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Copper corrosion inhibition in 1 M HNO 3 solution by some benzotriazole derivatives, namely N-(2-thiazolyl)-1H-benzotriazole-1-carbothioamide (TBC), N-(furan-2-ylmethyl)-1H-benzotriazole-1-carbothioamide (FBC) and N-benzyl-1H-benzotriazole-1-carbothioamide (BBC), was investigated by ac impedance, dc polarization and weight loss techniques. A significant decrease in the corrosion rate of copper was observed in presence of the investigated compounds. The corrosion rate was found to depend on the concentration and type of the inhibitor. The degree of surface coverage of the adsorbed inhibitor was determined by weight loss technique, and it was found that the results obeyed Langmuir adsorption isotherm. Tafel polarization data indicated that the three selected inhibitors were of mixed type. The reactivities of the compounds under investigation were analyzed through Fukui indices, derived from density functional theory (DFT), to explain their inhibition performance.

Titanium is the best metal for making dental implants and restorations. In the last decade, new titanium alloys have been developed in different areas of dentistry. Concurrently, treatments using fluoride supplementation, such as odontology fluoride containing gels, have also been widely used in odontology.The aim of this study is to investigate the electrochemical behaviour of a new titanium alloy containing Cu and Ag, in fluoridecontaining media, and compare it with the behavior of Ti and Ti6Al4V, which are used frequently as biomaterials. Open circuit potential, polarization resistance and electrochemical impedance spectroscopy measurements revealed that the corrosion resistance of titanium and its alloys is controlled by the fluoride ion concentration and the pH of the solution. The presence of F À ions in neutral solution does not hinder the formation of a protective layer of Ti and its alloys. Thus, the corrosion resistance of Ti is maintained in this medium. However, the corrosion of Ti and its alloys are enhanced in an acidic environment, because F À ions in the solution combines with H þ ion to form HF, even in low fluoride concentration.

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