الفهرس 
Chapter One IntroductionOnly 14 pages are availabe for public view
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Abstract
The present work is assigned to study the corrosion behaviour of carbon steel and zinc in 1 molar hydrochloric acid solutions and the inhibiting effect of some plant extracts by chemical and electrochemical methods. The obtained results showed that the inhibition efficiency of these extracts increased by increasing their concentration, so that the adsorption of these compounds is physical and the adsorption of the plant extracts on zinc surface in 1 molar hydrochloric acid follows Langmuir adsorption isotherm while the the adsorption of the plant extracts compounds on C. steel surface follows Temkin’s. Some thermodynamic parameters are computed and discussed. Galvanostatic polarization technique was used as a second method to study the inhibiting effect of the used inhibitors. Also, impedance spectroscopy measurements, and electrochemical frequency modulation measurements were computed and discussed. The charge transfer resistance (Rct) increases and capacitance double layer (Cdl) decreases by increasing the extracts concentration. The surface examination confirms that the investigated compounds adsorbed on the metal surface.