Thesis & Dissertations

Water cooling system is commonly used for cooling automobile internal combustion engines and large industrial facilities such as steam electric power plants, hydroelectric generators, petroleum refineries and chemical plants. Although the corrosiveness of the natural seawater depends on many variable factors, the main cause of the corrosiveness of seawater is chlorides. Seawater is one of the most abundant, efficient, and inexpensive cooling mediums avilable. The dissolved salts in the seawater create a number of engineering challenges including salt deposition. Deposit accumulations in cooling water systems reduce the efficiency of heat transfer and the carrying capacity of the water distribution system. In addition, the deposits cause oxygen differential cells to form. These cells accelerate corrosion and lead to process equipment failure. This is why periodic de-scaling and cleaning in hydrochloric acid pickling solutions are necessary. HCl is one of the most commonly used acids, among the acid solutions for acid pickling, industrial acid cleaning, acid descaling, oil well acidizing, and manufacturing processes in different industries. An industrial civilization depends upon the stability of metals. Complex design requirements can make it necessary to combine different metallic materials to obtain the desired performance. The selection of appropriate materials in a given environment is a key factor for corrosion control strategy. Materials selected for marine applications are selected to maintain the integrity of the structure and to be corrosion resistant. Traditional ferrous metals such as steel and stainless steel are continuously produced and machined. Aluminum owes its excellent corrosion resistance to the presence on the metal of a film of natural oxide that consists of alumina (Al2O3) and makes the metal “passive”. When exposed to environments containing halide ions, the oxide film breaks down leading to the formation of pits on the aluminum surface. The corrosion resistance of stainless steel is based on the bilayer structure of the spontaneously formed passive films on their surface in aqueous solutions. Steel is the most versatile, least expensive and widely used engineering material which has found extensive application in various industries. However, the corrosion resistance of steel is relatively limited. This causes many corrosion problems to be arising in the related industries. The aim of the work is to evaluate the behaviour of: 4,6-dichloro-2-(methylthio) pyrimidine, DCMTP; N, N, N′, N′-Tetramethyl-p-phenylenediamine, TMPPD on the corrosion of steel, stainless steel, and aluminum in 0.5 M NaCl and 1.0 M HCl. This study was investigated by electrochemical impedance spectroscopy (EIS) technique and potentiodynamic polarization measurements. The effect of temperature which has a vital effect on the rate of metal electrochemical process has been studied. Different adsorption isotherms were fitted to clarify the nature of adsorption.