Pbcoatings · New strategies for corrosion inhibition coatings for lead and its characterization by in-situ spectroelectrochemical studies

Lead is susceptible to corrosion in the presence of organic acids and humidity. This accelerated degradation seriously affects cultural heritage objects, it takes place in display cases in museums and is has become a serious issue on organ pipes in churches or concert halls. The pipes of ancient organs are made from lead and the organic acids are emitted from the wooden parts in the organ (the windtrunks and the windchests).The aim of this proposal is the development of environmentally safe corrosion protective coatings for lead heritage objects which are stable, reversible, easy to apply and to remove, and aesthetically justified. Monocarboxylate coatings have shown very promising results, but the effectiveness is highly dependent on carbon chain length, and carboxylate concentration in the solution: higher chain length and concentration, the better the corrosion inhibition effect. Unfortunately, the solubility of monocarboxylates drastically decreases with chain length. The project aims to tackle the key issue of the low solubility of monocarboxylates. As opposed to the strategy of using cyclic voltammetry for coating formation (only applicable to small objects), our idea is to test new coatings easily applicable on site to heritage objects of all sizes, for instance organ pipes. Ideas to be tested include solubilization of monocarboxylates in ethanol and propanol solutions; dispersion of monocarboxylic acids in microemulsions together with surfactant and co-surfactant; embedding this microemulsions in polymeric networks (gels); test of hydroxide nanoparticles as alternative coatings; and the combination of hydroxide nanoparticles and microemulsions as combined optimum coatings. The coating formation and its corrosion resistance will be fully characterized by several surface analyses techniques in the host lab, including electrochemistry, complemented by synchrotron spectroelectrochemical studies.