[vc_row][vc_column][vc_tta_accordion shape=»square» c_icon=»chevron» c_position=»right» active_section=»» no_fill=»true» collapsible_all=»true»][vc_tta_section title=»Resumen» tab_id=»resumen»][vc_column_text] The project involves developing new experimental methodologies for close-range electrochemical microscopy to study the physicochemical processes involved in the initial stages of corrosion, as well as characterizing the operating mechanisms with a view to developing intelligent protection systems (responsive to physicochemical stimuli) in technologically challenging experimental systems. The primary objective is to develop techniques that allow for a deep understanding of the mechanisms involved by obtaining real-time, spatially resolved chemical data at the micrometer and submicrometer scales. The reactions responsible for the breakdown of passivating oxide layers on iron and stainless steels will be investigated, analyzing the effects of inducing ions (especially chloride), ionic conductivity, pH, oxygen concentration, and temperature. The aim is not only to induce pit nucleation but also to kinetically determine the propagation regime and the transition to the stable regime or its eventual repassivation. The corrosion mechanism of magnesium and its alloys will also be investigated, seeking to clarify the anodic and cathodic reaction sites, the sites of hydrogen generation, the possible existence of pitting corrosion microsystems and repassivation for the displacement of reaction fronts, and the possible catalytic effects of surface regions that have previously acted as anodes. To this end, a novel experimental methodology will be followed, consisting of the physical separation of electrochemical half-reactions by galvanic coupling or the use of twin substrates, imposing the polarization of one with respect to the other by means of external electrical circuits. The effect of pH, the interaction of the generated hydrogen on the measuring probes, and the corroded samples themselves will be investigated. The mechanism of action of smart anti-corrosion coatings based on polymeric coatings containing nanocontainers that store corrosion inhibitors will also be investigated. These nanocontainers are activated by releasing the inhibitor only when corrosion has begun, in order to halt the degradation processes and heal the resulting defect. The aim is to develop new microelectrochemical methodologies that will allow the establishment of the fundamental stages of the self-healing processes of galvanized steels, based on the combination of SECM electrochemical microscopy and the operation of a Kelvin probe. The main objective will be to design a physicochemical parameter related to the corrosion process that activates the controlled release of inhibitor and stops it upon restoration of the protective coating, thus preventing its release into the environment. This will be achieved by analyzing the barrier properties of defect-free polymer matrices in order to enable the early detection of corrosion processes in micro-defects and to detect species flows between the coating and the electrolytic phase.
[/vc_column_text][/vc_tta_section][vc_tta_section title=»Abstract» tab_id=»abstract»][vc_column_text] This research deals with the development of novel experimental methods for scanning electrohemical microscopies in order to be used in the investigation of the physicochemical processes involved in the early stages of corrosion. These methods provide in situ chemical information from reactive systems with micrometric and submicrometric resolution for the investigation. This knowledge will be applied to the development of smart protection methods for corrosion systems of major technological challenges. The breakdown of the passive oxide layers formed on iron and stainless steels will be characterized as a function of the nature of aggressive anions (especially chloride ions), ionic conductivity, pH, oxygen concentration and temperature. Single pits will be produced by surface modification with scanning electrochemical microscopy (SECM) in order to kinetically monitor their nucleation and propagation steps, as well as to detect the transition into the stable regime or eventual repassivation. Another objective will consist of gaining experimental insights on the corrosion mechanism of magnesium and its alloys in aqueous environments. This work will be directed to visualize the cathodic and anodic corroding sites, the locations for hydrogen evolution, and the extent of pitting corrosion. The shift of the corroding front with time will be correlated with possible repassivation processes related to the formation of MgO at deactivated anodic sites. A novel experimental methodology for the physical separation of the anodic and cathodic sites using twin magnesium samples and external polarization will be applied. pH effects and the possible chemical interaction of hydrogen gas flows on the stability of the SECM probes will also be evaluated. The functionalization of self-healing coatings for smart corrosion protection will also be considered. These are polymeric coatings containing nanoreservoirs for corrosion inhibitors. Corrosion protection is achieved by the controlled release of the inhibitors triggered by the onset of a corrosion reaction, in order to heal the corresponding defect (self-healing) on galvanized steels. Novel microelectrochemical methods will be explored to gain experimental information on the initial stages of self-healing processes using a combination of SECM and the scanning Kelvin probe (SKP). Paramount is to identify a suitable release signal when a defect site starts to corrode for the effective release of the inhibitor, as well as to stop the further release of active agents when the defect has healed. The latter will prevent further leakage of the toxic inhibitors into the environment. Barrier characteristics of intact coatings will be monitored in order to make possible the detection of concentration gradients between the coating and the electrolytic phase related to the initiation of corrosion.
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