Sharif Digital Repository

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... 

Lead produced by pyrometallurgy method has a number of impurities. Most of these eimpurities can easily be removed, but this property does not apply in the case of bismuth. Since chemical properties of bismuth are close to the lead, refining of bismuth below 250 ppm is difficult and expensive. Because of problems related to electrochemical discussion of the batteries, bismuth it is possible to reduce below than 20 ppm. Jollivet and Dittmer process is capable of reducing bismuth below 20 ppm. As the main goal of this project is to reduce bismuth to small amounts, Jollivet process was used. Potassium needed for Jollivet process, produced by electrolysis of Potassium chloride salt.... 

Lithium is one of the most commonly used metals in industry with a wide variety of applications including batteries, lubricating grease and pharmaceutical products. Demand for lithium is expected to rise with the increasing adoption of electric vehicles. Market reports have predicted that world lithium demand will increase by 2.5 times from 2010 to 2020. Therefore, there is a pressing need to develop new sources of lithium to support this anticipated increase in demand. Lithium can be extracted from salt brine and lithium containing minerals as lithium compounds.
Salt brines are the most abundant lithium sources available in the world, comprising about 60% of all known lithium deposits.... 

Since the discovery of nanomaterials, the nanotubes have found special considerations. The high strength beside the low density, have attracted the interest of the scientists and engineers. Nowadays, one of the common methods to produce composites with high specific strength is to utilize of the nanotubes in the matrix of lightweight metals and alloys such as magnesium and aluminum. Recent researches indicate that very limited focus has been given to the production and properties of the magnesium - carbon nanotube composites and their workability. In this research, magnesium alloy - carbon nanotube composite is produced by casting method and its strength and workability are investigated as... 

In this work, friction stir welding of aluminum to magnesium sheets using alumina and zinc powders was investigated. A preliminary investigation has been carried out on the joining of aluminum 5052 to AZ61 magnesium alloys and finding the optimum welding parameters. The optimum parameters were found to be with the shoulder diameter, pin diameter, and pin height of 14 mm, 5 mm, and 2.7 mm, respectively, with the travel speed of 60 mm/min and rotating speed of 500 rpm. As regards the main purpose of the using zin and alumina powders are controlling of Al-Mg IMCs formation and benefiting from pinning effect of grain boundaries, hence by adopting preliminary investigations and fixing pervious... 

The aim of this study is developing and investigating heterogeneous catalysts based on natural calcite for the transesterification of canola oil and methanol in order to produce biodiesel as a renewable and alternative fuel for fossil fuels. At first calcite was calcined at high temperature to decompose calcium carbonate to calcium oxide. Afterward, Mg-Zr/CaO catalysts were prepared with mass ratio of 2:1 Mg:Zr and different weight percent(2.5, 5,7.5 and 10 wt%) on calcite supported by impregnation method. In order to characterized synthesized catalysts used different analysis such as energy dispersive X-ray (EDX) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy... 

In recent years, severe plastic deformation processes have been widely used to correct the grain size of metals. One of these methods is equal channel angular pressing. In this research, the improvement of mechanical property and structural changes of pure magnesium and AZ91 alloy after the ECAP process are investigated. The mold is made of H13 steel with a 90-degree channel crossing angle and a zero-degree external curve angle. The purpose of this study is to find the smallest average grain size at the optimum temperature on these materials. First, pure magnesium and AZ91 are subjected to the ECAP process at temperatures of 250, 300, 350, and 400 °C to calculate the best operating... 

Cyclic Contraction Expansion Extrusion (CCEE) is a new Severe Plastic Deformation (SPD) method used to refine the microstructure and improve mechanical properties of Magnesium AZ91 alloy. In this study, different CCEE process zones are investigated via optical microscopy to understand this process better. The average grain size in the contraction zone decreased to 8.5 microns from an initial value of 106 microns. In the expansion zone, the average grain size was equal to 4.8 microns. Microhardness tests were conducted to study the improvements in mechanical properties. Microhardness of the sample increased from the initial value of 66 HV to 74.4 HV in the contraction zone and 88 HV in... 

This research explored the corrosion effect of NaCl solution on the surface quality of AZ31 magnesium alloy. Cubic-shaped specimens were immersed in standard 3.5% NaCl solution for 1, 2, 3, and 4 hours. The size of corrosion pits, fatigue crack propagation area, and surface topology were characterized. Fatigue tests were carried out on pre-corroded AZ31 specimens under different stress amplitudes. The correlation between the corrosion time and the virtual crack size was obtained. The virtual crack size is a new parameter that can relate the corrosion to the fatigue life. A new model was proposed to map the surface topology on the virtual crack size of pre-corroded AZ31 magnesium alloy. The... 

Due to compability of Magnesium with the body, it is a suitable material for making biodegradable stents, Althogh, its mechanical properties are not desirable for stent application. Accordingly, lately, magnesium’s microstructure and mechanical properties have been improved using various methods, including the process of severe plastic deformation (SPD). Many severe plastic deformation methods have been introduced for the fabrication of ultrafine grain tubes till now, which the process of tubular channel angular pressing (TCAP) is the most effective one. In the first part of the research, Magnesium tubes with a thickness of 1 mm were processed using the TCAP with a trapezoidal channel, and... 

Electromagnetic levitation(EML) provides a process producing nanoparticles using gas condensation method. In gas condensation processes, vapor is produced by heating the sample then inert gas is applied to provide the inert atmosphere and also cool and condense the sample vapor into a nano powder to obtain a sample nanoparticle. In the EML method, rapidly alternating electromagnetic field induces eddy current in the conducting sample which will heat the sample. The current in the sample result in an induced magnetic field. Consequently, the sample droplet is heated and levitated simultaneously by an induction furnace as a generator. The sample temperature is dependent on parameters such as...