The present thesis consists of four chapters that throws the light on studying the corrosion behavior of`α-brass in the acidic media using the potentiostatic polarization. Each chapter discusses many topics can be demonstrated as following:
1. Chapter one discusses the introduction topics about corrosion, corrosion forms, electrochemical aspects and copper alloys.
2. Chapter two discusses the experimental procedures and techniques about characterization of the pomegranate and red apple peels and the polarization study.
3. Chapter three discusses the outcome results from experimental work, the activation calculations and adsorption calculations.
4. Chapter four demonstrates the highlights, conclusions and recommendations that come from the discussed results.The outcome results can be summarized as follow:
1. The characterization techniques (GC-MS) and (FT-IR) proved the presence of many organic compounds that responsible for the inhibition performance of the pomegranate and red apple peels.
2. The potentiostatic results show that the corrosion current density,corrosion rate and penetration rate increase with increasing temperature within the range (293-313) K.
3. The inhibition efficiency and surface coverage increase with increasing the concentration of both of the inhibitors (pomegranate and red apple peels). And decrease with increasing temperature.
4. The polarization results revealed that red apple peels was best inhibitor in both of acidic media.
5. Pomegranate and red apple peels were act as mixed-type inhibitor in H2SO4 solution and as cathodic inhibitor in HCl solution
.6. The activation parameters revealed that the values of E were positive and its values were found to be higher in presence of the inhibitors compared to blank solutions which indicate the difficulty of corrosion process in presence of inhibitor. The values of ΔHaa were positive meaning the endothermic nature of corrosion process. The ΔS values were mostly negative and increase toward positive direction indicating that the activated complex represents association rather than dissociation.
7. The thermodynamic parameters of adsorption showed that the values of ΔGº were large and negative which indicating that the adsorption process is spontaneous and its values were between (37.27 - 42.25)kJ.molads-1 which indicate that the adsorption of these inhibitors operate mostly via chemisorption mechanism. The large values of K indicate the formation of stable protective film by those inhibitors. The values of ΔHº were negative indicating the exothermic nature of the adsorption process. The ΔSº ads values were positive meaning the increase in randomness when the adsorption process occurred
.8. The XRD analysis proved the formation of ZnS and CuCl in H and HCl respectively and proved that the inhibitive performance of the pomegranate and red apple peels which they preventing formation of
those compounds.
9. The SEM micrographs show that damage of the alloy surface in the corrosive solutions (H2SO and HCl) and proved the adsorption of the used inhibitors.
