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The morpho-structural and electrochemical properties of the oxide film formed on the implants surface play a decisive role for the bio-compatibility of titaniumbased prosthesis. The aim of the present work is to investigate and compare the corrosion behavior of titanium dioxide (TiO 2 ) coated Ti-6Al-7Nb prepared by anodic oxidation in two different electrolytes (1 M acetic acid (CH 3 COOH) and sulfuric acid (H 2 SO 4 ) solutions) and at two different oxidation potentials. The corrosion behavior of oxidized samples was investigated in Hank's simulated physiological solution, using cyclic polarization method and electrochemical impedance spectroscopy and the obtained results were compared with those recorded on bare Ti-6Al-7Nb in the same experimental conditions. The oxidation in CH 3 COOH was proven to be more beneficial for the corrosion resistance of Ti-6Al-7Nb samples than the oxidation in H 2 SO 4 of same concentration.

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The present work reports a comparative investigation of the electrochemical behaviour of some new types of silica sol-gel coatings with enhanced corrosion resistance deposited on electrolytically or thermally (hot-dip) zinc-coated steel. The coatings were rendered hydrophobic by silylation. Dichlorodimethylsilane or trimethylchlorosilane were used as silylating agents and cetyltrimethylammonium bromide or Pluronic PE 10300, as templating agents. The morpho-structural and optical properties of compact and mesoporous silica coatings were characterised with different methods. The corrosion behaviour of the coatings was evaluated by open circuit potential measurements, Tafel interpretation of the polarisation curves and electrochemical impedance spectroscopy. Both silylating agents improve significantly the corrosion resistance of both porous and compact coatings by reducing the corrosion current density with at least one order of magnitude. The possibility to use the porous structure of the coatings as corrosion inhibitor carriers was explored by loading of mesoporous silica layers with 1H-benzotriazole.