Sharif Digital Repository

Condensation from a gaseous phase is a common method for the fabrication of metallic nanoparticles. Electromagnetic induction furnaces are the most common equipment used for this method. Since the sample doesn’t touch any foreign object, this method is one of very few ways to synthesize ultrapure nanoparticles. However, a major setback of this method is its low production rate.One of the only workarounds to this issue is to increase the melt’s surface area so as to present a larger surface for evaporation. In the common setup for this furnace the molten sample takes on a spherical shape which unfortunately holds the lowest surface to volume ration of any shape. The endeavor in this study has... 

Silver nanopowder is of great importance for various medical and industrial applications. Due to the significance of the solubility of silver nanoparticles in these applications as well as the high impact of the nanophysical morphology of the powder on their solubility, we prepared nanoparticles with plate morphology by the chemical reduction of silver nitrate in a soluble phase. Then we measure its solubility in a phosphate buffer salt, which greatly resembles the human blood chemically. The size and shape of the resulting nanosilver powder and also the use of non-toxic materials in their synthesis are important factors in the production of nanosilver powder.We confirmed the successful... 

Titanium nanoparticles were synthesized by chemical vapor condensation (CVC) process. Titanium tetrachloride (TiCl4) as titanium’s precursor reacted with potassium as reductant, in vapor phase and the products were titanium nanoparticles encapsulated in potassium chloride. Dried Argon gas was employed as carrier gas. Resulting powders gathered in ethanol bath. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and atomic adsorption spectroscopy (AAS) analysis were used to characterizing the products. The effect of Argon gas flow on nanoparticles size was investigated in this research. The particle size decreases with increasing Argon gas flow. The size of nanoparticles was under... 

In This project high purity Zinc (Zn) Nanoparticles were synthesized using Electromagnetic Levitation Melting Gas Condensation method. In this method the designed coil plays an important role on melting and suspension of the material and our design was costumed specifically for zinc nanoparticles. For each batch of synthesized Zn nanoparticles, 1.5 gr zinc platelet was levitated in the costumed coil and the effect of different parameters on the size and distribution of nanoparticles, was investigated including in- different cooling gas (He, N2 and Argon), gas flow rate, and the pressure inside the chamber. Inert gas was used to cool supersaturated vapor above the molten droplet and eliminate... 

Much research has been done in the electromagnetic levitation process, but there is not any information about carrying out this process to refine steel continuously. In this study inclusion behavior of molten steel in contact with slag, in the presence of an electeomagnetic field, has been investigated. The steel sample, in an elliptical section, was levitated in an electromagnetic field, in a chamber containing slag consisting of CaF2-Al2O3-CaO, in order to achieve a continuous process, and changes in time, temperature and slag composition parameters in this process were studied. According to ASTM E45 standard, after performing metallographic process on melted samples, using light... 

In this study, the performance of Inconel 617 anode as an inert anode in aluminum electrolysis process was studied. To carry out the research, first, an electrolyte was produced using NaF, KF, AlF3 and Al2O3 with a molar ratio of sodium and potassium fluoride to aluminum fluoride of 1.33. Next, aluminum electrolysis cell was made using Inconel 617 anode and cathode and the aforementioned electrolyte. To evaluate the Inconel 617 anode, the performance of the electrolysis cell in different conditions of temperature, anode-cathode distance, and excess potential was investigated in a period of one hour. Using anode mass measurements, cell potential and current density and scanning electron... 

High purity titanium nanoparticles were synthesized by utilizing Electromagnetic Levitation Melting Gas Condensation (ELM-GC) method. High purity titanium samples were melted by electromagnetic levitation to a temperature of 1700 ± 20 °C in a silica tube. High purity argon and helium were employed as carrier gases and cooling agent. Particlesize, morphology, and Purity of the produced nanoparticles were studied by Field-Emission Scanning Electron Microscopy (FE-SEM), X-ray Diffraction (XRD), Dynamic Light Scattering (DLS), X-ray fluorescence (XRF), and ICP-AES analysis. The FE-SEM, DLS and XRF studies confirmed narrow size distribution of almost spherical shape pure titanium nanoparticles... 

In the present project, in order to be self-sufficient and optimal use of boron mines in Iran, a study entitled “The effect of process variables on the production of boric acid” has been conducted, This project has two main objectives: the first objective is the production of boric acid from boron sources and mines in Iran and the second objective is to analyze the effect of variables such as temperature, time, acid concentration, solid to liquid ratio and particle size on the purity of boric acid produced. And finally achieve the optimal conditions for the production of boric acid.In this study, boric acid was made from leaching hydrobracite (magnesium-calcium ore with boron) with sulfuric... 

The sponge iron of the Hoganas process have a high metallization degree (93-96%) and its carbon content is about 0.1%. These characteristics are suitable for powder metallurgy but in order to use this DRI for steelmaking, it needs lower metallization degree and higher content of carbon. First, for using Hoganas sponge iron for steel production, 94% of metallization is adequate as some of iron is still in the form of FeO which its reduction in Electric Arc Furnace (EAF) cause better agitation in order to utilize heat transfer. Also, excess carbon content in the DRI can have many advantages other than preventing the sponge iron from re-oxidation. Some of the carbon can be in the form of Fe3C... 

In this study, the recovery mechanism of nickel oxide by carbon dissolved in molten iron with the study of reaction kinetics were investigated. Nickel oxide pellets into molten iron containing graphite were added in the neutral atmosphere and the release of CO gas as a function of reaction time was measured until the end. The volume of gas produced at different times shows the number of moles of Ni metal was revived. Reaction by a) the following decomposition reaction under 1475 °C ; and b) carbon diffusion rate at temperatures over ° C1475 is controlled. The main reaction mechanism in order to a) decomposition of NiO; b) penetration of oxygen atoms in the melt, and c) reaction between... 

Electromagnetic levitation gas condensation (ELGC) method was used to synthesize silver nanoparticles. Silver droplets were melted and levitated stably at about 1130 °C with appropriate flat coils in a 10 mm OD silica tube. High purity argon, nitrogen and helium were employed as carrier gases and cooling media. Morphology and particle size of the products were investigated by scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD) energy dispersive X-ray analysis (EDAX) and dynamic light scattering (DLS). The DLS, SEM and TEM studies demonstrated narrow size distribution of spherical shape Ag nanoparticles with particle size of about 60, 45 and 35 nm synthesized... 

In this study, silver nanoparticles (Ag NPs) with different morphologies were synthesize by physical and chemical methods. Spherical silver nanoparticles were synthesized by electro magnetic levitation melting approach, while silver nanoplates and nanorods were prepared by chemical reduction route. Ag NPs were then coated with thin porous silica shell. The dissolution behavior of synthesized Ag@SiO2 was investigated in PBS at 25, 37 and 55 °C. Spherical and triangular Ag@SiO2 were conjugated by Penicillin G molecules. The silver and penicillin contents of the synthesized nano-antibiotics were determined by ICP-OES and TGA analyses. The nanoparticles were characterized by X-ray diffraction... 

In this study, the effect of two main parameters, time and temperature, were investigated in the roasting process of zinc sulfide of Bafgh’s mine, and kinetics and the mechanism of the roasting reaction were examined, too. The oxidation process was performed in a muffle furnace in the presence of the oxygen of air atmosphere. The raw powder material (with the particle size of 74-250 micron) was poured in Alumina crucibles. The roasting process was run in eight temperatures of 650, 700, 750, 800, 850, 900, 950 and 1000 ◦C. Oxidation percent was calculated in six times of 5, 10, 15, 30, 45 and 60 minutes. The experiments were designed in a way that the effect of each parameter could be... 

In this study, industrial steel (DIN 17135) underwent a new purification process with the aim of removing non-metallic inclusions and producing clean steel. Samples of steel were levitated in synthetic slag from the CaO-CaF2-Al2O3 system by an electromagnetic field. The effect of time, temperature and slag composition factors on the inclusions content of sample has been investigated. The images of the optical microscope were evaluated according to the ASTM E 45 standard, which according to the extracted results, the removal process was done to the desired extent. On the other hand, as the time and temperature of the process and the weight percentage of CaF2 increase, the number and size of... 

In this research copper oxide ores were dissolved under acidic condition. Chemical analysis (XRF) and X-Ray diffraction analysis (XRD) were used to identify the phases and determine the percentage and amount of the elements in the mineral. The results showed that the mineral contains 4.464% by weight of copper, which is malachite in mineral. The experimental design method (DOE) was used to dissolve concentrate by sulfurice acid. The parameters of temperature, time, acid concentration and solid to liquid ratio, as well as the interaction of these parameters on leaching and optimization of parameters were also done by response surface method (RSM). To determine the amount of copper dissolved,... 

Sialons are materials which crystallize in four elements system (Si-Al-O-N). These materials have been widely observed by researchers because of their suitable properties like: high toughness and strength in high temperatures, high resistance to corrosion and stability in thermal shock. Because of these properties,Sialons are anti erosion materials. In this research, by controling the situations, mullite has been synthesized by sol-gel procedure. Then the powder has been ground by ballmill for 12 hours and by spex for 30 minutes. Then the produced powder was mixed with distinct amount of graphite and nano silica and was nitrided in the furnace at 1500 ̊C and was heated for 5 hours. Also... 

The purpose of this project is to survey the created kind of inclusion in super alloyed based nickel. primarily, for this matter for the preparing of super alloyed based nickel, the vacuum induction melting furnace has been designed and built , then for surveying the kind of inclusion the effective parameters such as temperature , timing and material of crucible has been considered accordingly , the material of crucibles was considered based on mud-clay- graphitic- pure graphitic- aluminum- zirconium. From the obtained analysis samples of SEM has been distinguished which, with increasing of the temperature and the time ,the percentage of impurity will go up in super- alloyed and the... 

In this study, the simulation of blood flow through a stenosed coronary artery and a bypass graft are discussed using fluid-structure interaction numerical method. Effects of the geometrical parameters of CABG surgery on hemodynamics have been studied. Investigated hemodynamic variables include shear stress on the vessel wall, the velocity profile in high-risk areas and the pathlines. Lower than 0.5 Pa shear stress on intimal layer of arteries causes the formation of plaque on the wall. Angle of 30 degrees and diameter ratio of bypass to host artery of 1:1 are proposed as the optimum geometry. The distance of the anastomosis from the site of occlusion has no effect on surgery. Also,... 

In the present work, aluminothermic reduction of vanadium pentoxide have been used to produce aluminium vanadium alloys. The effect of addition of lime and excess aluminium on the produced alloy was studied. The experiments were carried out in air and in argon. The alloys microstructure were analyzed bu light and scanning electron microscopy. Other methods such as XRD, XRF, ICP, AAS and titration were employed to analyzed the alloy and the slag. It was found that the addition of lime and excess aluminium increase the yield of the alloy. Vanadium recovery was not affected by the atmosphere used.
 

In current project, high purity nanoparticles were synthesized by use of Electromagnetic Levitation Melting Gas Condensation (ELM-GC) method. In this case high purity aluminum samples were melted by this method to a temperature of 1683 0C in a silica tube. High purity argon and helium gases were employed as carrier gases and cooling agents. To study particle size, morphology, and purity of obtained nanoparticles, Field Emission Scanning Electron Microscopy (FE-SEM), X-ray Diffraction (XRD), Dynamics Light Scattering (DLS), and ADS analysis were employed. The FE-SEM and DLS tests confirmed narrow size distribute of spherical shape pure aluminum nanoparticles under both inert gases. The...