BȊRDEANU Mihaela Ionela Politehnica University of Timisoara/INCEMC Timisoara

Comparative Research Regarding Corrosion Protective Effect of Different Sandwich Type Nanostructures obtained from Porphyrins and Pseudo-binary Oxides by Changing the Deposition Order

Co-authors BȊRDEANU Aurel – Valentin, POPA Iuliana, Bogdan ŢǍRANU, PETER Francisc, CREANGA I., PALADE A., FAGADAR-COSMA Eugenia

Macrocyclic compounds like porphyrins form very stable metallic complexes which show a great potential as corrosion-inhibiting agents. Free porphyrins and metalloporphyrins can be adsorbed on metal surfaces creating protective layers against corrosion. Furthermore, porphyrins can even form coordinative bonds with the base metal during the formation of the adsorbed layer. Recent studies proved that pseudo-binary oxides of zinc containing niobium and tantalum exhibit excellent corrosion resistance in many different environments. These experimental results focused on obtaining thin films based on porphyrins/pseudo-binary oxides and pseudo-binary oxides/porphyrins. The pseudo-binary oxide nanomaterials (Zn3Ta2O8 and Zn3Nb2O8) were synthesized by solid-state method. The novel mixed substituted A3B porphyrins, each containing one pyridyl group, have been obtained by multicomponent Adler-Longo synthesis. The topography of thin films was thoroughly characterized by AFM microscopic techniques. The corrosion protection exhibited by these nanostructures after deposition on carbon steel was comparatively assessed in 0.1M H2SO4 media. Different electrochemical techniques, such as: open circuit potential measurement and potentiodynamic polarization technique with Tafel representation were used. The performed tests reveal that corrosion protection is fairly good, with the best results indicating that the electrode covered with Zn3Ta2O8/5-pyridyl-10,15,20-tris(3.4-dimethoxy-phenyl)porphyrin has offered the best result of 95.91 %. ACKNOWLEDGEMENTS This paper is supported by the Sectoral Operational Programme Human Resources Development (SOP HRD), financed from the European Social Fund and by the Romanian Government under the project number POSDRU/159/1.5/S/134378. Regarding porphyrins authors from ICT acknowledge STAR Programme, project SAFEAIR-76/2013 and Programme 2-ICT of Romanian Academy.