Sharif Digital Repository

Nitinol alloy is important and increasingly used in medicine and industry due to its unique properties such as shape memory and superelasticity. Plasma Electrolytic Oxidation (PEO) is a relatively new method which in electrical discharge occurrence and formation of small plasma arcs on the anode surface and the electrochemical and thermochemical reactions in plasma environment prepare ceramic coating on the substrate. This method is taken into consideration because of its simplicity and effectiveness in the preparation of oxide ceramic coatings with porous structure on the surface of certain metals and alloys to improve their corrosion and wear properties. In this study, to improve the... 

The aim of this project is to load analgesic drug; Paracetamol on dental implant. The implant is titanium alloy (Ti-6Al-4V). There are two kinds of samples of anodized and HA coated onto anodized. They are in the shape of the sheets in this study. The electrodeposition and anodization carried out in order to treat the two samples. Nanotubes were formed during anodic oxidation of the samples in the 1M Ammonium sulfate (NH₄)₂SO4 and 5wt% Ammonium fluoride NH4F electrolyte. They are expected to play role of carrier for the model drug; paracetamol. The results showed that HA anodized Ti-6-4 has the ability to hold higher amounts of drug and also can keep the drug for a longer time than the... 

To investigate the vibrational damping behavior (for application in construction structures) and shape memory effect of Fe based alloy, quaternary low carbon Fe-30Mn-6Si-6Cr alloy having small amounts of carbon and molybdenum were selected. The experimental samples were produced by melting of commercially pure raw materials and hot rolling, cold rolling and machining of the produced ingots. Nano-precipitation treatment was performed on a sample of specific composition. Chemical composition determination, cyclic tension-compression, simple bending, differential scanning calorimetry (DSC), micro hardness, and microstructural studies by optical and scanning electron microscopes (SEM) were... 

In recent years magnesium nanoparticles due to their noticeable differences from bulk and their wide applications in various branches including the ability to absorb hydrogen, application in batteries, activation of propellant, different applications in biochemistry and strengthening secondary phase in composites, are well under investigation. The objective of this study is to find an easy, economical and high purity method to obtain magnesium nanoparticles and to introduce an innovative approach of magnesium nanoparticles synthesis in an industrial scale. To achieve this goal, milling process is applied. Micron-sized magnesium powders with different amounts of sodium chloride salt powders... 

Herein, cupric oxide (CuO)/graphitic carbon nitride (g-C3N4) is synthesized under microwave irradiation for enhanced photoelectrochemical (PEC) performance and photostability. A facile, one-pot method was utilized to directly deposit the nanocomposite onto FTO from a solution containing copper precursor and urea. Possible mechanisms of CuO/g-C3N4 formation and PEC performance improvement were examined via XRD, FTIR, FESEM, XPS, UV-Vis, and PL. Controlled amounts of urea determined the morphological evolution of CuO and the formation of a protective carbon layer, while its excess quantity converted to g-C3N4 in the presence of CuO. Through heat treatment of the nanocomposite, carbon-doped... 

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,... 

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,... 

This research is divided in three parts. In the first part of this research, we report the one-pot synthesis of carbonate-coated nanostructured LLO (Li2CO3@LLO) through a polyol-assisted method as a Li-ion battery cathode. Carbonate protects the cathode from adverse reactions with the electrolyte, also reduces the layered-to-spinel phase transition, thereby stabilizing the cathode structure. LLO nanostructure provides a fast Li+ diffusion. The target material exhibits excellent long-term stability with 77% capacity retention after 1000 cycles at 0.2C-rate. In the second part of research, Li(Na-doped)-Mn-Ni-O oxides were synthesized by different LiOH.H2O amount, type and amount of reducing... 

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... 

Selective Laser Melting (SLM) process is a powder-based metal Additive Manufacturing (AM) technique. This developing industry has many advantages like generation of geometrically complex shapes with high density. High Cost, production and characterization of powders, limited material choices and process parameters optimization are some of the challenges associated with SLM. Stainless steel 316L due to its unique properties, like corrosion resistance, high strength, biocompatibility, availability and cost is indeed a commonly used material in SLM. In this research, the characterization of the powder produced by the flame spraying device, which is a new method, was discussed. Wire with 3mm... 

This research tries to simulate the conditions of nanosized TiO2 powder production from pure commercial precursors, to produce nanosized TiO2 powder by leaching kahnouj ilmenite concentrate. For this purpose, the ilmenite concentrate was first oxidized to study the kinetics and optimization of oxidation process before leaching. Then the effect of pre-oxidation on the iron and titanium leaching efficiency was studied. Then the reductive leaching of concentrate using zinc and iron powders as reducing agent for Fe (III) to Fe (II) reaction was studied. The effect of reducing agent as well as oxidation and reduction on the leaching efficiency was studied. At the next step the optimum conditions... 

In recent years, semiconductor photocatalysts have attracted much attention because of cleanliness, no secondary pollution and profound oxidation and reduction reactions at room temperature. TiO2 is recognized as the best semiconductor photocatalyst due to its higher photocatalytic activity, nontoxicity, electronic and optical properties, chemical stability and low cost. There are some problems preventing from wide application of titania such as rapid recombination of photogenerated electrons and holes, the lack of visible-light utilization and difficult recovery of photocatalyst. In this study, to overcome these problems, TiO2/MWCNTs nanocomposite was prepared. Carbon nanotubes are... 

In this study, at first the V2O5 spent catalysts were characterized. The aim was to identifying whether these catalyst may be regenerated. Then, for feasibility study of them, three methods were applied: washing, diffusion and milling the spent catalysts for their subsequent reproduction. A variety of techniques such as XRD, XRF, AAS, TPR and TPO were applied in order to identify factors contributing in vanadium pentoxide catalysts deactivation. The results showed that approximately all of pollutants caused their performance deterioration, while they still have some active phases. Then, the polluted catalysts were washed (their yield increased from 43% to 72.2%). In the underside of the... 

In this work, the recovery of rhenium from ferromolybdenum furnace outgoing dust in semi industrial scale was conducted. The ferromolybdenum furnace outgoing dust contains rhenium as major part and large amounts of molybdenum plus Iron and copper as impurities. An overall flow sheet, consist of leaching, solvent extraction and precipitation methods, was design to recovery and purification of rhenium. Firstly, ferromolybdenum furnace outgoing dust was subjected to leaching treatment by 10 g/L sulfuric as solvent at 85 C. Secondly, solvent extraction method was employed, using LIX984N 10 %vol, to separate copper from rhenium containing solution. The results of MacCab thiele diagram for... 

Magnesium has recently been considered as a biocompatible metal with mechanical properties close to bone for use in biological applications. On the other hand, the degradation properties of this metal in the physiological environment have made this metal superior to permanent biomaterials such as stainless steel, titanium alloys. The most important challenge of using this alkaline earth metal in the body environment is its rapid corrosion, which causes problems such as alkaline toxicity and loss of supporting role before complete tissue repair. In this study, Mg-Zn-Ag-Cu alloys were manufactured to improve mechanical strength, corrosion resistance and antibacterial properties. Finally, after... 

Water-in-salt (WIS) electrolytes with a wide electrochemical stability window (ESW) have made great progress in the field of aqueous batteries and capacitors. However, the slow diffusion of metal ions, such as lithium or calcium, has limited the use of these devices. Meanwhile, adding an organic co-solvent can improve the penetration of metal ions in salt water electrolytes. This electrolyte category, which has also used organic solvent in addition to water, is called organic/aqueous hybrid electrolyte modification. Since the effect of organic solvent on the performance of aqueous electrolyte in calcium batteries has not been investigated so far, in this research the physical and chemical... 

Graphene quantum dots (GQDs) as a sort of carbon-based nanomaterials are applied in a multitude of exciting areas. They are effective fluorescent probe for many potential biological and medical applications. In comparison to conventional organic fluorescent probes (organic dyes), GQDs have substantial advantages, such as photostability, excellent solubility, low cytotoxicity and biocompatibility.
In this thesis, green fluorescent GQDs have been prepared via solvothermal method from graphite powder.Various analysis methods were utilized to characterization of the product. So, several experiments on GQDs in solution and in solid substrate at room temperature have been performed. The...