Sharif Digital Repository

The objective of this investigation was obtaining sound Friction Stir Welded (FSWed) Commercially Purity Titanium using suitable Tool’s Materials (for Shoulder and Pin) in order to be able to work in high temperature (>1000 ˚C) with great mechanical properties and minimum wear during process. Consequently, different materials and designs for Tool, such as High Speed Steel tool, Tungsten based tool, Tungsten Carbide (WC-Co) based tool and diverse tool geometry and designs like simple design, threaded design, fixed pin and inserted pin (adjustable pin) was used. The results demonstrated that using simple cylindrical WC-Co for pin and Tungsten for shoulder resulted in joints with the best... 

In this research, the effect of addition of titanium to the weld metal of API 5L-X70 steel at two levels of manganese (1.4 and 2.0%) was studied; and the microstructure, mechanical properties, and hydrogen cracking resistance of the weld metals were investigated carefully. The submerged arc welding method was used for preparation of the welds and the metallographic test, hardness test, longitudinal tension test, Charpy V-notch impact test, HIC and SSC evaluation tests and thermal desorption spectroscopy test were done for each weld. The results showed that the addition of titanium to the weld metal increased formation of acicular ferrite; therefore, toughness of the welds was increased... 

Porous titanium and titanium alloys products are proper to use as implants which because of good properties such as high corrosion resistance, good biocompatibility, high strength to weight ratio and low elastic modulus. Porosity induces a decrease in elastic modulus and an increase of bioactivity. In present work, porous specimens of pure titanium and Ti-26Nb-1Si alloy were produced via conventional powder metallurgy route by applying low pressure. The influence of TiH2 Powder addition on some physical and mechanical properties of samples was investigated. The amount of TiH2 powder was used in the range of 0-40 weight percent. The powders were firstly mixed for 3 hours and then compacted... 

In this experiment, first the Fe and Al powders with atomic ratio of 25 and 75 were mixed by mechanical alloying process. After obtaining the optimum conditions of milling, nano structural Fe3Al powder was synthesized by 40 hours alloying with a Ball to Powder Ratio (BPR) of 20:1. The synthesized powder was then milled with different weight ratios of titanium and Cr for 30 hours. Morphological changes, size of powder particles, lattice strain, grain size and phase transitions were studied for different powders in different time spans during milling process by means of scanning electron microscopy, X-ray diffraction and grain size analyzer. The smallest grain size gained for milled powder... 

This study was performed to synthesize Ag-doped TiO2 nanotubes and investigate the antibacterial property of the nanostructure. In the first step, self-organized TiO2 nanotubes were fabricated through anodizing in an electrolyte containing 0٫3 Wt% NH4F, 0٫2٪V DI water and ethylene glycol. Anodizing was performed in 30 and 60V for 2hrs in order to have different nanotube diameters. In the second step, photoreduction process was done on the way to dope Ag nanoparticles on the nanotubes. Herein, AgNO3 solution concentration, time period of TiO2 nanotubes soaking in the solution, time period of UV irradiation and ethanol solution concentration were taken as factors to achieve Ag nanoparticles in... 

Tungsten Inert Gas (TIG) process and different cored wires that were filled separately with nano TiC particles, micro TiC particles and graphite powders were employed to produce surface composite coating on CP-Ti substrate to improve wear resistance. At first using titanium strips, wire drawing process and different powders various cored wires were produced and then using TIG, these cored wires were coated on CP-Ti. This process was done for different current intensities and velocities. Composite coating tracks were found to be affected by the TIG heat input and the kinds of the cored wires. The microstructures of the surface composite coating showed phases of α'-Ti and primary and dendritic... 

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... 

During this research, ceramic coatings on titanium substrate were prepared by plasma electrolytic oxidation process at a constant current density. Effect of different parameters such as frequency, current density, additives and time on the characteristics of the coated samples was studied. Composition, structure and elemental distribution of the coatings were studied by XRD, SEM and wave-length dispersive spectroscopy (WDS), respectively. Various tests were carried out to calculate the amount of coatings porosity. Pin-On-Disk method was used to evaluate erosion resistance of coatings. Corrosion and erosion-corrosion behaviors of the coatings were studied in 3.5wt% sodium chloride aqueous... 

Titanium and its alloys have wide applications in industry and recently researches have been expanded in this area. The main reasons are unique features of titanium such as biological behavior, corrosion resistance and high strength to weight ratio. The fundamental problem of titanium is low wear resistance that leads to be worn in industrial applications. For more efficiency of titanium, extensive efforts have been made for solving this problem, one of the best solutions is coating.Micro Arc Oxidation (MAO) is a novel method to create ceramic coatings on metals to improve wear and corrosion resistance. In this research nano alumina particles were added to electrolyte to create... 

In present study, a CP-Ti surface was coated with cored wire electrodes filled with graphite powder by means of TIG cladding technique. The process was performed under controlled atmosphere with different composition of Argon and Nitrogen. The parameters of the process were changed in order to investigate the resulting effect on the coating microstructure and the wear properties. The microstructure and the composition in the weld and heat affected zone were carefully investigated by optical microscope, SEM, EDS and XRD. As the result, TiC dendrites were produced in-situ with different morphologies which are dependent on variation of the parameters. Moreover, TiN dendrites were in-situ... 

The rapid pace of development of nanoscience and nanotechnology and their applications in various fields have made the study of materials in smaller scales more important than any time ever. Having an insight of materials’ microstructure and the mechanism of different phenomena in the atomic scale will be very beneficent in designing new and advanced materials or modifying the current manufacturing processes. Since molecular dynamics (MD) method has been well known as a mean of studying materials in atomic scale, it has been used in this study to investigate two different phenomena. The selection of the appropriate interatomic potential is of great importance in MD; Embedded Atom Method... 

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... 

In this study, ternary metal oxide coating consisting of Ti, Ru, Ir were prepared by sol-gel method. In order to achieve optimal conditions, the effect of number of layers, temperature and velocity of the heat treatment, the amount of ruthenium and iridium, polymeric additive on the coating and also, comparisons of binary and ternary oxide coatings were studied. The corrosion behavior was examined by anodic polarization and cyclic voltammetry tests and accelerated stability test (AST), the morphology of coatings was studied by field emission scanning electron microscopy (FESEM), phase and elemental analysis was performed using X-ray diffraction (XRD) and energy dispersive spectroscopy... 

Plasma electrolytic oxidation is the novel surface engineering technology that used as the low cost and eco-friendly method for improvement of corrosion resistance and wear resistance of Mg and Ti alloys. The aim of this investigation is firstly joint the Ti and Mg, then optimization of coating process condition of Ti-Mg couple for achieve the best corrosion and wear resistance of coating. For this purpose, initially Ti and Mg were joint together by friction stir welding treatment and then the effect of coating variable such as type of electrolyte, coating voltage, coating time and the concentration of the bath constitute, on the coating properties were investigated, and then the effect of... 

In this project, a ceramic biocompatible coating was applied on Titanium which is included Hydroxyapatite by AC Plasma Electrolyte Oxidation method. First, coating was performed in 5 different solutions and various duration in 500mA/Cm2 as a current density. Then, by microscopic and macroscopic images and size of porosity and also thickness of coat, 3 solutions were chosen for adding nanoparticles: Solution 1 which includes NaH2PO4 and Ca(CH3COO)2 , Solution 3 which includes Ca(CH3COO)2 and Na-Beta G and Solution 4 which includes Ca(H2PO4)2, HMP, NA2(EDTA) and Ca(CH3COO)2 . Also the time 10 minutes was chose as a appropriate time. The average of the porosities size in solution 1 was about... 

Improvement of biological properties by modifying the composition and morphology of the surface layer is one of the main goals of using plasma electrolytic oxidation (PEO) for coating titanium implants. The purpose of this research is formation of biocompatible coating containing calcium, phosphorus and silicon on titanium by two-step PEO method in DC, constant voltage mode. In addition to good corrosion properties of the resultant coatings in simulated body environment (SBF), Having good adhesion due to the use of electrolytes with useful elements for biological function in both step of coating process rather than acidic electrolytes which are incompatible with the body environment, this... 

In the present study, the electrochemical oxidation process was introduced as a green process for complete degradation and removal of non-biodegradable pollutants from aquatic environments and effluents of various industries without the need to use chemicals and toxins. Research stages include comprehensive preliminary studies in the field of electrochemistry and wastewater treatment, software design of electro-oxidation reactor using titanium mesh anode and stainless steel cathode mesh inside a body made of polypropylene, designed cell construction and then evaluation of device performance in polluting environment Are different. In software simulation using COMSOL MULTIPHYSICS software, it... 

In various industries such as aerospace, biomedicine and automobile manufacturing, they seek to manufacture light parts with complex geometry and acceptable mechanical properties. Additive manufacturing processes have gained a special place in the field of rapid prototyping, reverse engineering, mold production, etc. brought It is very important to know the mechanical properties, especially the fatigue behavior of the parts obtained by this method. In this research, the stress-fatigue life graph of parts made of Ti-6Al-4V (grade 5), which is one of the most widely used alloys in aerial structures, was extracted by selective laser melting. For this purpose, several standard fatigue test... 

Connecting titanium and aluminum alloys is widely used in different industries such as transportation, chemical, aircraft manufacturing, etc. Friction stir welding is one of the methods of joining these two metals. In order to obtain a sound joint, the formation of intermetallic phases in the interface must be controlled. One of the ways to control these phases is the use of an interlayer, which in this research is the interlayer applied by plasma electrolytic oxidation method with different current densities and coating times. In this regards, first the optimal parameters of friction stir welding were determined. Then, Ti6Al4V and Al6061-t6 welding was performed in the presence of... 

Ti-UIO-66(Zr) nanocomposites have been prepared via a modified one-step solvothermal methodology and evaluated in photocatalytic oxidative desulfurization. Extensive characterization by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDX), ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence spectroscopy (PL), nitrogen adsorption-desorption, and thermogravimetric analysis (TGA), have revealed the role of Ti loading, on Ti speciation and the structure of the composite materials. Their performance have been...