testing were employed to study strain distribution as well as the recrystallisation behaviour of the examined alloy. It was found that the alloy is softened at 800°C or above, which shows its high thermal stability. Furthermore, a very fine completely recrystallised... 

    Wear characteristics of aluminum matrix nanocomposites with Ce-TZP/Al 2O3 nanocomposite produced by powder metallurgy at different sintering temperatures

    , Article TMS Annual Meeting, San Antonio, TX ; 2013 , Pages 1103-1110 ; 9781118605813 (ISBN) Soltani, N ; ABahrami ; Pech-Canul, M. I ; Sharif University of Technology
    2013
    Abstract
    In this work the effects of sintering temperature on the hardness, friction and wear characteristics of Al-10Ce-TZP/Al2O3 composites have been investigated. Aluminum and Ce-TZP/Al2O3 nanocomposite were selected as raw materials. Ce-TZP/Al2O3 nanocomposites were synthesized by the aqueous combustion method. 7 wt. % 10Ce-TZP/Al2O3 composites in the form of cylindrical samples were prepared at the sintering temperatures of 400, 450 and 500°C under an applied pressure of 600 MPa for 60 min. Wear tests were carried out using the pin-on-disk method under normal loads of 10 and 20 Kgf at constant sliding velocity of 0.25 m/s. The surfaces of the worn nanocomposite were examined by scanning electron... 

    Sintering of Al2O3-SiC composite from sol-gel method with MgO, TiO2 and Y2O3 addition

    , Article Ceramics International ; Volume 37, Issue 5 , 2011 , Pages 1681-1688 ; 02728842 (ISSN) Mohammad Rahimi, R ; Rezaie, H. R ; Nemati, A ; Sharif University of Technology
    2011
    Abstract
    Al2O3-SiC composite ceramics were prepared by pressureless sintering with and without the addition of MgO, TiO2 and Y2O3 as sintering aids. The effects of these compositional variables on final density and hardness were investigated. In the present article at first α-Al2O3 and β-SiC nano powders have been synthesized by sol-gel method separately by using AlCl 3, TEOS and saccharose as precursors. Pressureless sintering was carried out in nitrogen atmosphere at 1600 °C and 1630 °C. The addition of 5 vol.% SiC to Al2O3 hindered densification. In contrast, the addition of nano MgO and nano TiO2 to Al 2O3-5 vol.% SiC composites improved densification but Y2O3 did not have positive effect on...