Sharif Digital Repository

In this project ,it has been done different surface treatment on 6 samples of nitinol with 40 % prosity,three of them are anodized by H2SO4 ,Hf, Acetic acid, one of them is treated with plasma spray with TIO2 powder, one of them is putted in the furnace at 700 degrees for an hour, and the last one is bare ; Moreover, these treated samples are putted in Simulated body fluid for 16 days . After this period of time, we analyzed the results. Then the cell adhesion amount of osteo blast cells (MG 63) is measured to these samples by immersing them for 3 days in these cells.The results are investigated by SEM ,XRD(X pertpro produced by Panalitical), XRF(530-XRF-01), AAS( AA240), Roughness measuring... 

Magnesium is one of most important elements in bio hedroxyapatite. Magnesium effects on all stages of bone growth metabolism. Also increases bone’s osteoblastic and osteoclastic activities. That’s why incorporation of Mg ions into hudroxyapatite structure has become one of interesting fields for bone implants production. In addition Mg can improve sintering and mechanical properties of HAp. Thet’s why in this investigation the effect of incorporated Mg into HAp structure has been studied. Three kinds of powders have been prepared to perform this study. Pure HAp nano powder produced via sol-gel method, Mg contain HAp nano powder produced via sol-gel method and a mixture of nano HAp and nano... 

Solar energy is one of the man's solutions to cope with problems involved in exhaustible fossil resources. In this regard, using photocatalysts is a practical and rational pproach.Nanotechnology facilitates using catalysts and photocatalysts with more productivity.TiO2 semiconductor is one of the most popular material in this field but its efficiency is low by several factors such as being inactive in visible light, recombination and the high cost of using noble metals. In this research, we tried to fix these limitations by creating a p-n junction TiO2 - NiO nanocomposite. The samples are made by three methods: impregnation, ultrasonic assisted modified impregnation with ammonium hydroxide... 

In recent decades, due to the significant growth of implants’ application and considering the infection of the implants as the most momentous factor in implantation failure, study on the controlled drug release and other biologically active agents in modern drug delivery systems has attracted many kinds of research throughout the world and efforts are being made to use regulated drug delivery systems for implantation which is also the purpose of this current scientific work.To achieve this, the anodizing process was used to fabricate titanium oxide nanotubes (TNTs) to increase the absorption capacity of the drug in the implants and these TNTs were formed regularly and uniformly in an organic... 

In the last decade, a great deal of attention has been paid to the study of synthesis of Nanoparticles, because of the widespread use of this material in applications involving Fuel cells and magnetic devices. In this thesis, we report some interesting features in the electrodeposition of metallic nanoparticles. The electrochemical phase formation of rhenium and nickel on the surface of P-Si (100) substrate plus morphological, topographical and fractal aspects of the accumulated surface were investigated in this research by means of chronoamperometry method and by utilization of AFM and SEM. The nucleation and growth mechanisms on silicon electrode are characterized using cyclic voltammetry... 

This work examines the dissolution kinetics of Sodium meta vanadate in water medium. The effects of temperature, solid/liquid ratio, agitation speed on the leaching kinetics were investigated. the dissolution kinetics was controlled by the internal diffusion at the surface of the Sodium metavanadate particles. The activation energy for the leaching was2/13 kJ/mol. In the current project, we report the preparation of VO_2 nanorods crystals using a ethylenediaminetetracetic acid assisted and Cetyl Trimethyl Ammonium Bromide hydrothermal synthesis route. NH_4 Cl and NaVO_3 solution were used as the starting materials and vanadiumoxide crystals were obtained following growth at 180 °C for 24... 

The use of dental implants has grown considerably in recent years in Iran but this piece is the industrial imported parts that are not yet produced in Iran. So the main purpose of this research was to fabricate a dental implant from Ti-6Al-4V alloy by CNC machining techniques. On the other hand, the poor bonding strength of bioactive coatings and low cell growth on the surface of uncoated implants are the common problems in the use of dental implants. So another aim of this study was to investigate the effect of Nanoscale surface topography and nanostructured coatings on the surface modification of titanium implant in order to improve Osseointegration and the bonding strength of bioactive... 

Due to the ability in producing nanostructured materials, Mechanical Alloying has gained outstanding position in comparison with other materials fabrication techniques. In this research,with different milling condition, Alloying of Ni-Ti-Ag was performed. In order tofabricating the alloy, twodifferent initial materials were employed.In one process, nickel, titanium and silver were used as raw materials, and in another, titanium hydride was used instead of titanium.Initial powders were investigated in planetary mill, SPEX mill and vibratory disc indifferent times. Using XRD, microstructure information and phase analysis was obtained. EDS was employed for determination of elemental... 

The novel Micro Arc Oxidation technique (MAO) is gaining increased attention for depositing thick, dense, corrosion resistant and hard ceramic coating on metals. In this research, the effects of parameters including electrolyte composition and coating time on properties of MAO coatings formed on NiTi were investigated. The surface morphology, thickness and phase composition of coatings were investigated using scanning electron microscope and X-ray diffraction. Corrosion behavior of the coatings was examined by potentiodynamic polarization. Also wear resistance was examined by pin on disk test. It was found that MAO coatings improve corrosion resistance of NiTi. All of these applied... 

Nowadays, because of drastically decrease of copper sulfide ore’s grade, and difficulties in leaching of them, new processes of copper production like bioleaching technique become significant. Finding the optimal conditions for bioleaching, require investing a lot of time and cost. Computer simulation is useful in this case. Temperature, affects the kinetics of dissolution reactions, type and growth rate of bacteria, and finally, rate and amount of recovery of valuable copper metal from ores, so determination of temperature within the bioheap is very important. Thermophiles are better than mesophiles in chalcopyrite bioleaching and in the range of 55 to 65 degree centigrade, thermophiles... 

By consideration of increasing demands to use implants and efforts to get technical knowledge and localization of this implants, considerable research in this field is needed. Therefore, presentation of a coating which is able to provide parameters needed for an acceptable implant is the aim of this study. In this direction, modification of surface of metallic implants in order to achieve nanotubes of titanium oxide, with the purpose of providing biocompatibility was done. On the other hand, because chronic infection of the implant’s surrounding is one of the main important reasons in rejection of implants, 〖TiO〗_2 nanotubes as a drug carrier were used in order to solve this problem. So,... 

Semiconductor-based photo catalysts, titanium dioxide (TiO2) especially, have been extensively studied for the oxidative photo destruction of organic pollutants in wastewaters and hydrogen production as a green energy source. Much effort has been made to remove the restrictions on the use of TiO2 and challenges related to the recovery of powdery photocatalysts. In this study, copper oxide (CuO) and Zirconium oxide (ZrO2) were used to synthesize nanocomposites. Composition of TiO2/CuO and TiO2/ZrO2 with different weight percentages of second dioxide was synthesized by chemical methods and structural properties of samples were studied by X-ray diffraction and scanning electron microscopy.... 

For measuring damping capacity of shape memory alloy, samples containing Fe- 27Mn-6Si-4Cr-4Ni were prepared. In order to produce the alloy 99% pure elemental powders were mixed and pressed in a matrix rod. The packed powders put in 15cc alumina crucibles were held in a 200 °C oven for 10 hours before they were melted inside two–layered alumina and graphite grucible an induction furnace. Resulting samples went under hot and cold rolling, thermomechanical treatment and were shaped into strips by wirecut. Chemical composition ascertainment, Tensile, bending, differential scanning calorimetry (DSC), micro hardness and modal tests were operated. Microstructural investigation was done using... 

Influence of attachment of Multi Walled Carbon Nanotubes (MWCNT) on various nickel nanocatalysts produced by the electroless plating method was investigated via Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Spectroscopy (EDS), Atomic Absorption Spectroscopy (AAS), X-ray Diffraction (XRD), Brunauer-Emmett-Teller (BET) measurements, Temperature Programmed Reduction (TPR) and Temperature Programmed Oxidation (TPO) tests. Application of TPR/TPO data to Kissinger (Redhead) Equation yielded the activation energies of both nickel reduction and nickel oxidation reactions. Addition of MWCNT improved the catalytic effects by easing of... 

Based on the new standards, less than 10 ppm sulfur is allowed for the automotive fuels. This has led researchers to try improving the present conventional methods as well as seeking alternative routes for refinement of the petroleum products so much to comply with the requirements. Since thiophenic fragments such as dibenzothiophene (DBT) are the most durable sulfur compounds in the current hydrodisulfurization method, many studies have been conducted over recent years on how to remove these compounds. In this thesis, the desulfurization of dibenzothiophene from gasoline via adsorption method was studied. In order to carry out the adsorption process, a nanocomposite of graphitic-carbon... 

The g-C3N4/Fe2O3 nanocomposite was produced by the combustion synthesis. The product was characterized by x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FTIR), Brunauer-Emmett-Teller study (BET), Ultraviolet-visible analysis (UV-vis) and photoluminescence measurement (PL). Effect of iron nitrate on stability and photocurrent density under simulated visible-light irradiation was determined. The highest photocurrent density obtained (4.25 μA/Cm2) was twelve times the pure g-C3N4. This improvement was due to a bandgap decrease, the specific surface area increase, reduction of the electron-hole recombination, and... 

Methane steam reforming (MSR) is an assuring reaction using steam to produce H2 as clean energy over a nickel-based catalyst. We synthesized monometallic NiMgAl2O4 and bimetallic NiCoMgAl2O4 catalysts in a two-step combustion method using urea, glycine, and sucrose, as fuel. BET-BJH, XRD, TGA, TPR, FESEM, and EDX-mapping characterized surface area, porosity, morphology, crystalline structure, and metal-support interaction behavior. The products exhibited well-structured, simple MgAl2O4 spinel and NiO without NiAl2O4, in both specimens. The MSR evaluation tests at 750℃ under atmospheric pressure, CH4: H2O feed ratio of 1:1.6 showed the bimetallic catalyst has the highest conversion (99.30%)... 

Electric vehicles and electronics such as laptops and smartphones require an efficient amount of energy conversion and storage. As one of the reliable systems in this field, lithium-ion batteries have high energy density and lower emissions. Cathodic material is a bottleneck in the development of lithium-ion systems due to its high cost and limited energy capacity. In this study, lithium-rich oxide cathode was synthesized in the liquid phase using the co-precipitation synthesis method using six-aqueous nickel nitrate and four-aqueous manganese chloride precursors. The material was analyzed by structural characterization analysis as well as electrochemical characterizations. In this project,... 

In this research, synthesis and characterization of photocatalytic properties of g-C3N4 / TiO2 nanocomposite was carried out. The target of research was to increase the photocatalytic properties of g-C3N4. So at first, g-C3N4 was synthesized from melamine precursor via thermal pyrolysis. Then, TiO2 nanoparticles were synthesized via sol – gel method. g-C3N4 / TiO2 nanocomposite with heterojunction structure was synthesized in one step by thermal pyrolysis of certain amounts of melamine precursor and TiO2 nanoparticles mixture in 550 ℃. Characterization of synthesized samples was carried out by XRD, FT-IR, UV-Vis, PL, BET, DLS and FE-SEM tests. Characterization results showed that g-C3N4,... 

Dry reforming methane is a process during which two greenhouse gases, CH4 and CO2, using Ni-based catalysts, are altered into valuable H2 and CO gases, which are very useful from an economic and environmental point of view. The main problem with Ni-based catalysts is the formation of carbon in the dry methane reforming, which leads to rapid deactivation of the catalyst. In this research, a 10Ni-5Co/Al2O3 bimetallic catalyst was prepared by one-pot microwave-assisted combustion synthesis with a stoichiometric amount of fuel (urea) and without the use of additives. The catalyst was then calcined for 12 h at 550oC. The structure, chemical composition, particle distribution, and morphology of...