الفهرس 
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Abstract
The thesis consists of three main chapters: Chapter (I) is concerned with an introduction reviewing concisely the relevant literature related to the subject of the thesis, corrosion definition, types and theories of corrosion. Chapter (2) deals with the experimental part. It includes composition of C-steel used, the preparation of the test specimens for the different techniques of measurements and methods of preparation of materials of various solutions used. Also, the procedures followed for corrosion measurements, using weight loss, potentiodynamic polarization, and ac impedance and EFM techniques are including in this chapter. Chapter (3) deals with the results obtained and their interpretations. This chapter is divided into five separated sections; A, B, C, D and E. Section A: studied the effect of concentrations of azodye derivatives (1-5) on the corrosion rate of carbon steel in acidic solutions by weight loss method. Also, The role of anions addition in corrosion inhibition of carbon steel in acidic solutions and their synergistic effect. As well as, studied the effect of temperature on the corrosion rates in the presence and absence of the azodye derivatives in acidic medium. Several adsorption isotherms were assessed and the Langmuir adsorption isotherm was found to be the best description of the adsorption behavior of the investigated azodye derivatives. Section B : This section studied the effectiveness of various concentrations of the investigated azodye derivatives (1-5) on the corrosion rate of carbon steel in acidic solutions by electrochemical technique, namely, potentiodynamic polarization, electrochemical impedance (EIS) and electrochemical frequency modulation (EFM) techniques and the obtained electrochemical parameters were recorded from the different methods. The order of the inhibition efficiencies (%IE) obtained using different electrochemical measurements for corrosion of carbon steel in 2.0 M HCl solution in the presence of azodye derivatives(1-5) is found to be: 1 > 2 > 3 > 4 > 5. It is quite obvious that the data obtained from chemical measurement were in good agreement with the results obtained from and electrochemical measurements. Section C: The surface of carbon steel was examined using FT-IR, Uv-vis and Uv reflectance spectroscopy before and after immersion in the test solutions containing azodye derivatives. Section D: Some quantum chemical calculations were calculated and correlated with inhibition efficiency (% IE). Section E: The influence of the chemical structure of the investigated azodye derivatives on their inhibition efficiencies was discussed; the order of these inhibition efficiencies depends mainly upon the number of adsorption active centers, the Hammett constant, molecular size and complex formation. The adsorption of these derivatives in their neutral and protonated form were considered.