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    Theoretical model for evaluating the threshold reduction in roll bonding of Al/Al 2O 3/Al laminations

    , Article Metals and Materials International ; Volume 18, Issue 5 , 2012 , Pages 827-832 ; 15989623 (ISSN) Rezayat, M ; Akbarzadeh, A ; Sharif University of Technology
    Springer  2012
    Roll bonding is the most important stage of the accumulative roll bonding process, which is used to produce high strength composites. The presence of a particle layer at the interface alters the bonding condition and increases the threshold reduction for the commencement of bonding. In this study, the bonding mechanism in presence of powder at the interface is analyzed and a theoretical model is proposed to predict the required threshold reduction in warm roll bonding of commercially pure aluminum sheets as a function of amount of alumina particles at the interface. The model considers the rolling parameters and the effect of amount and size of particles by defining some constants, which are... 

    Roll bonding behaviour of Al-3003/Al-4043 and Al-3003/Zn sheets

    , Article Metals and Materials International ; Volume 17, Issue 4 , 2011 , Pages 665-670 ; 15989623 (ISSN) Movahedi, M ; Kokabi, A. H ; Madaah Hosseini, H. R ; Kiani, M ; Sharif University of Technology
    In the present study, the roll bonding behaviour of Al-3003/Al-4043 and Al-3003/Zn sheets were compared. The bi-layer sheets were produced by a roll bonding process at different reductions in thickness and rolling temperatures. The joint strengths of the sheets were evaluated by peel and bend testing before and after supplemental annealing treatment. The peeled surfaces were examined using a scanning electron microscope. The results indicated that the Al-3003/Al-4043 sheets were bonded with higher joint strength and lower threshold reductions in thickness with respect to the Al-3003/Zn sheets. In contrast to the Al-3003/Zn sheets, significant improvement was observed in the joint strength of... 

    Investigation and Synthesis of Zn-Ni-Mn Three Cationic Electrophosphate Coating

    , M.Sc. Thesis Sharif University of Technology Alimi, Zahra (Author) ; Ghorbani, Mohamad (Supervisor)
    The purpose of this study was to create a three-cationic electro phosphate coating of zinc-nickel-manganese by cathodic method and to investigate the effect of operating variables on the properties of zinc-nickel-manganese tri-cationic electro phosphate coating. Hence, the effects of variables such as coating acidity, coating thickness, coating temperature, coating time and concentration of manganese were studied in the bath on the properties such as coating morphology, corrosion resistance, coating thickness. Coating morphology was characterized by scanning electron microscopy and corrosion resistance by polarization test. The pH values of 1.4, 1.8, 2 and 2.2 were selected, and the results... 

    Formation and Investigation of Zinc-Nickel Two Cathionic Electrophospahte Coating Properties on Galvanized Steel

    , M.Sc. Thesis Sharif University of Technology Barati Darband, Ghasem (Author) ; Afshar, Abdollah (Supervisor)
    By using electrophoaphating treatment in the metal coating process, the operating temperature of chemical phosphating bath is decrease and also difficulties with the use of high temperature bath is eliminated. The aim of this study is investigate the effect of operating parameter on coating properties and also investigation the deposition mechanism of Zn-Ni electrophosphate coating. Coating properties such as morphology, corrosion resistance and porosity of the coating characterized using SEM, polarization test and electrochemical method respectively. The values used for pH effect was 1.6,1.8,2 and 2.2 results indicated that by increasing the pH value from 1.6 to 1.8 the icorr decrease from... 

    The Effect of Different Parameters on the Production of High Alumina Cetzp Al2o3 Nano Composite Produced by Aqueous Combustion Synthesis

    , M.Sc. Thesis Sharif University of Technology Tashi Shamsabadi, Safar (Author) ; Yoozbashizadeh, Hossein (Supervisor) ; Askari, Masoud (Co-Advisor)
    Combustion synthesis is the best and most effective method for producing ceramic nano-composites which is also a simple and economic way of producing very fine powders with high purity. In this method, a series of combustion reactions named aqueous combustion analysis are used for producing single-phase and nano-composite products ,in which the heat produced in reactions are used for completing the phase . several chemical substances such as glycine ,urea ,ammonium acetate and others are used as combustion agents. In order to obtain optimized nano fuel, we produced alumina powder with multiple combustion percentages and composition of 25%moli ammonium acetate (AA) with 75%moli urea was... 

    A case study in vapor phase synthesis of Mg-Al alloy nanoparticles by plasma arc evaporation technique

    , Article Chemical Engineering Journal ; Volume 259 , 2015 , Pages 918-926 ; 13858947 (ISSN) Karbalaei Akbari, M ; Derakhshan, R ; Mirzaee, O ; Sharif University of Technology
    Elsevier  2015
    Alloy nanoparticles in the Mg-Al system were prepared by plasma arc discharge method from the Mgx to Al (45%

    Pressing and Sintering of Ce-Tzp-Al¬2o3 Nanocomposite with a High Percent of Alumina And Investigation of Sinter Condition on Morphology

    , M.Sc. Thesis Sharif University of Technology Ameri Shahrabi, Hadi (Author) ; Yoozbashizadeh, Hossein (Supervisor)
    In this project alumina-zirconia-ceria nanocomposite with 80% mol alumina (0.2Ce0.1Zr0.9O2-0.8Al2O3) was produced by solution combustion synthesis method. In the mentioned method, optimal fuel with composition of 75% urea, 25% ammonium acetate, and stoichiometric amount of glycine (0.75U-0.25AA-1G) was used. Moreover, ammonium nitrate as aid combustion was added to optimal fuel. In order to calcinations, nanopowder obtained from combustion synthesis was heated to 500°C for 1 hour and kept at this temperature for 2 hours. To complete heat treatment, the nanopowder was heated to 1150°C for 2 hours and 10 min and kept at this temperature for 2 hours. Then the specimens were pressed at pressure... 

    The Effects of Alumina Mole Fraction on Morphology and Mechanical Properties of Ce-TZP/Al2O3 Nanocomposite Produced via Aqueous Combustion Synthesis

    , M.Sc. Thesis Sharif University of Technology Vahdat, Armin (Author) ; Yoozbashizadeh, Hossein (Supervisor)
    In the present study, nanocomposite of Ce-TZP/Al2O3 was synthesized via aqueous combustion synthesis. In order to investigate the effects of alumina on the morphology and the mechanical properties of this nanocomposite, four sample with 20, 40, 60 and 80 mole percent of alumina were prepared. At first, the synthesized powders were characterized with scanning electron microscope and X-ray diffraction technique. Then, in order to determine the effects of alumina mole percent on the mechanical properties of the nanocomposite, the powders were uniaxailly compacted with the press of 250 MPa followed by sintering at the temperature of 1400 °C for 4 hours. The density of the compacted powders was... 

    Design and Construct of Nd:YAG Laser and Using it in the Laser Ablation Process of Silver, Titanium and Zinc Element

    , M.Sc. Thesis Sharif University of Technology Gohari kamel, Nasser (Author) ; Sadighi Bonabi, Rasoul (Supervisor)
    The purpose of this project is to investigate the production of nano-micro metallic particles—of different elements—with different characteristics in size and optical property by employing a pulsed laser ablation processes in liquid medium. In this study, the means by which we build the laser, the experimental arrangement of the pulsed laser ablation process, the measurement of the absorption spectrum of generated nano-micro particles as well as the size of the particles are discussed.
    To satiate this aim, we have expressed the manner of constructing the Nd:YAG laser, the power supply circuits, along with its optics. This laser has some advantages such as high energy ~700mj, good... 

    Investigation on the Effect of Concentration Ratio of Iron Cations on the Formation of Carbon Nanotubes Synthezied via arc Discharge in Aqueous Solution

    , M.Sc. Thesis Sharif University of Technology Gheytani, Saman (Author) ; Simchi, Abdolreza (Supervisor) ; Khomamizadeh, Farzad (Supervisor)
    In this work, multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs) were synthesized in an aqueous solution of iron chloride and solfate via arc discharge. Thermogravimetric (TG) analysis showed that the multi layer structures including carbon nanotubes (CNTs) and multi-shell graphite particles were formed when DI-water was used. SWCNTs were synthezied in the presence of the iron ions. The effect of [Fe3+]/[Fe2+] ratio on the CNTs yield were investigated. Raman spectroscopy investigations showed that the highest yield was obtained when the ferric to ferro ratio was one. When the concentration of Fe3+ ion was higher than that of Fe2+, many short tubes were... 

    The Study and Comparison of Serrated Flow in IN600, IN625, and MP35N

    , M.Sc. Thesis Sharif University of Technology Nima Nikpoor Badr (Author) ; Asgari, Sirous (Supervisor)
    A large number of metals and alloys show an irregular plastic behavior called serrated flow when being deformed in a certain temperature and strain rate range. The occurrence of this phenomenon affects the mechanical properties of the material, such as work hardening rate and ductility; consequently, it exerts limitations on the service conditions in which the alloy can be used.
    IN600, IN625 and MP35N are wrought Ni based and Ni-Co based alloys which are thermo-mechanically processed. When these alloys are deformed in temperatures between 300-700 ˚C, serrated plastic flow occurs. In order to investigate the mechanisms responsible for irregularities, hot compression tests were conducted... 

    Improvement of Mechanical Properties of a Mg-Zn alloy using the Micro Alloying Elements

    , M.Sc. Thesis Sharif University of Technology Cheraghi Heyvedi, Hamid (Author) ; Karimi Taheri, Ali (Supervisor)
    The development of new wrought magnesium alloys for automotive industry has increased in recent years due to their high potential as structuralmaterials for low density and high strength/weight ratio demands. However, the poor mechanical properties of the magnesium alloys have led tosearch a new kind of magnesium alloys for better strength and ductility.In this research,a new type of magnesium alloy based on Mg-Zn-Si-Ca system has been developed using the permanent gravity casting process. For comparison, an alloy without Siby the same method was also produced. The effects of trace Si addition on the microstructure and mechanical properties in magnesium alloy with composition of... 

    Experimental Study of Mass Ratio and Carbon Nono Tube Size on Impact Toughness in Composite Polymers

    , M.Sc. Thesis Sharif University of Technology Salmani Givi, Foad (Author) ; Hosseini Kordkheili, Ali (Supervisor)
    Nowadays, composites have wide applications in different industries especially in aerospace industry because of their high strength to weight ratio. Epoxy 5052 for its relatively good mechanical properties and high thermal resistance has vaidly use for manufacturing of large composite components. However; fracture toghness of epoxy resins is not good in comparison to their other exceptional properties. Therefore, researchers have endeavored to improve this characteristic with different approaches. One of these methods is nanotechnology. Since the components in aerospace industry are often under impact loads and impact strength of these materials has been less studied, effect of carbon... 

    Study of Microstructural Changes Associated with Internal Resistance of a Li-ion Battery

    , M.Sc. Thesis Sharif University of Technology Tabean, Saba (Author) ; Asgari, Sirous (Supervisor)
    As one of the main features of Li-Ion batteries, internal resistance severely affects performance and characteristics of these batteries e.g. output power and working voltage. In this study, we tried to understand role of internal resistance on microstructure development and provide a correlative relation between microstructural features and performance of lithium-ion batteries. To catch this target, four types of Li-Ion battery chose, varying cathode type. These batteries were exposed to both normal and severe cycling conditions. Regarding to the key role of current rate on the performance of Li-ion batteries, an extensive research on different types of batteries at various current rates... 

    Feasibility Study of Deposition by SUT-PF

    , M.Sc. Thesis Sharif University of Technology Safarzadehamiri, Ali (Author) ; Vosoughi, Naser (Supervisor)
    Sharif University of Technology Plasma Focus (SUT-PF) is a Mather Type DPF device which has a 39 μF capacitor bank with 14 KV charging ability at its ultimate limit corresponding to 7 KJ stored energy. In the first step of this experiment, a test has been done at three distances 5, 7, 10 cm from anode tip with the different number of shots 20, 30, and 40 at 0 constant angles.In the following, a test is done at 5 and 10 degrees with 40 shots, and PF chamber has been filled up with nitrogen gas. Various tests have carried out for survey of this experiment, the result of which are as follow:The X-ray diffraction (XRD) analysis are used in order to reveal if the Nickel or Nickel nitride have... 

    Fabrication of Al/SiCp Composite and Nano-Composite with Functionally Graded Structure Via Friction Stir Processing

    , M.Sc. Thesis Sharif University of Technology Ziaei, Mohammad Reza (Author) ; Kokabi, Amir Hossein (Supervisor) ; Bagheri, Reza (Supervisor)
    The feasibility to fabricate Al/SiCp nano-composite with functionally graded structure (FG-Al/SiCp) via friction stir processing was studied successfully in this paper. The distribution of well-dispersed nano-SiCp got a range of 6mm×3mm on the cross-section of nano-composite. A compositionally graded structure of nano-SiCp in thickness direction of the 5083Al plate was obtained via four passes of FSP. The percentage of nano-SiCp over 15%, 9% and 5% was found at the depth of 1.0mm, 2.0mm and 3.0mm, under processed surface of 5083Al rolled plate, respectively. Results show that the microhardness of FG-Al/SiCp nano-composite can reach steady 46%, 34% and 15% higher than the one of the base... 

    Capturing Co2 of the Atmosphere by Molten Carbonates and Transforming to Carbon Nanofiber

    , M.Sc. Thesis Sharif University of Technology Zarei, Mohammad Mahdi (Author) ; Moosavi, Ali (Supervisor) ; Nouri Borujerdi, Ali (Supervisor)
    Capturing the atmospheric CO2 and turning it into value added products is a topic that has been extensively studied in recent years. One of the methods through which CO2 is valorized is via converting it into carbon nanofiber, CNFs. CNFs can be an important material in future human activities due to its valuable properties such as wide range of electrical conductivity, their superior flexibility and strength, But it is currently obstructed in use due to the high cost of manufacturing and the complexity of the synthesis. Furthermore, in today's world, human life is heavily influenced by greenhouse gases, and avoiding emitting gases like CO2, is almost infeasible. This thesis provides an... 

    Investigation of the Effects of Corrosive Environments on Mechanical and Microstructural Properties of Polymer and Portland Cement Concrete

    , M.Sc. Thesis Sharif University of Technology Ghassemi, Pedram (Author) ; Toufigh, Vahab (Supervisor)
    Polymer concrete is well-known for the quick repair of concrete structures and pavement. Many concrete structures such as bridges, offshore, and pavements are under cyclic loads when they are exposed to different environmental conditions during their lifespan. However, there are relatively few studies on the durability of Polymer concrete. The durability and fatigue performance of these structures are significant issues that should be considered. This study aims to investigate the long-term environmental effects on the mechanical properties of Polymer concrete. Therefore, polymer and ordinary cement concrete specimens were prepared and exposed to four chemical solutions with pH values of... 

    Evaluation of Deformation and Formability Behaviors of the Ferritic-Pearlitic Steel Sheets by Employing the Experimental Approaches and Micromechanical Modeling

    , Ph.D. Dissertation Sharif University of Technology Isavand, Samaneh (Author) ; Assempour, Ahmad (Supervisor)
    A broad range of plain carbon steels have ferrite-pearlite microstructures, which are used in many industrial applications due to the good strength and formability provided by the typical combination of ferrite grains and pearlite colonies. The mechanical behavior of ferrite-pearlite steels inherently originates from the configurations of ferrite grains and pearlite colonies, which comprised alternating lamellae of cementite with randomly distributed orientations in a ferrite matrix. In this thesis, three different experimental-numerical approaches were employed to investigate the deformation behavior, damage mechanisms, and formability of the ferrite-pearlite steels. At the first step, two... 

    A Microstructural Investigation on the Influence of Pore Fluid Osmotic Potential on Volume Changes and Soil Water Retention Curve, Low Plasticity Clay

    , M.Sc. Thesis Sharif University of Technology Heydari, Ali (Author) ; Sadeghi, Hamed (Supervisor)
    Understanding many issues related to environmental geotechnics and soil sciences such as: instability and collapse of soil slopes, sinkholes, leakage from landfills and isolation of nuclear landfills, and optimization Agricultural processing depends on our knowledge of the behavior of unsaturated soils and their volume changes. To better understand the behavior of unsaturated soils, it is important to study the soil-water retention curve (SWRC) and the factors affecting it. These include factors such as porosity, grain size distribution, soil minerals, pore size distribution, and pore water chemistry, which affect soil-water retention curves and volume changes. Since the simultaneous effect...