الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 197 |  |  |
| | | from | 197 | | |
Abstract
The aim of the present work is to study the corrosion behavior of aluminum in 1 M HCl using some natural compounds named (Acacia (Gumarabic), Garlic, Chamomile, Syzygium aromaticum, Domiana, Cassia acutofolia and Drumsticks.
The thesis comprises three main chapters:-
Chapter 1:
This chapter deals with the introduction, which includes definition, classification of corrosion, corrosion inhibitors. Literature survey on corrosion behavior of aluminum in aqueous solutions.
Chapter 2:
Deals with the experimental part include complete description of the working procedures, preparation of solutions, electrode treatment, electrolytic cell and electrochemical measurements.
Chapter 3:
Part (A):
Contains the results of weight loss measurements for aluminum in 1M HCl solution containing different concentrations natural compounds solutions at 30 o c (Acacia (Gumarabic) , Garlic, Chamomile, Syzygium aromaticum, Domiana, Cassia acutofolia and Drumsticks).and also contain the results of weight loss measurements at different temperatures.
These results revealed that these compounds behave similarly and the weight losses generally decrease with increasing the concentrations of these compounds and depend on the nature and type of investigated inhibitors. In addition, the increasing in the temperature has a reverse relationship with the percentage efficiency this means that the adsorption of natural compounds on the metal surface is physically.
The inhibition efficiency of these compounds decreases in the following order:
Acacia (Gumarabic) > Garlic> Chamomile > Syzygium aromaticum > Domiana > Cassia acutifolia > Drumsticks.
Part (B):
This part study the effect of addition of different concentrations of natural compounds on the galvanostatic polarization curves of aluminum in 1 M HCl. Some corrosion parameters were calculated such as corrosion potential (Ecorr), corrosion current density (Icorr), anodic (ba) and cathodic (bc) Tafel slopes. By increasing the concentrations of natural compounds the corrosion current density decrease and consequently the inhibition efficiency is increased.
The adsorption isotherm for each natural compound on the aluminum surface follow Langmuir adsorption isotherm at constant temperature.
Part (C):
This part contains the results of addition the natural compounds on the corrosion aluminum in 1M HCL solution by using electrochemical impedance spectroscopy (EIS). Some corrosion parameters were calculated such as (Rct) charge transfer resistance of Al, dl) capacitance double layer. By increasing the concentrations of natural compounds the charge transfer resistance, increase and capacitance double layer decrease and consequently the inhibition efficiency is increased.
Part (D):
In this part potentiodynamic anodic polarization curves of aluminum in 1 M HCl solution containg different concentrations of NaCl solution were studied. It was found that the addition Cl- ions cause the destruction of the passivation oxide film and initiate pitting corrosion. The pitting corrosion potential for these additives are shifted to more negative values with increasing chloride ion concentrations. Trials were made to inhibit the pitting corrosion of aluminum by using natural compounds in HCl solution. These compounds shifted the pitting potential to more positive values, indicating the inhibiting effect of these compounds.
-Finally the mechanism of inhibition for the additives compounds was suggested.
-This thesis contains also references, English and Arabic summaries.