الفهرس 
Chapter (I) IntroductionOnly 14 pages are availabe for public view
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Abstract
The objective of the study was to investigate the inhibiting properties of four newly synthesized surfactants on the corrosion of carbon steel in aqueous solution, especially acidic solutions commonly used in industry. This study consists of three main chapters; the first chapter is an introduction about corrosion (definition, forms, corrosion control), application of steel and its chemical composition, an introduction about surfactants (definition, classification, and applications) and literature survey on using surfactants as corrosion inhibitors for carbon steel. Chapter two includes the materials used in the study and the experimental techniques. This chapter also includes the chemical composition and preparation of the investigated metal, test solutions, inhibitors solution, the instruments, and the techniques used for the corrosion measurements such as chemical technique, electrochemical techniques, and surface characterization techniques. The third chapter presents the results obtained from the study and discusses these results in three parts. The first part presents the results obtained from chemical measurements on corrosion of carbon steel (CS) in 1.0 M HCl containing different concentrations of the prepared surfactants by Mass Loss (ML) technique. The results revealed that the existence of inhibitors in the aggressive solution decreased the corrosion rate (CR) and increased the inhibition efficiency (%η), and therefore, the adsorption of inhibitor molecules on the CS surface, leads to the formation of a protective layer on the metal surface, which retard both the anodic and cathodic reaction sites in the test solution of corrosion. The temperature effect on CR of CS in 1.0 M HCl solution with and without different concentrations of the inhibitors was studied at temperature range 25-45 oC. the inhibition efficiency was found to decrease with increasing the temperature. This indicates that the surfactants are physically adsorbed on the CS surface. Several mathematical relationships for the adsorption isotherms have been tested to fit the experimental data for the present work. The best fit was followed by Langmuir isotherm which represents the relation between (C/θ) and C of the tested compounds where it gave the highest regression coefficient factor (R2). The second part presents the results obtained from the electrochemical measurements on corrosion of CS in 1.0 M HCl containing different concentrations of surfactants by 1) Potentiodynamic polarization (PP) measurements were conducted on CS in 1.0 M HCl in the absence and presence of different concentrations of the investigated surfactants. The polarization curves confirmed that these compounds interfere with the cathodic and anodic process. The inhibition values were in good agreement with that obtained from ML measurements. 2) Electrochemical impedance spectroscopy (EIS) measurements were carried out for CS in 1.0 M HC l with and without different concentrations of surfactants. from EIS data, we conclude that the charge transfer resistance (Rct) increases with increasing the concentration of inhibitors while the double layer capacitance (Cdl) decreases and the %η obtained from the EIS technique were in good agreement with those obtained from ML and PP techniques. 3) Electrochemical frequency modulation (EFM) measurements were carried out for CS in 1.0 M HCl in absence and presence of different concentrations of the prepared surfactants. from the EFM data, we conclude that the corrosion current density decreases with increasing the concentration of inhibitor, The inhibition efficiency (%η) increases with increasing the inhibitor concentration and the results obtained from EFM technique were inconsistent with previous ML, PP and EIS measurements. Finally, the third part, which presents the carbon steel surface examination by Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDX) analysis and Atomic Force Microscope (AFM). SEM and AFM images suggest that the inhibitors adsorbed on the metal surface forming a protective film that protects the surface from corrosion attack. EDX analysis confirmed the presence of inhibitor molecules on the CS surface instead of HCl which responsible for corrosion.