الفهرس 
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Abstract
SUMMARY
The corrosion problem is a great problem, 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 C-steel in 1M HCl.
This work contains 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 C-steel corrosion and aim of this study
Chapter two: ” EXPERIMENTAL AND TECHNIQUES”
It includes the chemical composition of the investigated material, preparation of the used hydrochloric acid solution, the used metal organic frame work compounds, solutions and procedures used for the corrosion measurements such as a weight loss and electrochemical techniques.
Chapter three: ”RESULTS AND DISCUSSION”
It deals with the results obtained and their discussion and this chapter is divided into five sections:
Section (A):
Evaluation of the inhibitor efficiency by weight loss method in the presence and absence of three compounds in 1M HCl at 25 0 C. This reveled that the inhibitor efficiency increases with the concentration. from these studies the order of inhibition efficiency of investigated compounds (1-3) in 1M HCl is found to be:
(1)>(2)>(3)
These metal organic derivatives obey langmuir’s adsorption isotherm showing that the inhibition is by adsorption. The degree of surface coverage (θ) for the inhibitors on the metal surface increases with increasing the concentration in the corrosive medium. The action of the inhibitors in the aggressive acid was assumed to be due to their adsorption at the metal /solution interface. The effect of temperature
on the corrosion inhibition of C-steel in 1M HCl was determined over the temperature range 25-450 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 on C-steel surface. Thermodynamic functions of activation were calculated.
Section (B):
The effect of organic compounds on the cathodic and anodic polarization of C-steel in 1M HCl was investigated. Corrosion rate decreased with increasing of concentration of the metal organic frame work compounds together with increase in both cathodic and anodic polarization, but the corrosion inhibition has a great effect on the cathodic polarization. Variation of inhibition efficiency with the structure of metal organic frame work compounds were interpreted in terms of the number of adsorption sites in the molecule and their electron charge density, molecular size, mode of adsorption and the polar effect of the substituent groups. The order of increased inhibition efficiency for C-steel corrosion in 1M HCl at all concentrations in the range (1x10-6 – 3x10-6 -5x10-6-7x10-6-9x10-6M - 11x10-6) by polarization technique is (1) >(2)>(3)
Section (C):
The results obtained from (EIS) show that the corrosion reactions 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 C-steel. The double layer capacitance (Cdl) of the corroding C-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 C-steel surface.
Section (D):
The new technique electrochemical frequency modulation (EFM) was used as a rapid and non-destructive technique for corrosion rate measurements. Corrosion current densities (icorr) obtained with this technique was in good agreement with those obtained from Tafel extrapolation technique. In addition of the causality factors were good internal check for verifying the validity of data obtained by this technique.
Section (E):
SEM analysis showed that the inhibition of the investigated metal organic frame work compounds was adsorbed on the metal surface forming a thin layer by which metal was protected from corrosion.
The influence of the chemical structure of the investigated metal organic frame work compounds on their inhibition efficiencies was discussed; the order of these inhibition efficiencies depends mainly upon the number of adsorption active centers and molecular weight.
In conclusion:
The weight loss, polarization, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) measurements, electrochemical frequency modulation method (EFM) and SEM analysis support the assumption that corrosion inhibition primarily takes place through adsorption of the inhibitors on the C-steel surface. Agreement among these different independent techniques indicates the validity of the obtained results.
This thesis contains also references, Arabic and English summaries.
Chapter Four: ” EXPERIMENTAL TECHNIQUES PART 2”
It includes the chemical composition of the investigated material, the used organic compounds, solutions and procedures used for the corrosion measurements such as an electrochemical techniques.
Chapter five: ”RESULTS AND DISCUSSION PART 2”
Section (A):
These organic derivatives obey langmuir’s adsorption isotherm showing that the inhibition is by adsorption. The degree of surface coverage (θ) for the inhibitors on the metal surface increases with increasing the concentration in the corrosive medium. The action of the inhibitors in the aggressive acid was assumed to be due to their adsorption at the metal /solution interface.
Section (B):
The effect of organic compounds on the cathodic and anodic polarization of C-steel in 1M HCl was investigated. Corrosion rate decreased with increasing of concentration of the organic compounds together with increase in both cathodic and anodic polarization, but the corrosion inhibition has a great effect on the cathodic polarization. Variation of inhibition efficiency with the structure of metal organic frame work compounds were interpreted in terms of the number of adsorption sites in the molecule and their electron charge density, molecular size, mode of adsorption and the polar effect of the substituent groups. The order of increased inhibition efficiency for C-steel corrosion in 1M HCl at all concentrations in the range (1x10-6 – 3x10-6 -6x10-6-9x10-6-15x10-6M - 18x10-6 ) by polarization technique is
(1) >(2)
Section (C):
The results obtained from (EIS) show that the corrosion reactions 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 C-steel. The double layer capacitance (Cdl) of the corroding C-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 C-steel surface.
Section (D):
The new technique electrochemical frequency modulation (EFM) was used as a rapid and non-destructive technique for corrosion rate measurements. Corrosion current densities (icorr) obtained with this technique was in good agreement with those obtained from Tafel extrapolation technique. In addition of the causality factors were good internal check for verifying the validity of data obtained by this technique.
Section (E):
The influence of the chemical structure of the investigated organic compounds on their inhibition efficiencies was discussed; the order of these inhibition efficiencies depends mainly upon the number of adsorption active centers and molecular weight.
In conclusion:
The weight loss, polarization, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) measurements, electrochemical frequency modulation method (EFM) and SEM analysis support the assumption that corrosion inhibition primarily takes place through adsorption of the inhibitors on the C-steel surface. Agreement among these different independent techniques indicates the validity of the obtained results.
This thesis contains also references, Arabic and English summaries.