Corrosion of metals is a problem of great importance and world’s scale, for the institutions as well as for the user. In the fight against the natural trend of metals, such as steel, to corrode, the use of organic coatings is the most spread way to stop or decelerate the corrosion process due to the high performance and variety of products that these kind of coatings present. The field of powder coatings presents the major growing in the industry of organic paints, mainly due to their great environmental advantages (less than a 4% of volatile organic contents (VOC)) and relative low-costs application.
    Epoxy coatings are the most extended coatings amongst those used for anticorrosive protection of metallic substrates such as steel and aluminium. The nowadays most employed powder epoxy systems, use compounds derived from dicyandiamide (DICY), such as orto-tolylbiguanide (TBG), as latent curing agents. Nevertheless, the ranges of curing temperature and time that this kind of systems need in the curing process are relatively high (with temperatures above 160ºC), thus presenting two main handicaps: high application costs, and the impossibility of using these systems on thermo-sensitive substrates such as wood or plastic. Therefore, it is necessary the development of new organic systems in which curing temperature and time are reduced. The use of Lewis acids as initiators (or catalysts) of the crosslinking reaction of the epoxy resin appears as an alternative to conventional systems, although if their use in powder anticorrosive organic coatings has not yet been investigated.
    The anticorrosive characteristics of an organic primer applied on metallic substrates are usually obtained by accelerated tests such as the resistance to salt fog spray.  Moreover, due to the fact that the aqueous corrosion process is a whole of oxidation-reduction reactions, since the 90’s different electrochemical techniques are used for the evaluation, such as the electrochemical impedance spectroscopy (EIS). Nevertheless, both kinds of techniques present long evaluation periods (1 month to one year), high number of tested samples, and high evaluation costs. Thus, the industrial sector is still having the need to find new evaluation methods with lower economic costs and lower testing times.
    In the present doctoral thesis it is proposed the development of an accelerated electrochemical technique, named AC/DC/AC, and the study of its viability on different kind of organic coatings (powder and cataphoretic ones), as well as its use as a tool to develop new coatings or to optimize the application and curing processes.
    In chapter II of this doctoral thesis it is briefly presented the theoretical background and general knowledge of the topic of study found in the literature and at the same time the objectives of the study are presented. Chapter III shows the used materials, while chapter IV presents the techniques, equipment and applied tests used along the thesis. Chapter V is the main body text of the doctoral thesis where it is presented, in the form of articles, the obtained results in the course of the realization of this thesis for, in chapter VI, presenting the main conclusions obtained in function of the fixed general objectives and the results presented on chapter V.