The idea of smart inhibitors is based on the principle that an inhibitor is used where needed. This will reduce the use of inhibitors and protect materials in hostile environments. On the other hand, direct addition of the inhibitor within the coating can be harmful, resulting in the loss of inhibitors ability, deterioration in the coating or both of them. An appropriate method for solving these problems is the use of neutral host systems that act as a nanocontainer system or reservoir and are filled with arbitrary inhibitor. In this study, mesoporous silica with and without corrosion inhibitor (benzotriazole) were dispersed within an epoxy coating to protect the steel sheet. Then, the corrosion properties of these coatings with and without mesoporous silica particles were compared in a saline solution. Electrochemical studies showed that coatings containing particles could protect the surface of steel in the chloride environment. The impedance modulus (Z100 mHz) and corrosion resistance (Rcorr) regarding the coating embedded with mesoporous silica doped with inhibitor showed a value about one order of magnitude higher than that of a coating without inhibitor. This behavior could be due to the release of benzotriazole at the interface of the epoxy coating. In addition, the scratched coating with mesoporous silica doped with inhibitor exhibited less corrosion products compared to the coating without inhibitor which also confirmed the release of benzotriazole on demand of the corrosion process. تفاصيل المقالة

In this work, Zn-Co-Mo coatings were electrodeposited on mild steel substrate from a citrate solution at current densities of 5, 7.5 and 10 mA.cm-2 and pH values of 4.5, 5, and 5.5. The coated samples were studied by scanning electron microscope and potentiodynamic polarization. The corrosion behavior of the coatings was related to the molybdenum content and formation of local anodes and cathodes. According to the results, a distinct range of current and pH was recognized to provide high quality and corrosion resistant coatings. The percentage of molybdenum as an alloying element plays an important role in the improvement of the corrosion properties of the coating. The formed coating at pH of 5.5 with 13 wt. % Mo showed the lowest corrosion current density with a value of 0.5 µA.cm-2.The molybdenum coating also showed a passive-like behavior in the anodic region due to the presence of molybdenum in the coating composition. تفاصيل المقالة