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ABSTRACT

In this work, Ni and Ni-graphene, Ni-G, films were electrodeposited on copper substrate by potentiostatic deposition. To achieve superhydrophobicity, myristic acid, MA, was used to modify the surface of the electrodeposited coatings. The manufactured Ni film modified with myristic acid, Ni-MA, and the Ni-G film modified with myristic acid, Ni-G-MA, show excellent superhydrophobic, SHP, properties with a water contact angle of 159° and 162°, respectively. The surface morphology of the prepared SHP films was investigated using a Scanning Electron Microscope, and the results revealed micro-nano structures in both Ni-MA and Ni-G-MA films. The Fourier Transform Infrared Spectrophotometer data showed that the Ni-MA and Ni-G-MA films were successfully grafted on the copper metal. The Ni-G-MA film possessed higher chemical stability and mechanical abrasion resistance than Ni-MA. The Ni-MA and Ni-G-MA films exhibit long-term durability in the outdoor environment for more than four months. The potentiodynamic polarization and electrochemical impedance spectroscopy results demonstrated that the SHP films on the copper substrate exhibit remarkable corrosion resistance in 0.5 M NaCl.

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The corrosion of aluminium in 1M HClO 4 at 40°C has been investigated using the potentiodynamic polarisation technique. The effect of various inorganic additives has been investigated. It was found that NO 3 , NO 2 and SCN anions exhibit an inhibiting action on acid corrosion of aluminium by reducing the general corrosion rate as well as raising the pitting potential E p . It was found that CrO 2 4 ions were unique in demonstrating a remarkably high inhibiting action but their in uence on the pitting potential was less pronounced than that of the group above. On the other hand, added halides induced an accelerating effect on the corrosion rate and lowered the pitting potential. However, SO 2 4 ions do not show any signi cant effect on the corrosion behaviour of Al in 1M HClO 4 . The results have been interpreted on the basis of the adsorption mechanism followed by incorporation into the native lm.

Superhydrophobic films were successfully designed for a copper substrate using potentiostatic deposition of Ni and Ni-graphene composite followed by treatment with stearic acid (SA). A scanning electron microscope was used to examine the surface morphology of the prepared superhydrophobic films, and the results revealed that both Ni-SA and Ni-graphene-SA films have micro-nano structures. FTIR measurements revealed that the copper substrates had been coated with Ni-SA and Ni-graphene-SA films. The Ni-graphene-SA film has the highest chemical stability and mechanical abrasion resistance. Potentiodynamic polarization and electrochemical impedance spectroscopy results indicated that the formulated superhydrophobic films on the copper substrate have high corrosion resistance in 0.5 M NaCl.

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The corrosion behavior of steel in water from certain oil fields with various organic inhibitors was studied by applying potentiodynamic technique at pH 5.9. The inhibitors which were used include 2-methylbenzimidazole (I), 2-mercaptobenzimidazole (II), 2mercapto-5-methylbenzimidazole (III), and 2-mercaptothiazole (IV). The inhibiting efficiency of the different additives was evaluated from their anodic and cathodic polarization curves at different temperatures.A comparative study of curve fitting procedures using the kinetic thermodynamic model and those utilizing well-known adsorption isotherms was undertaken. Three types of isotherms were used, Langmuir, Frumkin and Flory-Huggins isotherm. The results show that the kinetic-thermodynamic model and Flory-Huggins isotherms are more suitable to fit the data for the four inhibitors, at all applied temperatures. From the values of binding constants, K, the order of inhibitor efficiency is:III > IV > II > I and thus 2-mercapto-5-methylbenzimidazole was the most effective inhibitor. The thermodynamic parameters obtained for all the compounds used showed low values of H ads , which indicates that the action of these inhibitors is physically adsorptive in nature.Mit Hilfe potentiodynamischer Messungen bei pH 5,9 wurde das Korrosionsverhalten von Stahl in Wasser aus bestimmen Ö lfeldern bei Zugabe verschiedener organischer Inhibitoren untersucht. Die eingesetzten Inhibitoren beinhalten 2-Methylbenzimidazole (I), 2-Mercaptobenzimidazole (II), 2-Mercapto-5-Methylbenzimidazole (III), and 2-Mercaptothiazole (IV). Die Inhibitorwirksamkeit der verschiedenen Zusätze wurde aus deren anodischen und kathodischen Polarisationskurven bei verschiedenen Temperaturen ermittelt.Eine vergleichende Untersuchung der Kurvenanpassungen mit Hilfe des kinetisch-thermodynamischen Modells sowie bekannter Adsorptionsisotherme wurde durchgeführt. Dabei wurden drei Arten von Isothermen verwendet, die Langmuir-, die Frumkin-und die Flory-Huggins-Isotherme. Die Ergebnisse zeigen, dass das kinetisch-thermodynamische Modell und die Flory-Huggings-Isotherme bei allen untersuchten Temperaturen besser geeignet sind, die Daten für die vier Inhibitoren anzupassen.Aus den Werten der Bindungskonstanten K ergibt sich die Reihenfolge der Inhibitorwirksamkeit:III > IV > II > I Das bedeutet, dass 2-Mercapto-5-Methylbenzimidazol der wirksamste Inhibitor war. Die für alle eingesetzten Inhibitoren ermittelten thermodynamischen Parameter zeigten niedrige Werte für H ads , was darauf schließen lässt, dass die Wirkung dieser Inhibitoren physikalisch-adsorptiver Natur ist.