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Tesi amb menció de Doctorat Internacional, Tesi en modalitat de cotutela: Universitat Politècnica de Catalunya i Universidade Federal do Rio Grande do Sul, Tesi amb continguts retallats per motius de confidencialitat, (English) During the past century the way humans relate to the environment has undergone important changes, and currently it is a global consensus that our well-being should not be achieved at the expense of enlarging our footprint in the planet. The metal finishing industry is notan exception to this trend. Thus, there is the urgency to replace surface treatments, such as chromate conversion coatings (CCC) or phosphating, to more sustainable technologies; as well as the need ofreducing the use of petroleum derivativas in the formulation of raw materiaIs for coatings and adhesivas indus tries. A promising substitute for CCC are the zirconium oxide based conversion coatings (ZrCC), which have been under continuous devalopment for nearly 30 years, resulting in a powerful tool for metal passivation with lower environmental impact than CCC. In this work, the electro-assisted deposition (EAD) technique was used to improve the ZrCC's covering properties on aluminum substrates, bystimulating electrochemically the coating formation, in a process that would typically be carried out relying exclusively in surface spontaneous reactions. On the other hand, this necessityof covering such passivation layer with organic coatings, that actas long-term barrier protection against corrosion, is another usual industrial process. Nevertheless, the constant generation of plastic waste has led to the need of searching for more sustainable, bio-degradable and/or recyclable polym ers to replace the essentially synthetic ones. In this way, the present thes is reports the production, characterization and application of thermoset epoxy polymers, containing a bio-based epoxy prepolymer deri\ed from limonene (PLCO) and industrial hardeners. For that, these results were compared to those of the traditional epoxy prepolymer diglycidyl ether of bisphenol A(DGEBA). The results indicate that PLCO has sorne enhanced properties in comparison to the synthetic epoxy polymer dueto its chemical structure (, (Español) A lo largo del último siglo la manera como la humanidad se relaciona con el medio ambiente ha sufrido cambios importantes y, actualmente, es un consenso global que nuestro bienestar no debe ser obtenido al coste de aumentar la huella negativa que dejamos en el planeta. La industria de acabado de metales no es una excepción a esta tendencia. Por ello, urge la sustitución de tratamientos de superficie, como los recubrimientos de conversión de cromados (CCC) o fosfatados, hacía tecnologías más sostenibles; así como urge reducir el uso de derivados del petróleo en la formulación de materia-primera para la industria de pinturas y adhesivos. Un sustituto prometedor para los CCC son los recubrimientos de conversión a base de óxido de zirconio (ZrCC), cuyos procesos se han ido desarrollando de forma continuada, alrededor de unos 30 años, como una potente alternativa de menor impacto ambiental para la pasivación de metales. En este trabajo, la técnica de deposición electro-asistida (EAD) fue empleada para mejorar las propiedades del recubrimiento de ZrCC en substratos de aluminio, estimulando su generación electroquímicamente, en un proceso que típicamente sería realizado dependiendo exclusivamente de reacciones superficiales espontáneas. Por otro lado, la necesidad de recubrir esta capa pasivante con sistemas orgánicos que actúan de barrera eficaz a largo plazo contra la corrosión, es otro proceso industrial habitual. Sin embargo, la constante generación de residuos plásticos ha llevado también a la necesidad de buscar polímeros sostenibles, biodegradables y/o reciclables en sustitución a los esencialmente sintéticos. En este sentido, la presente tesis reporta la producción, caracterización y aplicación de polímeros epóxidos termoestables, conteniendo un prepolímero epóxido de origen natural derivado del limoneno (PLCO) y endurecedores comerciales. Para ello se ha comparado los resultados obtenidos con el prepolímero epóxido tradicional, conocido como "diglycidyl, Postprint (published version)

In this work, the use of ZrO2 nanocoating in aluminum substrates, generated by controlled electrochemical chronoamperometry in hexafluorozirconic acid solutions (H2ZrF6·5H2O), resulted in a lower porous films than that obtained by chemical conversion coating. After the application of an epoxy coating, long-term cyclic immersion corrosion tests and scratch tests proved the superior protection of the dual system and the coating lifespan, thanks to the enhanced adhesion of ZrO2 intermediate layer and the organic coating. As zirconium-based electrolytes are considered more friendly bath if compared to that of other conversion coating processes, like chromating, phosphating or anodizing processes, the study opens new insights to the protection of structural metals in sectors such as automotive, naval and aerospace industries. The main advantages are the employment of lightweight intermediate pre-treatment (nanoscale), compared to conventional ones (microscale), and reduction of waste slurry (electrolyte bath free of additives)., Peer Reviewed, Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura, Postprint (published version)

Herein, the influence of the substrate in the formation of zirconium oxide monolayer, from an aqueous hexafluorozirconic acid solution, by chemical conversion and by electro-assisted deposition, has been approached. The nanoscale dimensions of the ZrO2 film is affected by the substrate nature and roughness. This study evidenced that the mechanism of Zr-EAD is dependent on the potential applied and on the substrate composition, whereas conversion coating is uniquely dependent on the adsorption reaction time. The zirconium oxide based nanofilms were more homogenous in AA2024 substrates if compared to pure Al grade (AA1100). It was justified by the high content of Cu alloying element present in the grain boundaries of the latter. Such intermetallic active sites favor the obtaining of ZrO2 films, as demonstrated by XPS and AFM results. From a mechanistic point of view, the electrochemical reactions take place simultaneously with the conventional chemical conversion process driven by ions diffusion. Such findings will bring new perspectives for the generation of controlled oxide coatings in modified electrodes used, as for example, in the construction of battery cells; in automotive and in aerospace industries, to replace micrometric layers of zinc phosphate by light-weight zirconium oxide nanometric ones. This study is particularly addressed for the reduction of industrial waste by applying green bath solutions without the need of auxiliary compounds and using lightweight ceramic materials, Peer Reviewed, Postprint (published version)

The current standards for evaluating corrosion during salt spray tests rely on the visual analysis of the specimens, and this may be a limitation when higher resolution quantitative outputs are desired. In this work, computational image analysis was used to measure the area affected by corrosion during salt spray tests with aluminum alloy, copper, carbon steel and galvanized steel plates. The software ImageJ was used to select and measure the corroded areas differentiating the corrosion products from the metals uncorroded surfaces according to their different colors. With ten measurements for each selected exposure time, a 95 % confidence interval was calculated for each material and time of exposure, giving an indication of the precision of the estimated corroded area. These data were compared with a visual inspection carried out by an experienced technician. The results indicate that computational image analysis may be a powerful tool to obtain higher resolution in the results interpretation in comparison with the standard visual analysis, Postprint (published version)

n the present work, the corrosion affectation of an artistic and historical building, declared UNESCO World Heritage Site and constructed with AISI 1012 UPN profiles, was investigated. Micro-Raman and microscopy approaches highlight the complementarity and versatility of these techniques to evaluate the macroscopic and microscopic effect of the corrosion products in such reinforcing structures. The rust phases have been assessed by separating the oxide layers according to their environment placement and contaminants contact. The composition of iron oxides and oxyhydroxides in the metal surface depend not only on the oxygen concentration, but also on other elements that penetrated into the porous layers, as for example, chorine ions, sulfur ions, and microorganisms. Taking into account the scarce information on the indoor corrosion of AISI 1012 steel, results obtained in this work are expected to help for understanding the long-term impact of such oxides and oxyhydroxides on the material durability, as well as on its structural maintenances., Peer Reviewed, Postprint (author's final draft)

In order to overcome the difficulties associated to the solubility and mechanical integrity of polyaniline (PAni) films, in this work we develop a binder by mixing PAni in the oxidized and undoped state (emeraldine base form) with 4-chloro-3-methylphenol, a plasticizer, and solvent. This binder has been used as a coating alone or combined with a conventional nitrocellulose paint to formulate the called Smart Paint. The characterization of binder films, which are cohesive and self-standing, shows the preservation of PAni properties, indicating that they satisfy the typical characteristics of anticorrosive coatings. Electrochemical assays have been carried out in H2SO4 solution using AISI 1006 steel plates coated with the binder and the Smart Paint. Results indicate that the binder and the Smart Paint promote the passivation of the metal substrate, reflecting their protecting abilities against corrosion. (C) 2014 Elsevier B.V. All rights reserved., Peer Reviewed, Postprint (author’s final draft)

The polaronic and bipolaronic forms of polyaniline emeraldine salt (PAni-ES) in the amorphous solid state have been simulated using classical molecular dynamics (MD) and hybrid quantum mechanical/molecular mechanical-molecular dynamics (QM/MM-MD) approaches. It should be remarked that the electronic state of PAni-ES has been theoretically investigated in the gas phase, solution phase, and crystalline state, but this is the first study in the amorphous solid state, which is the most typical for this conducting polymer. MD simulations were carried out using force-field parametrizations explicitly developed for polaronic and bipolaronic models. QM/MM-MD calculations were performed using a quantum mechanical zone defined by four repeat units. In addition of the structural and electronic characteristics of the two forms of PAni-ES, MD and QM/MM-MD simulations indicate that the bipolaronic is the most stable state of amorphous PAni-ES. Complementary studies have been carried out using different experimental techniques. Although the morphology and topography of doped and undoped PAni are very similar, comparison of their UV–vis spectra supports the preference toward the bipolaronic form of PAni-ES., Postprint (published version)