Sharif Digital Repository

Microstructure and mechanical properties developments of X80 weld metal by addition of different amounts of alloying elements such as: Nickel and Manganese in coated electrodes were investigated. For this reason samples were welded by electrodes that Ni value has been changed between 0.8%- 3.2% in tow critical amounts of Mn: 0.7 and 1.6. The weld quality was evaluated using nondestructive testing methods (NDT), such as visual inspection and radiography. Tensile test, Charpy impact test and microhardness results indicated the suitable range of Ni and Mn for achieving acceptable mechanical properties. In addition, optical microscopy and scanning electron microscopy (SEM) were applied to link... 

ZnFe2O4 nanoparticles have been successfully prepared through a controlled microwave–assisted co-precipitation as well as conventional co-precipitation. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM) were used for the structural, morphological and magnetic investigation of the product. Average particle size was obtained as 12 nm from XRD. Catalytic activity of ZnFe2O4 nanopowder for O-acylation of alcohol and phenol has been investigated. A trace amount of ZnFe2O4 has been effectively used as a nanocatalyst for the acylation of alcohol and phenol in acetic anhydride.

 

So far, investigations have shown that open dielectric resonator antennas (DRAs) offer several advantages at microwave and millimeter wave frequencies. These advantages include small size, large impedance bandwidth, high radiation efficiency, ease of manufacturing and simple feed-coupling mechanisms (such as probe coupling, aperture coupling or proximity coupling to micro-strip lines). Most microwave ferrites have dielectric constants in the desirable range and they can be used in place of dielectric materials. Such ferrite resonator antennas (FRAs) offer a potential advantage in that their permeability tensor can be controlled by applying an external magnetic field. Up to now and by the... 

In this study, transformation of austenite to ferrite under continuous cooling condition of a low carbon steel was investigated. In the first step, a heat transfer model was employedconsidering governing heat transfer boundary conditions and a microstructure model based on Cellular Automaton method was used simultaneouslyto predict austenite to ferrite transformation progress. The influence of pre-heating temperature and primary austenite grain size on the final ferrite grain size and distribution were perdected. To verify the simulation results, experimental processes were utilized. The microstructure distribution was determined by means of Clemex Pro software then, these results were... 

Circular polarization (CP) is one of the common polarization types used in wireless systems for frequency identification (RFID), global positioning (GPS) and wireless local area networks (WLAN), since it can provide greater flexibility in orientation angle between transmitter and receiver, and better mobility and weather penetration than the linearly polarized antennas. Magnetic permeability in ferrites can be tuned by external magnetic field ; So ferrites can be good candidates for new reconfigurable CP antenna technology. In this project, we will consider circularly polarized slot antenna with a wide axial ratio beamwidth that consists of a normally magnetized ferrite substrate mounted... 

Dark and light conductivity has been investigated in Ca-doped bismuth ferrite thin films. Higher conductivity in the order of 105 magnitude of pure Bismuth ferrite has been observed for Bi0.85Ca0.15FeO3-δ. Structural analysis using Rietveld refinement showed a deviation from volume reduction for Bi0.85Ca0.15FeO3-δ that could be the reason of the abnormally high conductivity for this compound. Although higher calcium doping reduced conductivity but photoresponse could be revived. Atomic Forec Microscopy investigations showed that surface roughness decreases with increasing calcium concentration. Enhanced photoconductivity is reported for Bi0.7Ca0.3FeO3-δ with ~2.9 eV direct optical band gap... 

In this research, for optimization of repair welding of control valve and flange that use in East Oil& Gas Company, effect of chemical composition, microstructure, hardness and stress relive on sulfide stress cracking (SSC) investigated with select of four electrodes. All welds were prepared by shielded metal arc welding (SMAW) and investigated with optical microscope, hardness test, tensile test and SSC test. The results showed that increase of nickel content in the range of 0.032–1.58 wt. % in weld metals, decrease of acicular ferrite and increase of side plate ferrite, grain boundary ferrite and M/A micro constituent in microstructure. Ni3S2 decrease SSC resistance and (FeCu).S increase... 

The ability of Ferro spinels to catalyze the reactions, along with their ability to become easily separated, has attracted many attentions. These Ferro spinels are synthesized in an efficient way and are used as a catalyst for carbon-carbon bond formation. Nanoparticles of Spinel ferrites, for instance three-metal ferrites, have unique characteristics and have very interesting and important applications in synthetic organic chemistry. In the first section of this thesis, synthesis and analysis of copper cobalt ferrite is considered. In the second section, several organic chemical reactions are investigated to evaluate the catalytic activity of these nanoparticles. Finally, the catalytic role... 

In this study, the aging of the LiFePO4/graphite cell was investigated in two different types of 18650 Li-ion batteries during cycling at various C-rates (0.5, 1, 2, 3, 4C) and high temperature under long-term cycling. An amount of 20% Capacity loss was considered as the end of the cycling. Batteries with a capacity of 1500 mAh after this capacity drop, experience 60, 120, 1502, and 2155 cycles, at the rates of 4, 3, 2, and 1C , and batteries with capacity of 1400 mAh was also 60, 360, 1100, 1000, and 805 cycles at a rate of 0.5C. Capacity decrease of the cell is in linear relationship with cycle number and the slope of the capacity-fading line increases with elevating current rate. Aging... 

The main aim of present thesis is to synthesis and characterize of ferrite nanocomposites as a new generation phtocalyst and their application in degradation of various types of environmental pollutants in different irradiation time and dark conditions. Ferrites have been used anchored to carbon allotropes such as graphene oxide and carbon nanotubes, in order to improve their photocalytic activity as well as phase structure, textural and optical properties. Firstly, a new SnS2-BiFeO3/rGO nanocomposite has been prepared to increase the visible-light-responsive photodegradation of organic dyes such as cationic methylene blue (MB) and anionic methyl orange (MO). The obtained results showed... 

In this study, low carbon steels were joined with TLP bonding method; using a Fe based interlayer. Transient Liquid Phase bonding is a diffusional process in which as tempreture rises a melting point depressant element difuses in to the base metal and as a result the interlayer will isothermally solidify. Due to the fact that Ferrite grain size can effect the amount of diffusion which is taking place, in this study the effect of this variable on the isothermal solidification time was investigated using steels with different initial grain sizes. Microstructural studies indicated that as the mean grain size increases the time needed for the isothermal solidification to complete increases.... 

In this research, we focused on demonstration of features and advantages of supercritical fluids technology to formation of fine particles (nano and micro scales) from bulk materials (solid) and synthesized metal oxides nanoparticles. Therefore, using two different fluids, carbon dioxide and water, and two completely different methods, the Rapid expansion of supercritical solution and supercritical hydrothermal, were used to produce fine particles of drug (acetaminophen) and nano metal oxide (zirconium dioxide and bismuth ferrite). The summary of this research are as follows:1. The solubility of acetaminophen in SuperCritical-Carbon Dioxide (SC-CO2) with and without menthol as a cosolvent... 

So far, investigations have shown that open dielectricresonator antennas(DRAs) offer several advantages at microwaveand millimeter wave frequencies and make them appropriate in low directional-gain applications . These advantages include small size, large impedance bandwidth, high radiation efficiency, ease of manufacturing and simple feed-coupling mechanisms (such as probe coupling, aperture coupling or proximity coupling to micro-strip lines). Most microwave ferrites have dielectric constants in the desirable range and they can be used in place of dielectric materials. Such ferrite resonator antennas (FRAs) offer a potential advantage inthat their permeability tensor can be controlled by... 

In the first chapter, high substituted pyrrole derivaitives were synthesized through a one pot four compounent reaction using carbonyl and amin compounds at the presence of magnetic nanoparticles of superparamagnetic ferrospinel NiFe2O4nanoparticles as catalyst.In the second chapter, NiFe2O4magnetic nanoparticles were employed in the Sonogashira reactions using phenyl acetylene as coupling partner with different types of aryle and alkyl halides in water as a green solvent. The results of these reactions were considered comprehensively  

The effect of alloying elements such as Chrome, Molybdenum and Chrome-Molybdenum on microstructure and mechanical properties of submerged-arc weld of structural St37 and 4135 Chromoly Steel was investigated. Addition of alloying elements was done through flux and slag-weld metal reactions. Bonded flux was used to achieve this purpose. Mechanical properties were studied by means of Longitudinal Tensile, Hardness and Charpy V-notch tests. Microstructure was studied by means of Optical and Scanning Electron Microscope. The results show that chromium increase Ultimate Tensile Strength (UTS) and impairs Impact Toughness (IT), although it increases the percentage of acicular ferrite (AF). In the... 

This study investigates effect of cold roll prior to inter-critical annealing on microstructure and mechanical properties of ferrite-martensite dual phase steel. Samples were heated to 850oC for 1h followed by oil quench, then the steel sheet were cold rolled by 0%,10%,15% and 20% reduction in thickness, Then an inter-critical annealing(750oC,120min) was performed to generate a ferrite-martensite microstructure. Microstructural study showed that increase in applied Cold roll, leading to increase volume fraction of martensite and decrease in ferrite grain size. Mechanical properties of dual phase steel were tested by Tensile test, impact test and micro-hardness Test. Results shows that... 

Due to many vast application of C-C bond formation in the areas including bioactive compounds and natural products, over the past few years, the C-C coupling reactions have become a versatile tool in organic synthesis.First, a two-metal catalyst (CoFe2O4) was synthesized and its catalytic activity was evaluated in unsymmetrical thioether synthesis which offered an odorless, ligand-free and aryl halide-free rout for the formation of desired products. The catalyst was recovarable and was able to catalyze the reaction for 10 runs with retention of catalytic activity.In the next step, three-metal catalyst (CoCuFe2O4) was synthesized using the co-precipitation method and characterized.Then, these... 

Ferrite spinels are very valuable as heterogeneous catalysts and have the ability to separate. In this dissertation, ferrite nanoparticles were synthesized by co-precipitation method and used in carbon-phosphorus and phosphorus-sulfur bond formation reactions. The structure of these compounds was investigated by different techniques. The ferromagnetic CuFe2O4 ferrite catalyst was expanded in the C-P bond formation reaction, resulting in a convenient and efficient method. Phosphorylation of alkenes was performed using a model reactant, dialkyl phosphite as a source of phosphorous compounds, and beta-ketophosphosphonates were synthesized. Beta-ketophosphonates are important intermediates for... 

In present work, we fabricated novel heterojunction magnetic composite and the goo visible-light-harvesting photocatalysts through integration of ZnFe2O4 and MIL-53 by facile solvothermal method. To understand physical and chemical structure prepared material and morphology of samples, The XRD,FTIR, FESEM, DRS and VSM analysis were carried out. The ZFO/M53Fe/vis-light system reveled 92.3% dye degradation which enhanced photo catalyst reactivity for the decolorization of Direct red 23 as anionic dye under irraditation of LED lamp through AOP environment friendly technology, which are significantly higher than those of pure ZFO and M53Fe semiconductors. more ever ,aforementioned composite... 

In this study, CoFe2O4/CuO nanocomposite was synthesized by hydrothermal method and utilized for removal of metronidazole in electro-Fenton process. Nanocomposite was characterized by FT-IR, XRD, FE-SEM, VSM and BET methods. The Results of XRD patterns confirmed the monoclinic structure formation for copper(Ⅱ) oxide and the spinel structure for CoFe2O4. The FE-SEM images displayed the formation of CuO nanosheets for copper(Ⅱ) oxide and the decoration of cobalt ferrite nanoparticles on the surface of CuO nanosheets. Measurement of the surface area of nanocatalysts using BET isotherm represented the high surface area for CuO nanosheets and the increase of surface area of nanocomposite in...