Sharif Digital Repository

The cathodic protection system was employed for protection of the reinforced concrete of the foundations using the mixed metal oxide anodes embedded in concrete for current distribution. . In this system, after required measurements for zone design calculation of the surfaces current density, IR drop and the circuit’s resistance has been measured. After specifying the appropriate locations for the reference Electrodes (Ag/AgCl) in order for cathodic protection monitoring these three electrodes are installed in three protection zones. After design and supply of all the materials, the installation was started. The protection criterion of steel in concrete was studied and all the measured... 

It is very important to determine why there is still external corrosion on pipelines even though NACE RP0169 criteria are satisfied. The cathodic shielding problem is the most relevant finding to this kind of situation. In this research, the shielding behavior of three types of coatings (FBE, 3LPE and Polyurethane) used in Iranian gas industries are evaluated under laboratory condition by four major procedures. It has been found out that the FBE coating has no shielding effect and instead 3LPE coating has a shielding effect by not allowing electrical conductivity through the coating. Finally, the Polyurethane coating presented a mid-behavior effect but almost near to non-shielding behavior.... 

Selection of appropriate coating system is the most important subject in corrosion control of buried pipelines. Corrosion control of buried pipelines is achieved by using a combination of barrier coatings and cathodic protection (CP). Applying barrier coating can decrease the protection current of CP. However, at the coating holidays the pipeline act as cathode generating hydroxyl ion and hydrogen electrochemically. Therefore the selected coating should be compatible with the alkaline condition.This research focuses on evaluating of an epoxy-tar and a urethane-tar based coating. Coatings performance has been tested by accelerated corrosion test methods (i.e. Salt spray according to ASTM... 

Although using cathodic protection in addition to coating with paint will extend the life of pipelines drastically, it can also accelerate disbondment of coating at coating defects. In this research four usual pipeline coating systems have been examined from applicational aspects and the best coating system among them has been introduced. The four coating systems were consisted of: epoxy coal tar 212 with epoxy 155 primer, solvent free polyamine epoxy 474HG without primer, glasscote 440 witout primer and glasscote 440 with epoxy 155 primer. According to ASTM G8, cathodic disbondment test was accomplished for eight samples simultaneously. During the tests cathodic protection current and... 

Nitrates of lithium, cobalt and nickel were used to synthesize LiNi0.8Co0.2O2 cathode material through sol-gel technique. Various synthesis parameters such as calcination time, temperature, chelating agent and the solvent were studied to determine the optimized condition for processing the cathode nono materials. TG/DTA tests were used to identify the optimized calcination temperature. Different techniques such as ICP, XRD and TEM were employed to characterize the chemical composition, crystal structure, size and morphology of the powders. Micron and nano-sized powders were produced using citric / oxalic and TEA as chelating agent, respectively. Results show that the best condition for... 

In industial applications such as linear accelerators, pulsed lasers, nuclear fusion, radar systems, medical applications and etc. that need great ratio of instantanuse to the average power, pulsed power supplies are used. These power supplies store energy in an energy storage element and discharge this energy to load in a short period of time. The most important characterisitics of them are output pulse quality, reliability and longevity of the resource, efficiency and cost. One of the devices that produce high instantaneous RF power is magnetron tube. In some applications such as radar systems, quality of the output RF is very important and the most important factor that affect the quality... 

Microbial electrolysis cell is a novel technology for hydrogen production. The biggest challenges for this new technology are low rate of hydrogen production and high investment cost.
In this research, catholite condition was investigated for increasing the rate of hydrogen production. Low price stainless steel was used as cathode electrod. The microbial electrolysis cell operated applying 1.3 v external voltage. Basic pH was found to be the best condition for maximum rate of hydrogen production, where the average rate of hydrogen production was 100.006 1.866 L/m3.d. However, the hydrogen production rate for the acidic and neutral cathodic condition, were 92.89 1.13 and 91.845 1.485... 

For improving cost competitiveness of both SOEC and SOFC technology, it is desirable to reduce the temperature of operation preferably down towards 500 oC – 600 oC, as this will slow down the rate of various degradation processes and allow use of much cheaper materials for auxiliary components. In this range, the oxygen electrode typically dominates the cell resistance, and hence there is a need to develop cost effective electrodes with improved performance at low temperature. Whereas the oxygen exchange on Ruddlesden-Popper type Ni based compounds like Pr2NiO4 with interstitial oxygen defects is known to be very fast, reported electrode performance of micron-sized composites based on these... 

In this project, a model which had been suggested for a lithium battery is used with the assumption of using C.N.T instead of activated carbon for the cathode. This battery include lithium foil, C.N.T and solution as anode, cathode and electrolyte. The electrolyte solution consist of lithium salt and a separator. The mathematical solving of the model consisted of using two CPM and DFM methods. In DFM method, a concentration gradient was considered as the driving force for diffusion and in the CPM method chemical potential as the driving force. Furthermore CPM method considered energy interaction between ions. Changing physical parameters of cathode and modification of model parameters... 

In this study, orthosilicate materials with chemical formula of Li2MSiO4 (M one or two transition metal/metals) were investigated experimentally and theoretically as cathode material of Li-ion batteries. The most important material in this category i.e. Li2FeSiO4 was synthesized by three methods including nitrate-based sol-gel, oxalate-based solid state reaction and oxide-based solid state reaction. Based on XRD and SEM evaluations, grain size of synthesized powders was estimated to be between 15 to 100 nanometers. Of these three methods, oxide-based solid state reaction was employed in this study for the first time. This syntheses method is very important due to the significant lower...