| The losses caused by the effect of the corrosion are of the order of 2-3,5% of the GDP of the developed countries or developing only in direct costs, losses in structures or products. This figure doubles by the indirect costs, losses of productivity or demands for delays. Beside the possible losses of human lives, any intent leaded to the decrease of the corrosion in rusty metals is a commendable objective from the point of view of the protection of the environment.; Building industry employing reinforced concrete is able to project some structural elements (pillars, wrought, beam, etc.) in principle free of corrosion, assuring during many years the useful life of the work in service. However, the reinforced concrete would be' a perfect solution if the indefinite permanency of the passive state of the steel could be guaranteed. Indeed, although the steel is protected against corrosion due to basic pH which provides the cement, the severe action of saline media or the effect of CO2 can diminish this protection conditions beginning the corrosion in steel elements.; Type-p doped conducting polymers, as polypyrrole, are firm candidates to protect carbon steel providing galvanic protection by stabilising the passive layer of Fe oxides initially grown. Doping the polymeric matrix with polioxometalates, concretely phosphotungstate PW12O403-, is a very interesting hypothesis due to their oxidising effect, improving the anodic protection by the hybrid material electrosynthesised on carbon steel substrate.; First in the present work, a new method was developed by cyclic voltammetry in LiClO4 + acetonitrile medium in order to diminish the unavoidable oxidation of carbon steel when the electrosyntesis of the hybrid material polypyrrole/PW12O403- is carrying out. The beginning potential of polypyrrole polymerisation is about 0.8 V (vs. Ag/AgCl), a positive potential where oxidation of Fe substrate is high, not allowing the electrodeposition of the hybrid material. On the other hand, this pretreatment should guarantee appropriate conditions in order to obtain a coating with high adhesion on carbon steel.; Once studied the better parameters for the synthesis of the hybrid material by cyclic voltammetry, hybrid material is morphological, chemical and electrochemical characterised by the following techniques: Cyclic Voltammetry, Scanning Electron Microscopy, Energy Dispersive X Ray, X Ray Photoelectron Spectroscopy and Electrochemical Impedance Spectroscopy. The hybrid material polypyrrole/PW 12O403-. chemical structure presents Fe oxides and hydroxide within the polypyrrole polycationic matrix.; Hybrid material polypyrrol/PW12O403- diminishes the corrosion of carbon steel in NaOH and Porland cement filtering solutions. These cement solutions simulate the pore fluid conditions existing in cured mortar or concrete elements. Fe ion concentration data were determinated in corrosion tests. Voltammetric response of polymeric coatings was evaluated by cyclic voltammetry.; Finally, the protection provided by hybrid material polypyrrole/PW 12O403, in oxidised and reduced state, was evaluated on carbon steel electrodes embedded in Portland cement mortars immersed in seawater and submitted to an accelerated carbonation process for 265 days. Polymeric material covered carbon steel electrodes in reduced state suffer a Fe gravimetric loss 15 times lower than the ones of bare electrodes against chlorides attack, due to the effect of physical barrier. Hybrid material covered electrodes in oxidised state after being submitted to a carbonation process suffer a Fe gravimetric loss 2.5 times lower than the ones of bare electrodes, due to galvanic protection provided by hybrid material polypyrrole/PW 12O403- on carbon steel. |
