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Modification of Surface Nanostructure and Mechanical Properties by Friction Stir Processing in Al 5083 with Al2O3 and Cu Particles
, M.Sc. Thesis Sharif University of Technology ; Kokabi, Amir Hossein (Supervisor) ; Akbarzadeh Changiz, Abbas (Supervisor)
Abstract
Al 5083 is a non-heat treatable alloy that widely used in the aerospace and automotive industry due to its low density and high strength. However, poor wearing behavior and low elastic modulus restrict its engineering applications. Metal matrix composites (MMCs) have advantages of high strength and modulus by reinforcement of second phase. Also, MMCs have excellent dimensional stability, damping capacity and wear, creep and fatigue resistances as compared with the corresponding monolithic alloys. Vast loss in ductility and toughness occurs by non- deformable ceramic reinforcements. For the surface engineering purposes, ceramic particles are added in the surface layers of components, whereas...
Evaluation of Bonding and Mechanical Properties of Metal-Polymer Sheets Manufactured by Roll Bonding
, Ph.D. Dissertation Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor) ; Kokabi, Amir Hossein (Co-Advisor)
Abstract
Emission of the greenhouse gases is a great concern and use of lightweight materials in transport vehicles has found a major importance in this respect. Metal/polymer laminated composites are of great interest due to their special mechanical properties and thoughness. Application of metal/polymer sheets is limited because of low bonding strength of metals and polymers in these sheets, which is not sufficient, to endure the stresses and strains during deformation processes such as deep drawing and bending. In this research, roll bonding of AA5052/Polypropylene sheets is investigated and the effects of bonding parameters on strength are evaluated and finally the bonding mechanisms during...
The nano-based theranostics for respiratory complications of COVID-19
, Article Drug Development and Industrial Pharmacy ; 2021 ; 03639045 (ISSN) ; Hashemian, S. M. R ; Memarnejadian, A ; Akbarzadeh, I ; Hossein Khannazer, N ; Vosough, M ; Sharif University of Technology
Taylor and Francis Ltd
2021
Abstract
High morbidity and mortality caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has made coronavirus disease 2019 (COVID-19) the leading challenge for health experts all over the world. Currently, there is no specific treatment for COVID-19; however, thanks to worldwide intense attempts, novel vaccines such as mRNA-1273 (Moderna TX, Inc.) and BNT162b2 (Biontech/Pfizer) were developed very fast and FDA approved them for emergency use. Nanomedicine-based drug delivery can be an advanced therapeutic strategy to deal with clinical complications of COVID-19. Given the fact that SARS-CoV-2 typically affects the respiratory tract, application of inhalable nanoparticles (NPs)...
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
FGM sheets with component or grain size gradient in their thickness direction provide mechanical and physical gradient properties through ND direction. FGMs are fabricated by various methods including centrifugal casting, powder metallurgy, PVD and CVD,all of which suffer from some shortcomings such as porosity of the products, low rate and high cost of production and restrictions on mass production. In this study, 2 and 4 layered Al matrix FGM sheets containing SiC and Al2O3 powders were fabricated by laminating method of Accumulative Roll Bonding(ARB). Two approaches of stacking were chosen as accumulative coupled roll bonding (ACRB) and (ASRB) for initial roll bonding and subsequent...
Using ARB Process for Metal Matrix Foam and Composite Production
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
Metal matrix composites (MMC) and metal foams (MF) have been the topic of numerous researches during the last decades. The appropriate mechanical and physical properties of these materials make them useful in various industries. In this research, a unique approach is introduced for producing MMCs and MFs in which accumulative roll bonding (ARB) is employed in order to achieve a homogeneous distribution of ceramic particles in the metal matrix. Also, foamed structures can be made by subjecting Al/TiH2 composite to an appropriate annealing heat treatment where TiH2 particles decompose to hydrogen and titanium. In this work, the effect of number of ARB cycles on the size and distribution of...
Bonding Feasibility, Mechanical Properties and Formability of Three-layered St/AZ31/St Composites Fabricated by Roll Bonding
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
New materials as hybrid materials or laminate composites, due to combination of many properties, can be used in many industries. The aim of this research is bonding of three-layered St/AZ31/St composite by roll-bonding process. The roll-bonding process was performed at three preheating temperatures, 340, 400 and 450 ⁰C, with thickness reduction of 30 to 68% and different thicknesses of intermediate layer (AZ31). In order to improve the bonding strength, the as-rolled specimens were annealed at constant temperature of 375 ⁰C. For evaluation of bond strength and investigating the formation of a diffusion layer, the results of peel test and microscopic images were studied. Tensile specimens...
Using FSP Method to Create Composite and Surface Foam with Distribution Gradient of Particles and Porosity as FGM and Study of Physical and Mechanical Properties
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
Nowadays, the tendency to use Al/SiC composites with FGM structure has increased in the automotive and aerospace industries, because in this type of composite, the properties can be gradually changed in the direction of thickness. For example, one composite surface is used as a wear-resistant or high-temperature-resistant coating, and the other surface can be welded, has high thermal conductivity, or has a good toughness. In recent years, methods have been used to make surface composites, most of which are in the molten state and at high temperatures. In this case, the reactions between the compounds can not be easily controlled and the possibility of the formation of undesirable or...
Design and Manufactur, Medical Stent at Stainless Steel 316L
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
Due to increased mortality from Coronary Heart Disease, it is important to work on ways to treat this disease. An effective method of treatment on this disease is the coronary stent implantation. There are nearly two decades passed since implanting the first heart stent. The main objective of this research is design and manufacturing of the medical stents of stainless steel 316 L. Stent materials should have excellent corrosion resistance and biocompatibility. Various materials such as stainless steel 316 L, platinum alloys, niobium alloys, cobalt alloys are used for manufacturing the stents. In this project, at the first stage seam tube was prodected with laser welding of a tube with...
Effect of Geometric Distortion on the Flow Field and Performance of an Axisymmetric Supersonic Inlet
, M.Sc. Thesis Sharif University of Technology ; Farahani, Mohammad (Supervisor)
Abstract
Inlets must decelerate the air with lowest loss and drag together with a given pressure and Mach number with best quality and uniformity to the engine. This is done based on flight Mach number, by an arrangement of shock waves and surfaces gradient in the inlet. Any distortion in the flow field and the inlet geometry parameters may disrupt such arrangement and influence on the inlet performance, in addition, under critical conditions, it might affect the stability of the intakes. Any distortion in the flow field and the inlet geometry parameters may disrupt such arrangement and influence on the inlet performance, in addition, under critical conditions, it might affect the stability of the...
Deposition of Ceramic Nanoparticles on Aluminum Sheet by Air Gun Spraying for ARB Processing of Nanocomposite Sheets
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
Particle reinforced aluminum matrix composites have considerable attraction in automotive and aerospace industries due to their special properties as light weight, high ratio of strength/density, improved elastic modulus, low coefficient of thermal expansion and high wear and corrosion resistance. Among the production processes of metal matrix composites, accumulative roll bonding process has particular importance due to producing ultrafine grained composite sheets. However, uncontrolled and undesired agglomeration of particles is the main problem in producing these composites. In this research, the Al2O3 and SiC nanoparticles were electrostatically stabilized against agglomeration by...
Evaluation the Effect of Thermo-Mechanical Parameters on Microstructure and Texture of Electrical Steel for Improving Magnetic Permeability
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
Dependence of some magnetic properties such as core loss and permeability on temper rolling was studied in this thesis. It is shown that with a proper temper rolling sharper textures are obtained in the electrical steel and the magnetic properties in the longitudinal and traverse directions are improved. By texture analysis, it is shown that because of temper rolling, shear strain on the surface of the sheet is the main factor for abnormal grain growth and shear texture formation on the surface. The result of formation of this texture is enhancement of the {100} intensity and reduction of the {111} intensity, leading to the improvement of the permeability. Temper rolling is always...
Hot Workability of a Free-cutting Steel with Severe Sulfur Segregation During Continuous Casting
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
Splitting in ingot cast structures and transverse cracks in continuous cast structures are the main problems of hot rolling of low carbon resulfurized free-cutting (LCRF) steels. Presence of high volume fraction of manganese sulfide inclusions in cast structure increases the risk of alligatoring in hot rolling. Because of high sulfur content of these steels and probability of formation of low melting point phases, minimum level of manganese and maximum level of copper and tin is necessary. Morphology of manganese sulfide is another important factor in hot forming of these steels, which can be controlled by level of deoxidation in steel making. In fact, MnS2 is present in fully killed...
Hot workability of a high carbon high chromium tool steel
, Article Materials and Design ; Volume 46 , 2013 , Pages 654-659 ; 02641275 (ISSN) ; Naghdy, S ; Sharif University of Technology
2013
Abstract
In this work, hot tension tests were conducted on as cast and wrought samples of a high carbon high chromium tool steel to study the hot workability under the rolling conditions. The flow curves illustrate the classical shape of dynamic recrystallization (DRX). It is observed that broken carbide nets in the wrought samples result in lower deformation activation energy 398. kJ/mol in comparison to the as cast samples 432. kJ/mol. Necking strains were calculated using the inflection point of the work-hardening (θ) vs. stress curves. Wrought samples show higher hot ductility and lower maximum stress than the as cast ones. It is shown that lower activation energy of deformation and lower stress...
Optimizing the geometry of a half-toroidal CVT
, Article Powertrain and Fluid Systems Conference and Exhibition, San Antonio, TX, 24 October 2005 through 27 October 2005 ; 2005 ; 01487191 (ISSN) ; Zohoor, H ; Sharif University of Technology
SAE International
2005
Abstract
In this research a model is developed which calculates the torque transmission efficiency of a half-toroidal CVT as a function of variator geometry, gear ratio and input torque. The different criteria which are considered to be important in a half toroidal CVT performance are torque transmission efficiency, variator weight, roller fatigue life and bearing torque loss. Variation of geometrical characteristics such as roller curvature, number of power rollers, aspect ratio and half cone angle affect these criteria in different ways. Therefore, in order to find the optimal quantity for each geometrical parameter an optimization problem should be developed. The objective function of this...
Fabrication and Investigation of the Microscopic Structure and Mechanical Properties of Zx00 Magnesium Alloy by Applying the Multi-Directional Forging Process on Extruded and Homogenized Samples
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
Magnesium and its alloys have gained significant attention in medical applications due to their good biocompatibility. However, their widespread use has been limited by some inherent drawbacks, such as poor mechanical properties. The ZX00 magnesium alloy has been used in medical applications, including implants, due to its slow degradation rate and good ossification. However, this alloy lacks sufficient strength and ductility. The severe plastic deformation method can create an ultrafine grain structure and improve mechanical properties. In this study, to improve the mechanical properties and create an ultrafine grain structure, the multi-directional forging process was performed on...
Sensitivity analysis of torque transmission efficiency of a half-toroidal CVT
, Article 2006 SAE World Congress, Detroit, MI, 3 April 2006 through 6 April 2006 ; 2006 ; 01487191 (ISSN) ; Zohoor, H ; Sharif University of Technology
SAE International
2006
Abstract
In this research a computer model based on elasto hydrodynamic fluid film lubrication is developed in order to calculate the torque transmission efficiency of a half-toroidal CVT variator. Validation of this model is verified by comparing the experimental and the model results. Sensitivity of torque transmission efficiency to eleven parameters is investigated. These parameters are: dimensionless roller curvature, aspect ratio, half cone angle, fluid viscosity index, pressure constant for Roelands model, input rotational velocity, absolute viscosity at atmospheric pressure, Young modulus of disks and power rollers, Poisson ratio of disks and power rollers, number of power rollers and variator...
Effects of Rolling Process on Mechanical Properties and Formability of Reinforced Polymeric Matrix with Stainless Steel Mesh as Cladding Composite Sheet
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
In this study, the mechanical properties of composite sheet polymer matrix reinforced with steel mesh were investigated. This bonding was carried out by rolling of a three layers of steel mesh in between two composite polymer sheets. Then, the effective parameters of process; Sample maintenance temperature inside the furnace, reduction during rolling, rolling speed, rolling direction and Number of rolling passes were investigated to determine the optimized processing conditions. In this way, adding mesh to the polymeric matrix improves the strength and polymer / polymer bond in the sandwich structure. Placing the mesh in the sandwich structure converts the brittle behavior of the polymeric...
Experimental Investigation of Formability and Mechanical Properties of Composites Manufactured by Direct Roll Bonding
, M.Sc. Thesis Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
In this study, the ST14 low carbon steel sheet was used as a skin layer in the construction of three-layer laminates. The use of this steel was due to its high mechanical properties and excellent formability. A thermoplastic polyurethane sheet was also used as the core layer. The selection criteria of this polymer were no need for adhesive (for bonding metal to polymer) as well as proper mechanical properties (elongation and strength) and physical (density). The perfect process for manufacturing three-layer laminates is the roll bonding process. To manufacturing a laminate with the desired properties of the designer, the rolling parameters (rolling speed and thickness reduction) must be...
Texture and Microstructure of Ultra Fine Grained Structure Produced by Accumulative Roll Bonding (ARB) and Warm Rolling Processes in an IF Steel
, Ph.D. Dissertation Sharif University of Technology ; Akbarzadeh, Abbas (Supervisor)
Abstract
Accumulative Roll Bonding (ARB) process has been developed during last decade to produce the Ultra Fine Grained (UFG) structures with high strength. In the present study, a Ti-IF steel was deformed up to equivalent strain of 4.8 at 500 ˚C using ARB process. For comparing the ARB with conventional forming processes, some samples were deformed with similar equivalent strain to ARB conditions at 500 ˚C and 300 ˚C as warm rolling. Moreover, the thermo-mechanical warm rolling was simulated by warm torsion. The ARB and warm rolled samples with largest strains were annealed at 750 ˚C. The microstructure and texture were studied using Electron Back Scattered Diffraction (EBSD) method. The...
A molecular-dynamics study of thermal and physical properties of platinum nanoclusters
, Article Fluid Phase Equilibria ; Volume 280, Issue 1-2 , 2009 , Pages 16-21 ; 03783812 (ISSN) ; Parsafar, G. A ; Sharif University of Technology
2009
Abstract
Metallic nanoclusters are interesting because of their utility in catalysis and sensors. The thermal and physical characteristics of metallic Pt nanoclusters with different sizes were investigated via molecular-dynamics simulations using Quantum Sutton-Chen (QSC) potential. This force field accurately predicts solid and liquid states properties as well as melting of the bulk platinum. Molecular dynamic simulations of Pt nanoclusters with 256, 456, 500, 864, 1372, 2048, 2916, 4000, 5324, 6912, 8788 atoms have been carried out at various temperatures. The Pt-Pt radial distribution function, internal energy, heat capacity, enthalpy, entropy of the nanoclusters were calculated at some...