الفهرس 
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Abstract
The corrosion problem is of a great importance, which faced the world from the last years until now, we can’t hide this problem from our live but we can reduce “inhibit” it in the metals by several methods as the environment need. This work discusses the corrosion of carbon steel in 2M HCl. This work consists of three basic chapters Chapter one: “INTRODUCTION “ This chapter discusses: corrosion theory, causes of corrosion, forms of corrosion, corrosion migration, types of inhibitors, Literature survey of corrosion of carbon steel and aim of this study. Chapter two: ” EXPERIMENTAL AND TECHNIQUES” It includes the chemical composition of the investigated material, preparation of HCl and investigated derivatives, solutions and procedures used for the corrosion measurements such as a weight loss and electrochemical techniques (potentiodynamic and ac impedance). Chapter three: “RESULTS AND DISCUSSION” It deals with the results obtained and their discussion and this chapter is divided into three sections: Section (A): Evaluation of the inhibitor efficiency by weight loss method for all the organic derivatives in 2M HCl at 30 ± 10 C revealed that the inhibitor efficiency increases with the concentration. from these studies the order of inhibition efficiency of these compounds (I-III) in 2M HCl is: (I) > (II) > (III) These organic additives obey Temkin’s adsorption isotherm showing that the inhibition is by adsorption. The degree of surface coverage (θ) of the inhibitors was found to increase with increasing the concentration of the additives in the corrosive medium. The effect of temperature on the corrosion inhibition of carbon steel in 2M HCl was determined over the temperature range 30-550 C using weight loss measurements. The rate of corrosion increases with increasing the temperature together with decrease in inhibition efficiency indicating that the inhibition occurs through physical adsorption of the additives. Thermodynamic functions of activation were calculated in the presence of different concentrations of organic additives. Section (B): Contains the results of potentiodynamic polarization. The results obtained are presented in many Tables and Figures, also the effect of inhibitors on the cathodic and anodic polarization of carbon steel in 2M HCl solution was investigated. Corrosion rate (Icorr) was found to decrease with increase in the concentration of the additives. The polarization curves indicated that these compounds influence both cathodic and anodic reactions. The order of decreasing inhibition efficiency for carbon steel in 2M HCl at all concentrations used (3×10-5 to 15×10-5M) by polarization is: (I) > (II) > (III) Section (C): The results obtained from (EIS) show that the corrosion reaction in the absence and presence of organic derivatives proceed under charge transfer control. The increase in concentration of the inhibitors leads to an increase in the value of the charge transfer resistance (Rct) i.e. a decrease of the corrosion rate of carbon steel. The double layer capacitance (Cdl) of the corroding carbon steel interface decreases with increase in the inhibitor concentration, suggesting an increase of the surface coverage of the inhibitor due to the adsorption of the inhibitor species at the carbon steel surface. In conclusion: The weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) measurements support the assumption that corrosion inhibition primarily takes place through adsorption of the inhibitors on carbon steel surface. Agreement among these different independent techniques indicates the validity of the obtained results.