الفهرس 
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Abstract
Studies of electrochemistry of metal and alloy are very important fields for scientific and industrial work. The present work includes detailed electrochemical studies on the corrosion of copper in Nitric-Phosphoric acids mixture solution with and without some plant extract as eco-friendly corrosion inhibitors.
This work contains three basic chapters
Chapter one: “INTRODUCTION“
This chapter discusses corrosion theory, the basics of metal corrosion, causes of corrosion, forms of corrosion, types of inhibitors, methods of protection, Literature survey of copper corrosion and aim of this study
Chapter two: ”EXPERIMENTAL AND TECHNIQUES”
It includes the chemical composition of the investigated material, preparation of the used Nitric, Phosphoric acids solution, the used Moringa Oleifera, Tamarix Boveana Leaf extracts 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 include:
3.1-Non Electrochemical Method (Weight Loss Method)
Evaluation of the inhibitor efficiency by weight loss method in the presence and absence of two compounds in 1M HNO3-H3PO4 mixture at 25oC. This revealed that the inhibitor efficiency increases with the concentration.
These inhibitors obey Langmuir 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 copper in 1M HNO3-H3PO4mixture was determined in temperatures 25-450 C using weight loss measurements. The corrosion rate increases with temperature rise and hence the efficiency of inhibition was deoveueed and the adsorption of extract of the copper surface was through physical adsorption. Thermodynamic functions of activation were calculated of investigated compounds.
3.2-Electrochemical techniques:
3.2.1-Potentiodynamic Polarization
Potentiodynamic polarization measurements were carried out for copper in 1 M HNO3-H3PO4 in the absence and presence of different concentrations of Moringa Oleifera leaf (MOL) exrract, Tamarix Boveana Leaf (TBL) extract. The polarization curves indicated that these inhibitors are mixed type inhibitors which influence both cathodic and anodic processes . The inhibition efficiency for copper corrosion in 1M HNO3-H3PO4 at all concentrations in the range 50 – 300 ppm is increase by polarization technique
3.2.2- Electrochemical Impedance Spectroscopy
AC impedance spectroscopy measurements were carried out for copper in 1 M HNO3-H3PO4 in the absence and presence of different concentrations of the investigated compounds under charge transfer control.
from the impedance data, we conclude that:
1-The value of Rct increases with increase in the concentration of the inhibitors and this indicates an increase in the corrosion inhibition efficiency in acidic solution. This is due to the replacement of water molecules present on copper surface by inhibitor molecules
2- The value of double layer capacitance Cdl 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 copper surface, suggesting an increase of the surface coverage (θ) of the inhibitor.
3- The % IE obtained from EIS measurements are close to those deduced from polarization and weight loss.
3.2.3- Electrochemical Frequency Modulation
The new technique electrochemical frequency modulation (EFM) was used as a rapid and non-destructive technique for corrosion rate measurements. It was carried out for copper in 1 M HNO3-H3PO4 in the absence and presence of different concentrations of the investigated compounds.
The obtained results showed good agreement of corrosion kinetic parameters obtained with the EFM, Tafel extrapolation and EIS methods.
3.3-Surface Examination
3.3.1-Scanning Electron Microscope
SEM analysis showed that the inhibitions of the investigated compounds were adsorbed on the metal surface forming a thin layer by which metal was protected from corrosion.
3.3.1-Atomic force Microscope
It is used to give a topographic picture of the copper metal in the presence and absence of the optimal dose of inhibitors
3.4-Mechanism Of Inhibition Action
In conclusion:
The weight loss, polarization, electrochemical impedance spectroscopy (EIS) and EFM measurements support the assumption that corrosion inhibition primarily takes place through adsorption of the inhibitors on the copper surface. Agreement among these different independent techniques indicates the validity of the obtained results.
This thesis contains also references, Arabic and English summaries.