الفهرس 
Corrosion of PipelineOnly 14 pages are availabe for public view
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Abstract
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 life 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 mechanisms, types of inhibitors and literature survey of C-steel corrosion
Chapter two: ”EXPERIMENTAL TECHNIQUES”
It includes the chemical composition of the investigated compounds, preparation of the corrosive medium (hydrochloric acid solution), the investigated 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 discussions and this chapter is divided into four sections:
Section (A):
Evaluation of the inhibitor efficiency by weight loss method in the presence and absence of the used compounds in 1M HCl at 25 ± 10 C. This reveled that the inhibitor efficiency increases with the concentration. from these studies the order of inhibition efficiency of investigated compounds in 1M HCl is found to be:These compounds 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 were found to increase 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 25-550 C using weight loss measurements. The rate of corrosion increases with increasing the temperature together with increase in inhibition efficiency, indicating that the inhibition occurs through chemical adsorption of the additives on C-steel surface. Thermodynamic functions of activation were calculated.
Section (B):
The Electrochemical Techniques which Include:
(1) The results of potentiodynamic polarization measurements for C-steel in 1.0 M HCl solution in the absence and presence of different concentrations of investigated compounds at 25 ± 1 °C. The polarization curves indicated that the investigated compounds influence both cathodic and anodic processes.
(2) Ac impedance spectroscopy measurements for copper in 1.0 M HCl in the absence and presence of different concentrations of investigated inhibitors at 25 ± 1 °C.The values of Rct increases with increase the concentration of the inhibitors and this indicates an increase in the corrosion inhibition efficiency in acidic solution. The value of double layer capacitance decreases by increasing the inhibitor concentration. This is due to the adsorption of these compounds on the electrode surface leading to a film formation on the C-steel surface.(3) The new technique electrochemical frequency modulation (EFM) was used as a rapid and non-destructive technique for corrosion rate measurements for C-steel in 1.0 M HCl solution in the absence and presence of different concentrations of investigated compounds at 25 ± 1 °C.
Section (C):
The third section include theoretical Studies Include the calculation of some quantum chemical parameters for the investigated thiophene derevatives, such as highest occupied molecular orbital (EHOMO), lowest unoccupied molecular orbital (ELUMO), energy gab (ΔE) and dipole moment using semi-empirical PM3 method and discussed the obtained result.